Dormancy Release Process Research Articles

Genome-wide analysis of non-coding RNA reveals the role of a novel miR319c for tuber dormancy release process in potato

Abstract Tuber dormancy and sprouting are significant for potato cultivation, storage, and processing. Although the substantial role of miRNAs in some biological processes has been recognized, the critical role of miRNA in breaking potato tuber dormancy is not well understood to date. In this investigation, we expand research on miRNA-mediated gene regulation in tuber dormancy release. In this work, 204 known and 192 novel miRNAs were identified. 136 differentially expressed miRNAs (DE-miRNAs) were also screened out, of which 56 DE-miRNAs were regulated by temperature during tuber dormancy release. Additionally, degradome sequencing revealed that 821 target genes for 202 miRNAs were discovered. Among them, 63 target genes and 48 miRNAs were predicted to be involved in plant hormone signaling pathways. This study used degradome sequencing, tobacco co-transformation system, and GUS staining technology to confirm that stu-miR319c can target StTCP26 and StTCP27 and effectively suppress their expression. The transgenic approach exhibited that stu-miR319c overexpressed tubers sprouted in advance, while silent expression of stu-miR319c showed delayed sprouting. Treatment of wild-type tubers with exogenous MeJA revealed that 1 mg/L MeJA significantly broke dormancy and enhanced potato sprouting ability. Furthermore, transgenic tubers revealed variance in JA content and relative expression of genes associated with JA synthesis pathway, including StAOC, StLOX2, and StLOX4, suggesting that the miR319c may participate in the JA pathway to regulate tuber dormancy release. In summary, our research offers evidence that miRNA regulates potato dormancy release and supports the idea that stu-miR319c is a unique epigenetic regulator for dormancy-sprouting transition in potatoes.

StSnRK1.1 protein kinase positively regulates tuber dormancy release of potato

SnRK1 is a plant-specific serine/threonine protein kinase, that plays a vital role in maintaining the energy balance, nutrient distribution, growth, and development of organisms for survival. The period of tuber dormancy seriously affects potato production. To elucidate the effect of the StSnRK1.1 gene on dormancy release, the gene was cloned from the potato cultivar 'Desiree', and the overexpression and interfering expression lines were obtained through genetic transformation. StSnRK1.1 promoted early dormancy release and sprouting of potato tubers in the overexpression line, while it delayed tuber sprouting in the StSnRK1.1-interfering expression line. In addition, it was discovered that abscisic acid (ABA) in the StSnRK1.1 overexpression line was significantly reduced compared with the wild type plants, while the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were increased. Conversely, the opposite result was found in the StSnRK1.1 gene interference expression line, which indicated that the dormancy release was accelerated, the reactive oxygen species metabolism efficiency was high, and the reactive oxygen species could be quickly removed and the accumulation of reactive oxygen species could be avoided during the dormancy release process. The positive regulatory genes StSnRK2.2 and StABI5 of ABA signal transduction were lower than those of wild type in the overexpression line and higher than that of the wild type in the interfering expression line, while the negative regulatory genes StPP2CA1 and StPP2CA3 of ABA signal transduction were higher than those of the wild type in the overexpression line and lower than that of the wild type in the interfering expression line. In summary, StSnRK1.1 affects ABA signaling by mediating the expression of StSnRK2.2, StABI5, StPP2CA1 and StPP2CA3, which provides a theoretical basis for the molecular mechanism of StSnRK1.1 to positively regulate the release of potato tuber dormancy. Through yeast two-hybrid (YH2) screening, two interacting proteins, StCAT3 and StFBA1, were identified. The interaction between StCAT3, StFBA1 and StSnRK1.1 was confirmed through bimolecular fluorescence complementation. These results provide novel information for further study on the molecular mechanism of StSnRK1.1 regulating dormancy and germination of potato tubers.

Transcriptomic and Metabolomic Research on the Germination Process of Panax ginseng Overwintering Buds.

