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Ethylene Is Not Involved in Hormone- and Bromoethane-Induced Dormancy Break in Russet Burbank Minitubers

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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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... Dormancy of a potato tuber is defined as the physiological state in which autonomous sprout growth will not occur, even when the tuber is placed under conditions for sprout growth (Suttle, 2009;Reust, 1986) [91,72] . At harvest, potato tubers are dormant and will not sprout. ...
... Similarly, Suttle (2007) [92] indicated that long tuber dormancy is generally found in wild potato populations whereas the reverse is often true in potato lines developed by modern breeding. The length of the dormancy period depends on the genetic background and is affected by pre-harvest and post-harvest conditions (Suttle, 2004a) [90] . With the onset of sprouting, the tuber turns into a source organ supporting growth of the developing sprout. ...
... Dormancy period is influenced by the age of tuber and environmental conditions that prevail during the tuber development on the mother plant and after harvest (Struik, 2007;Rehman et al., 2001) [82,71] . In order to terminate premature dormancy and induce sprouting there are diverse range of physical, chemical and hormonal treatments (Coleman, 1987;Burton, 1989;Suttle, 2009) [17,13,91] . A number of exogenous chemicals can remove dormancy from field grown tubers (Coleman, 1987;Wiltshire and Cobb, 1996) [17,110] , but similar evaluation for micro-tubers have been limited. ...
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The production of potato in two or more cycles within a year is increasing in the country and it is a common practice in most potato producing regions of Ethiopia. However, the characteristic long tuber dormancy of improved potato varieties in Ethiopia constrains double or triple cropping using irrigation during the long dry season of the year. Thus, it is important to break the long dormancy of tubers for early sprouting and timely planting. Therefore, several types of researches were conducted so far to assess the effect of plant growth regulators and other chemicals to assess its effect on tubers dormancy break, sprouting, sprouts growth, and subsequent effect on tuber yield, yield related and tuber quality of potato varieties. For dormancy break, sprouting and subsequent yield various methods of applications (haulm & dipping) and concentration rates were applied. Moreover, the effect of dormancy-breaking treatment and storage methods were conducted. Results of the studies indicated that, tuber dormancy period and sprout vigour were significantly influenced by the interaction of GA3 and variety, while other sprouting as well as sprout growth traits were significantly influenced by the main effects of GA3 and varieties. The interaction effect of varieties and GA3 significantly influenced days to maturity. Planting of tubers treated with the highest concentration of GA3 produced a significantly highest marketable tuber yield. The optimum tuber size (medium size) for planting purpose was attained from planting of tubers treated with 40 ppm GA3. Significant increase in tuber number and weight due to GA3 application contributed to the increase of total tuber yield. Application of GA3 and storage methods as well as the interaction among the varieties and treatments significantly affected tuber dormancy period, sprouting characteristics and subsequent tuber yield. The mean values for tuber quality (DM & SG) related traits increased in response to treating the tubers with higher concentrations rate of GA3 for both methods of application. Potato varieties treated with GA3 showed significantly higher tuber dry matter yields, specific gravity and total starch content than the other variety. The highest net benefit with an acceptable marginal rate of return was attained in response to treating tubers with higher rates of GA3. Therefore, it could be concluded that haulm application and dipping tuber in GA3 at higher concentration increased tuber yield with a possibility of cultivating potato for two to three production cycles in a year that enhance productivity per unit area, food and nutrition security as well as farmers' income.
... Hormonal control of tuber dormancy release and sprouting in the dark has been investigated in several studies, but is still not well understood (see review by Sonnewald and Sonnewald, 2014). Mainly abscisic acid (ABA) and ethylene have been linked to the onset and maintenance of tuber dormancy (Suttle and Hultstrand, 1994;Suttle, 2004b): ABA levels are highest in deeply dormant tubers and decline during storage, as dormancy is released (Biemelt et al., 2000;Destefano-Beltran et al., 2006); ethylene has been recognized to play a dual role in sprouting, promoting or inhibiting etiolated bud growth at low and high concentrations, respectively (Suttle, 1998(Suttle, , 2004b(Suttle, , 2009Pierik et al., 2006). Gibberellins (GAs) and cytokinins (CKs) have been associated with dormancy release and etiolated sprouting of post-harvest potato tubers or their detached buds (Suttle, 2004a;Hartmann et al., 2011;Rentzsch et al., 2011). ...
