Kun-Song Chen

Zhejiang University, Hang-hsien, Zhejiang Sheng, China

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Publications (35)69.09 Total impact

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    ABSTRACT: The AP2/ERF gene family encodes plant-specific transcription factors. In model plants, AP2/ERF genes have been shown to be expressed in response to developmental and environmental stimuli, and many function downstream of the ethylene, biotic, and abiotic stress signaling pathways. In citrus, ethylene is effective in regulation citrus fruit quality, such as degreening and aroma. However, information about the citrus AP2/ERF family is limited, and would enhance our understanding of fruit responses to environmental stress, fruit development and quality. CitAP2/ERF genes were isolated using the citrus genome database, and their expression patterns analyzed by real-time PCR using various orange organs and samples from a fruit developmental series. 126 sequences with homologies to AP2/ERF proteins were identified from the citrus genome, and, on the basis of their structure and sequence, assigned to the ERF family (102), AP2 family (18), RAV family (4) and Soloist (2). MEME motif analysis predicted the defining AP2/ERF domain and EAR repressor domains. Analysis of transcript accumulation in Citrus sinensis cv. 'Newhall' indicated that CitAP2/ERF genes show organ-specific and temporal expression, and provided a framework for understanding the transcriptional regulatory roles of AP2/ERF gene family members in citrus. Hierarchical cluster analysis and t tests identified regulators that potentially function during orange fruit growth and development.
    Molecular Biology Reports 02/2014; · 2.51 Impact Factor
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    ABSTRACT: Peach fruits are sensitive to chilling injury (CI) during postharvest cold storage and their subsequent shelf-life, which results in loss of quality and market value. Many studies have examined the development of CI, including analyses of changes in biochemical composition, enzyme activity and gene expression; however, the molecular mechanism of CI remains unresolved. Six C-repeat (CRT) / dehydration-responsive element (DRE) binding factor (CBF) genes (PpCBF1-6) were isolated and characterized in peach fruit based on their homology to CBF genes that are available in public Prunus persica genome databases. The expression patterns of these genes were analyzed in response to varying temperatures and durations of treatment. Transcription of PpCBF1/5/6 was induced at low temperatures, whereas expression of other CBF genes remained relatively constant. The results presented here indicate that treating peach fruit with a CI-delaying temperature (0 °C) resulted in a greater accumulation of PpCBF1/5/6 transcripts than that observed in fruit treated with a CI-inducing temperature (5 °C). CBF gene induction was accompanied by a decrease in CI symptoms, including a loss of firmness, flesh browning and increased electrical conductivity, throughout the experimental 21-day cold storage period. An analysis of the upstream nucleotide sequence of CBF genes showed that a cis element inducer of CBF expression 1 (ICEr1) was detected in the promoter of PpCBF1/5/6.
    Plant Molecular Biology Reporter 12/2013; · 5.32 Impact Factor
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    ABSTRACT: Anthocyanins, being important for both plant functions and human health, were transcriptionally regulated by the MYB–bHLH–WD40 transcription complex. The key MYB regulator for Chinese bayberry (Myrica rubra), MrMYB1, has been characterized in previous studies, while the specific bHLH partner(s) are unknown. In this study, MrbHLH1 and MrbHLH2 were isolated based on their homology to known plant bHLHs involved in anthocyanin biosynthesis regulation. Coordinate expression of MrbHLH1 with MrMYB1 and the anthocyanin biosynthetic genes was observed during fruit development, while MrbHLH2 showed a weaker correlation. Further transient assays in tobacco leaves suggested that MrbHLH1, but not MrbHLH2, was associated with MrMYB1 and triggered significant anthocyanin production. The lack of function of the MrbHLH2 in anthocyanin biosynthesis regulation suggested that different MrbHLH genes within the same phylogenic subfamily have different functions. Overexpression of MrMYB1 and MrbHLH1 in tobacco confirmed the crucial role of MrMYB1–MrbHLH1 in anthocyanin biosynthesis and all of the structural genes from NtCHS were up-regulated by the complex. Dual luciferase assays, however, indicated that MrMYB1 and MrbHLH1 selectively activated five of the eight promoters of biosynthetic genes from bayberry (MrCHI, MrF3′H, MrDFR1, MrANS, MrUFGT), although expression levels of all eight biosynthetic genes including MrCHS and downstream genes were coordinately increased during fruit ripening. Moreover, the interaction between MrbHLH1 and MrMYB1 was confirmed by yeast two-hybrid assay. In conclusion, MrbHLH1, but not MrbHLH2, was the essential partner of MrMYB1 during anthocyanin biosynthesis regulation in tobacco and bayberry, however, the biosynthetic genes in these two species responded differently to the MrMYB1–MrbHLH1 complex.
