Search

Flowering time is an important agronomic trait of Chinese cabbage with late flowering being a primary breeding objective. In our previous work, we obtained Chinese cabbage-cabbage translocation lines that contained several beneficial cabbage genes. Cabbage-specific molecular markers show that these genes were coming from chromosome C01 of cabbage. In this study, we investigated the inheritance of flowering time in a couple of translocation lines and analyzed the transmission rate of molecular markers in the offspring. Consequently, we obtained the late flowering Chinese cabbage-cabbage translocation line ‘AT7-4’ in which the flowering time was later than that of ‘85-1’ by about 7 days under 4-week vernalization. Based on previous studies of the genomes of Chinese cabbage and cabbage, we located the cabbage-specific molecular markers that were closely linked at the top of the chromosome A01 in the F2 mapping population generated by self-crossing F1s derived from a cross between the translocation line ‘AT7-4’ and Chinese cabbage ‘14-36’. Five flowering-related genes in the alien fragment were found by functional annotation and their molecular markers were developed. This study lays the foundation for the future improvement of Chinese cabbage varieties using A-C translocation lines.

Vernalization is a physiological process in which prolonged cold exposure establishes flowering competence in winter plants. In hexaploid wheat, TaVRN1 is a cold-induced key regulator that accelerates floral transition. However, the molecular mechanism underlying the gradual activation of TaVRN1 during the vernalization process remains unknown. In this study, we identified the novel transcript VAS (TaVRN1 alternative splicing) as a non-coding RNA derived from the sense strand of the TaVRN1 gene only in winter wheat, which regulates TaVRN1 transcription for flowering. VAS was induced during the early period of vernalization, and its overexpression promoted TaVRN1 expression to accelerate flowering in winter wheat. VAS physically associates with TaRF2b and facilitates docking of the TaRF2b-TaRF2a complex at the TaVRN1 promoter during the middle period of vernalization. TaRF2b recognizes the Sp1 motif within the TaVRN1 proximal promoter region, which is gradually exposed along with the disruption of a loop structure at the TaVRN1 locus during vernalization, to activate the transcription of TaVRN1. The tarf2b mutants exhibited delayed flowering, whereas transgenic wheat lines overexpressing TaRF2b showed earlier flowering. Taken together, our data reveal a distinct regulatory mechanism by which a long non-coding RNA facilitates the transcription factor targeting to regulate wheat flowering, providing novel insights into the vernalization process and a potential target for wheat genetic improvement.

Plants evolved different strategies to better adapt to the environmental conditions in which they live: the control of their body architecture and the timing of phase change are two important processes that can improve their fitness. As they age, plants undergo two major phase changes (juvenile to adult and adult to reproductive) that are a response to environmental and endogenous signals. These phase transitions are accompanied by alterations in plant morphology and also by changes in physiology and the behavior of gene regulatory networks. Six main pathways involving environmental and endogenous cues that crosstalk with each other have been described as responsible for the control of plant phase transitions: the photoperiod pathway, the autonomous pathway, the vernalization pathway, the temperature pathway, the GA pathway, and the age pathway. However, studies have revealed that sugar is also involved in phase change and the control of branching behavior. In this review, we discuss recent advances in plant biology concerning the genetic and molecular mechanisms that allow plants to regulate phase transitions in response to the environment. We also propose connections between phase transition and plant architecture control.

Camelina [Camelina sativa (L.) Crantz] has two distinctive biotypes, summer and winter, with winter biotypes requiring a vernalization treatment to enter the reproductive phase. Increased interest in broadening the diversity of winter-hardy cover crops in the northern Great Plains of the U.S. to reduce soil erosion through the winter months has led seed companies to offer winter camelina seed outsourced from other states. Regrettably, in 2017, outsourced camelina seed from other states turned out to be summer biotypes that did not survive the North Dakota winter. The objectives of this study were to determine the morphological characteristics of seed and seedlings from summer- and winter-biotypes. Morphological characteristics of seedlings were determined by growing nineteen summer- and eleven winter-biotypes in an environmental chamber. The experimental design was a randomized complete block design with three replicates. To determine differences in seed wavelength absorbance between winter- and summer-biotypes both visible and near infrared spectra were examined, which encompass 400–2498 nm wavelengths. Mixtures of cultivars Joelle (winter) and one summer type were analyzed using near infrared spectroscopy (NIRS). Seed mixtures were prepared in increments of 5% of ‘Joelle’. Mixtures of different lots of Joelle were prepared in increments of 25%. Significant interactions were present and observed for pairs of vegetative leaves, growth stage, height, leaf length, leaf width and the number of lobes. The equation for the ratio of winter seed (r2 = 0.96) performed very well, being able to distinguish known field grown cultivars used in the equation. Differences in seed and seedling morphological characteristics can be used to differentiate winter- or summer-biotypes. Having a rapid method to determine the percentage of winter camelina in an unknown seed sample will be very favorable for all producers, as well as seed companies, interested in growing winter camelina as either a winter-hardy cover crop or as a winter annual cash crop.