... Tubers were washed in tap water and dried at room temperature. Treatment with exogenous phytohormones was performed according to Suttle (2009) with some modifications: the treated bud base was stabbed to a depth of 3 mm with a 1-mm diameter sterile tip, 2 mm from the fifth LT (counted from the AP down the tuber) and then subjected to vacuum infiltration for 10 min. The AP and sixth LT (middle of the tuber and opposite to the treated fifth LT) were sampled at 0, 24, 48 and 72 h after treatment using a 0.3-mm diameter cork borer into N 2 and stored at -80 °C until use. ...
... Most ethylene-related genes were down-regulated in response to GA 3 , especially in the AP (Fig. 9). Suttle (2009) suggested that ethylene is not involved in dormancy break. In our study, some of the ethylene-metabolism genes were down-regulated in the AP and some of the ethylene receptorencoding genes were up-regulated in the LT, both after GA 3 treatment (Fig. 9), suggesting ethylene's role in controlling bud burst and elongation. ...
Article
The potato tuber is a swollen underground stem that can sprout under dark conditions. Sprouting initiates in the tuber apical bud (AP), while lateral buds (LTs) are repressed by apical dominance (AD). Under conditions of lost AD, removal of tuber LTs showed that they partially inhibit AP growth only at the AD stage. Detached buds were inhibited by exogenous application of naphthaleneacetic acid (NAA), whereas 6-benzyladenine (6-BA) and gibberellic acid (GA3) induced bud burst and elongation, respectively. NAA, applied after 6-BA or GA3, nullified the latters’ growth-stimulating effect in both the AP and LTs. GA3 applied to the fifth-position LT was transported mainly to the tuber’s AP. GA3 treatment also resulted in increased indole-3-acetic acid (IAA) concentration and cis-zeatin O-glucoside in the AP. In a tuber tissue strip that included two or three buds connected by the peripheral vascular system, treatment of a LT with GA3 affected only the AP side of the strip, suggesting that the AP is the strongest sink for GA3, which induces its etiolated elongation. Dipping etiolated sprouts in labeled GA3 showed specific accumulation of the signal in the AP. Transcriptome analysis of GA3’s effect showed that genes related to the cell cycle, cell proliferation, and hormone transport are up-regulated in the AP as compared to the LT. Sink demand for metabolites is suggested to support AD in etiolated stem growth by inducing differential gene expression in the AP.
... While the role of ethylene during seed dormancy release (Corbineau et al. 2014) and submergence-induced growth promotion (Fukao and Bailey-Serres 2008) may imply a similar function in buds, its role during bud dormancy maintenance and release, and in growth resumption remains unclear. The role for ethylene in potato tuber dormancy maintenance and release remains quite ambiguous (Aksenova et al. 2013;Sonnewald and Sonnewald 2014): on the one hand, ethylene treatments can either shorten or delay the dormancy period, depending on treatment duration and concentration (Prange et al. 1998;Rylski et al. 1974), Bromoethane (BE), a dormancy release stimulus, temporarily increases ethylene production (Alexopoulos et al. 2009;Suttle 2009), and ethylene response functions are downregulated during sprouting (Hartmann et al. 2011). On the other hand, the effect of BE is not negatively influenced by inhibitors of ethylene signalling, and ethylene synthesis inhibitors did not inhibit bud break. ...
... On the other hand, the effect of BE is not negatively influenced by inhibitors of ethylene signalling, and ethylene synthesis inhibitors did not inhibit bud break. Additionally, ethylene and ACC treatments do not break minituber dormancy (Suttle 2009). ...
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Key message Transient increases in ethylene biosynthesis, achieved by tight regulation of transcription of specific ACC oxidase and ACC synthase genes, play a role in activation of grapevine bud dormancy release. Abstract The molecular mechanisms regulating dormancy release in grapevine buds are as yet unclear. It has been hypothesized that its core involves perturbation of respiration which induces an interplay between ethylene and ABA metabolism that removes repression and allows regrowth. Roles for hypoxia and ABA metabolism in this process have been previously supported. The potential involvement of ethylene biosynthesis in regulation of dormancy release, which has received little attention so far, is now explored. Our results indicate that (1) ethylene biosynthesis is induced by hydrogen cyanamide (HC) and azide (AZ), known artificial stimuli of dormancy release, (2) inhibitors of ethylene biosynthesis and signalling antagonize dormancy release by HC/AZ treatments, (3) ethylene application induces dormancy release, (4) there are two sets of bud-expressed ethylene biosynthesis genes which are differentially regulated, (5) only one set is transiently upregulated by HC/AZ and during the natural dormancy cycle, concomitant with changes in ethylene levels, and (6) levels of ACC oxidase transcripts and ethylene sharply decrease during natural dormancy release, whereas ACC accumulates. Given these results, we propose that transient increases in ethylene biosynthesis prior to dormancy release, achieved primarily by regulation of transcription of specific ACC oxidase genes, play a role in activation of dormancy release.