    Plant Cell Tissue and Organ Culture 12/2013; · 3.63 Impact Factor
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    ABSTRACT: Codon usage analysis has been a classical topic for decades and has significances for studies of evolution, mRNA translation, and new gene discovery, etc. While the codon usage varies among different members of the plant kingdom, indicating the necessity for species-specific study, this work has mostly been limited to model organisms. Recently, the development of deep sequencing, especial RNA-Seq, has made it possible to carry out studies in non-model species.Result: RNA-Seq data of Chinese bayberry was analyzed to investigate the bias of codon usage and codon pairs. High frequency codons (AGG, GCU, AAG and GAU), as well as low frequency ones (NCG and NUA codons) were identified, and 397 high frequency codon pairs were observed. Meanwhile, 26 preferred and 141 avoided neighboring codon pairs were also identified, which showed more significant bias than the same pairs with one or more intervening codons. Codon patterns were also analyzed at the plant kingdom, organism and gene levels. Changes during plant evolution were evident using RSCU (relative synonymous codon usage), which was even more significant than GC3s (GC content of 3rd synonymous codons). Nine GO categories were differentially and independently influenced by CAI (codon adaptation index) or GC3s, especially in 'Molecular function' category. Within a gene, the average CAI increased from 0.720 to 0.785 in the first 50 codons, and then more slowly thereafter. Furthermore, the preferred as well as avoided codons at the position just following the start codon AUG were identified and discussed in relation to the key positions in Kozak sequences. A comprehensive codon usage Table and number of high-frequency codon pairs were established. Bias in codon usage as well as in neighboring codon pairs was observed, and the significance of this in avoiding DNA mutation, increasing protein production and regulating protein synthesis rate was proposed. Codon usage patterns at three levels were revealed and the significance in plant evolution analysis, gene function classification, and protein translation start site predication were discussed. This work promotes the study of codon biology, and provides some reference for analysis and comprehensive application of RNA-Seq data from other non-model species.
    BMC Genomics 10/2013; 14(1):732. · 4.40 Impact Factor
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    ABSTRACT: Low temperature storage slows ripening and reduces decay of peach fruit, although storage life is limited due to chilling injury. Intermittent warming (IW) can be used to alleviate fruit chilling injury, however, its effect on aroma remains unknown. Yellow-fleshed peach (Prunus persica L. Batsch cv. Jinxiu) fruit (melting type) was stored at 5 °C or exposed to 20 °C for 1 d every week during storage. Changes in fruit esters, alcohol acyltransferase (AAT) activity and gene expression were investigated. Flesh browning (FB) was observed on the third day of shelf-life at 20 °C after 21 d of storage at 5 °C, while no FB was found in IW-treated fruit for up to 28 d. Significant lower ester contents were found in peach fruit with flesh browning. Expression profiles of PpAAT1 were similar to AAT activity profiles, both of which increased during shelf-life of fruit treated with IW. As precursors of esters, levels of linoleic and linolenic acids were high in IW-treated peach fruit. Treatment with IW effectively alleviated the loss of aroma-related esters associated with FB, and high levels of AAT activity and PpAAT1 expression in IW-treated peach fruit contributed to the formation of the esters.