Ginseng (Panax ginseng C. A. Meyer) is a perennial plant with a long dormancy period. While some researchers employ gibberellin and other substances to stimulate premature germination, this method is limited to laboratory settings and cannot be applied to the field cultivation of ginseng. The mechanism underlying the germination of ginseng overwintering buds remains largely unexplored. Understanding the internal changes during the dormancy release process in the overwintering buds would facilitate the discovery of potential genes, metabolites, or regulatory pathways associated with it. In this study, we approximately determined the onset of dormancy release through morphological observations and investigated the process of dormancy release in ginseng overwintering buds using transcriptomic and metabolomic approaches. Our analyses revealed that the germination process of ginseng overwintering buds is regulated by multiple plant hormones, each acting at different times. Among these, abscisic acid (ABA) and gibberellic acid (GA) serve as classical signaling molecules regulating the dormancy process, while other hormones may promote the subsequent growth of overwintering buds. Additionally, metabolic pathways associated with arginine may be involved in the dormancy release process. Polyamines synthesized downstream may promote the growth of overwintering buds after dormancy release and participate in subsequent reproductive growth. This study provides insights into the germination process of ginseng overwintering buds at the molecular level and serves as a reference for further exploration of the detailed mechanism underlying ginseng overwintering germination in the future.

Transcription factors BZR2/MYC2 modulate brassinosteroid and jasmonic acid crosstalk during pear dormancy.

Bud dormancy is an important physiological process during winter. Its release requires a certain period of chilling. In pear (Pyrus pyrifolia), the abscisic acid (ABA)-induced expression of DORMANCY-ASSOCIATED MADS-box (DAM) genes represses bud break, whereas exogenous gibberellin (GA) promotes dormancy release. However, with the exception of ABA and GA, the regulatory effects of phytohormones on dormancy remain largely uncharacterized. In this study, we confirmed brassinosteroids (BRs) and jasmonic acid (JA) contribute to pear bud dormancy release. If chilling accumulation is insufficient, both 24-epibrassinolide (EBR) and methyl jasmonic acid (MeJA) can promote pear bud break, implying that they positively regulate dormancy release. BRASSINAZOLE RESISTANT 2 (BZR2), which is a BR-responsive transcription factor, inhibited PpyDAM3 expression and accelerated pear bud break. The transient overexpression of PpyBZR2 increased endogenous GA, JA, and JA-Ile levels. In addition, the direct interaction between PpyBZR2 and MYELOCYTOMATOSIS 2 (PpyMYC2) enhanced the PpyMYC2-mediated activation of Gibberellin 20-oxidase genes PpyGA20OX1L1 and PpyGA20OX2L2 transcription, thereby increasing GA3 contents and accelerating pear bud dormancy release. Interestingly, treatment with 5 μm MeJA increased the bud break rate, while also enhancing PpyMYC2-activated PpyGA20OX expression and increasing GA3,4 contents. The 100 μm MeJA treatment decreased the PpyMYC2-mediated activation of the PpyGA20OX1L1 and PpyGA20OX2L2 promoters and suppressed the inhibitory effect of PpyBZR2 on PpyDAM3 transcription, ultimately inhibiting pear bud break. In summary, our data provide insights into the crosstalk between the BR and JA signaling pathways that regulate the BZR2/MYC2-mediated pathway in the pear dormancy release process.

Methodological and physiological study of seed dormancy release in Tilia henryana

Tilia henryana is a rare tree of the Tilia family, found exclusively in China. Its seeds have severe dormancy features that limit its normal conditions of reproduction and renewal. Its seeds have severe dormant characteristics that limit its normal conditions of reproduction and renewal. The Dormancy in T. henryana seeds is a comprehensive dormancy (PY + PD) caused by mechanical and permeability barriers of seed coat and the presence of germination inhibitor in endosperm. L9 (34) orthogonal test was used to determine the best procedure for releasing the dormancy of T. henryana seeds, that is, first treating the seeds with H2SO4 for 15 min, followed by the application of 1 g L−1 GA3, stratification at 5 °C for 45 days, and finally germination at 20 °C, which can achieve a 98% seed germination rate. Large amounts of fat are consumed throughout the dormancy release process. As quantities of protein and starch marginally increase, soluble sugars are continuously decreased. Acid phosphatase and amylase activities increased rapidly, and the combined enzyme activities of G-6-PDH and 6-PGDH related to the PPP were also significantly increased. The levels of GA and ZR continued to increase, while the levels of ABA and IAA gradually decreased, among which GA and ABA changed most rapidly. The total amino acids content continued to decrease. Asp, Cys, Leu, Phe, His, Lys and Arg decreased with dormancy release, while Ser, Glu, Ala, Ile, Pro and Gaba showed an upward trend. The physical dormancy of T. henryana seeds is broken with H2SO4 in order to make the seed coat more permeable, which is a prerequisite for germination. As a result, the seeds can absorb water and engage in physiological metabolic activities, particularly the hydrolysis and metabolism of fat, which supply a significant amount of energy for dormancy release. In addition, rapid variations in the levels of different endogenous hormones and free amino acids, induced by cold stratification and GA3 application, are another important factor promoting the quick physiological activation of seeds and breaking the endosperm barrier.

