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Abstract

Long term storage of potato tubers allows year round availability of the crop but is limited by sprouting. Continuous exposure to ethylene during storage prolongs storage life of potatoes by suppressing sprouting, yet there is a lack of information on whether continuous ethylene treatment is required throughout storage. Potato cvs. Saturna and Russet Burbank were stored at 6 °C under four ethylene treatments (viz. continuous ethylene (10 μL L−1), continuous air, transfer from air to ethylene after first indication of sprouting and vice versa) for thirty weeks in 2008–2009 (Year 1). In Year 2 (2009–2010), tubers were stored under the same treatments and duration as in Year 1, with the addition of 1-MCP (1 μL L−1) applied for 24 h at harvest or at first indication of peeping. Samples were taken after harvest and at specific intervals during storage. Respiration rate measured at each sampling point. Fructose, glucose and sucrose were determined in potato flesh of all cultivars as ethylene has been reported to have some negative effects on non-structural carbohydrate metabolism. Sprouting was also measured at the end of the experiment. Ethylene applied after first indication of sprouting was as effective at suppressing sprouting for cv. Russet Burbank as when applied continuously; the implications of which are that the cost of ethylene application in store rooms could be reduced by manipulating timing of continuous application. In addition, application of ethylene after the first indication of sprouting had little to no effect on tuber sugar accumulation compared with continuous ethylene application from harvest.

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... Over the last 10 years, CIPC has been under regulatory scrutiny, and in June 2019 the European Union legislated for its withdrawal, such that the 2019− 2020 season was the last storage season where the application of CIPC will be permissible. Among the alternative sprout suppressant strategies available, continuous ethylene supplementation has received much attention Foukaraki et al., 2014, Foukaraki et al., 2016a, 2016bPrange et al., 1998Prange et al., , 2005Rylski et al., 1974;Suttle, 1998), and in 2003 the Chemical Residue Directorate (UK) approved its use as a sprout suppressant (Alamar et al., 2017a). The inhibition of potato sprout growth by ethylene is well-known; and similar effects of using ethylene to extend ecodormancy have been described in other low-ethylene-producing storage organs, like onion bulbs (Cools et al., 2011;Ohanenye et al., 2019) and sweetpotato roots (Amoah et al., 2016). ...
... The inhibition of potato sprout growth by ethylene is well-known; and similar effects of using ethylene to extend ecodormancy have been described in other low-ethylene-producing storage organs, like onion bulbs (Cools et al., 2011;Ohanenye et al., 2019) and sweetpotato roots (Amoah et al., 2016). Morover, continuous ethylene supplementation induced an accumulation of abscisic acid (ABA) in potato tubers (Foukaraki et al., 2016a), and has been associated with tuber dormancy (Alamar et al., 2017a;Sonnewald and Sonnewald, 2014). ...
... Despite the positive effect on extending dormancy, ethylene is also known to elicit the accumulation of reducing sugars Foukaraki et al., 2016aFoukaraki et al., , 2016b, similarly to storage temperature below 7 • C (Bhaskar et al., 2010;Liu et al., 2013). Thus, ethylene-induced and low temperature induced sweetening can result in darker fry colour and associated acrylamide formation during high temperature (>120 • C) cooking. ...
Article
Continuous ethylene supplementation suppresses postharvest sprouting, but it can increase reducing sugars, limiting its use as an alternative to chlorpropham for processing potatoes. To elucidate the mechanisms involved, tubers were treated after curing with or without the ethylene binding inhibitor 1-methylcyclopropene (1-MCP at 1 μL L⁻¹ for 24 h), and then stored in air or air supplemented with continuous ethylene (10 μL L⁻¹). Across three consecutive seasons, changes in tuber physiology were assessed alongside transcriptomic and metabolomic analysis. Exogenous ethylene alone consistently induced a respiratory rise and the accumulation of undesirable reducing sugars. The transient respiratory peak was preceded by the strong upregulation of two genes encoding 1-aminocyclopropane-1-carboxylate oxidase (ACO), typical of wound and stress induced ethylene production. Profiles of parenchymatic tissue highlighted that ethylene triggered abscisic acid (ABA) catabolism, evidenced by a steep fall in ABA levels and a transient rise in the catabolite phaseic acid, accompanied by upregulation of transcripts encoding an ABA 8ˊ-hydroxylase. Moreover, analysis of non-structural carbohydrate-related genes revealed that ethylene strongly downregulated the expression of the Kunitz-type invertase inhibitor, already known to be involved in cold-induced sweetening. All these ethylene-induced effects were negated by 1-MCP with one notable exception: 1-MCP enhanced the sprout suppressing effect of ethylene whilst preventing ethylene-induced sweetening. This study supports the conclusions that: i) tubers adapt to ethylene by regulating conserved pathways (e.g. ABA catabolism); ii) ethylene-induced sweetening acts independently from sprout suppression, and is similar to cold-induced sugar accumulation.
... Sound sweet cherry fruit on the stem (as 200 g polypropylene punnets) were placed into 12 Lock & Lock 12 L (315 × 230 × 230 mm) polypropylene boxes (L & Nordic OÜ, Estonia) in a cool room at 1 ± 0.5°C and 90 ± 5% relative humidity (RH) for 30 days. The following treatments were applied: i) continuous air (control); ii) continuous ethylene (10 μL L −1 ) (Amoah et al., 2017); iii) single 1-methylcyclopropene (1-MCP) application (1 μL L −1 for 24 h) (Foukaraki et al., 2016) followed by air storage. The gas flow was controlled by mass flow controllers (Alicat Scientific, Tucson, USA), making use of a continuous flow of 350 mL min −1 . ...
... Sugars were analysed as described by Foukaraki et al. (2016). Fructose, glucose, and sucrose concentrations were determined using an Agilent ; and 1-MCP [1 μL L −1 for 24 h at room temperature followed by air]) on disorders (%) in sweet cherry fruit 'Burlat' during 30 days storage at 1 ± 0.5°C and 90 ± 5% RH. ...
Article
Sweet cherries (Prunus avium L.) are highly appreciated because of their bioactive compound content and attractive organoleptic characteristics; however, they are very perishable. The aim of this work was to investigate whether ethylene and its antagonist 1-MCP affect the postharvest quality of an early-season sweet cherry cultivar, allowing storage life extension. ‘Burlat’ sweet cherries were subjected to three treatments at 1 °C for one month: i) control (air); ii) continuous ethylene supplementation (10 μL L−1); and iii) 1-Methylcyclopropene (1-MCP; 1 μL L−1 for 24 h) followed by air. The incidence of postharvest physiological disorders, the evolution of physical and functional quality traits, and fruit senescence were evaluated at 0, 7, 14, 21, and 30 days. Results showed that sweet cherries were sensitive to both ethylene and 1-MCP treatments. Continuous ethylene exposure reduced abscisic acid accumulation, resulting in higher weight and firmness loss. Moreover, ethylene application decreased titratable acidity through storage, indicating an effect on sweet cherry senescence. No significant differences among treatments were found for soluble solids content and individual sugars. Conversely, 1-MCP preserved firmness during the first 7 days of storage, while reduced the incidence of physiological disorders at the end of storage life. Furthermore, 1-MCP delayed the accumulation of cyanidin-3-O-glucoside for 7 days compared to control and ethylene treated cherries. Taken together these results highlight the potential use of 1-MCP to extend the postharevst life of early season sweet cherry fruit.
... Continuous presence of ethylene may be an alternative to control potato and sweet potato sprouting. However, so far, there is no conclusive explanation regarding the mechanism by which continuous exogenous ethylene slows sprout growth (Cheema et al., 2013;Amoah et al., 2016;Foukaraki et al., 2016aFoukaraki et al., , 2016b. ...
... The effects of 1-MCP on fruits and vegetables include prolonging shelf life, preventing physiological disorders, such as the development of superficial scalding in 'd'Anjou' pears (Yuab et al., 2017), and control of senescence by inhibiting the production of ethylene in durian fruits -Durio zibethinus (Amornputtia et al., 2016). Furthermore, the application of 1-MCP can also control sprouting in potato and sweet potato (Cheema et al., 2013;Foukaraki et al., 2016b). ...
Article
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Sprouting and mass loss in sweet potato tuberous roots stored at room temperature compromise the quality and commercialization; nevertheless, sprouting control methods are very limited. The objective was to evaluate the control of sprouting and metabolic changes in tuberous roots of sweet potato cv. BRS Rubissol treated with ethylene (10 μL L-1), amino-oxyacetic acid-AOA (1 mg L-1) and 1-methylcyclopropene-1-MCP (1 mg L-1) during storage for five weeks at 25 °C and 90% relative humidity. The following variables were evaluated: mass loss, number and length of sprouts, activity of peroxidase and polyphenoloxidase enzymes, total soluble sugars, starch, anthocyanins, flavonols, malonaldehyde content and total proteins. During storage the mass loss, number and length of sprouts were lower in roots treated with AOA and 1-MCP. The activity of peroxidase and polyphenoloxidase enzymes was higher in roots treated with ethylene. Total soluble sugars increased and the starch contents decreased in all treatments. Levels of anthocyanins and total proteins reduced, while flavonoids and malondialdehyde increased during storage. Sprouting was controlled in roots treated with AOA and 1-MCP, extending shelf life and improving marketing potential. Brotação e metabolismo de raízes de batata-doce cv. BRS Rubissol durante armazenamento RESUMO: A brotação e perda de massa em raízes tuberosas de batata-doce armazenadas à temperatura ambiente comprometem a qualidade e comercialização, ainda assim, métodos de controle de brotação são muito limitados. O objetivo foi avaliar o controle da brotação e alterações metabólicas em raízes tuberosas de batata-doce cv. BRS Rubissol tratadas com etileno (10 μL L-1), ácido amino-oxiacético-AOA (1 mg L-1) e 1-metilciclopropeno-1-MCP (1 mg L-1) durante o armazenamento por cinco semanas a 25 °C e 90% de umidade relativa. Foram avaliadas as variáveis: perda de massa, número e comprimento de brotações, atividade das enzimas peroxidase e polifenoloxidase, açúcares solúveis totais, amido, antocianinas, flavonois, teor de malonaldeído e proteínas totais. Durante o armazenamento a perda de massa, número e comprimento de brotações foram menores em raízes tratadas com AOA e 1-MCP. A atividade das enzimas peroxidase e polifenoloxidase foi maior em raízes tratadas com etileno. Os açúcares solúveis totais aumentaram e os teores de amido reduziram em todos os tratamentos. Os níveis de antocianinas e proteínas totais reduziram, enquanto os de flavonois e malondialdeído aumentaram durante o armazenamento. A brotação foi controlada em raízes tratadas com AOA e 1-MCP, prolongando a vida útil e melhorando o potencial de comercialização. Palavras-chave: carboidratos; etileno; Ipomoea batatas; decadência da raiz; controle da brotação
... Endogenous ethylene is required at the earliest stage of dormancy initiation (endodormancy induction) (Suttle, 1998); however, its role during dormancy and sprouting is still unclear. Exogenous ethylene (10 µL L −1 ) has been reported to break endodormancy following short-term treatments (Foukaraki et al., 2014), but also to inhibit sprout growth and promote ecodormancy when supplied continuously -either starting immediately after harvest or at first indication of sprouting (Foukaraki et al., 2016a). However, work carried out on cv. ...