    Postharvest Biology and Technology 12/2012; 74:42–48. · 2.45 Impact Factor
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    ABSTRACT: • Premise of the study: In Chinese bayberry (Myrica rubra), the available simple sequence repeat (SSR) markers are insufficient to meet the developing demand for genetic and molecular breeding research. This study was aimed at developing a large number of polymorphic expressed sequence tag (EST)-SSRs from the transcriptome of Chinese bayberry.• Methods and Results: Five hundred ninety-four compound EST-SSRs and 5557 noncompound ones were identified from 41239 unigene sequences generated from the transcriptome of M. rubra cv. Biqi. Using 10 Chinese bayberry cultivars, 109 polymorphic EST-SSRs were screened from 412 selected. In total, they generated 389 alleles, with a polymorphism ratio of 93.8%. In addition, it was observed that the polymorphism levels of compound EST-SSRs were somewhat lower than those of noncompound ones.• Conclusions: The 109 polymorphic EST-SSRs developed from the Chinese bayberry transcriptome should greatly promote the development of genetic and molecular breeding studies in this as well as other Myricaceae species.
    American Journal of Botany 11/2012; · 2.59 Impact Factor
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    ABSTRACT: The persimmon fruit is a particularly good model for studying fruit response to hypoxia, in particular, the hypoxia-response ERF (HRE) genes. An anaerobic environment reduces fruit astringency by converting soluble condensed tannins (SCTs) into an insoluble form. Although the physiology of de-astringency has been widely studied, its molecular control is poorly understood. Both CO(2) and ethylene treatments efficiently removed the astringency from 'Mopan' persimmon fruit, as indicated by a decrease in SCTs. Acetaldehyde, the putative agent for causing de-astringency, accumulated during these treatments, as did activities of the key enzymes of acetaldehyde synthesis, alcohol dehydrogenase (ADH), and pyruvate decarboxylase (PDC). Eight DkADH and DkPDC genes were isolated, and three candidates for a role in de-astringency, DkADH1, DkPDC1, and DkPDC2, were characterized by transcriptional analysis in different tissues. The significance of these specific isoforms was confirmed by principal component analysis. Transient expression in leaf tissue showed that DkPDC2 decreased SCTs. Interactions of six hypoxia-responsive ERF genes and target promoters were tested in transient assays. The results indicated that two hypoxia-responsive ERF genes, DkERF9 and DkERF10, were involved in separately regulating the DkPDC2 and DkADH1 promoters. It is proposed that a DkERF-DkADH/DkPDC cascade is involved in regulating persimmon de-astringency.
    Journal of Experimental Botany 10/2012; · 5.24 Impact Factor
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    ABSTRACT: Chinese bayberry (Myrica rubra Sieb. and Zucc.) is an important subtropical fruit crop and an ideal species for fruit quality research due to the rapid and substantial changes that occur during development and ripening, including changes in fruit color and taste. However, research at the molecular level is limited by a lack of sequence data. The present study was designed to obtain transcript sequence data and examine gene expression in bayberry developing fruit based on RNA-Seq and bioinformatic analysis, to provide a foundation for understanding the molecular mechanisms controlling fruit quality changes during ripening. RNA-Seq generated 1.92 G raw data, which was then de novo assembled into 41,239 UniGenes with a mean length of 531 bp. Approximately 80% of the UniGenes (32,805) were annotated against public protein databases, and coding sequences (CDS) of 31,665 UniGenes were determined. Over 3,600 UniGenes were differentially expressed during fruit ripening, with 826 up-regulated and 1,407 down-regulated. GO comparisons between the UniGenes of these two types and interactive pathways (Ipath) analysis found that energy-related metabolism was enhanced, and catalytic activity was increased. All genes involved in anthocyanin biosynthesis were up-regulated during the fruit ripening processes, concurrent with color change. Important changes in carbohydrate and acid metabolism in the ripening fruit are likely associated with expression of sucrose phosphate synthase (SPS) and glutamate decarboxylase (GAD). Mass sequence data of Chinese bayberry was obtained and the expression profiles were examined during fruit ripening. The UniGenes were annotated, providing a platform for functional genomic research with this species. Using pathway mapping and expression profiles, the molecular mechanisms for changes in fruit color and taste during ripening were examined. This provides a reference for the study of complicated metabolism in non-model perennial species.