Facing and controlling the adverse effects of global warming on crop production, especially under arid and semi arid conditions is an important question, which must be addressed by research work. This may be achieved by alternating crop phonological properties including the vernalization stage, essential for the vegetative/reproductive transition of winter wheat (Triticum aestivum L.). Shortening vernalization, during spring, can be a suitable method for the earlier production of crop plants, especially under stress conditions. Accordingly, it was hypothesized that it is possible to shorten vernalization, using priming (seeds) and spraying (plants) treatments while achieving optimum yield, in winter wheat, under the arid and semi arid conditions of Isfahan, Iran. The objective was to investigate the effects of plant growth regulators including gibberellic acid (GA, 100 mg/l), kinetin (100 and 200 mg/l), 6-benzyl adenine (BA6, 50 mg/l) and cold stratification on shortening vernalization in winter wheat. The research was a split plot experiment on the basis of a completely randomized block design, with four replicates, conducted in 2016. Different traits including number of fertile tillers (NFT), number of grains per spike (NGS), weight of 1000 grains (W1000), number of spikelet per spike (NST), grain yield (GY), protein percentage (PRO), and moist gluten percentage (MGP) were determined. The results indicated that priming and spraying winter wheat with the single or combined use of GA, kinetin and BA6 is the most suitable replacement for vernalization and increasing grain yield, under arid and semi arid conditions. However, priming winter wheat with cold stratification was not as effective, compared with the use of plant growth regulators. The highest grain yield (15.13 t/ha) was resulted by autumn planting + B8 (GA + BA6), followed by spring planting + GA and B9 (14.82 t/ha). Spraying wheat planted in spring (without priming and vernalization) with kinetin + GA3+GA7 (100 mg/l), increased PRO and MGP. The important results of this research work are: 1) planting winter wheat as spring wheat (vernalization not required) resulted in optimum yield amounts by priming and spraying techniques using gibberellins, kinetin and 6-benzyl adenine. This is of significance, with respect to the issue of global warming. 2) Shortening vernalization in winter wheat, which is especially important under arid and semi arid conditions, as the plant is subjected to different stresses including drought. 3) Improving wheat grain quality by the increased rate of protein and gluten. It is possible to plant winter wheat under arid and semi arid conditions using gibberellins, kinetin and benzyl adenine. Such a method results in alleviating the adverse effects of global warming on wheat production. It is also possible to plant winter wheat under different stresses including drought and cold by controlling the vernalization process.

Comprehensive analysis of how wheat phenology responds to environmental factors in global scale is helpful for tackling the possible adverse effects of ongoing climate change on wheat production. In this study, six phenological parameters of global wheat, i.e., the growing season start (SGS), peak (PGS), end (EGS), length (LGS), as well as the vegetative period length (LVP) and reproductive period length (LRP), were retrieved from remote sensing data (1981-2014) by threshold-, logistic-, and shape-based methods. And then, we analyzed the effects of temperature, precipitation, short-wave (SW) radiation, and frost on spatiotemporal patterns of wheat phenology. In addition, haze impacts on wheat phenology were investigated in China and India where haze weather appears frequently in winter-spring seasons. Results showed that the occurrence time of SGS/PGS/EGS is gradually advanced from the pole to the equator and annual mean air temperature can explain >70% of their spatial variations. A dominant advanced SGS/PGS/EGS and a shortened LGS/LVP/LRP were detected in the study region due to the significant increase in temperature and SW radiation, as well as the decrease in frost days. Interannual fluctuations of SGS/PGS/EGS are primarily controlled by air temperature, while precipitation and frost only exerted some obvious impacts in some locations. Higher preseason temperature would induce an earlier wheat phenology and a shorter growing season, while adequate precipitation and frequent frost in preseason could delay the occurrence timing of wheat phenology and lead to a longer growing season. Besides, the decreased temperature resulted from severe haze weather may have partly counteracted the global-warming-induced advancing trend of wheat phenology in China, but further advanced the occurrence timing of wheat phenology through prompting vernalization in India. Overall, though wheat growth is largely constrained by human management, we still highlight the strong impacts of global climate change on wheat phenology.