... Ethylene is one of the growth regulators commonly used in agriculture, due to the effects of many physiological processes. Due to the high diffusion rate (gas hormone), it becomes difficult to apply in plants, under field conditions (Suttle, 2009). However, this limitation can be overcome by the use of compounds that release ethylene (Coleman et al., 2001). ...
... reported that pre-treatment of the rhizomes with growth regulators BAP (250 mg L -1 ) + Ethrel (250 mg L -1 ) does not induce greater formation of lateral buds in tannia genotypes Comum, Roxa and Caxixe. The promoting effect of ethylene (Ethrel) is to increase the release and the movement of these hydrolytic enzymes and cause increased breathing and sugar content (Suttle, 2009). ...
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Specific clones of tannia are commonly used as cooking leaves in some Brazilian states. The crop is propagated exclusively asexually by planting the rhizomes usually after a few years of production. Because of that, there is the need to establish strategies to propagate healthy plantlets with higher sprouting rate for leaf production. This work had the goals to evaluate the influence of growth regulators and carving of the rhizomes sprouting and growth of tannia. Cured rhizomes from the clone 'Caipira' were stored for three months at 5°C and 89% relative humidity. Afterward, the top of half of the rhizomes were carved in a V shape at the top (carving), to stimulate lateral sprouting. The rhizomes were submerged for 30 minutes in solutions containing 6-benzylaminopurine (BAP) and/or 2-chloroethylphosphonic acid (ethephon), and the respective control. The production of new leaves and expansion of leaf area were stimulated by treating the rhizomes with 500 mg L-1 BAP and 250 mg L-1 BAP + 250 mg L-1 ethephon. Regardless the use of growth regulators, the carving induced higher number of new sprouted leaves after 35 days of planting. Similarly, rhizomes treated with 500 mg L-1 BAP or 250 mg L-1 BAP + 250 mg L-1 ethephon had higher number of sprouts after 49 days of planting. Sprouting was anticipated when the carved rhizomes were treated with 250 mg L-1 BAP + 250 mg L-1 ethephon.
... While endodormancy is controlled by mechanisms endogenous to the bud, paradormancy is due to the control of other organs on a given bud, as it is the case in apical dominance. Apical dominance can be lifted by stem beheading (Dun et al., 2006) or by exogenous application of chemical products (Ophir et al., 2009;Suttle, 2009;Walton et al., 2009). Ecodormancy relies on environmental control over a bud. ...
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Shoot branching is highly dependent on environmental factors. While many species show some light dependence for branching, the rosebush shows a strict requirement for light to allow branching, making this species an excellent model to further understand how light impinges on branching. Here, in the first part, we provide a review of the current understanding of how light may modulate the complex regulatory network of endogenous factors like hormones (SL, IAA, CK, GA, and ABA), nutrients (sugar and nitrogen), and ROS to control branching. We review the regulatory contribution of microRNAs (miRNAs) to branching in different species, highlighting the action of such evolutionarily conserved factors. We underline some possible pathways by which light may modulate miRNA-dependent regulation of branching. In the second part, we exploit the strict light dependence of rosebush for branching to identify putative miRNAs that could contribute to the photocontrol of branching. For this, we first performed a profiling of the miRNAs expressed in early light-induced rosebush buds and next tested whether they were predicted to target recognized regulators of branching. Thus, we identified seven miRNAs (miR156, miR159, miR164, miR166, miR399, miR477, and miR8175) that could target nine genes ( CKX1/6 , EXPA3 , MAX4 , CYCD3;1 , SUSY , 6PFK , APX1 , and RBOHB1 ). Because these genes are affecting branching through different hormonal or metabolic pathways and because expression of some of these genes is photoregulated, our bioinformatic analysis suggests that miRNAs may trigger a rearrangement of the regulatory network to modulate branching in response to light environment.
... A study carried out on cv. Russet Burbank minitubers demonstrated that ethylene was not involved in the hormone-induced dormancy break (Suttle 2009). Therefore, the effect of ethylene seems to depend on the physiological state of potato tubers. ...
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.
... A study carried out on cv. Russet Burbank minitubers demonstrated that ethylene was not involved in the hormone-induced dormancy break (Suttle 2009). Therefore, the effect of ethylene seems to depend on the physiological state of potato tubers. ...
Chapter
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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.
... However, work carried out on cv. Russet Burbank minitubers showed that ethylene was not involved in hormone-induced dormancy break (Suttle, 2009). These findings support the suggestion that the effect of ethylene depends on the physiological state of potato tubers. ...
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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.
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Chapter
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Chapter
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