... As previously mentioned, continuous ethylene supplementation is currently used as a sprout suppressant during storage; yet, it can induce sucrose hydrolysis (ethyleneinduced sweetening). A recent study has shown that this type of sweetening can be prevented with a single application (24 h) of 1-methylcyclopropene (1-MCP) prior to early and late ethylene supplementation (Foukaraki et al., 2016a). The impact of CO 2 , another storage extension gas, on frying quality is less clear. ...
Article
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Potatoes represent an important staple food crop across the planet. Yet, to maintain tuber quality and extend availability, there is a necessity to store tubers for long periods often using industrial-scale facilities. In this context, preserving potato quality is pivotal for the seed, fresh and processing sectors. The industry has always innovated and invested in improved post-harvest storage. However, the pace of technological change has and will continue to increase. For instance, more stringent legislation and changing consumer attitudes have driven renewed interest in creating alternative or complementary post-harvest treatments to traditional chemically reliant sprout suppression and disease control. Herein, the current knowledge on biochemical factors governing dormancy, the use of chlorpropham (CIPC) as well as existing and chemical alternatives, and the effects of pre- and post-harvest factors to assure potato tuber quality is reviewed. Additionally, the role of genomics as a future approach to potato quality improvement is discussed. Critically, and through a more industry targeted research, a better mechanistic understanding of how the pre-harvest environment influences tuber quality and the factors which govern dormancy transition should lead to a paradigm shift in how sustainable storage can be achieved.
... Globally, potatoes are an essential food crop (Gómez-Castillo et al. 2013) and their long-term storage allows year-round availability (Foukaraki et al. 2016). Proper management of potato stores is critical to maintain crop quality throughout the storage period (AHDB-Potatoes 2011). ...
... Proper management of potato stores is critical to maintain crop quality throughout the storage period (AHDB-Potatoes 2011). The long-term storage of potato tubers can be achieved by controlling temperature and humidity in stores (Cools et al. 2014;Foukaraki et al. 2016) and by the application of sprout suppressants (Cools et al. 2014). The sprout suppressant chlorpropham (CIPC, carbamate) is most commonly used (Blenkinsop et al. 2002) and is typically applied in the UK as a hot fog (spherical particles of about 5-μm diameter) on stored potatoes (Gouseti et al. 2015). ...
Article
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The loss of the sprout suppressant, chlorpropham (CIPC), to the fabric of potato stores is currently of concern due to the risk of potential cross contamination of other crops subsequently housed in these stores. HPLC UV/VIS and GCMS methods were successfully employed to detect CIPC in the concrete flooring of research and commercial potato stores with histories of between 1 and 26 years of use. The concentrations in identical research stores, with different numbers of applications, were in the range 0.58–5.7 and 3.4–112 μg g⁻¹, suggesting the magnitude of contamination was influenced by the number of applications. Commercial store A, with a history of 18 seasons of applications (estimate of total CIPC applied 2040 kg), had concentrations varying between 6 and 48 μg g⁻¹ in the top three centimetres, with more than 92% within the top centimetre. In contrast, commercial store B, with a history of less than five seasons of applications (estimate of total CIPC applied 319 kg), had concentrations varying between 0.58 and 304 μg g⁻¹ in the top four centimetres, with less than 47% within the top centimetre. The difference in depth distributions between A and B may be due to the structural integrity of the concrete, which was much poorer in B. CIPC was persistent in all stores irrespective of the total quantities of CIPC applied and date of the final application.
... Nevertheless, the application of ethylene at 10% eye movement may be riskier in a commercial setting. In this situation regular well managed tuber monitoring would be essential, but will have the advantage of saving costs on ethylene application and potentially extend storage when compared with continuous ethylene application (Foukaraki et al., 2016a). Foukaraki et al. (2016a) using cvs. ...
... In this situation regular well managed tuber monitoring would be essential, but will have the advantage of saving costs on ethylene application and potentially extend storage when compared with continuous ethylene application (Foukaraki et al., 2016a). Foukaraki et al. (2016a) using cvs. Russet Burbank and Saturna noticed that if ethylene application is delayed after 10% eye movement there will be still sprout inhibition without a dramatic rise in sugar content. ...
Article
This review details the current knowledge of potato tuber dormancy, dormancy break and sprouting, with specific focus on the current position facing GB potato growers. Concerns over the persistence and risks associated with residues following pre-harvest treatment with Maleic hydrazide (MH), and post-harvest application of Chloropropham (CIPC) has driven the search for alternative strategies for sprout inhibition. A non-renewal notice preventing re-registration of CIPC in the EU as a sprout suppressant for potato and as a herbicide for horticultural crops came into force on the 8th July 2019. This enforcement stipulated a maximum use up grace-period up to the 8th October 2020, beyond which no CIPC application will be permitted in the UK or elsewhere in the EU. The scope of the review covers the interaction of plant hormones in orchestrating dormancy break and sprout vigour alongside downstream signalling events, changes in transcriptional and protein activity associated with changes in meristem activity within buds linked to the cell. The influence of storage conditions and tuber respiration on dormancy break and tuber quality is covered. The review includes a brief description of conventional and non-conventional alternative products with activity to retard sprout growth and/or extend dormancy. The final section highlights current research gaps on tuber dormancy.
... To alleviate the problem, research has been focused on decreasing the content of total reducing sugars in potato tubers as the most effective method to decrease acrylamide content in fried potatoes (Muttucumaru et al. 2008). CIS has been widely studied in potato tubers (Foukaraki et al. 2016;Mehdi et al. 2013;Wiberley-Bradford et al. 2016), and it has been reported that CIS occurs due to an imbalance between the metabolism of starch and sugar (Ezekiel et al. 2010). The degradation pathway from starch to hexoses is complex, and several enzymes are involved in this progress, including sucrose synthase (SuSy), sucrose phosphate synthase (SPS), ADP-glucose pyrophosphorylase small subunit (AGPase), granulebound starch synthase (GBSS) (Wiberley-Bradford et al. 2014). ...
Article
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The storage of potato tuber (Solanum tuberosum L.) at low temperatures minimizes sprouting and disease but can cause cold-induced sweetening (CIS), which leads to the production of the cancerogenic substance acrylamide during the frying processing. The aim of this research was to investigate the effects of UV-C treatment on CIS in cold stored potato tuber. ‘Atlantic’ potatoes were treated with UV-C for an hour and then stored at 4 °C up to 28 days. The UV-C treatment significantly prevented the increase of malondialdehyde content (an indicator of the prevention of oxidative injury) in potato cells during storage. The accumulation of reducing sugars, particularly fructose and glucose, was significantly reduced by UV-C treatment possibly due to the regulation of the gene cascade, sucrose phosphate synthase, invertase inhibitor 1/3, and invertase 1 in potato tuber, which were observed to be differently expressed between treated and untreated potatoes during low temperature storage. In summary, UV-C treatment prevented the existence of oxidative injury in potato cells, thus, lowered the amount of reducing sugar accumulation during low temperature storage of potato tubers.
... Besides the familiar role ethylene plays in promoting the ripening of climacteric fresh produce, ethylene supplementation has been shown to inhibit sprouting in many bulbs, tubers and roots (Amoah, Landahl, & Terry, 2016;Cools, Chope, Hammond, Thompson, & Terry, 2011;Foukaraki, Cools, Chope, & Terry, 2016). Exogenous ethylene, however, elicits variable, and sometimes contrasting, responses in plant tissues depending on a matrix of crop factors and the application regime employed. ...
Article
The design and construction of a laboratory-scale apparatus for generating variable concentrations and flow rates of exogenous ethylene for fresh produce supplementation during storage trials is described. A stock of compressed ethylene in nitrogen (5000 μl l⁻¹) was blended into a continuous flow stream of air and diluted to the desired concentrations. The ethylene and air flow rates were controlled with calibrated mass flow control valves. An empirical mathematical model was derived for real-time variation of both the mixed concentration and flow rate during continuous flow. Validation of the model was performed using fresh sweet potato as a case study where a steady continuous ethylene concentration of 10 μl l⁻¹ was achieved for three months. The bespoke system offers easy-to-manage ethylene supplementation for research.
... Cheng et al. (2015) Yali pear 1µl/L reduces oxidative damage, inhibit oxidation of phenols and development of core browning. Dong et al. (2015) Potato 1µl/L prolong storage life and suppress sprouting, prevent ethylene induced sugar accumulation Foukaraki et al. (2016) Broccoli 2µl/L, 20 o C delay senescence of florets maintain higher chlorophyll content and sugar content Xu et al. (2016) Apricot cv Xiaobai 1µl/L, 20±1 o C delay ripening, softening and decay development, maintain quality and extend shelf life Wu et al. (2015) Effect of 1-MCP on ripening and senescence 1-MCP shows a positive effect on delaying of ripening and senescence. It binds to copper metal present in the ethylene receptors and blocks the normal as well as system II of ethylene production (Paul and Pandey, 2010). ...
Article
The use of 1-methyl cyclopropene (1-MCP) is a commercial strategy commonly used for handling of several fruits and vegetables, as pre and postharvest application extends their shelf life. Ethylene promotes rapid ripening, softening and early senescence of fruits and vegetables. It binds with receptors present in fruit tissues and elicits functions.1-MCP binds with ethylene receptors and blocks ethylene mediated responses in fruits and vegetables. Its efficacy depends on various factors such as cultivar, harvesting and maturity stage, concentration, exposure duration, time, etc. It delays many physiological disorders and chilling injury development in several commodities. This review explores the role of 1-MCP for quality preservation of fruits and vegetables.