Garlic flowering and bulbing are prone to photo-thermal regulation during its annual cycle. As in many other geophytes, these pathways are parallel but competitive, and can be manipulated by the environment. Both flowering and bulbing are of paramount physiological value, and of great horticultural interest. We argue that, in bolting garlic, differential regulation of only one of the two pathways by pre-planting vernalization is unfeasible, and that garlic's response to cold shows an optimal curve. Within limits, long vernalization treatments have resulted in rapid development of 'Reproductive and Bulbing Phenotype’, with fast leaf elongation, early transition of the apical meristem to the reproductive state, development of axillary buds, flowering and bulbing. Low temperatures trigger primary signaling components, thus modulating organogenesis even under a relatively short photoperiod. We therefore propose that under a suboptimal photoperiod, favorable temperatures could substitute the plant's requirements for photoperiod and signal for the meristem transition, flowering and bulbing. The optimum response of the studied genotype was obtained after vernalization of four weeks at 4 °C. No transition of the apical meristem was evident in plants exposed to only short or no vernalization, namely the apex remained vegetative. These plants continuously produced foliage leaves, thus forming a “Leafy Phenotype”, which did not branch, bulb or flower. Comprehension of the plant’s response to environment is expected to facilitate physiological manipulations on the production of either bulbs or true seeds in garlic.

Flowering time is an important agronomic trait that is highly influenced by the environment. To elucidate the genetic mechanism of flowering time in rapeseed (Brassica napus L.), a genome-wide QTL analysis was performed in a doubled haploid population grown in winter, semi-winter and spring ecological conditions. Fifty-five consensus QTLs were identified after combining phenotype and genomic data, including 12 environment-stable QTLs and 43 environment-specific QTLs. Importantly, six major QTLs for flowering time were identified, of which two were considered environment-specific QTLs in spring ecological condition and four were considered environment-stable QTLs in winter and semi-winter ecological conditions. Through QTL comparison, 18 QTLs were colocalized with QTLs from six other published studies. Combining the candidate genes with their functional annotation, in 49 of 55 consensus QTLs, 151 candidate genes in B. napus corresponding to 95 homologous genes in Arabidopsis thaliana related to flowering were identified, including BnaC03g32910D (CO), BnaA02g12130D (FT) and BnaA03g13630D (FLC). Most of the candidate genes were involved in different flowering regulatory pathways. Based on re-sequencing and differences in sequence annotation between the two parents, we found that regions containing some candidate genes have numerous non-frameshift InDels and many non- synonymous mutations, which might directly lead to gene functional variation. Flowering time was negativly correlated with seed yield and thousand seed weight based on a QTL comparison of flowering time and seed yield traits, which has implications in breeding new early-maturing varieties of B. napus. Moreover, a putative flowering regulatory network was constructed, including the photoperiod, circadian clock, vernalization, autonomous and gibberellin pathways. Multiple copies of genes led to functional difference among the different copies of homologous genes, which also increased the complexity of the flowering regulatory networks. Taken together, the present results not only provide new insights into the genetic regulatory network underlying the control of flowering time but also improve our understanding of flowering time regulatory pathways in rapeseed.