    BMC Genomics 01/2012; 13:19. · 4.40 Impact Factor
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    ABSTRACT: Chinese bayberry fruit is a rich source of anthocyanins, especially cyanidin-3-glucoside (C3G). The present study investigated the protective effects of C3G-rich bayberry fruit extract (CRBFE) against pancreatic β cells against oxidative stress-induced injury as well as its hypoglycemic effect in diabetic mice. Bayberry extract from "Biqi" was used for both in vitro and in vivo testing because of its high C3G content and high antioxidant capacity. Pretreatment of β cells with CRBFE (containing 0.5 μmol/L C3G) prevented cell death, increased cellular viability, and decreased mitochondrial reactive oxygen species production and cell necrosis induced by 800 or 1,200 μmol/L H₂O₂. CRBFE dose-dependently up-regulated pancreatic duodenal homeobox 1 gene expression, contributing to increased insulin-like growth factor II gene transcript levels and insulin protein in INS-1 cells. In addition, administration of CRBFE (150 μg of C3G/10 g of body weight twice per day) significantly reduced blood glucose in streptozotocin-induced diabetic ICR mice and increased the glucose tolerance in an oral glucose tolerance test (P<.05). Such results indicated that CRBFE might be useful in prevention and control of diabetes mellitus and diabetes-associated complications.
    Journal of medicinal food 12/2011; 15(3):288-98. · 1.39 Impact Factor
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    ABSTRACT: Thirteen ethylene signaling related genes were isolated and studied during ripening of non-astringent 'Yangfeng' and astringent 'Mopan' persimmon fruit. Some of these genes were characterized as ethylene responsive. Treatments, including ethylene and CO(2), had different effects on persimmon ripening, but overlapping roles in astringency removal, such as increasing the reduction in levels of soluble tannins. DkERS1, DkETR2, and DkERF8, may participate in persimmon fruit ripening and softening. The expression patterns of DkETR2, DkERF4, and DkERF5 had significant correlations with decreases in soluble tannins in 'Mopan' persimmon fruit, suggesting that these genes might be key components in persimmon fruit astringency removal and be the linkage between different treatments, while DkERF1 and DkERF6 may be specifically involved in CO(2) induced astringency removal. The possible roles of ethylene signaling genes in persimmon fruit astringency removal are discussed.
    Planta 11/2011; 235(5):895-906. · 3.35 Impact Factor
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    ABSTRACT: The biosynthesis of volatile compounds in plants is affected by environmental conditions. Lactones are considered to be peach-like aroma volatiles; however, no enzymes or genes associated with their biosynthesis have been characterized. White-fleshed (cv. Hujingmilu) and yellow-fleshed (cv. Jinxiu) melting peach (Prunus persica L. Batsch) fruit were used as materials in two successive seasons and responses measured to four different temperature treatments. Five major lactones accumulated during postharvest peach fruit ripening at 20 °C. Peach fruit at 5 °C, which induces chilling injury (CI), had the lowest lactone content during subsequent shelf life after removal, while 0 °C and a low-temperature conditioning (LTC) treatment alleviated development of CI and maintained significantly higher lactone contents. Expression of PpACX1 and activity of acyl-CoA oxidase (ACX) with C16-CoA tended to increase during postharvest ripening both at 20 °C and during shelf life after removal from cold storage when no CI was developed. There was a positive correlation between ACX and lactones in peach fruit postharvest. Changes in lactone production in response to temperatures are suggested to be a consequence of altered expression of PpACX1 and long-chain ACX activity.