... The sugar metabolism process has been studied for a long time, but the regulation of genes related to sugar metabolism under different storage conditions remains poorly understood. Several treatments were stated to be effective on controlling CIS in potatoes according to previous studies, such as low oxygen level storage [14], heat treatment [15], UV-C treatment [16] and 1-MCP treatment [17]. Gibberellin is a plant hormone which has been reported to play an important role in sucrose synthesis and abiotic stress responses [18]. ...
Article
Full-text available
Potato tubers (Solanum tuberosum L.) are usually stored at low temperature, which can suppress sprouting and control the occurrence of diseases. However, low temperatures lead potatoes to easily suffer from cold-induced sweetening (CIS), which has a negative effect on food processing. The aim of this research was to investigate potential treatments on controlling CIS in potatoes during postharvest storage. “Atlantic” potatoes were treated with gibberellin and (S)-carvone, respectively, and stored at 4 °C for 90 days. The results showed that gibberellin can significantly accelerate sprouting and sugar accumulation by regulating expressions of ADP-glucose pyrophosphorylase (AGPase), granule-bound starch synthase (GBSS), β-amylase (BAM1/2), UDP-glucose pyrophosphorylase (UGPase) and invertase inhibitor (INH1/2) genes. The opposite effects were found in the (S)-carvone treatment group, where CIS was inhibited by modulation of the expressions of GBSS and INH1/2 genes. In summary, gibberellin treatment can promote sugar accumulation while (S)-carvone treatment has some effects on alleviating sugar accumulation. Thus, (S)-carvone can be considered as a potential inhibitor of some of the sugars which are vital in controlling CIS in potatoes. However, the chemical concentration, treatment time, and also the treatment method needs to be optimized before industrial application.
... Higher level of reducing sugar content could also cause lower processing quality of potato tubers (Sowokinos, 2001). Therefore, alternative methods to suppress sprouting of tubers, including low temperature storage, ethylene and 1-MCP (1-methylcyclopropene) fumigation, ultraviolet-C irradiation and plant essential oils fumigation have been developed (Sowokinos, 2001;Gómez-Castillo, Cruz, Lguaz, Arroqui, & Vírsed, 2013;Cools, Alamar, & Terry, 2014;Foukaraki, Cools, Chope, & Terry, 2016). ...
Article
Effect of citronella essential oil (CEO) fumigation on sprout suppression and quality of potato tubers during storage was investigated. Potato tubers were treated under conditions of single-phase (30 μL L⁻¹, 0–10 d) and dual-phase (30 μL L⁻¹, 0–10 d; 30 μL L⁻¹, 35–90 d) fumigation. Changes in germination rate, weight loss, starch, reducing sugar, gibberellins (GA3), and α-solanine were measured. The results showed that CEO fumigation could control sprouting and improve the quality of potato tubers during storage compared to the non-treated tubers. CEO treatments inhibited the degradation of starch and the increase of reducing sugar content. The production of gibberellins (GA3) was suppressed, and the levels of α-solanine in the skin and flesh of potato tubers were decreased by CEO fumigation. Dual-phase CEO fumigation had a better effect on sprout suppression than single-phase fumigation, and possesses potential for postharvest application.
... Exogenous ethylene treatment of potato tubers can promote sugar (Suc, Glc and Fru) accumulation [38], which is similar to the effect of cold incubation [39]. Additionally, gene mutations related to ethylene signalling pathways caused changes in the sugar response [40]. ...
Article
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Background The rhizome of Polygonatum kingianum Coll. et Hemsl ( P. kingianum ) is a crucial traditional Chinese medicine, but severe bud dormancy occurs during early rhizome development. Low temperature is a positive factor affecting dormancy release, whereas the variation in carbohydrates during dormancy release has not been investigated systematically. Therefore, the sugar content, related metabolic pathways and gene co-expression were analysed to elucidate the regulatory mechanism of carbohydrates during dormancy release in the P. kingianum rhizome bud. Results During dormancy transition, starch and sucrose (Suc) exhibited opposing trends in the P. kingianum rhizome bud, representing a critical indicator of dormancy release. Galactose (Gal) and raffinose (Raf) were increased in content and synthesis. Glucose (Glc), cellulose (Cel), mannose (Man), arabinose (Ara), rhamnose (Rha) and stachyose (Sta) showed various changes, indicating their different roles in breaking rhizome bud dormancy in P. kingianum . At the beginning of dormancy release, Glc metabolism may be dominated by anaerobic oxidation (glycolysis followed by ethanol fermentation). After entering the S3 stage, the tricarboxylic acid cycle (TCA) and pentose phosphate pathway (PPP) were may be more active possibly. In the gene co-expression network comprising carbohydrates and hormones, HYD1 was identified as a hub gene, and numerous interactions centred on STS/SUS were also observed, suggesting the essential role of brassinosteroids (BRs), Raf and Suc in the regulatory network. Conclusion We revealed cold-responsive genes related to carbohydrate metabolism, suggesting regulatory mechanisms of sugar during dormancy release in the P. kingianum rhizome bud. Additionally, gene co-expression analysis revealed possible interactions between sugar and hormone signalling, providing new insight into the dormancy release mechanism in P. kingianum rhizome buds.
... The effect of ethylene on accelerating ripening and senescence of fruits and vegetables has been established. Recently, additional functions of ethylene have been elucidated such as enhancing the resistance of sweet potato against black rot [30] , mediating dormancy and sprout growth [31,32] , and reducing chilling injury of the pear fruit [33] . On the other hand, studies also show that exogenous ethylene escalated the root decay of the sweet potato [34,35] . ...
... Recent studies reported that the reduction in RS levels occurs due to the sprouting occurrence (Finger et al. 2018;Foukaraki et al. 2016;Jia et al. 2019). During sprouting emergence, cellular metabolism cues synthesis of reserve compounds towards degradation processes. ...
Article
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ABSTRACT High incidence of sprouts and loss of quality of sweet potato is one of the negative aspects that compromises the commercialization most, and the methods of sprout control are still very limited. The appearance of sprouts promotes the wilting of sweet potato roots, reducing their commercialization period. The main objectives of this study were to evaluate sprout control and physiological and biochemical changes, in addition to the impact on the quality of postharvest chips in sweet potato roots cultivar BRS Cuia treated with methyl jasmonate (MeJa) and nonanoic acid (NA). Roots were fogged with 10 μmol·L–1 MeJa or 5 μmol·L–1 NA applied at first sprout initiation and control. Physiological and biochemical alterations such as fresh weight loss assessment, sprouting incidence and sprout length, total soluble sugars, reducing sugars, nonreducing sugars, enzymatic peroxidase and polyphenol oxidase, chips quality after frying were then assessed. Besides that, to determine the influence of treatments and storage periods, multivariate analysis was also performed using the main components. The MeJa reduced the incidence of sprouting and maintained the root quality during storage at room temperature. Notably, such events led to an increased both shelf life and potential of commercialization. Moreover, MeJa-treated chips displayed lighter color appearance after frying than control and NA-treated roots. Roots fogged with NA did not suppress the growth of sprouts, which consequently triggered a higher browning intensity in fried sweet potato chips.
... Low levels of reducing sugars are preferred in processing potatoes since when tubers are cooked at high temperatures (>120•C) the Maillard reaction can occur. However this type of sweetening can be prevented with a single application (24 h) of 1methylcyclopropene (1-MCP) prior to early and late ethylene supplementation (Foukaraki et al., 2016a). The impact of CO2, another storage extension gas, on frying quality is less clear. ...
Article
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Potato (Solanum tuberosum L.) is one of the tuber crops grown in mid and highlands of Ethiopia as a high potential food security crop due to its high yield potential per hectare and nutritious tubers. It is also used as income generating commodity for farmers. Even though, the edaphic and climatic conditions are suitable for production of high quality potato in Ethiopia, the national average production is as low as 8 t ha-1. The low acreage and yield are attributed to many factors. However, one of most significant constraints to increasing productivity and overall production is the chronic shortage of good quality seed tubers. In Ethiopia, aspects of potato tuber seed quality like purity, genetic quality, health, size, physical damage and physiological age are serious problem because of varietal mix-up, poor storage mechanisms, prevalence of diseases and pests and poor knowledge of seed selection. Farmers use a potato tuber of inferior quality as a planting material which is less accepted by market to sell as a ware potato. This is because of scarcity of potato seed tuber produced by specialized seed growers and also lack of awareness of the farmer about the appropriate size of tubers which result with vigor plant stand as well as better final yield. In the production of potato, quality of seed potatoes is an important determinant of the yield and quality of the final product. Hence, to increase potato production and productivity calls for improvement of the quality of seed potato with in the country is very important. Therefore, this review briefly presents factors affecting potato tuber seed quality and their management in mid and highlands of Ethiopia. Keywords: Preharvest factors, postharvest factors, potato tuber seed & quality.
... Residual effects of CIPC is noticed not only in the stored potatoes but also in the processed potato products 34,35 . Besides CIPC, there are several reports of sprout suppressants derived from natural and synthetic compounds such as ethylene and 1-MCP (1-methylcyclopropene) as well as techniques like ultraviolet-C irradiation and fumigation using plant [36][37][38][39] . Table 1 provides the compounds documented by various scientists and their comparative efficacy as anti-sprouting agents. ...
Article
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Inhibiting sprouting of potatoes is an interesting subject needed for potato storage and industry. Sprouting degrades the quality of tuber along with releasing α-solanine and α-chaconine, which are harmful for health. Sprout suppressants, available in the market, are either costly or toxic to both health and environment. So, there is a need for developing countries to explore new sprouting suppressant compound which is cheap, non-toxic and reasonably efficient in comparison to commercial ones. We have established that simple maleic acid and l-tartaric acid are effective sprout suppressant agents. Both can hinder sprouting up to 6 weeks and 4 weeks post treatment respectively at room temperature in dark. These do not affect the quality parameters, retain the moisture content and maintain the stout appearance of the tubers along the total storage period. Thus maleic acid and l-tartaric acid would qualify as alternative, cheap, efficient sprout suppressant for potato storage and processing
Article
Potato tuber dormancy is critical for the postharvest quality. The supply of carbohydrates is considered as one of the important factors controlling the rate of potato tuber sprouting. Starch is the major carbohydrate reserve in potato tuber, but very little is known about the specific starch degrading enzymes responsible for controlling tuber dormancy and sprouting. In this study, we demonstrate that an α-amylase gene StAmy23 is involved in starch breakdown and regulation of tuber dormancy. Silencing of StAmy23 delayed tuber sprouting by one to two weeks compared with the control. This phenotype is accompanied by reduced levels of reducing sugars and elevated levels of malto-oligosaccharides in tuber cortex and pith tissue below the bud eye of StAmy23-deficient potato tubers. Changes in soluble sugars is accompanied by a slight variation of phytoglycogen structure and starch granule size. Our results suggest that StAmy23 may stimulate sprouting by hydrolyzing soluble phytoglycogen to ensure supply of sugars during tuber dormancy.