Transcriptome and proteome analyses reveal the potential mechanism of seed dormancy release in Amomum tsaoko during warm stratification

BackgroundIn Amomum tsaoko breeding, the low germination rate is the major limitation for their large-scale reproduction. We found that warm stratification was an effective treatment to break the seed dormancy of A. tsaoko prior to sowing and could be an important component of improving breeding programs. The mechanism of seed dormancy release during warm stratification remains unclear. Therefore, we studied the differences between transcripts and proteomes at 0, 30, 60, and 90 days of warm stratification, to identify some regulatory genes and functional proteins that may cause seed dormancy release in A. tsaoko and reveal their regulatory mechanism.ResultsRNA-seq was performed for the seed dormancy release process, and the number of differentially expressed genes (DEGs) was 3196 in three dormancy release periods. Using TMT-labelling quantitative proteome analysis, a total of 1414 proteins were defined as differentially expressed proteins (DEPs). Functional enrichment analyses revealed that the DEGs and DEPs were mainly involved in signal transduction pathways (MAPK signaling, hormone) and metabolism processes (cell wall, storage and energy reserves), suggesting that these differentially expressed genes and proteins are somehow involved in response to seed dormancy release process, including MAPK, PYR/PYL, PP2C, GID1, GH3, ARF, AUX/IAA, TPS, SPS, and SS. In addition, transcription factors ARF, bHLH, bZIP, MYB, SBP, and WRKY showed differential expression during the warm stratification stage, which may relate to dormancy release. Noteworthy, XTH, EXP, HSP and ASPG proteins may be involved in a complex network to regulate cell division and differentiation, chilling response and the seed germination status in A. tsaoko seed during warm stratification.ConclusionOur transcriptomic and proteomic analysis highlighted specific genes and proteins that warrant further study in fully grasping the precise molecular mechanisms that control the seed dormancy and germination of A. tsaoko. A hypothetical model of the genetic regulatory network provides a theoretical basis for overcoming the physiological dormancy in A. tsaoko in the future.

The dehiscence process in Panax ginseng seeds and the stigmasterol biosynthesis pathway in terms of metabolomics

BackgroundGinseng, officially known as Panax ginseng Meyer, has been traditionally used as a medicinal herb, particularly in Asia. Ginseng is propagated from seeds; however, seed germination is challenging, especially in its natural environment on farms. The seeds typically exhibit morphophysiological dormancy and require release from both morphological and physiological dormancy before germination. Although some studies have proposed methods for increasing seed germination rates, the underlying mechanisms of its dormancy release process remain unclear. Here, we investigated metabolic alterations during dehiscence in P. ginseng to determine their potential roles in dormancy release. MethodsWe compared the ginseng seed metabolome before and after dehiscence and the ginsenoside and phytosterol compositions of the seeds in both periods in the presence of related enzymes. ResultsAfter seed dehiscence, the sugar, amino acid, and squalene concentrations were significantly altered, phytosterols associated with the stigmasterol biosynthesis pathway were increased, while ginsenoside and brassinosteroid levels were not significantly altered. In addition, squalene epoxidase, cycloartenol synthase, 24-methylenesterol C-methyltransferase, and the stigmasterol biosynthesis pathway were activated. ConclusionOverall, our findings suggest that morphological activities that facilitate ginseng seed growth are the primary phenomena occurring during the dehiscence process. This study improves the understanding of P. ginseng germination processes and promotes further research of its germination and cultivation.

