Dormant Buds Research Articles

Peculiarity of transcriptional and H3K27me3 dynamics during peach bud dormancy

Bud dormancy facilitates the survival of meristems under harsh environmental conditions. To elucidate how molecular responses to chilling accumulation controlling dormancy in peach buds, chromatin immunoprecipitation sequencing to identify the H3K27me3 modifications and RNA sequencing of two peach cultivars with pronounced differences in chilling requirement were carried out, the results showed that genes associated with abscisic acid and gibberellic acid signal pathways play key roles in dormancy regulation. The results demonstrated that peach flower bud differentiation occurred continuously in both cultivars during chilling accumulation, which was correlated with the transcript abundance of key genes involved in phytohormone metabolism and flower bud development under adverse conditions. The more increased strength in high chilling-requirement cultivar along with the chilling accumulation at the genome-wide level. The function of the dormancy-associated MADS-box gene PpDAM6 was identified, which is involved in leaf bud break in peach and flower development in transgenic Nicotiana tabacum (NC89). In addition, PpDAM6 was positively regulated by PpCBF, and the genes of putative dormancy-related and associated with metabolic pathways were proposed. Taken together, these results constituted a theoretical basis for elucidating the regulation of peach bud dormancy transition.

Genome-wide identification of the NCED gene family and functional characterization of PavNCED5 related to bud dormancy in sweet cherry

Abscisic acid (ABA) is involved in responding to various stresses and regulating the dormancy of flower buds in fruit trees. The cleavage of carotenoids is catalyzed by 9-cis epoxy carotenoid dioxygenase (NCED), and is a key step in ABA biosynthesis. Although NCED genes have been identified in a variety of plants, the characteristics of these genes in sweet cherry (Prunus avium L.) trees have been seldom reported. In the present study, 10 PavNCED genes were identified in the sweet cherry genome and distributed on three chromosomes. Cis-element analysis of PavNCEDs indicated that they might be related to hormone regulation, stress responses, and plant development. Through co-expression network analysis, the transcription factors were identified, such as ERF, bHLH and TCP, which might be involved in the regulation of PavNCEDs. Expression pattern analysis of the PavNCED family genes showed that PavNCED1–5 genes were highly expressed during the flower bud dormancy. Importantly, the expression of PavNCED5 was decreased with the decline of ABA content in the sweet cherry. Additionally, the overexpression of PavNCED5 in Arabidopsis showed dormancy deficiency of seeds. This implies that PavNCED5 may play an important role during the dormancy stage of sweet cherry. In general, we characterized the NCED family in sweet cherry and revealed the essential role of PavNCED5 in flower bud dormancy. These findings open up future research directions and provide valuable information for the further functional study of PavNCEDs in sweet cherry.

Co-expression network analysis of the H3K27me3/H3K4me3-modified genes correlated with chilling accumulation in apple dormant flower buds

Co-expression network analysis of the H3K27me3/H3K4me3-modified genes correlated with chilling accumulation in apple dormant flower buds

Upregulation of TCP18s in dormant buds of transgenic apple expressing Japanese apricot PmDAM6

Upregulation of <i>TCP18s</i> in dormant buds of transgenic apple expressing Japanese apricot PmDAM6

The development and transcriptome regulation of the secondary trunk of Ginkgo biloba L.

Secondary trunk Ginkgo biloba is one of the specific germplasms of G. biloba. In this study, paraffin sectioning, high-performance liquid chromatography and transcriptome sequencing technology were used to study the development of the secondary trunk of G. biloba from the morphological, physiological and molecular levels. The results showed that the secondary trunk of G. biloba originated from the latent buds in the stem cortex at the junction of the root and stem of the main trunk. The development process of secondary trunk was divided into 4 periods: the dormancy period of the secondary trunk buds, the differentiation period, the formation period of transport tissue, and the budding period. Transcriptome sequencing was performed by comparing the germination period and elongation growth period of the secondary trunk with the normal parts of the same period where no secondary trunks occurred. Differential genes involved in phytohormone signal transduction, phenylpropane biosynthesis, phenylalanine metabolism, glycolysis and other pathways can regulate not only the inhibition of early dormant buds but also the later development of the secondary trunk. Genes related to IAA synthesis are upregulated and indole-3-acetic acid content is increased, leading to the up-regulated expression of IAA intracellular vector genes. The IAA response gene (SAUR) receives and responds to IAA signals to promote the development of the secondary trunk. Through the enrichment of differential genes and functional annotations, a key regulatory pathway map for the occurrence of the secondary trunk of G. biloba was sorted out.