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Potato (Solanum tuberosum L.) tubers are rich in starch, protein, vitamins, minerals and other nutrients. However, sprouting can produce solanine and reduce the commodity value during periods of storage. Some research has suggested that some essential oils from plants reduce tuber sprouting. Garlic essential oil (GEO) is reported to have antioxidant, anti-inflammatory, and antimicrobial properties. In this study, we first found that GEO reduced tuber sprouting, and the starch content, soluble sugar content and ɑ-amylase activity were altered after 60 d of GEO treatment. Then, comparative proteomic analysis of tuber bud eyes revealed 140 and 180 differentially abundant proteins (DAPs) with increased and decreased levels of abundance respectively after 30 d of GEO treatment. Among them, StHSP26.5 protein abundance decreased after GEO treatment, however, as the storage time increased, the expression level of this gene increased. Further research suggested that overexpressing StHSP26.5 tobacco showed increased seed germination and POD activity after GEO treatment. Our results provide new insights into proteomic mechanisms in the sprouting process after GEO treatment and suggest the potentially utility of StHSP26.5 as a target gene in tuber molecular breeding programs.
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The aim of this study was to investigate the role of ethylene to control sprouting of potatoes by observing the effect of exogenous ethylene on carbohydrate metabolism and key enzymes. The initial time of potato tuber sprouting and sprouting index were recorded, and rate of respiration, total sugar, total reducing sugar, starch, fructose, glucose, sucrose and the activities of acid invertase (AI), neutral invertase (NI), sucrose synthase (SS), sucrose phosphate synthase (SPS), starch phosphorylase and amylase during sprouting were measured. Exogenous ethylene inhibited sprouting of potato tubers. Moreover, exogenous ethylene increased respiration total sugar, AI activity, SPS activity, SS activity, and reduced sugar and assay activity. Nevertheless, starch, glucose, fructose, NI activity and starch phosphorylase activity showed lower variation. Lower sprouting resulted into potatoes with higher levels of total sugar, total reducing sugar and glucose, and lower level of fructose and sucrose. And sprouting could be inhibited by increasing the activities of SS, SPS and AI by treatment with 199.3 μl L−1 exogenous ethylene. Overall, exogenous ethylene inhibited sprouting of potato tubers by influencing its carbohydrate metabolism.
Chapter
Harvest and postharvest management determine not only that potato reaches its maximum storage potential (genetically defined) but also the organoleptic, nutritional, and functional quality maintenance of the final product. The potato must be harvested in endodormancy state. After harvest and before storage, curing occurs (15-20 °C and 90-95% HR for 5-10 days) and periderm is formed to protects tubers from dehydration and pathogens entry. During storage, temperature management allows to prolong dormancy (2-4 °C) and reduce metabolic activity, which reaches minimum values between 4-5 °C. However, the storage temperature will depend on potato destination since it is sensitive to cold and when stored below 4 °C, glucose and fructose levels increase, and it would not be suitable for frying (non-enzymatic browning). Potato is a source of beneficial compounds such as vitamins, polyphenols, anthocyanins, carotenoids, and minerals. More than 50% of the marketed potato is destined for industrial processing (frozen or minimally processed) and is consumed in several forms: fried, steamed and/or microwaved. The suitability of the potato genetic material for these preparations depends fundamentally on the dry matter content, determined genetically and on the reducing sugars, mainly dependent on the storage conditions. Processing prior cooking and cooking itself determine changes at the functional quality, in some cases reducing or increasing compounds. This chapter reviews the main aspects of potato postharvest from harvest, postharvest practices, and storage. Aspects related to organoleptic and functional quality linked to the genetic material characteristics, and to the storage and processing conditions, are also addressed.
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Fresh fruit is important for a healthy diet. However, due to their seasonal production, regional specific cultivation and perishable nature, it is essential to develop preservation technologies to extend the post-harvest shelf life of fresh fruits. Climacteric fruit adopt spoilage because of ethylene, a key hormone associated with the ripening process. Therefore, controlling ethylene activity by following safe and effective approaches is a key to extend the post-harvest shelf life of fruit. In this review, ethylene control technologies will be discussed aiming for the need of developing more innovative and effective approaches. The biosynthesis pathway will be given firstly. Then, the technologies determining the post-harvest shelf life of climacteric fruit will be described with special attention to the latest and significant published works in this field. Special attention is given to 1-methylcyclopropene (1-MCP), which is effective in fruit preservation technologies. Finally, the encapsulation technology to improve the stability of 1-MCP will be proposed, using a potential encapsulation agent of 1-MCP, calixarene.
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Microbial diversity has been found to be associated with the plant systems and beneficial properties of agricultural microbiomes, which improve crop sustainability. This chapter is a review of the microbiota associated with potato crop and their use in sustainable production systems. The chapter highlights the plant microbiome's importance in the potato production system and potato adaptation to its biotic environment, including its productivity benefits. Thus, it is possible to visualize the response of the potato microbiota to the environment and the complex interactions in the ecosystem, and the development of new agricultural practices that include the management of specific microbiomes for potato crop production. The data presented here reinforces the idea that the microbiome should be considered as an important strategy to reach sustainability in potato crops, as the use of growth-promoting microorganisms in potatoes can help reduce the vulnerability of the crop, increasing the level of sustainability at the farm level.
Chapter
This chapter provides a review of information related to production, physicochemical, functional, phytochemical and nutritional properties, and manufacturing of major potato products. It tabulates world potato production and area harvested since 1990. Potatoes are classified based on their skin color, texture, tuber shape, flesh color, pest and disease resistance, physiological maturity, and performance during storage. Processors of chips, French fries, dehydrated and other products usually require potatoes with high specific gravity to obtain better quality and higher-yielding finished product. Processing of potatoes involves preparatory steps of grading, testing, washing, peeling, and blanching. Blanching is aimed at inactivating microorganisms and enzymes such as polyphenol oxidase, removing tissue gases, and gelatinizing starch, which swells and, upon cooling, enables a compact texture. The manufacturing of potatoes into products uses Hazard Analysis Critical Control Points (HACCP) principles, and standard operating procedures to prevent defective and unsafe products from entering into the market.
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Background: The potential of 1-methylcyclopropene (1-MCP) to maintain postharvest storage of sweetpotato was studied. In two separate experiments, the orange-fleshed sweetpotato cv. Covington was fumigated with 1-MCP (1.0 μL L-1, 24 h) and roots stored at 15oC. During storage, samples were evaluated for the respiration rate, sprout growth, weight loss, incidence of decay and changes in dry matter. The roots were further assayed for the temporal changes in individual non-structural carbohydrates and phenolic compounds in the skin and flesh tissues of the proximal (stem end), middle, and distal (root end) regions. Results: 1-MCP treatment reduced root weight loss and decay but respiration rate and non-structural carbohydrates were not affected. No sprouting was recorded irrespective of the treatment. 1-MCP transiently suppressed the accumulation of individual phenolic compounds, especially in the middle and distal segments. This accentuated the proximal dominance of phenolic compounds. Isochlorogenic acid A and chlorogenic acid were the dominant phenolics in the skin and flesh tissues, respectively. Conclusion: 1-MCP treatment may have anti-decay effect and reduce weight loss. Therefore, storage trials which involve the use of continuous ethylene supplementation to inhibit sprout growth may be combined with 1-MCP to alleviate ethylene-induced weight loss and decay in sweetpotato.
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Straw mushroom (Volvariella volvacea) is economically important in China, but after harvest, it can be stored for only 1–2 d, because it rapidly deteriorates. The role of the ethylene signal transduction pathway in the regulation of these processes in higher fungi is unclear. In this study, we aimed to identify and analyze the acs genes in the genome of V. volvacea. Bioinformatic analyses were performed to identify differences between the acs sequences of V. volvacea and homolog gene sequences of plants. Furthermore, ethylene production and acs expression in V. volvacea during storage were measured before and after ethephon and 1-methylcyclopropene (1-MCP) treatments. The results showed that there are four acs genes in the genome of V. volvacea, and the phylogenetic tree revealed that the proteins encoded by these genes had high homology to the ACS proteins in plants, with some differences. A conserved motif was found in these ACS proteins. Ethephon accelerated endogenous ethylene production and upregulated acs expression in V. volvacea, whereas 1-MCP inhibited endogenous ethylene production and downregulated acs expression in V. volvacea. Our study provides valuable data to further investigate the roles of acs in the mechanisms of senescence of V. volvacea. Further, acs could be used to develop molecular markers enabling screening and selective breeding of V. volvacea strains with slowed senescence, prolonging the shelf life of the product.
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Despite frequently being described as a carbohydrate-laden, calorie-rich unimportant part of the human diet, potatoes (Solanum tuberosum L.) are one of the most nutritive vegetable food crops in the world and, in comparison to most other vegetables are richer in essential human nutrients. These include proteins, starch and fibre, major, secondary and trace minerals, vitamins, antioxidants and phytochemicals. Potatoes have an abundance of vitamin C and the mineral potassium (K) which are vital for health. Potassium reduces the risk of Blood Pressure (BP), cardiovascular diseases (CVDs), osteoporosis and strokes. Vitamin C helps reduce strokes and hypertension and prevents scurvy. The predominant form of carbohydrate (CHO) in the potato is starch. A small but significant part of this starch is resistant to digestion by enzymes in the stomach and small intestine, so it reaches the large intestine essentially intact. This resistant starch is considered to have similar physiological effects and health benefits as fibre. A medium size potato (148 g) contains 4 g protein and very small amount of fat or cholesterol. The fibre content of a potato with skin is equivalent to that of many whole grain breads and pastas. Potatoes contain rather large amount of the enzyme catalase, which converts hydrogen peroxide into oxygen and water and thus prevents cell injury. Potatoes contain phytochemicals such as lutein and zeaxanthin; which protect and preserve eyesight and may help reduce the risk of macular degeneration. It is not the high Glycemic Index (GI) in potatoes or in any other food, but the number of calories consumed from all foods that causes weight gain. Overall, potatoes are an underrated source of essential human nutrients. Potatoes also contain toxic compounds, such as α-solanine and α-chaconine which are known to induce toxicity. These poisons cause gastrointestinal disturbances causing vomiting and diarrhea but severe poisoning may lead to paralysis, cardiac failure and comma. Green areas in potatoes containing chlorophyll are harmless but indicate that toxins may be present. According to the American Cancer Society, food born toxin such as acrylamide is formed when starchy foods such as potatoes and potato products are cooked at temperatures above 121C. However, deep frying at 170C is known to effectively lower the level of toxic compounds, while microwaving is only somewhat effective and freezedrying or dehydration has little effect. The highest levels of acrylamide are found in CHO-rich foods, such as potato chips and French fries, which had been cooked at high temperatures.