Cichorium intybus is a biennial plant species forming a taproot and a leaf rosette during the first year and which requires low temperature during vernalization to flower during the second year of its cycle. Heat stress, however, is known to induce premature flowering during the first year. The present work aims to compare the effect of heat treatment (38 °C during 3 days) and vernalization (4 °C during 6 weeks) on the phytohormonal profile and the expression of two chicory genes (CiFL1 and CiFT) homologous to the Arabidopsis flowering genes FLOWERING LOCUS C (FLC) and FLOWERING LOCUS T (FT). In Arabidopsis, FLC and FT code, respectively, for a repressor and an activator of flowering. Although CiFL1 was inhibited by vernalization, its expression was increased by heat treatment in both vernalized and non-vernalized seedlings while high temperature unexpectedly inhibited FT expression in vernalized seedlings. Vernalization induced a modification in the hormonal profile of C. intybus (cv. Melci) in a sense of a decrease in ethylene production, abscisic acid and total jasmonates content, while the level of salicylic and benzoic acids as well as polyamine spermidine increased. A limited effect on the gibberellins’ profile was observed. The subsequent impact of heat stress on phytohormone content was different in non-vernalized and vernalized seedlings, with a higher abscisic acid and jasmonates and a lower 1-aminocyclopropane-1-carboxylic acid concentration in the former than in the latter. These data are discussed in relation to the putative involvement of phytohormones in stress-induced flowering. It appears that heat stress implies different pathways than vernalization to hasten flowering process.

Orchids take years to produce the most precious and expensive flowers. Continuous flowering is a rare characteristic of bamboo orchid (Arundina graminifolia). Therefore, finding genetic regulators of this flowering pattern can set new directions for other orchids. Present study demonstrates transcriptome analysis to identify a number of zinc finger transcription factors (ZF TFs) from five stages of flower development and four tissue types. About 480 DEGs were annotated to the zinc finger category, which may involve multiple signaling pathways for flowering control. The highest number of ZF TFs belonged to CCCH domain, followed by BED and INDETERMINATE. Some important ZF TFs were found to control the flowering genes at transcriptional levels. LATE and B-box ZFs respond to photoperiod and hormone signaling. MAD1 and SUF4 control flowering time through FLC. BZR1 and ELF6 possibly respond to vernalization pathway and HUA1 controls flowering through AGAMOUS pathway. WGCNA-based ZF candidates BBX22 and BBX24 involve circadian and hormonal pathways in association with floral integrators to regulate flowering time in A. graminifolia. Thus, our ZF mining can do a great deal to understand the molecular mechanism of continuous flowering in A. graminifolia.

MADS-box genes play a significant role for plant flowering. Keratin-like (K) domains are involved in protein-to-protein interactions in the formation of the MIKC-type MADS-box domain proteins. In this study, the potential of utilizing the K domain of a Vaccinium corymbosum SOC1-like gene (VcSOC1K) was investigated to modulate expression of other blueberry MADS-box genes for increasing blueberry productivity. Chilled transgenic blueberry plants overexpressing the VcSOC1K showed a significant increase in the number of canes, floral buds, and flower and fruit clusters compared to chilled non-transgenic plants. Additionally, nonchilled transgenic plants flowered whereas nonchilled non-transgenic plants did not. Transgenic plants showed an increase in tolerance to high soil pH. Comparative transcriptome analysis of transgenic and non-transgenic leaves showed differential expression of 17% of the MADS-box genes identified in blueberry. These differentially expressed (DE) MADS-box genes were associated with genes related to plant flowering, phytohormones, and response to various biotic and abiotic stimuli. The phenotypic changes and the DE MADS-box genes caused by the overexpression of VcSOC1K not only reveal that the MADS-box genes are involved in chilling/vernalization-mediated flowering in blueberry but also demonstrated that the overexpression of the K domain can effectively modulate plant reproductive processes.

Quantifying historic increases in water-limited potential yield (PYw) achieved through breeding provides insight into associated changes in physiology and can assist with future cultivar improvement. We compared PYw of bread wheat cultivars popular in southern New South Wales released between 1901 and 2014. In both 2015 and 2016, cultivars were sown at multiple sowing dates to allow comparisons to be made at a consistent optimal flowering date (early October), and thus control for the large differences in life cycle duration. Seasonal conditions were close to average in 2015 and extremely favorable in 2016. In both, grain yield increased across the historic period studied at 26 kg/ha per annum, regardless of whether a common sowing date or flowering date was used. Yield gain was not linear, and there was a period of rapid yield increase during the middle of the 20th century, that culminated with the release of semi-dwarf cultivars. Yield gain was relatively slower from the 1980s until the present day, possibly due to selection for grain quality traits (grain size) at the expense of grain number. Historic yield increases were not associated with earlier flowering, but with an interplay between greater grain number/m2 and greater grain weight which was the result of increased partitioning of assimilates to spikes, and greater number of grains per unit spike weight (fruiting efficiency). Greater partitioning to the spike in modern cultivars was associated with reduced dry matter (DM) production prior to flowering. Modern cultivars have a less stable flowering time across sowing dates, and shorter life cycle, but improved partitioning in modern cultivars appeared decoupled from shorter developmental phases prior to flowering. The performance of the novel vernalisation sensitive cultivar Longsword showed that future yield gain may be achieved through the combination of early sowing and slow development, increased DM production and superior partitioning to grain.