The Cryopreservation of Medicinal and Ornamental Geophytes: Application and Challenges.

Nowadays, plant genetic resources are often at risk of loss and destruction. Geophytes are herbaceous or perennial species that are annually renewed by bulbs, rhizomes, tuberous roots, or tubers. They are often subject to overexploitation, which, combined with other biotic and abiotic stresses, can make these plants more vulnerable to a decline in their diffusion. As a result, multiple endeavors have been undertaken to establish better conservation strategies. Plant cryopreservation at ultra-low temperatures in liquid nitrogen (-196 °C) has proven to be an effective, long-term, low-cost, and suitable conservation method for many plant species. Over the last two decades, major advances in cryobiology studies have enabled successful explants of multiple genera and types, including pollen, shoot tips, dormant buds, and zygotic and somatic embryos. This review provides an update on recent advances and developments in cryopreservation and its application to medicinal and ornamental geophytes. In addition, the review includes a brief summary of factors limiting the success of bulbous germplasm conservation. The critical analysis underpinning this review will benefit biologists and cryobiologists in their further studies on the optimization of geophyte cryopreservation protocols and will support a more complete and wider application of knowledge in this area.

MADS-box protein PpDAM6 regulates chilling requirement-mediated dormancy and bud break in peach.

Bud dormancy is crucial for winter survival and is characterized by the inability of the bud meristem to respond to growth-promotive signals before the chilling requirement (CR) is met. However, our understanding of the genetic mechanism regulating CR and bud dormancy remains limited. This study identified PpDAM6 (DORMANCY-ASSOCIATED MADS-box) as a key gene for CR using a GWAS (Genome-Wide Association Study) analysis based on structural variations (SVs) in 345 peach (Prunus persica (L.) Batsch) accessions. The function of PpDAM6 in CR regulation was demonstrated by transiently silencing the gene in peach buds and stably overexpressing the gene in transgenic apple (Malus × domestica) plants. The results showed an evolutionarily conserved function of PpDAM6 in regulating bud dormancy release, followed by vegetative growth and flowering, in peach and apple. The 30-bp deletion in the PpDAM6 promoter was substantially associated with reducing PpDAM6 expression in low-CR accessions. A PCR marker based on the 30-bp indel was developed to distinguish peach plants with non-low and low CR. Modification of the H3K27me3 marker at the PpDAM6 locus showed no apparent change across the dormancy process in low- and non-low-chilling requirement cultivars. Additionally, H3K27me3 modification occurred earlier in low-CR cultivars on a genome-wide scale. PpDAM6 could mediate cell-cell communication by inducing the expression of the downstream genes PpNCED1 (9-cis-epoxycarotenoid dioxygenase 1), encoding a key enzyme for ABA biosynthesis, and CALS (CALLOSE SYNTHASE), encoding callose synthase. We shed light on a gene regulatory network formed by PpDAM6-containing complexes that mediate CR underlying dormancy and budbreak in peach. A better understanding of the genetic basis for natural variations of CR can help breeders develop cultivars with different CR for growing in different geographical regions.

Isolation of FLOWERING LOCUS C and Preliminary Characterization in the Floral Transition of Xinjiang Precocious Walnut

Walnut (Juglans regia L.) plants typically flower after eight to ten years of juvenile growth. Precocious germplasm, also known as early-flowering or early-mature genotypes, have shortened juvenile phases of one to two years and are therefore crucial for enhancing breeding efficiency. However, such precocious germplasms are very limited. Here, we isolated and characterized the key flowering-time gene FLOWERING LOCUS C (FLC) in the precocious walnuts of the Xinjiang Uygur Autonomous Region. Sequence alignment showed that Juglans regia FLC (JrFLC)contained a conserved MINICHROMOSOME MAINTENANCE 1 (MCM1), AGAMOUS (AG), DEFICIENS (DEF), and SERUM RESPONSE FACTOR (SRF) (MADS)-box domain. Analysis of an FLC–green fluorescent protein (GFP) fusion protein revealed that JrFLC was localized to the nucleus. Gene expression analysis showed that JrFLC was specifically expressed during the bud dormancy stage of precocious walnut, and that expression levels gradually decreased as the ambient temperature warmed. Exogenous JrFLC overexpression in Arabidopsis thaliana delayed flowering and increased the total leaf number, suggesting a similar function of JrFLC as a floral repressor in walnut and in other plants. Together, these results showed that JrFLC played an important role in regulating the floral transition of Xinjiang precocious walnut. Further studies, including a detailed characterization of JrFLC, are expected to validate JrFLC as a strong target for genetic improvement in flowering time in walnut.