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Potato tuber bud dormancy break followed by premature sprouting is a major commercial problem which results in quality losses and decreased tuber marketability. An approach to controlling premature tuber sprouting is to develop potato cultivars with a longer dormancy period and/or reduced rate of sprout growth. Our recent studies using a potato diploid population have identified several QTLs that are associated with tuber sprout growth. In the current study we aim to characterise a candidate gene associated with one of the largest effect QTL for rapid tuber sprout growth on potato chromosome 3. Underlying this QTL is a gene encoding a TERMINAL FLOWER 1/ CENTRORADIALIS homologue (PGSC0003DMG400014322). Here we use a transgenic approach to manipulate the expression level of the CEN family member in a potato tetraploid genotype (cv. Désirée). We demonstrate a clear effect of StCEN expression manipulation, with decreased expression levels associated with an increased rate of sprout growth, and over-expressing lines showing a lower rate of sprout growth than controls. Associated with different levels of StCEN expression were different levels of ABA and cytokinins implying a role in controlling the levels of plant growth regulators in the apical meristem.
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In Canada, the potato (Solanum tuberosum) is by far the most cultivated vegetable and plays a major nutritional role. However, during storage, the potato can easily undergo germination. In this study we have shown the inhibition potential of ethylene as an anti-germinative agent acting especially on phenols. In both varieties assayed (Yukon Gold and Russet Burbank) in this study, the ethylene treatment led to a decrease in total phenol concentration of about 20%. The analysis of potato extracts showed the decrease of specific phenol concentrations which was dependant on the time and temperature of extraction. Our hypothese that the transformation of phenols into phenolic ethyl ethers via possible radical mechanism were then formulated and confirmed by LC and LC/MS.
Article
The effects of continuous supplemental ethylene (10 μL L−1) timing on the physiology and biochemistry of sweetpotato roots during storage at 25 °C were examined. Alongside continuous ethylene or air treatments, a subset of the roots were transferred at dormancy break, from those previously stored in ethylene into air and vice-versa. The study showed distinctive ethylene-induced effects on the metabolism of individual sugars, phenolic compounds and phytohormones (abscisic acid and zeatin riboside) across the spatial gradient of the root flesh and skin tissues. Although ethylene flushing doubled root respiration, sprout growth was significantly suppressed. Supplementation of roots with ethylene after dormancy break effectively inhibited sprout growth as much as continuous ethylene alone. On the other hand, truncating ethylene application after dormancy release promoted vigorous sprout growth. After prolonged storage, ethylene treatment was associated with increased weight loss and incidence of proximal rots. Supplemental ethylene also accelerated the catabolism of monosaccharides, and promoted accumulation of phenolic compounds in the proximal root sections.
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The effect of ethylene on tuber sprout growth and quality in potato (Solanum tuberosurn L. 'Russet Burbank') was tested in laboratory and commercial studies for 6 and 3 years, respectively, in comparison with untreated (laboratory study) and CIPC-treated tubers (laboratory and commercial studies). In both studies, ethylene was applied continuously at 166 μmol·m-3 for at least 25 weeks, beginning in early December (laboratory study) or early December to early January (commercial study). In the laboratory study, ethylene delayed the appearance of sprouts for 5 to 15 weeks, compared with untreated tubers. In the ethylene-treated tubers in both studies, sprouts appeared on many eyes but most of them remained very small (<5 mm long). Longer sprouts (>5 mm) appeared after 15 weeks but did not exceed 12 and 59 mm in the laboratory and commercial studies, respectively. Sprouts on ethylene-treated tubers were more easily detached up to 6 weeks after ethylene treatment ended, compared with untreated tubers. In both studies, ethylene treatment was not associated with decay, disorder or internal sprouting problems. In both studies, the Agtron fry color [or U.S. Dept. of Agriculture (USDA) color grade] of ethylene-treated tubers was darker than CIPC-treated tubers at almost all sampling times. Continuous exposure to ethylene was an effective sprout control agent but it produced a darker fry color, compared with CIPC-treated potatoes.
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The potato tuber constitutes a model system for the study of dormancy release and sprouting, suggested to be regulated by endogenous plant hormones and their balance inside the tuber. During dormancy, potato tubers cannot be induced to sprout without some form of stress or exogenous hormone treatment. When dormancy is released, sprouting of the apical bud may be inhibited by sprout control agents or cold temperature. Dominance of the growing apical bud over other lateral buds decreases during storage and is one of the earliest morphophysiological indicators of the tuber's physiological age. Three main types of loss of apical dominance (AD) affect sprouting shape. Hallmarks of programmed cell death (PCD) have been identified in the tuber apical bud meristem (TAB-meristem) during normal growth, and are more extensive when AD is lost following extended cold storage or chemical stress. Nevertheless, the role of hormonal regulation in TAB-meristem PCD remains unclear.
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Ethylene effectively inhibits sprouting of potatoes (Solanum tuberosum L.) during storage, but it often darkens fry color. The objective of the work described here was to determine if altering the concentration of ethylene applied would reduce the darkening while retaining adequate sprout inhibition. Trials were conducted over three consecutive years (1991–1992, 1992–1993, and 1993–1994). Tubers of cv Russet Burbank (ca 150–300 g) were stored at 9 C for 25 wk in closed chambers in a refrigerated room under continuous exposure to 0.4, 4, 40, or 400 µL L−1 ethylene gas delivered with the ventilation airstream (ca 0.5 air exchanges per h, for 6 h each day). Untreated control and chlorpropham-treated (CIPC) check tubers were stored under the same conditions but without ethylene supplementation. Sprout number, length, and biomass, fry color, loss of tuber mass, disease, and dry matter content were evaluated at 5-wk intervals. Dose-dependent effects (400>40>4>0.4 µL L−1) of ethylene on sprout growth and fry color were observed. The 400, 40, and 4 µL L−1 ethylene treatments inhibited sprout growth as effectively as CIPC, whereas in 0.4 µL L−1 ethylene sprouting was midway between CIPC and the untreated control. Sprout mass and maximum sprout length in all ethylene treatments were significantly lower (P−1 ethylene treatments were, however, still darker than tubers stored with CIPC. Inhibition of sprout growth was slightly more effective in the 400 and 40 µL L−1 ethylene treatments than in 4 µL L−1, although there were no significant differences (P−1 ethylene was lighter, but inhibition of sprout growth was significantly (PP
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Based on ethylene management in potato storage, we hypothesized that the applied treatments would modify number of sprouts per seed tuber. Thus, in combination with in-row spacing (closer for seed, wider for processing) in the field treatments will give either (1) a high number of small tubers destined for seed use, or (2) a relatively smaller number of large, uniform tubers suitable for processing. A three-year study (2001–2003), conducted with two french fry processing cultivars, Russet Burbank (RB) and Shepody (SH), aimed at the development of a novel modified atmosphere seed tuber storage treatment. Seed tubers were stored at 4 C from October to May of each year in a cold room under five modified atmospheric regimes: (1) air ventilation only (Control); (2) 4 µl L−1 ethylene applied continuously beginning in November and (3) beginning in February; (4) 1 µ1 L−1 MCP (1-methylcyclopropene) applied as a gas for 48 h only in early December followed by continuous 4 µl L−1 ethylene and (5) MCP alone applied as above. Each year, once a month (mid-January until end of April), a number of seed tubers was taken from each storage treatment, planted to pots and grown for 4 wk in a growth-room. In these studies, shoot emergence from the ethylene-treated seeds of both cultivars occurred significantly earlier, giving higher number of stems per tuber and stolons per stem than Control and MCP treatments. Moreover, the time to emergence after planting decreased with the increased length of storage. Field studies that were conducted from the end of May (planting) until October each year, produced similar trends (although not significant atP≤0.05) and resulted in a higher number of tubers per stem. In RB at the closer in row spacing (30 cm) used for seed production, ethylene enhanced yield of smaller tubers in the 30- to 115-g and 115- to 300-g categories. The ethylene storage treatments also increased tuber number per plant, but not the total mass of harvested potatoes. The MCP treatment, in combination with the wider in-row spacing (40 cm) used for the production of processing tubers, significantly increased the percentage of large tubers (>300 g). In SH, contrary to RB, the ethylene treatments did not alter tuber size distribution and the application of MCP reduced tuber size rather than increasing it. Results from this study suggest that both ethylene and MCP can be used in seed potato storage to influence the tuber size distribution of the crop from that seed. Basado en el manejo de etileno para el almacenamiento de papa, hemos asumido la hipótesis de que los tratamientos aplicados modificarían el número de brotes por tubérculo semilla, así en combinación con el espaciamiento en el campo (corto para semilla y largo para procesamiento) nos dará ya sea (1) un gran número de tubérculos pequeños destinados a semilla o (2) un número relativamente pequeño de tubérculos grandes y uniformes adecuados para procesamiento. Se realizó un estudio de tres años (2001 a 2003) con dos cultivares para procesamiento de papa frita, Russet Burbank (RB) y Shepody (SH), destinado al desarrollo de un novedoso tratamiento de atmósfera modificada para el almacenamiento de tubérculos semilla. Los tubérculos semilla fueron almacenados a 4 C de octubre a mayo de cada año en un ambiente frío bajo cinco regímenes atmosféricos modificados: (1) solamente ventilación de aire (Testigo); (2) 4 Llq de 1 etileno aplicado continuamente a partir de noviembre y (3) comenzando en febrero; (4) 1 Llq de 1 MCP (1-metilcloropropeno) aplicado como gas por 48 horas solamente a principios de diciembre seguido de 4 Llq de 1-etileno y (5) MCP solo aplicado en la forma anterior. Cada año, una vez al mes (mediados de enero hasta fines de abril), se tomaron unos cuantos tubérculos semilla de cada tratamiento de almacenaje, fueron sembrados en macetas y llevados a la cámara de crecimiento por 4 semanas. En estos estudios, la emergencia de brotes de las semillas tratadas con etileno se realizó en ambos cultivares mucho más antes, con un número mayor de tallos por tubérculo y estolones por tallo que en el testigo y los tratamientos con MCP. Más aún, el tiempo de emergencia después de la siembra disminuyó con un mayor tiempo de almacenamiento. Los estudios de campo que se realizaron desde fines de mayo (siembra) hasta octubre de cada año mostraron tendencias similares (aunque no significativas aP≤0.05) y dieron un mayor número de tubérculos por tallo. En RB a menor espaciamiento (30 cm) usado para la produción de semilla, el etileno elevó el rendimiento de tubérculos más pequeños en las categorías de 30–115 g y 115–300 g. Los tratamientos de almacenamiento con etileno también incrementaron el número de tubérculos por planta, pero no la masa total de papa cosechada. El tratamiento con MCP, en combinación con un mayor espaciamiento entre plantas (40 cm) usado para la producción de papa para procesamiento incrementó significativamente el porcentaje de tubérculos más grandes (>300 g). En SH, contrariamente a RB, los tratamientos con etileno no alteraron la distribución de tamaño y la aplicación de MCP redujo el tamaño del tubérculo en lugar de incrementarlo. Los resultados de este estudio sugieren que tanto el etileno como el MCP pueden usarse en almacenamiento para influenciar la distribución de tamaño del tubérculo del cultivo a diferencia de lo que se quiere para semilla.