    Plant Cell and Environment 09/2011; 35(3):534-45. · 5.14 Impact Factor
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    ABSTRACT: Using tomato (Solanum lycopersicum L. cv. Micro-Tom) leaf as material, a simple and rapid DNA preparation protocol was established. This method required only 2-20 mm2 leaf with only one extraction solution and involved one pipetation and one centrifugation each. No precipitation was required. The suitable volume of prepared DNA solution, as PCR template, for real-time quantitative PCR was determined to be 0.10.2 μL in 12.5 μL final reaction volume. The excessive template DNA solution was confirmed to reduce PCR efficiency and even can result in PCR failure. This technique for rapid preparation of DNA and a compatible real-time quantitative PCR were successfully applied in transgene detection of tomato plants.
    Hereditas (Beijing) 09/2011; 33(9):1017-22.
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    ABSTRACT: High performance liquid chromatography (HPLC) method was applied to determine the content of oleanolic acid (OA) and ursolic acid (UA) in different tissues of 'Ruantiaobaisha' and 'Dayeyangdun' loquat (Eriobotrya japonica Lindl.) fruits in this research. The results demonstrated that peel contained higher OA and UA contents, while flesh and kernel contained very lower amounts of OA and UA. On the basis of above results, the OA and UA contents in the peel of different developmental stages and different cultivars of loquat fruits were analyzed and compared. It is found that OA and UA contents in the peel varied with different developmental stages and cultivars. The OA and UA content in the peel of ripe fruit of different cultivars were in the range of 0.59-1.68 and 2.82-8.20 mg/g DW, respectively. These results can provide a theoretical basis for the comprehensive utilization of loquat fruit in the future.
    Journal of Medicinal Plants Research. 04/2011; 5:1735-1740.
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    ABSTRACT: Melting flesh peach (Prunus persica L. Batsch., cv. Hujingmilu) fruit were harvested and stored at 0, 5, 8°C for up to 21 d. Data on emission of characteristic aroma-related volatiles, and expression patterns of related genes, including lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), and alcohol acyltransferase (AAT), were obtained from fruit at the different low temperatures for 7, 14 and 21 d and a subsequent shelf-life for 3 d after each of those storage times. Production of volatiles was markedly influenced by storage temperature and time. In general, fruit at 5°C were sensitive to chilling injury (CI) and had the lowest levels of volatile compounds, especially fruity note volatiles such as esters and lactones. An electronic nose (e-nose) was used to evaluate peach aroma, and the CI fruit could be separated from those at low temperature but which had not developed the disorder. Relative expression levels of genes involved in the LOX pathway were repressed in fruit with CI. Of the LOX family genes, PpLOX1 and PpLOX3 were upregulated in association with accumulated ethylene during shelf-life, while levels of PpLOX2 and PpLOX4 declined after removal. Expression of PpHPL1, PpADH1, PpADH2, and PpADH3 exhibited similar decreasing patterns during shelf-life, whereas transcript levels of PpAAT1 were induced. The results suggest that reduced levels of fruity note volatiles in fruit with CI were the consequence of modifications in expression of PpLOX1, PpLOX3 and PpAAT1; the significance of ethylene in relation to aroma-related volatiles production after cold storage is discussed.
    Postharvest Biology and Technology - POSTHARVEST BIOL TECHNOL. 01/2011; 60(1):7-16.