Expression profiling and function analysis highlight the positive involvement of sweet cherry PavTCP17 in regulating flower bud dormancy

The TCP transcription factors function diversely in plant growth, development and stress response. The flower bud dormancy was particularly important for the yield formation of fruit trees. However, there has been no in-depth study on the involvement of TCP genes in regulating flower bud dormancy in sweet cherry so far. In the present study, a total of 18 TCP genes were obtained based on the whole genome, which were divided into two subfamilies and three subclasses (PCF, CIN, CYC/TB1) by multiple sequence alignment and evolutionary analysis. Four TCP genes targeted by miR319 were identified in the degradome results. Tissue-specific expression of TCP gene was verified based on transcriptome data and qRT-PCR. The expression patterns of PavTCPs under cold treatment in dormant buds of two cold-requiring sweet cherry cultivars were analyzed, among which PavTCP17 was significantly positively correlated with the gene expressions of gibberellin (GA) degradation and abscisic acid (ABA) synthesis. The abundance of PavTCP17 gene expression was significantly reduced after low cold-requiring cultivars met its chilling demand. The qRT-PCR quantification also showed a decreasing trend of PavTCP17 expression level during blooming process. To further unravel the role of PavTCP17 gene in positively regulating floral bud dormancy, transgenic Arabidopsis overexpressed PavTCP17 was obtained by genetic transformation. Compared with the WT, the number of main branches and rosette leaves was significantly reduced in PavTCP17-overexpressing lines. Moreover, the outgrowth of lateral buds of the PavTCP17-overexpressing lines were remarkably inhibited, mirroring the formation of bud dormancy. Furthermore, PavTCP17 might directly bind to PavNCED3 promoter of sweet cherry, suggesting the implication of PavTCP17 in promoting ABA synthesis, which was essential for bud dormancy. Our study bettered the understanding of TCP gene functions and revealed the mechanism by which PavTCP17 positively regulates flower bud dormancy in sweet cherry.

Identifying appropriate prediction models for estimating hourly temperature over diverse agro-ecological regions of India

The present study tests the accuracy of four models in estimating the hourly air temperatures in different agroecological regions of the country during two major crop seasons, kharif and rabi, by taking daily maximum and minimum temperatures as input. These methods that are being used in different crop growth simulation models were selected from the literature. To adjust the biases of estimated hourly temperature, three bias correction methods (Linear regression, Linear scaling and Quantile mapping) were used. When compared with the observed data, the estimated hourly temperature, after bias correction, is reasonably close to the observed during both kharif and rabi seasons. The bias-corrected Soygro model exhibited its good performance at 14 locations, followed by the WAVE model and Temperature models at 8 and 6 locations, respectively during the kharif season. In the case of rabi season, the bias-corrected Temperature model appears to be accurate at more locations (21), followed by WAVE and Soygro models at 4 and 2 locations, respectively. The pooled data analysis showed the least error between estimated (uncorrected and bias-corrected) and observed hourly temperature from 04 to 08 h during kharif season while it was 03 to 08 h during the rabi season. The results of the present study indicated that Soygro and Temperature models estimated hourly temperature with better accuracy at a majority of the locations situated in the agroecological regions representing different climates and soil types. Though the WAVE model worked well at some of the locations, estimation by the PL model was not up to the mark in both kharif and rabi seasons. Hence, Soygro and Temperature models can be used to estimate hourly temperature data during both kharif and rabi seasons, after the bias correction by the Linear Regression method. We believe that the application of the study would facilitate the usage of hourly temperature data instead of daily data which in turn improves the precision in predicting phenological events and bud dormancy breaks, chilling hour requirement etc.