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The study examined the efficacy of 1-methylcyclopropene (1-MCP), an anti-ethylene compound, as a preventative treatment for ethylene-induced fry color darkening in potato (Solanum tuberosum L.) tubers, without reducing the effectiveness of ethylene as a tuber sprouting control agent. The experiment was conducted for two years with ‘Shepody’ and ‘Russet Burbank.’ Tubers of each cultivar from four separate growers received one of the following treatments: Air (control), Air + 1-MCP (1 (μL.L-1 for 48 h), isopropyl N (3-chlorophenyl) carbamate (chloropropham; CIPC; 1% a.i. [v/v]); continuous ethylene (4 μL.L-1) in air; continuous ethylene pre-treated with 1-MCP once; continuous ethylene pre-treated with 1-MCP and repeated monthly; and continuous ethylene pre-treated with 1-MCP and repeated bi-monthly. Treatment started after suberization and cooling to 9 C, and samples were evaluated at 3-wk (year 1) or 4-wk (years 2 and 3) intervals thereafter until April (Shepody) or June (Russet Burbank). Sprout growth (sprout fresh weight per tuber), fry color (Agtron reflectance units), tuber weight loss, incidence of disease infection and internal disorders were evaluated. Weight loss, tuber infection, and the occurrence of disorders were not affected by any of the treatments. Sprout growth was controlled by the continuous ethylene supply in both cultivars, and single or multiple additions of 1-MCP to the ethylene treatment did not affect the ethylene control of sprouting. As expected, ethylene treatment alone enhanced fry color darkening in both cultivars. In Russet Burbank tubers, fry color was not darkened in any of the ethylene + 1-MCP (once, monthly, or bimonthly) treatments. In Shepody, fry color was not darkened in the ethylene + 1-MCP monthly or bimonthly treatments, but started darkening 4 wk after exposure in the single ethylene + 1-MCP treatment. It is concluded that 1-MCP can be used to control fry color darkening induced by ethylene without blocking ethylene control of tuber sprouting. However, the number of 1-MCP applications required may vary with the cultivar, e.g., one application was sufficient in Russet Burbank but not in Shepody. Se examinó la eficacia del 1-metilciclopropeno (1-MCP), que es compuesto anti-etileno como tratamiento preventivo del oscurecimiento de tubérculos de papa (Solanum tuberosum L.) después de ser fritos, sin reducir el efecto del etileno como controlador del brotamiento de los tubérculos. El experimento se condujo por tres años con ‘Shepody’ y dos años con ‘Russet Burbank’. Tubérculos de cada cultivar provenientes de cuatro productores diferentes recibieron uno de los siguientes tratamientos: Aire (testigo); Aire + 1-MCP (μL.L-1 por 48 horas); isopropil N-(3 clorofenil) carbamato (cloroprofano); CIPC1% i.a. (v/v); etileno continuo (4 (μL.L-1) en el aire; etileno continuo y pre tratamiento con 1-MCP por una sola vez; etileno continuo y pre tratamiento con 1-MCP cada mes y etileno continuo, pre tratamiento con 1-MCP cada 2 meses. El tratamiento comenzó después de la suberización y enfriamiento a 9 C y las muestras fueron evaluadas a intervalos de 3 semanas (el primer año) o a intervalos de 4 semanas (el segundo y tercer año) y luego en abril (Shepbody) o junio (Russet Burbank). Se evalué el crecimiento de los brotes (peso fresco de los brotes por tubérculo), color de la fritura (unidades de reflejo Agtron), pérdida de peso del tubérculo, incidencia de infecciones por enfermedades y desérdenes internos. La pérdida de peso, la infección del tubérculo y la presencia de desórdenes no fue afectada por ninguno de los tratamientos. El desarrollo de los brotes fue controlado por el continuo suministro de etileno y la adición simple o multiple de 1-MCP al tratamiento con etileno en ambos cultivares y no afectó el control ejercido por el etileno sobre el brotamiento. Como se esperaba, el tratamiento con etileno sólo intensificó el oscurecimiento de la papa frita en ambos cultivares. Los tubérculos de Russet Burbank, no se oscurecieron por fritura en ninguno de los tratamientos de etileno + 1-MCP (por una vez, mensual o bimensual). En tubérculos de Shepody el color de la fritura no se oscureció en los tratamientos con etileno + 1-MCP mensual o bimensualmente, pero comenzó a oscurecer a las 4 semanas después de expuestos al tratamiento simple de etileno + 1-MCP. Se concluye que el 1-MCP puede ser usado para controlar el oscurecimiento del color al ser fritos inducido por el etileno, sin bloquear el control ejercido por el etileno sobre el brotamiento. Sin embargo, el número de aplicaciones requeridas de 1-MCP puede variar con el cultivar, por ejemplo, una aplicación fue suficiente en Russet Burbank pero no en Shepody.
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At harvest, potato (Solanum tuberosum L.) tubers are dormant and will not sprout. As the period of postharvest storage is extended, tuber dormancy is broken and sprout growth commences. The loss of tuber dormancy and onset of sprout growth is accompanied by numerous biochemical changes, many of which are detrimental to the nutritional and processing qualities of potatoes. Endogenous hormones have been proposed to play a significant role in tuber dormancy regulation. The involvement of all major classes of endogenous hormones in tuber dormancy is reviewed. Based on available evidence, it is concluded that both ABA and ethylene are required for dormancy induction, but only ABA is needed to maintain bud dormancy. An increase in cytokinin sensitivity and content appear to be the principal factors leading to the loss of dormancy. Changes in endogenous IAA and GA content appear to be more closely related to the regulation of subsequent sprout growth.
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Ethylene is an effective potato (Solanum tuberosum L.) sprout inhibitor, but it often darkens fry colour. Trials were conducted over nine consecutive storage seasons to identify ethylene application methods which would mitigate darkening while retaining adequate sprout inhibition, using cv. Russet Burbank plus cvs Shepody, Asterix and Santana in some years. Tubers were stored for up to 35weeks in closed chambers with ethylene gas delivered via the ventilation airstream. Exposure to continuous 4μl l−1 ethylene after suberization and cooling were completed was designated the ethylene check. Alternative ethylene treatments included commencing exposure either before or after suberization was completed; gradually introducing the ethylene either by a concentration gradient of eight steps over 4 or 8weeks or by increasing the duration of exposure from 6to 24h per day in fourweekly steps; repeatedly interrupting exposure for several hours per day or for durations of 1 or more days; and warm storage. Selected ethylene treatment combinations were applied in each year, plus untreated controls, chlorpropham-treated (CIPC) checks and ethylene checks. Sprout growth, fry colour, loss of mass and disease incidence were evaluated at regular intervals. In all cultivars and all years, the ethylene check darkened fry colour more than the other treatments. Commencing before suberization ended, gradually introducing the ethylene by either concentration or time gradient and interrupting the exposure all reduced the negative effect of ethylene sprout inhibitor on fry colour. Continuous ethylene treatments inhibited sprout growth as effectively as CIPC, except at 13 °C storage. Interruptions of 18h and 2 or more days reduced sprout inhibition. Regardless of cultivar variations, an early start using either a concentration or time-increment gradient had the least effect on fry colour while maintaining good sprout inhibition.
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Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can suppress sprouting while the ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) can also suppress sprout growth; yet, it is unknown how ethylene and 1-MCP elicit the same response. In this study, onions were treated with 10 μL L(-1) ethylene or 1 μL L(-1) 1-MCP individually or in combination for 24 h at 20°C before or after curing (6 weeks) at 20°C or 28°C and then stored at 1°C. Following curing, a subset of these same onions was stored separately under continuous air or ethylene (10 μL L(-1)) at 1°C. Onions treated with ethylene and 1-MCP in combination after curing for 24 h had reduced sprout growth as compared with the control 25 weeks after harvest. Sprout growth following storage beyond 25 weeks was only reduced through continuous ethylene treatment. This observation was supported by a higher proportion of down-regulated genes characterized as being involved in photosynthesis, measured using a newly developed onion microarray. Physiological and biochemical data suggested that ethylene was being perceived in the presence of 1-MCP, since sprout growth was reduced in onions treated with 1-MCP and ethylene applied in combination but not when applied individually. A cluster of probes representing transcripts up-regulated by 1-MCP alone but down-regulated by ethylene alone or in the presence of 1-MCP support this suggestion. Ethylene and 1-MCP both down-regulated a probe tentatively annotated as an ethylene receptor as well as ethylene-insensitive 3, suggesting that both treatments down-regulate the perception and signaling events of ethylene.