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    ABSTRACT: Three ethylene biosynthesis related genes, EjACS1, EjACO1, and EjACO2, were cloned from the non-climacteric loquat fruit (Eriobotrya japonica Lindl. cv. Luoyangqing). Real-time quantitative PCR (Q-PCR) analysis showed the specific expression of the EjACS1 and EjACO1 genes in fruit, whereas EjACO2 was also expressed in leaves and petals. The expression pattern of EjACO2 was consistent with ethylene production during fruit development, which reached a peak when the fruit color was turning. EjACS1, EjACO1, and EjACO2 all showed low transcript levels throughout 20 °C storage in the postharvest ripening loquat. This is the first time that the expression of ethylene biosynthesis related genes has been studied in loquat fruit. Climacteric increases in ethylene production and respiration rate were observed during the development of loquat fruit, and EjACO2 may play an important role in this process.Highlights► Ripening of non-climacteric loquat fruit may be regulated by ethylene biosynthesis. ► Climacteric increase in ethylene synthesis was observed during loquat development. ► Climacteric increases in respiration rate were observed during loquat development. ► EjACO2 may play an important role in loquat ethylene biosynthesis.
    Scientia Horticulturae 01/2011; 130(2):452-458. · 1.40 Impact Factor
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    ABSTRACT: Kiwifruit (Actinidia deliciosa) is a climacteric fruit sensitive to low concentrations of ethylene. To investigate the transcriptional mechanisms underlying kiwifruit ethylene response, transcription factors encoding four EIN3-Like (EILs) and 14 Ethylene Response Factors (ERFs) were cloned from kiwifruit. Expression of these transcription factors was examined during fruit development. The expression of transcripts of most AdERFs was higher during early fruit development, with the exception of AdERF3, which increased with maturity. Several AdERFs were apparently down-regulated by ethylene, as they were affected by the ethylene inhibitor 1-methylcyclopropene and by antisense suppression of ACO (for 1-aminocyclopropane-1-carboxylic acid oxidase) in the fruit. In contrast, AdEILs were constitutively expressed during fruit development and ripening. The transcription factors AdEIL2 and AdEIL3 activated transcription of the ripening-related genes AdACO1 and AdXET5 (xyloglucan endotransglycosylase gene) and, when overexpressed in Arabidopsis (Arabidopsis thaliana), stimulated ethylene production. The potential repressor AdERF9 suppressed this promoter activity. These results support a role for kiwifruit EILs and ERFs in transcriptional regulation of ripening-related genes and in the regulation of kiwifruit fruit-ripening processes.
    Plant physiology 05/2010; 153(3):1280-92. · 6.56 Impact Factor
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    ABSTRACT: Chinese bayberry (Myrica rubra) is a fruit crop with cultivars producing fruit ranging from white (Shuijing, SJ) to red (Dongkui, DK) and dark red-purple (Biqi, BQ), as a result of different levels of anthocyanin accumulation. Genes encoding the anthocyanin biosynthesis enzymes chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase (F3H), flavonoid 3'-hydroxylase (F3'H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS) and UDPglucose: flavonoid 3-O-glucosyltransferase (UFGT), as well as MrMYB1, a R2R3 MYB transcription factor homologous to known activators of anthocyanin biosynthesis, were isolated from ripe fruit of BQ. Differences in mRNA abundance of MrF3H, MrF3'H, MrDFR1, MrANS and MrUFGT were highly correlated with differential accumulation of anthocyanins between cultivars, suggesting coordinated regulation by transcription factors. The transcript level of MrMYB1 was strongly associated with the anthocyanin content in ripe fruit of the three cultivars, as well as different anthocyanin containing tissues of BQ fruit. Fruit bagging strongly inhibited anthocyanin accumulation in fruit as well as the expression of all anthocyanin biosynthetic genes and MrMYB1. Overexpression of MrMYB1 stimulated both anthocyanin accumulation and activated an Arabidopsis-DFR promoter in tobacco (Nicotiana tabacum). MrMYB1d, an allele with a 1 bp deletion at nucleotide 30 of coding sequence, was observed in SJ and DK fruit, suggesting that a nonsense mutation of the MYB1 protein may be responsible for no or low expression of MYB1 in the white and red fruit. These results show that coordinated expression of multiple biosynthetic genes is involved in anthocyanin accumulation in Chinese bayberry fruit, and this is regulated by MrMYB1.