Chilling induces sugar and ABA accumulation that antagonistically signals for symplastic connection of dormant potato buds.

Endodormancy (ED) is a crucial stage in the life cycle of many perennial plants. ED release requires accumulating a certain amount of cold exposure, measured as chilling units. However, the mechanism governing the effect of chilling on ED duration is poorly understood. We used the potato tuber model to investigate the response to chilling as associated with ED release. We measured the accumulation of specific sugars during and after chilling, defined as sugar units. We discovered that ED duration correlated better with sugar units accumulation than chilling units. A logistic function was developed based on sugar units measurements to predict ED duration. Knockout or overexpression of the vacuolar invertase gene (StVInv) unexpectedly modified sugar units levels and extended or shortened ED, respectively. Silencing the energy sensor SNF1-related protein kinase 1, induced higher sugar units accumulation and shorter ED. Sugar units accumulation induced by chilling or transgenic lines reduced plasmodesmal (PD) closure in the dormant bud meristem. Chilling or knockout of abscisic acid (ABA) 8'-hydroxylase induced ABA accumulation, in parallel to sweetening, and antagonistically promoted PD closure. Our results suggest that chilling induce sugar units and ABA accumulation, resulting in antagonistic signals for symplastic connection of the dormant bud.

What Is Wrong with Winter Chill Models in Warm Climates?

Bud dormancy is an evolutionary strategy that protects temperate fruit trees from low temperatures during winter. With adequate winter chilling, it is a process consisting of a rapid entrance phase where growth inhibition increases to a maximum and is then released via an exit phase. This progression is, however, different in areas with insufficient winter chill. In such areas, the dormancy entrance phase is protracted, and the exit phase is often incomplete. Several chill models have been designed to describe the plants’ response to chill accumulation to match cultivar and site. Although it is known that these models are less accurate in warm winter areas, their accuracy during the two dormancy phases has always been assumed equal. The aim of this study was to investigate the accuracy of four chill models during the entrance and exit phases of bud dormancy of ‘Royal Gala’ buds from two contrasting climatic areas. One-year-old shoots were collected from commercial orchards and forced to determine their bud dormancy level. Before forcing, the shoots received varied amounts of chill additional to the field chill. The bud dormancy progression was represented as joint two- or three-line models to determine the entrance and exit phases. For each phase, the dormancy level of every sample was plotted against its chill accumulation based on four chill models (Chilling Hours, Utah, Positive Utah, and Dynamic Model). Results were compared to determine the ability of each model to predict the linearity of the dormancy progression. The results indicated that although all the models were able to describe the exit phase of bud dormancy successfully, none could describe a linear entrance phase. This suggests that during the onset of dormancy, buds respond to temperature differently to what is measured by the chill models making the models unreliable when winter chill is inadequate.

Seasonal dynamics of shoots growth in &lt;i&gt;Forsythia ovata&lt;/i&gt; Nakai plants: Rhythmicity of apical and radial growth

The aim of the study was to establish the type (linear or non-linear) and shape (presence of extremes and trends) of the time dependences of apical and radial growth rates for shoots of two types (branching and formation) in woody plants. The object of the study was an introduced in the Middle Urals ornamental early-flowering shrub species Forsythia ovata Nakai. Seasonal dynamics of morphometric parameters of two types of shoots, which differ in intensity of growth and origin (developing from the apical or dormant buds of the skeletal branch respectively), was examined. Also, there was made an assessment of their relationship with air temperature and precipitation values. Apical and radial growth are accompanied by oscillations of increments. The duration of individual phases of oscillations is about 7 or more days, which makes it possible to attribute this phenomenon to infradian growth rhythms. The weak relationship between the characteristics of the observed oscillations and weather conditions indicates the predominantly endogenous nature of the observed morphogenetic processes. The growth of formation shoots begins 4 weeks later than branching shoots. This delay is apparently related to the time necessary for activation of dormant bud growth. Seasonal dynamics curves of rates and accelerations of the apical and radial shoot’s growth have the shape of previously unobserved oscillations with phases fading in amplitude and changing in duration. The growth ends 1–2 months before the environmental conditions become unfavorable. The oscillations of the growth rate of shoots are apparently associated with the action of two or more differently directed factors, which determine the increase in volume of different segments of the shoot. These factors include the different contribution of cell division and elongation to the change in the geometric dimensions of the apical meristem domains. The main differences in the seasonal dynamics of the apical and radial increments for both types of shoots are: the duration of growth (6–8 and 4 weeks, respectively), the number of extremes, the amplitude and the duration of individual phases of oscillations. Higher amplitudes of the growth rate oscillations in shoots formation compared with branching shoots, cause bigger values of the formation shoots total increments. The dynamic curves of the apical growth rates have two maxima, while those of the radial growth have only one. Each type of growth, despite the delay in the onset of the formation shoots, has the same total duration. The shapes of curves of seasonal changes in speeds and accelerations of shoot growth values are also similar for different types of shoots. These similarities indicate that shoots have the same “programs” of growth regulation, ultimately determined by the genotype. The rhythmic growth of both types of shoots during the season suggests the existence of the relationship in time between the rates of division and growth of cells located in functionally different groups of cells in the apical meristem zone.