Interplay among Antioxidant System, Hormone Profile and Carbohydrate Metabolism during Bud Dormancy Breaking in a High-Chill Peach Variety.

(1) Background: Prunus species have the ability to suspend (induce dormancy) and restart growth, in an intricate process in which environmental and physiological factors interact. (2) Methods: In this work, we studied the evolution of sugars, antioxidant metabolism, and abscisic acid (ABA) and gibberellins (GAs) levels during bud dormancy evolution in a high-chill peach variety, grown for two seasons in two different geographical areas with different annual media temperature, a cold (CA) and a temperate area (TA). (3) Results: In both areas, starch content reached a peak at ecodormancy, and then decreased at dormancy release (DR). Sorbitol and sucrose declined at DR, mainly in the CA. In contrast, glucose and fructose levels progressively rose until DR. A decline in ascorbate peroxidase, dehydroascorbate reductase, superoxide dismutase and catalase activities occurred in both seasons at DR. Moreover, the H2O2-sensitive SOD isoenzymes, Fe-SOD and Cu,Zn-SOD, and two novel peroxidase isoenzymes, were detected. Overall, these results suggest the occurrence of a controlled oxidative stress during DR. GA7 was the major bioactive GA in both areas, the evolution of its levels being different between seasons and areas. In contrast, ABA content decreased during the dormancy period in both areas, resulting in a reduction in the ABA/total GAs ratio, being more evident in the CA. (4) Conclusion: A possible interaction sugars-hormones-ROS could take place in high-chill peach buds, favoring the DR process, suggesting that, in addition to sugar metabolism, redox interactions can govern bud DR, regardless of chilling requirements.

Light sensitivity changes during dormancy induction in Polygonum aviculare L. seeds: development of a predictive model of annual changes in seed‐bank light sensitivity in relation to soil temperature

AbstractSeeds of weed species require light to terminate dormancy and give way to germination. It is documented that sensitivity to light in Polygonum aviculare seeds increases during dormancy release. However, it is not known whether this sensitivity is lost during dormancy induction. The aim of this study was to investigate and quantify the changes in dormancy level of P. aviculare seeds during secondary dormancy induction as measured by changes in sensitivity to light in relation to soil temperature. Polygonum aviculare seeds were stratified at 5ºC until obtaining a minimum dormancy level. The seeds were then induced into secondary dormancy by burying them in pots containing soil which were stored at 10, 15, 20 and 25ºC for different time‐periods. Polygonum aviculare seeds were exhumed periodically, exposed to different light treatments (Pfr/Ptotal‐pythochrome = 0.76, 0.03 and 7.6 × 10−4) or darkness, and incubated at 15ºC to test germination. Our results showed that the high sensitivity to light acquired during dormancy release and decreased during dormancy induction at a rate that was temperature‐dependent. These changes in sensitivity to light were quantified as a function of the accumulation of thermal‐time over a base‐temperature of 7.9ºC during dormancy induction and were coupled with previous thermal‐time index established for the dormancy release process. Both thermal‐time indices allowed us to develop a model for the prediction of cyclic changes in sensitivity to light in relation to the thermal environment experienced by the seeds during burial. This model constitutes a valuable tool for predicting weed emergence in the field and to design management practices accordingly.

Metabolomics analysis reveals Embden Meyerhof Parnas pathway activation and flavonoids accumulation during dormancy transition in tree peony

BackgroundBud dormancy is a sophisticated strategy which plants evolve to survive in tough environments. Endodormancy is a key obstacle for anti-season culture of tree peony, and sufficient chilling exposure is an effective method to promote dormancy release in perennial plants including tree peony. However, the mechanism of dormancy release is still poorly understood, and there are few systematic studies on the metabolomics during chilling induced dormancy transition.ResultsThe tree peony buds were treated with artificial chilling, and the metabolmics analysis was employed at five time points after 0–4 °C treatment for 0, 7, 14, 21 and 28 d, respectively. A total of 535 metabolites were obtained and devided into 11 groups including flavonoids, amino acid and its derivatives, lipids, organic acids and its derivates, nucleotide and its derivates, alkaloids, hydroxycinnamoyl derivatives, carbohydrates and alcohols, phytohormones, coumarins and vitamins. Totally, 118 differential metabolites (VIP ≥ 1, P < 0.05) during chilling treatment process were detected, and their KEGG pathways involved in several metabolic pathways related to dormancy. Sucrose was the most abundant carbohydrate in peony bud. Starch was degradation and Embden Meyerhof Parnas (EMP) activity were increased during the dormancy release process, according to the variations of sugar contents, related enzyme activities and key genes expression. Flavonoids synthesis and accumulation were also promoted by prolonged chilling. Moreover, the variations of phytohormones (salicylic acid, jasmonic acid, abscisic acid, and indole-3-acetic acid) indicated they played different roles in dormancy transition.ConclusionOur study suggested that starch degradation, EMP activation, and flavonoids accumulation were crucial and associated with bud dormancy transition in tree peony.