    Planta 03/2010; 231(4):887-99. · 3.35 Impact Factor
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    ABSTRACT: To avoid winter frost, Ponkan (Citrus reticulata Blanco cv. Ponkan) fruit in Zhejiang Province, China, is frequently harvested early, while chlorophylls are still present in the peel. Postharvest degreening of Ponkan fruit, through either ethylene fumigation or ethephon dipping, was carried out to study the effects of both treatments on color development and carotenoid accumulation. An earlier and deeper orange color development after treatments was indicated by a decline in hue angle (H°) and an increase in the citrus color index (CCI). Total carotenoid content increased, while chlorophyll content decreased during storage at 10°C, and these changes were accelerated by both treatments. The treatments stimulated preferential accumulation of carotenoids with orange color (β-carotene and β-cryptoxanthin) while reducing the abundance of carotenoids with yellow color (lutein, violaxanthin and 9-cis-violaxanthin). Gene expression of β-carotene hydroxylase (BCH) was inhibited by both treatments, which could be related to the changes in composition of these differently colored carotenoids.
    Scientia Horticulturae - SCI HORT-AMSTERDAM. 01/2010; 126(2):229-235.
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    ABSTRACT: During postharvest ripening of kiwifruit [ Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa cv. Bruno] at 20 degrees C, six lipoxygenase (LOX) genes exhibited different expression patterns. AdLox1 and AdLox5 were up-regulated during ripening, and transcript accumulation was delayed by 1-methylcyclopropene (1-MCP), whereas AdLox2, AdLox3, AdLox4, and AdLox6 were down-regulated with ripening. Levels of two volatiles arising from the LOX pathway, that is, n-hexanal and (E)-2-hexenal, were highest after harvest and declined during ripening at 20 degrees C, whereas the characteristic kiwifruit esters ethyl and methyl butanoate levels increased late in the ripening process. Individual fatty acid concentrations underwent little change during ripening, with linoleic (LA) and linolenic (LeA) acids constituting about 40% of the total. Application of LA and LeA to kiwifruit flesh disks promoted LOX activity and n-hexanal and (E)-2-hexenal generation, whereas inhibitors of LOX, n-propyl gallate (n-PG) and nordihydroguariaretic acid (NDGA), caused a parallel reduction in enzyme activity and in the production of C6 aldehydes. The six LOX genes showed different sensitivities to the LOX substrates and inhibitors. The ethylene up-regulated genes AdLox1 and AdLox5 were induced by LA and LeA and inhibited by n-PG and NDGA. Of the LOX genes that were down-regulated by ethylene, only AdLox4 and AdLox6 were stimulated in response to the substrates and retarded by the inhibitors. The possible roles of the six LOX genes in kiwifruit ripening and aroma development are discussed.
    Journal of Agricultural and Food Chemistry 05/2009; 57(7):2875-81. · 2.91 Impact Factor
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    ABSTRACT: The aim of this study was to follow expression of ethylene signalling genes during storage and ripening of kiwifruit at low temperature. Kiwifruit (Actinidia deliciosa [A. Chev.] C.F. Liang et A.R. Ferguson var. deliciosa cv. Hayward) were stored at 0 °C for 12 weeks, followed by 6 d of shelf-life at 20 °C. Fruit ripened and softened slowly during storage at 0 °C, and no ethylene was detectable at the end of storage or during shelf-life. Five ethylene receptor genes, two CTR1-like genes and four EIN3-like genes showed different changes in expression during low temperature storage. Those genes showing altered expression could be divided into three groups: AdERS1a, AdETR2, AdETR3, AdCTR1 and four EIN3-like genes were up-regulated, while AdERS1b and AdETR1 were suppressed, and AdCTR2 was largely unchanged. On transfer to 20 °C shelf-life, most genes showed no substantial change, except for AdETR3 which was suppressed and AdETR1 and AdERS1b which were up-regulated. These gene expression patterns are indicative of specific and differential gene responses to low temperature during kiwifruit ripening.
    Postharvest Biology and Technology. 01/2009;