A high-quality assembled genome of a representative peach landrace, ‘Feichenghongli’, and analysis of distinct late florescence and narrow leaf traits

BackgroundPeach (Prunus persica L. Batsch) is one of the most popular fruits worldwide. Although the reference genome of ‘Lovell’ peach has been released, the diversity of genome-level variations cannot be explored with one genome. To detect these variations, it is necessary to assemble more genomes.ResultsWe sequenced and de novo assembled the genome of ‘Feichenghongli’ (FCHL), a representative landrace with strict self-pollination, which maintained the homozygosity of the genome as much as possible. The chromosome-level genome of FCHL was 239.06 Mb in size with a contig N50 of 26.93 Mb and only 4 gaps at the scaffold level. The alignment of the FCHL genome with the reference ‘Lovell’ genome enabled the identification of 432535 SNPs, 101244 insertions and deletions, and 7299 structural variants. Gene family analysis showed that the expanded genes in FCHL were enriched in sesquiterpenoids and triterpenoid biosynthesis. RNA-seq analyses were carried out to investigate the two distinct traits of late florescence and narrow leaves. Two key genes, PpDAM4 and PpAGL31, were identified candidates for the control of flower bud dormancy, and an F-box gene, PpFBX92, was identified as a good candidate gene in the regulation of leaf size.ConclusionsThe assembled high-quality genome could deepen our understanding of variations among diverse genomes and provide valuable information for identifying functional genes and improving the molecular breeding process.

Late Pruning and Forced Vine Regrowth in Chardonnay and Pinot Noir: Benefits and Drawbacks in the Trento DOC Basin (Italy)

Targeted pruning techniques may have the potential to shift phenological progression in grapevines. These approaches can be useful to escape late frost (after budburst) and to delay ripening, maintaining yield and berry quality under specific environmental scenarios and for targeted oenological aims. In this work we tested a series of pruning methods (late pruning and different forcing approaches to unlock the para-dormant buds) with the primary objective of delaying phenological onset while increasing must quality components in the Trento DOC basin (Italy) over three field seasons either in cv Chardonnay or cv Pinot noir. Delayed pruning shifted the onset of most of the phenological stages by 3 to 10 days with a general increase in must acidity at harvest over two seasons. Forcing techniques, and in particular forcing vine regrowth (i.e., removing primary productivity along with leaves and secondary shoots to force dormant bud growth), substantially reduced yield per vine (p &lt; 0.001) but significantly (p &lt; 0.001) enhanced total acidity and yeast available nitrogen when compared to winter pruning vines in both Chardonnay and Pinot noir. Different spring pruning for unlocking para-dormant buds aimed at double-cropping in 2022 did not yield a secondary harvest potentially due to lack of vigor in the vineyard (Pinot noir) and unfavorable environmental conditions that putatively anticipated bud pre-dormancy. However, reduced sugar levels in the primary productivity bunches of the treated vines were observed, suggesting that early source limitation (e.g., at fruit set) applied via reduced active photosynthetic leaf area may slow down technological ripening even if compensatory behaviors were observed in the treated plants through enhanced stomatal conductance. Our work provides evidence of the potential usefulness of different pruning approaches for manipulating phenological progression and berry ripening dynamics under climate change scenario in the Trento DOC area and suggests a lack of efficacy and specific drawbacks particularly in dry and hot years.