Plant hormonal changes and differential expression profiling reveal seed dormancy removal process in double dormant plant-herbaceous peony.

Herbaceous peony (Paeonia lactiflora Pall.) is a popular ornamental and medicinal plant. Taking approximately six to seven months, the seeds germination under natural conditions experiences dual dormancies, which seriously affects horticultural cultivation. Few studies have been conducted on exploring both biological and molecular mechanism that regulates dormancy removal process in hypocotyls double dormant plants. Here, we first measured ABA and GA3 content changes at four key dormancy break stages, and then performed transcriptomic analyses to identify the differentially expressed genes (DEGs) using RNA-seq. We subsequently carried out Quantitative real-time PCR (qRT-PCR) to validate RNA-seq data. ABA content decreased during the whole dormancy removal process and GA3 content exhibited decreasing slightly and then increasing trend. RNA sequencing de novo assembly generated a total of 99,577 unigenes. 20,344 unigenes were differentially expressed in the whole dormancy release process. The qPCR results of 54 selected unigenes were consistent with the FPKM values obtained from RNA-seq. Our results summarize a valuable collection of gene expression profiles characterizing the dormancy release process. The DEGs are candidates for functional analyses of genes affecting the dormancy release, which is a precious resource for the on-going physiological and molecular investigation of seeds dormancy removal in other perennial plants.

Starch and hexoses concentrations as physiological markers in dormancy progression of sweet cherry twigs

KEY MESSAGE: High starch concentrations in woody tissue of sweet cherry trees were associated with deep stages of dormancy, while increasing concentrations of hexoses were related to the dormancy release process. Dormancy is an intrinsic characteristic of deciduous forest and fruit trees. Release from dormancy and subsequent bud burst occur after chill requirements (CR) have been met. Currently, chilling metrics are poorly interchangeable among climates, probably due to a lack of physiological parameters involved in earlier model development, and, therefore, the reported CR values differ across locations. Here, we propose a way to improve our understanding on physiological markers involved in dormancy of deciduous fruit trees studying the dynamics of starch and hexoses (glucose + fructose) in sweet cherry twigs. Probabilities of bud break were estimated through logistic regression analysis using as independent variable the concentration of carbohydrates. In this experiment, we used 960 twigs and 160 sub-samples of twig portions (~ 2 cm of stem) from 8 sweet cherry cultivars exposed to different amounts of chill in the field. The timing of bud burst in forcing conditions and the concentration of starch and hexoses in the sub-samples were recorded. We found that concentrations of starch and hexoses are closely related to dormancy progression. Specifically, starch concentrations decreased by 43%, while concentrations of hexoses increased by 58% during the transition from 16 to 70 Chill Portions. Responses differed among varieties at the same chill received in the orchard. The logistic regression analysis revealed that the predicted probability of bud break at the moment of recorded bud burst was highest (i.e., up to 0.5) in the varieties Santina, Skeena, Rainier, Lapins, Regina, Kordia and Bing. In contrast, the variety Sweetheart showed the lowest probability (i.e., 0.49) of having met its CR when bud burst was recorded. This may suggest that in this variety, carbohydrate metabolism is not the most important predictor involved in dormancy release. The method presented here improves our understanding on dormancy and might serve to focus further research on dormancy modeling. This is especially important in warm winter regions where the classical way of determining CRs and quantifying chill accumulation is consistently failing.

DNA Methylation Analysis of Dormancy Release in Almond (Prunus dulcis) Flower Buds Using Epi-Genotyping by Sequencing.