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Reactivation of dormant meristems is of central importance for plant fitness and survival. Due to their large meristem size, potato (Solanum tuberosum) tubers serve as a model system to study the underlying molecular processes. The phytohormones cytokinins (CK) and gibberellins (GA) play important roles in releasing potato tuber dormancy and promoting sprouting, but their mode of action in these processes is still obscure. Here, we established an in vitro assay using excised tuber buds to study the dormancy-releasing capacity of GA and CK and show that application of gibberellic acid (GA(3)) is sufficient to induce sprouting. In contrast, treatment with 6-benzylaminopurine induced bud break but did not support further sprout growth unless GA(3) was administered additionally. Transgenic potato plants expressing Arabidopsis (Arabidopsis thaliana) GA 20-oxidase or GA 2-oxidase to modify endogenous GA levels showed the expected phenotypical changes as well as slight effects on tuber sprouting. The isopentenyltransferase (IPT) from Agrobacterium tumefaciens and the Arabidopsis cytokinin oxidase/dehydrogenase1 (CKX) were exploited to modify the amounts of CK in transgenic potato plants. IPT expression promoted earlier sprouting in vitro. Strikingly, CKX-expressing tubers exhibited a prolonged dormancy period and did not respond to GA(3). This supports an essential role of CK in terminating tuber dormancy and indicates that GA is not sufficient to break dormancy in the absence of CK. GA(3)-treated wild-type and CKX-expressing tuber buds were subjected to a transcriptome analysis that revealed transcriptional changes in several functional groups, including cell wall metabolism, cell cycle, and auxin and ethylene signaling, denoting events associated with the reactivation of dormant meristems.
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The involvement of ethylene in the dormancy breaking actions of cytokinins, GA, and BE was investigated using Russet Burbank minitubers. Injection of 10 µg tuber−1 BA, CP, GA, NG, or ZEA or 24 hour exposure to BE effectively broke dormancy and stimulated sprout growth over a two-week period. Although ethylene production was slightly enhanced by all treatments, a significant increase in ethylene production was observed in minitubers treated with BE, CP, or NG. Pretreatment with the ethylene antagonists STS or MCP did not affect the dormancy breaking actions of any of the agents tested. Application of the ethylene synthesis inhibitor AVG to NG-treated minitubers, completely suppressed ethylene production but had no effect on dormancy break. Application of exogenous ethylene or stimulation of endogenous ethylene production by ACC treatment did not break minituber dormancy or stimulate sprout growth. Collectively, these results indicate that endogenous ethylene does not play a role in the dormancy breaking actions of cytokinins, GA, or BE.
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Potato (Solanum tuberosum L.) single-node explants undergoing in vitro tuberization produced detectable amounts of ethylene throughout tuber development, and the resulting microtubers were completely dormant (endodormant) for at least 12 to 15 weeks. The rate of ethylene production by tuberizing explants was highest during the initial 2 weeks of in vitro culture and declined thereafter. Continuous exposure of developing microtubers to the noncompetitive ethylene antagonist AgNO3 via the culture medium resulted in a dose-dependent increase in precocious sprouting. The effect of AgNO3 on the premature loss of microtuber endodormancy was observed after 3 weeks of culture. Similarly, continuous exposure of developing microtubers to the competitive ethylene antagonist 2, 5-norbornadiene (NBD) at concentrations of 2 mL/L (gas phase) or greater also resulted in a dose-dependent increase in premature sprouting. Exogenous ethylene reversed this response and inhibited the precocious sprouting of NBD-treated microtubers. NBD treatment was effective only when it was begun within 7 d of the start of in vitro explant culture. These results indicate that endogenous ethylene is essential for the full expression of potato microtuber endodormancy, and that its involvement may be restricted to the initial period of endodormancy development.
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Changes in ADP-glucose and UDP-glucose pyrophosphorylase activities were followed during tuber development of Solanum tuberosum and prolonged storage at 4 and 11 C. Potato tuberization was accompanied by a sharp increase in starch synthesis simultaneous with a marked rise in ADP-glucose pyrophosphorylase activity. When tubers reached an average diameter of 1 centimeter (0.5 gram average tuber weight) and had already established 58% starch on a dry weight basis, ADP-glucose pyrophosphorylase increased 16- to 24-fold over its activity seen in low starch containing stolon tissue. During this same period UDP-glucose pyrophosphorylase increased approximately 2- to 3-fold. Although participation of UDP-glucose in starch formation can not be neglected, it is suggested that the onset of rapid non-photosynthetic potato tuber starch biosynthesis may be closely related to the simultaneous increase in ADP-glucose pyrophosphorylase activity.Evidence that UDP-glucose and ADP-glucose pyrophosphorylases are separate protein entities was indicated by their (a) activity ratio variations during tuber development and storage, (b) extraction stabilities, (c) morphological localization, (d) separation with ammonium sulfate, (e) pH optima, and (f) differential activation with 3-P-glycerate.
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Dormant potato tubers (Solanum tuberosum L.) of two cultivars were treated with various concentrations of ethylene gas for various exposure periods. As has been shown by others, ethylene caused a rapid but transient increase in respiration rate, which appeared to be independent of any effects on dormancy. All concentrations tested caused accelerated sprouting, 2 microliters per liter being the most effective. Ethylene exerts a dual effect on potato tubers: it markedly shortens the duration of rest, but it inhibits elongation of the sprouts during extended treatment. Comparing these results with published work on seeds, bulbs, and corms suggests that ethylene must have a significant but as yet unexplained role in rest and dormancy. However, since the most effective ethylene treatment did not equal the response elicited by treatment with ethylene chlorhydrin, other factors must also contribute to termination of rest.
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The respiration of potato tubers (Solanum tuberosum var. Russet Burbank) which have been kept at room temperature for 10 days is stimulated upon subsequent treatment with C(2)H(4) (10 microliters per liter) and O(2). The respiratory rise reaches a peak in 24 to 30 hours and thereafter declines. Coincident with the rise in tuber respiration is an increase in the respiratory rates of fresh slices and isolated mitochondria. Slices and mitochondria from C(2)H(4)- and O(2)-treated tubers also display substantial resistance to CN, and the resistant respiration is inhibited by hydroxamates.The longer the tubers are stored after harvest, the less effective is C(2)H(4) in causing CN resistance in slices and mitochondria from treated tubers. Addition of 10% CO(2) to the C(2)H(4)-O(2) mixture, however, causes extensive CN resistance to develop, even in slices and mitochondria from old tubers. The results show that C(2)H(4), O(2), and CO(2) act synergistically to induce alternative path development in potatoes.
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Since its discovery more than 100 years ago, potato (Solanum tuberosum) tuber cold-induced sweetening (CIS) has been extensively investigated. Several carbohydrate-associated genes would seem to be involved in the process. However, many uncertainties still exist, as the relative contribution of each gene to the process is often unclear, possibly as the consequence of the heterogeneity of experimental systems. Some enzymes associated with CIS, such as beta-amylases and invertases, have still to be identified at a sequence level. In addition, little is known about the early events that trigger CIS and on the involvement/association with CIS of genes different from carbohydrate-associated genes. Many of these uncertainties could be resolved by profiling experiments, but no GeneChip is available for the potato, and the production of the potato cDNA spotted array (TIGR) has recently been discontinued. In order to obtain an overall picture of early transcriptional events associated with CIS, we investigated whether the commercially-available tomato Affymetrix GeneChip could be used to identify which potato cold-responsive gene family members should be further studied in detail by Real-Time (RT)-PCR (qPCR). A tomato-potato Global Match File was generated for the interpretation of various aspects of the heterologous dataset, including the retrieval of best matching potato counterparts and annotation, and the establishment of a core set of highly homologous genes. Several cold-responsive genes were identified, and their expression pattern was studied in detail by qPCR over 26 days. We detected biphasic behaviour of mRNA accumulation for carbohydrate-associated genes and our combined GeneChip-qPCR data identified, at a sequence level, enzymatic activities such as beta-amylases and invertases previously reported as being involved in CIS. The GeneChip data also unveiled important processes accompanying CIS, such as the induction of redox- and ethylene-associated genes. Our Global Match File strategy proved critical for accurately interpretating heterologous datasets, and suggests that similar approaches may be fruitful for other species. Transcript profiling of early events associated with CIS revealed a complex network of events involving sugars, redox and hormone signalling which may be either linked serially or act in parallel. The identification, at a sequence level, of various enzymes long known as having a role in CIS provides molecular tools for further understanding the phenomenon.
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Ethylene is used as a commercial potato sprout suppressant, but the role of ethylene in potato dormancy is unclear and contradictory. Two potato cultivars 'Estima' and 'Marfona' were treated with air or continuous ethylene (10μLL-1), transferred from air to ethylene or vice versa at first indication of sprouting (10% peeping of the control tubers), over three seasons. The ethylene binding inhibitor, 1-methylcyclopropene, was applied (1μLL-1 for 24h) either at harvest and/or at first indication of sprouting. Tubers were stored at 6°C for 30 weeks and assessed for sprout length and number, and non-structural carbohydrate content. Abscisic acid (ABA) metabolism in tubers throughout storage was monitored. Ethylene applied from harvest or the first indication of sprouting reduced sprout growth significantly for both cultivars while ethylene induced sugar accumulation was prevented by 1-MCP application prior to ethylene storage. Multiple applications of 1-MCP showed no additional benefit to ethylene induced sugar accumulation. A rise in ABA content in flesh tissue was observed in response to ethylene application while 1-MCP blocked the ethylene induced rise in ABA caused by exogenous and endogenous ethylene. The increase in ABA caused by ethylene may delay dormancy break yet 1-MCP blocked this rise in ABA with no apparent effect on sprout behaviour. Sucrose is a prerequisite signalling molecule for hormonal dormancy control. 1-MCP reduced the ethylene induced rise in sucrose content therefore although 1-MCP reduced ABA, the reduction in sucrose content may still have delayed sprout initiation. However, the level of sucrose in the 1-MCP treated tubers did not decrease below that of the control. Taken together, ABA and sucrose may play a role in the sprout suppressing ability of exogenously applied ethylene, but it is clear that other factors are involved.
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Long-term storage of potato (Solanum tuberosum L.) tubers provides year-round availability of the crop, but is limited by sprouting. Continuous exposure to ethylene during storage can prolong the storage-life of potato tubers by suppressing sprouting, yet there is little information on the effects of ethylene on a wide selection of common cultivars. Six different UK potato cultivars were stored at 6ºC for 30 weeks under continuous 10 μl l�1 ethylene treatment, under continuous air, or transferred from air to 10 μl l�1 ethylene at the first indication of sprouting, or vice versa. Fructose, glucose, and sucrose concentrations were determined in samples of tuber flesh and in potato skins. Texture and sprouting were measured after 30 weeks in cold storage. Ethylene applied at the first indication of sprouting was as effective at suppressing further sprouting in ‘Desiree’, ‘Sylvana’, and ‘Fianna’ as observed when ethylene was applied continuously and resulted in no additional ethylene-induced sugar accumulation. The texture data suggested that ethylene treatment had an indirect effect on tuber firmness through the inhibition of sprout growth only in ‘Sylvana’ potato tubers. The implications of these results are that the cost of ethylene application in cold-store rooms could be reduced by manipulating the timing of its application.