Conservation of plant biodiversity by biotechnology methods

Several methods of plant preservation are currently used in the Republic of Kazakhstan: 1) field gene banks in natural growing areas and pomological collections; 2) preservation of seeds at +4°С, –18°С, and –196°С; 3) сold storage of in vitro shoots at +4°С and +10 ± 2°С; 4) cryopreservation of plant tissues and organs at –196°C; 5) preservation of plant DNA at –80°C.Ex situ field collections of plants in Kazakhstan are maintained in botanical gardens of the Republic, arboretums, pomological gardens, nurseries, peasant and farm enterprises, and personal plots. The largest collection of fruit and berry plants is located in the Pomological Garden and includes about 4 thousand varieties, more than 40 thousand hybrids and wild forms of various crops.The Republic of Kazakhstan has about 42,000 accessions in the seed collection. The cereal crop collection is mainly concentrated in the Kazakh Research Institute of Agriculture and Plant Growing – 1/3 of the national genetic resources. The main seed collection of vegetable crops and potatoes (14,700 accessions) is held by the Kazakh Research Institute of Potato and Vegetable Growing. Collections are also available at the Institute of Botany and Phytointroduction and in the Institute of Plant Biology and Biotechnology (IPBB), with the storage mode of + 4°C and –18°C. IPBB also uses cryopreservation technology at –196°C for seed storage.The main in vitro collection of Kazakhstan is kept at the IPBB at + 4°С and +10 ± 2°С; it includes more than 140 accessions of various fruit, berry, nut, vegetable, ornamental, and woody crops, grapes, potatoes, etc. A cryogenic collection of seeds, shoot tips, dormant buds, and embryonic axes in liquid nitrogen (–196°C) is found only in IPBB. The collection includes more than 700 accessions.

The potential impacts of climate change on ex situ conservation options for recalcitrant-seeded species

Recalcitrant seeds are characterized by desiccation and freezing sensitivity, and short storage longevity. These physiological attributes obviate their ex situ conservation in conventional seed banks, where seeds are stored dry at sub-zero temperatures (typically, 15% relative humidity and –20°C) for extended periods of time. Propagation of plants for field collections (e.g., botanical gardens, nurseries, and arboretums) is a valuable ex situ conservation option. However, these collections are relatively costly, require high maintenance, preserve limited genetic diversity and/or are directly exposed to biotic (e.g., pests) and abiotic (e.g., climatic) threats. Therefore, recalcitrant-seeded (RS) species are dependent on cryopreservation for their safe and long-term ex situ conservation. Different explant sources such as whole seeds, zygotic embryos, dormant buds, shoot tips, and pollen, can be used for plant propagation of RS species in field collections as well as for their cryopreservation. The success of the propagation or the cryopreservation of these explants often depends on their developmental status, vigor, and/or tolerance to desiccation and chilling/freezing. These attributes are modulated by the environment where the donor plant grows and we hypothesize that climate change, by affecting these biological attributes, would impact the success of explant propagation and cryopreservation. To support this hypothesis, we have reviewed how temperature changes and drought, the two main climate change scenarios, affect the main biological attributes that are directly involved in the success of ex situ conservation of tropical and temperate RS species. In general, increases in temperature and drought will negatively affect plant development in field collections and the quality of the explants used in cryopreservation. Consequently, field collections of RS species may need to be moved to more suitable places (e.g., higher latitudes/altitudes). Additionally, we may find a reduction in the success of cryopreservation of RS species germplasm directly harvested from field collections. However, we cannot always generalize these effects for all species since they often depend on the origin of the species (e.g., tropical and temperate species tend to respond to climate change differently), the genotype, the adaptive genetic potential of each population, and the severity of the environmental change. On the other hand, the increase in temperatures and water stress in donor plants at high-latitude areas and also some tropical environments may favor the production of seeds and seedlings better adapted to drying, and hence, increase the success of plant propagation and zygotic embryo cryopreservation.