DNA methylation and histone post-translational modifications have been described as epigenetic regulation mechanisms involved in developmental transitions in plants, including seasonal changes in fruit trees. In species like almond (Prunus dulcis (Mill.) D.A: Webb), prolonged exposure to cold temperatures is required for dormancy release and flowering. Aiming to identify genomic regions with differential methylation states in response to chill accumulation, we carried out Illumina reduced-representation genome sequencing on bisulfite-treated DNA from floral buds. To do this, we analyzed almond genotypes with different chilling requirements and flowering times both before and after dormancy release for two consecutive years. The study was performed using epi-Genotyping by Sequencing (epi-GBS). A total of 7317 fragments were sequenced and the samples compared. Out of these fragments, 677 were identified as differentially methylated between the almond genotypes. Mapping these fragments using the Prunus persica (L.) Batsch v.2 genome as reference provided information about coding regions linked to early and late flowering methylation markers. Additionally, the methylation state of ten gene-coding sequences was found to be linked to the dormancy release process.

Identification and characterization of microRNAs in tree peony during chilling induced dormancy release by high-throughput sequencing

Tree peony, one of the most valuable horticultural and medicinal plants in the world, has to go through winter to break dormancy. Growing studies from molecular aspects on dormancy release process have been reported, but inadequate study has been done on miRNA-guided regulation in tree peony. In this study, high-throughput sequencing was employed to identify and characterize miRNAs in three libraries (6 d, 18 d and 24 d chilling treatments). There were 7,122, 10,076 and 9,097 unique miRNA sequences belonging to 52, 87 and 68 miRNA families, respectively. A total of 32 conserved miRNAs and 17 putative novel miRNAs were identified during dormancy release. There were 771 unigenes as potential targets of 62 miRNA families. Total 112 known miRNAs were differentially expressed, of which 55 miRNAs were shared among three libraries and 28 miRNAs were only found in 18 d chilling duration library. The expression patterns of 15 conserved miRNAs were validated and classified into four types by RT-qPCR. Combining with our microarray data under same treatments, five miRNAs (miR156k, miR159a, miR167a, miR169a and miR172a) were inversely correlated to those of their target genes. Our results would provide new molecular basis about dormancy release in tree peony.

Transcriptomic analysis of American ginseng seeds during the dormancy release process by RNA-Seq.

American ginseng (Panax quinquefolius L.) is an important herb that is cultivated in China, North American, and South Korea. It is propagated from seed, but the seed has deep dormancy characteristics described as morphophysiological dormancy. Two-stage temperature stratification, a warm (15–20°C) and cold (2°C) stratification period of 6 months, has been used successfully for seed dormancy release. However, little is known about the molecular mechanisms of seed dormancy release in the stratification process. In this study, seed development after pollination and seed development in the dormancy release process were investigated in American ginseng. The transcriptome during seed dormancy release was analyzed using RNA-Seq technology and 78,207 unigenes (mean length 531 bp) were generated. Based on similarity searches of public databases, 54,292 of the unigenes (69.4%) were functionally annotated. Further, three digital gene expression (DGE) libraries were sequenced and differences in gene expression at three stages during seed cold stratification were examined. The greatest number of differentially expressed genes occurred in the 90DCS versus 180DCS libraries, while the lowest number of differentially expressed genes occurred in the 135DCS verus 180DCS libraries. GO enrichment analysis revealed that 59, 29, and 39 GO terms were significantly enriched in the biological process, molecular function, and cell component GO categories, respectively. There were 25,190 genes with KEGG pathway annotation in the three DGE libraries and their enrichment pathways were compared. The gene expressions of 30 selected unigenes were validated using quantitative PCR. This study is the first to provide the transcriptome sequences for seed dormancy release in American ginseng, and demonstrates the successful use of DGE profiling data for analyzing transcriptomic variation during dormancy release. These data provide a basis for future researches of seed dormancy in morphophysiological dormancy seeds in non-model plants.