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The storability of onion bulbs is dependent on the incidence and rate of sprout growth. Exogenous ethylene applied continuously has been demonstrated to act as a sprout suppressant in onion. However, the ethylene binding inhibitor, 1-methylcyclopropene (1-MCP), can also suppress sprouting in onion. Given this seemingly contradictory result, the precise role that ethylene plays during onion storage and the effect of curing on its efficacy is not understood.‘Sherpa’ and ‘Wellington’ onion bulbs were treated before or after curing (28°C for 6 weeks) with a single dose of 10μLL−1 ethylene or 1μLL−1 1-MCP for 24h at 20°C, or no treatment (control). Replicated out-turns were sampled during 38 weeks storage at 0–1°C. Sprout growth (31 weeks after harvest) was reduced in ‘Sherpa’ treated before curing with ethylene or before or after curing with 1-MCP. However, sprout growth of ‘Wellington’ was not affected by any treatment. Following treatment, the cured, thick-skinned ‘Wellington’ released a lower concentration of treatment gas compared with the newly harvested, thin-skinned ‘Sherpa’. Onion bulb respiration rate increased immediately after being treated with ethylene but to a lesser extent or not at all when treated with 1-MCP. Fructose concentrations of onions treated with ethylene or 1-MCP before curing were not significantly different, however, after curing concentrations were about 2-fold higher compared with the control. Mean glucose and sucrose concentrations for both cultivars were higher immediately after being treated before curing with ethylene or 1-MCP than control bulbs. It appears that inhibition of sprout growth can be achieved using just a short 24h treatment with ethylene or 1-MCP. However, skin thickness or permeability, which is dependent on cultivar and curing, may affect ethylene or 1-MCP influx and therefore efficacy of sprout suppressant action.
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There is a paucity of information on the role of ethylene in onion bulb dormancy, and the available literature is conflicting. Onion cv. SS1 bulbs were treated with 1μll−1 1-MCP for 24h at 20°C and then stored at 4, 12 or 20°C. Sprout growth was reduced in onions treated with 1-MCP and stored at 4 or 12°C, but not when stored at 20°C. Greater concentrations of sucrose, glucose and fructose were measured in 1-MCP treated bulbs stored at 12°C as compared with untreated bulbs. Dry weight was also maintained in onions treated with 1-MCP. Abscisic acid (ABA) concentration before storage has previously been shown to be correlated with storage life, but there were no differences in the ABA concentration between 1-MCP treated and untreated bulbs. It appeared that 1-MCP reduced the rate of carbon utilisation. The mechanism by which this occurred is unknown although it is unlikely to be mediated by ABA.
Article
The effects of postharvest storage duration and temperature on endogenous cis-zeatin (cis-Z) and cis-zeatin riboside (cis-ZR) levels in potato (Solanum tuberosum L.) tubers were determined in relation to tuber bud dormancy. The tubers used in these studies were completely dormant for at least 81 days of storage. Thereafter, tuber bud dormancy diminished gradually and after 165 days of postharvest storage, the tubers were completely non-dormant. Immediately after harvest, endogenous levels of cis-Z and cis-ZR were approximately 25 pmol (g fresh weight)−1 and 8 pmol (g fresh weight)−1, respectively. In tubers exiting dormancy but stored at a growth-inhibiting temperature (3°C), endogenous levels of cis-Z rose over threefold after 25 days of storage and remained elevated for the duration of the study. Levels of cis-ZR remained essentially constant during this same period. In tubers transferred to a growth permissive temperature (20°C) prior to use, the rise in endogenous cis-Z was less dramatic and more protracted; increasing twofold after 53 days of storage. No change in cis-Z riboside content was observed in these tubers during this period. Dose-response studies using either cis-Z or trans-Z demonstrated a time-dependent increase in cytokinin sensitivity during postharvest storage. Immediately after harvest, dormant tubers were insensitive to both zeatin isomers. Thereafter, tubers exhibited a dose-dependent increase in premature sprouting following injection with either cytokinin isomer. After injection into dormant tubers, cis-[8-14C]-zeatin was metabolized primarily to adenine/adenosine and cis-Z riboside. Seven days after injection, less than 10% of the recovered radioactivity was associated with trans-ZR. These results are consistent with a role for endogenous cis-Z (and its derivatives) in the regulation of potato tuber dormancy.
Article
Although many crops were brought to Europe by Columbus and others soon after the discovery of the New World in 1492, the potato arrived much later. This is because it is a cool-temperate crop of the high Andes of South America, and these were not discovered by the Spaniards until 1532. Potatoes were not recorded in the literature until 1537 in what is now Colombia, and did not feature in published works until 1552. No actual account has yet been discovered (and very probably does not exist) of potatoes being brought to Europe. All we can do is to record, where possible, their earliest presence there.One of the problems in such a study is to recognize in the literature whether the Solanum tuberosum potato or the Ipomoea batatas sweet potato is under discussion, or whether they are being confused with each other. Even the word potato known in Spanish as patata is obviously derived from batata yet the early Spanish authors seem always to have clearly distinguished between them. We ourselves checked the Seville archive records to make sure that the Solanum potato records of 1573 and 1576 were correct, and indeed we found that they were. The earlier English records, apart from that of Gerard, seem to have referred to the Ipomoea sweet potato.We report in this paper even earlier records from the Canary Isles, where patatas and batatas are clearly distinguished, and the South American word papa for Solanum tuberosum is also used sometimes (never, however, in continental Spain). Barrels of potatoes (patatas) were exported from Gran Canaria to Antwerp in November 1567 and from Tenerife via Gran Canaria to Rouen in 1574. Thus the potato was obviously being grown as a crop in Gran Canaria and Tenerife in 1567 and 1574, respectively. We can therefore assume with some certainty that it would have needed some five years to bulk it up sufficiently as an export crop, and hence might well have been introduced in about 1562. This is only ten years after the first published account in 1552 by Lpez de Gmara, and only thirty years after its presumed first sighting in Peru by Pizarro in 1532. It also seems to point towards the introduction of potatoes from South America into the Canary Isles, and not, as we had previously assumed, directly into continental Spain.
Article
The metabolism of [3H]-zeatin (Z) and[3H]-isopentenyladenosine (IPA) in potato tubers was examined inrelation to changes in cytokinin efficacy during postharvest storage anddormancy progression. Exogenous radiolabeled cytokinins were rapidlymetabolizedby dormant and nondormant tubers. Following injection, [3H]-Z wasmetabolized to zeatin riboside, adenine derivatives andzeatin-riboside-5-monophosphate. Four hours after injection, less than60% of the recovered radioactivity was associated with unmetabolized[3H]-Z. [3H]-IPA was also rapidly metabolized to severalmetabolites including: IPA-5-monophosphate, adenine derivatives andzeatin riboside. Four hours after injection, less than 50% of therecovered radioactivity was associated with [3H]-IPA. Cytokininsensitivity was assessed by determining the effects of exogenous Z or IPA ontuber sprouting. Immediately after harvest and during the initial period ofstorage, tubers were dormant and exogenous Z or IPA were completely ineffectivein breaking tuber dormancy. Thereafter, dormant tubers exhibited a gradualincrease in sensitivity to both cytokinins. Cytokinin sensitivity continued toincrease as postharvest storage was extended and dormancy weakened. The lengthof postharvest storage (hence dormancy status) had no apparent effects on themetabolism of either cytokinin. Neither the rate of metabolism nor the natureofmetabolites detected was affected by the length of postharvest storage. Theseresults suggest that changes in cytokinin efficacy in dormant potato tubersduring postharvest storage are not the result of differential catabolism butrather are due to other cellular processes such as hormone perception and/orsignal transduction.
Article
Since the discovery of 1-methylcyclopropene (1-MCP) as an inhibitor of ethylene action, over 100 studies have examined details of its action, application and effects on ethylene inhibition. This plant growth regulator is a tool that can help scientists make major advances in understanding the role of ethylene in plants. 1-MCP prevents ethylene effects in a broad range of fruits, vegetables and floriculture crops. Effective concentrations are low and range from 2.5 nl l−1 to 1 μl l−1. Concentration interacts with temperature such that low concentrations of 1-MCP applied over longer durations may be as effective as high concentrations. 1-MCP is most commonly applied at 68–77 °F (20–25 °C), but can be used at lower temperatures in some commodities. Generally, treatment durations of 12–24 h were sufficient to achieve a full response. A variety of factors may need to be considered when using 1-MCP including cultivar, developmental stage, time from harvest to treatment, and multiple applications. Depending on the species being treated, 1-MCP may have a variety of effects on respiration, ethylene production, volatile production, chlorophyll degradation and other color changes, protein and membrane changes, softening, disorders and diseases, acidity and sugars. This review compiles what is known about the technological uses for 1-MCP, defines where discrepancies exist between reports, and aims to define areas requiring further study.
Article
The recent availability of the inhibitor of ethylene perception, 1-methylcyclopropene (1-MCP), has resulted in an explosion of research on its effects on fruits and vegetables, both as a tool to further investigate the role of ethylene in ripening and senescence, and as a commercial technology to improve maintenance of product quality. The commercialization of 1-MCP was followed by rapid adoption by many apple industries around the world, and strengths and weaknesses of the new technology have been identified. However, use of 1-MCP remains limited for other products, and therefore it is still necessary to speculate on its commercial potential for most fruits and vegetables. In this review, the effects of 1-MCP on fruits and vegetables are considered from two aspects. First, a selected number of fruit (apple, avocado, banana, pear, peaches and nectarines, plums and tomato) are used to illustrate the range of responses to 1-MCP, and indicate possible benefits and limitations for commercialization of 1-MCP-based technology. Second, an outline of general physiological and biochemical responses of fruits and vegetables to the chemical is provided to illustrate the potential for use of 1-MCP to better understand the role of ethylene in ripening and senescence processes.
The use of ethylene for sprout control
  • A Briddon
Briddon, A., 2006.The use of ethylene for sprout control, British Potato Council Research Review No. 279
Dualeffectsofethyleneonpotatodormancyand sprout growth
  • I Rylski
  • L Rappaport
  • H K Pratt
Rylski,I.,Rappaport,L., Pratt,H.K.,1974.Dualeffectsofethyleneonpotatodormancyand sprout growth. Plant Phys. 33, 638-662.