SHORT VEGETATIVE PHASE 3 mediates hormonal signals control of bud dormancy in grape

Bud dormancy is an essential and complex physiological process in perennial plants. Abscisic acid (ABA) is the major hormone regulating bud dormancy, however, the gene, SHORT VEGETATIVE PHASE (SVP) also plays a pivotal role. The combined regulation of SVP and ABA in the endodormancy network remains poorly characterized. In the present study, we demonstrate the growth inhibitory functions of VvSVP3 by its overexpressing it in tobacco and poplar. VvSVP3-overexpressing poplar plants prematurely stopped growing under short day, exhibiting delayed bud break in early spring. VvSVP3 regulates ABA, the gibberellic acid (GA) pathway, and the callose synthesis to promote dormancy within its network. In addition, exogenous application of ABA positively affects VvSVP3 expression. A transcriptomics and proteomics combined approach identified that VvPYL9 is a target gene of VvSVP3, which directly binds to a CArG motif in the VvPYL9 promoter to activate its expression. In summary, our results revealed the feedback regulation between VvSVP3 gene, ABA metabolism, and the dormancy signaling pathway in grape. It also provides new insights into the functional role of callose and ABA regulation in dormancy.

Integrated genome-wide chromatin accessibility and expression profile identify key transcription factors involved in bud endodormancy break in tea plants

It is essential for tea plants (Camellia sinensis) to undergo bud endodormancy in order to survive winter and grow again the following spring. Molecular pathways underlying the release and break of endodormancy, however, remain unclear. Accessible chromatin regions play a crucial role in precise gene expression regulation. Here, we profiled the chromatin accessibility and transcriptional features of transcription factors (TFs) using ATAC- and RNA-seq technologies. We revealed dynamic changes during bud dormancy break in tea plants and detected open chromatin regions and TF binding sites. Numerous transcripts associated with open chromatin regions were found to exhibit dormant-preferential expression among TF-target genes. We focused on several crucial TF motifs, including MADS-box, AP2EREBP, bZIP, MYB, bHLH, E2FDP, REMB3, TCP, and G2-like factors, that were enriched in open chromatin regions at different budbreak stages, and predicted networks of TF-target genes. Then, we used qRT-PCR to investigate the expression patterns of budbreak-related genes.We found a set of differentially regulated peaks of MADS-box TFs and related genes enriched in plant hormone signal transduction pathway, photosynthesis, secondary metabolism, plant-pathogen interaction functions. Correlation analysis with the phytohormones abscisic acid and indole-3-acetic acid also provided details of the regulation network. Moreover, we identified the core TFs (SVP, CO, AP1, SOC, ABI, CBF, FRUITFULL, and ULTRAPETALA) of several pathways related to budbreak, providing the guideposts for future study.

Overexpression of mango MiSVP3 and MiSVP4 delays flowering time in transgenic Arabidopsis

SHORT VEGETATIVE PHASE (SVP) belongs to the MADS-box gene family, its main function is to regulate plant flowering, maintain normal flower development and bud dormancy. However, its function in mango (Mangifera indica L.) flowering needs further study. In this research, we obtained two SVP genes, MiSVP3 and MiSVP4, from genomic and transcriptomic data of M. indica L. cv. ‘SiJiMi’. Sequence analysis showed that MiSVP3 and MiSVP4 were typical MADS-box transcription factors. Promoter element analysis suggested that MiSVP3 and MiSVP4 were associated with several hormone responses, stress responses and CArG box cis-elements. Expression analysis indicated that MiSVP3 and MiSVP4 were lowly expressed in flower/buds and highly expressed in vegetative tissue. Subcellular localization indicated that MiSVP3 and MiSVP4 were localized in the nucleus. Overexpression of MiSVP3 and MiSVP4 delays flowering time and results in abnormalities in inflorescences and floral organs in Arabidopsis. MiSVP3 was sensitive only to prohexadione-calcium (Pro-Ca) treatment, while MiSVP4 was sensitive to abscisic acid (ABA), gibberellin (GA3) and Pro-Ca treatment. The Y2H and BiFC assays showed that MiSVP3 interacted with MiSEP1–1 and MiSOC1D but not MiFLC, MiAP1–1 and MiAP1–2, MiSVP4 interacted with MiFLC, MiAP1–1, MiAP1–2 and MiSOC1D but not MiSEP1–1. The Y1H assay showed that MiSVP3 and MiSVP4 could interact with MiFLC, but only MiSVP3 could interact with MiSOC1D. These results suggest that MiSVP3 and MiSVP4 can inhibit mango flowering and participate in the regulation of mango flower formation gene network.