Transcriptomic changes during tuber dormancy release process revealed by RNA sequencing in potato

Potato tuber dormancy release is a critical development process that allows potato to produce new plant. The first Illumina RNA sequencing to generate the expressed mRNAs at dormancy tuber (DT), dormancy release tuber (DRT) and sprouting tuber (ST) was performed. We identified 26,639 genes including 5,912 (3,450 up-regulated while 2,462 down-regulated) and 3,885 (2,141 up-regulated while 1,744 down-regulated) genes were differentially expressed from DT vs DRT and DRT vs ST. The RNA-Seq results were further verified using qRT-PCR. We found reserve mobilization events were activated before the bud emergence (DT vs DRT) and highlighted after dormancy release (DRT vs ST). Overexpressed genes related to metabolism of auxin, gibberellic acid, cytokinin and barssinosteriod were dominated in DT vs DRT, whereas overexpressed genes involved in metabolism of ethylene, jasmonate and salicylate were prominent in DRT vs ST. Various histone and cyclin isoforms associated genes involved in cell division/cycle were mainly up-regulated in DT vs DRT. Dormancy release process was also companied by stress response and redox regulation, those genes related to biotic stress, cell wall and second metabolism was preferentially overexpressed in DRT vs ST, which might accelerate dormancy breaking and sprout outgrowth. The metabolic processes activated during tuber dormancy release were also supported by plant seed models. These results represented the first comprehensive picture of a large number of genes involved in tuber dormancy release process.

Proteomic changes during tuber dormancy release process revealed by iTRAQ quantitative proteomics in potato

Given that limited information is available with regard to tuber dormancy release related proteome, we conducted proteome analysis of tuber dormancy release process at dormant tuber (DT), dormancy release tuber (DRT) and sprouting tuber (ST) using the iTRAQ technology. A total of 1,752 proteins were identified. Among them, a subset of 316 proteins was screened as significant up- (137) and down regulated (179) between DT vs DRT. A subset of 120 proteins experienced significant up- (40) or down-regulation (80) between DRT vs ST. The differentially expressed proteins were grouped into 11 functional categories. Proteins enriched in functional categories of major carbohydrate (CHO) metabolism, glycolysis, fermentation, amino acid metabolism, protein and transport were highly up-regulated, while functional categories of photosynthesis and RNA were down-regulated between DT vs DRT. Proteins enriched in functional groups of protein, cell wall, lipid metabolism, miscellaneous, and signaling were strongly up-regulated, while functional categories of photosynthesis, hormone metabolism and protein were down-regulated between DRT vs ST. Consistent with previous documented differentially expressed genes, most of differentially expressed proteins were also identified between DT and DRT, indicating the metabolism shift from growth suspension to growth activation as tubers dormancy breaking. The changes in protein profiles showed lower concordance with corresponding alterations in transcript levels, indicating possible transcriptional and posttranscriptional regulation. Furthermore, the possible mechanism of tuber dormancy release was discussed in relation to what was known in transcripts change and other plant models from carbohydrate metabolism, protein metabolism, stress response, redox regulation, transcription regulation, DNA metabolism, amino acid metabolism, development, signaling as well as hormone metabolism.

Cloning and expression analysis of the R2R3-PsMYB1 gene associated with bud dormancy during chilling treatment in the tree peony (Paeonia suffruticosa)

Transcription factor (TF) MYB-like proteins are involved in many physiological and biochemical processes. This study isolated the full length cDNA encoding a MYB from the tree peony (Paeonia suffruticosa Andr.), whose GenBank Accession No. is KC282466. The deduced MYB-like protein sequence shares extensive sequence similarity with previously characterized plant R2R3-MYBs, and was named PsMYB1 according to the accepted nomenclature for TFs. Phylogenetic analysis showed that the deduced amino acid of PsMYB1 was closely related to VvMYB30 from grape. The PsMYB1 gene was expressed in all tissues, but it was most strongly expressed in the stem, and least expressed in the root. When exposed to chilling at 4 °C, PsMYB1 was up-regulated at 7 days and then decreased until 21 days suggesting it responded to low temperature, and it might negatively regulate dormancy release. In addition, the PsMYB1 quicker response to the temperature changes in flower buds of complete dormancy release might be that PsMYB1 involved in eco-dormancy and accelerated budbreak. These experiments enhance our knowledge of PsMYB1 and provide more information for understanding the genetic and physiological changes during the dormancy release process in the tree peony.