Preliminary evidence indicates that Rht5, a gibberellin-responsive (GAR) dwarfing gene, could reduce plant height without affecting coleoptile length and seedling vigour. However, Rht5 delayed ear emergence and anthesis, which would hinder its utilization in wheat improvement. To advance the flowering time of Rht5 dwarf plants, the dominant vernalization gene Vrn-B1 and the photoperiod-insensitive gene Ppd-D1 were introduced through two crosses between Ningchun45 (Vrn-B1) and Jinmai47 (Ppd-D1) with Marfed M (Rht5), respectively. Fifty-nine and 71 F2:3 and F3:4 homozygous lines from the first and the second cross were used to evaluate the effects of Vrn-B1 and Ppd-D1, respectively on the developmental and agronomic traits of Rht5 dwarf plants during two growing seasons in Yangling, Shaanxi, China. The results showed that Rht5 significantly reduced plant height (40.1% and 38.9%) but delayed the flowering time (14.0% and 4.8% in thermal time) in both populations. In general, Rht5 significantly decreased the spike length by 22.6% and 16.7, grain number by 14.5% and 11.5%, 1000-grain weight by 24.1% and 18.4%, and grain yield by 35.1% and 21.5% in the two populations, respectively. Vrn-B1 could not compensate for the negative effect of Rht5 on spike development and the flowering time and had no significant effect on plant height or other agronomic traits. However, Ppd-D1 was able to overcome the delaying effect of Rht5 on spike development by shortening the duration of the reproductive phase (double ridge stage-anthesis) and finally promoting earlier flowering (8.7% in thermal time) in Rht5 dwarf lines. Ppd-D1 also reduced plant height (10.0%), and the combination of Ppd-D1 and Rht5 produced even shorter plants (45.0%), achieving dwarf plants with higher lodging resistance. Additionally, Ppd-D1 increased the grain number (6.3% and 9.6%), 1000-grain weight (13.0% and 21.5%), plant yield (22.6% and 39.5%) and harvest index (31.1% and 49.6%) in both tall and dwarf plants, respectively. Clearly, the combination of Rht5 and Ppd-D1 had no negative effect on plant growth or grain yield, advanced spike development and the flowering time, and improved agronomic traits, which may be conducive to exploiting Rht5 for wheat improvement.

The turnip (Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the next spring for flowering and seeds. FLOWERING LOCUS C (FLC) is a MADS-box transcription factor that acts as a major repressor of floral transition by suppressing the flowering promoters FT and SOC1. Here we show that vernalization effectively represses tuber formation and promotes flowering in Tibetan turnip. We functionally characterized four FLC homologues (BrrFLC1, FLC2, FLC3, and FLC5), and found that BrrFLC2 and BrrFLC1 play a major role in repressing flowering in turnip and in transgenic Arabidopsis. In contrast, tuber formation was correlated with BrrFLC1 expression in the hypocotyl and was repressed under cold treatment following the quantitative downregulation of BrrFLC1. Grafting experiments of non-vernalized and vernalized turnips revealed that vernalization independently suppressed tuberization in the tuber or hypocotyl of the rootstock or scion, which occurred in parallel with the reduction in BrrFLC1 activity. Together, our results demonstrate that the Tibetan turnip is highly responsive to cold exposure, which is associated with the expression levels of BrrFLC genes., Graphical abstract

Using heavy-ion beam mutagenesis of Triticum monococcum strain KU104-1, we identified a mutant that shows extra early-flowering; it was named extra early-flowering 3 (exe3). Here, we carried out expression analyses of clock-related genes, clock downstream genes and photoperiod pathway genes, and found that the clock component gene PHYTOCLOCK 1/LUX ARRHYTHMO (PCL1/LUX) was not expressed in exe3 mutant plants. A PCR analysis of DNA markers indicated that the exe3 mutant had a deletion of wheat PCL1/LUX (WPCL1), and that the WPCL1 deletion was correlated with the mutant phenotype in the segregation line. We confirmed that the original strain KU104-1 carried a mutation that produced a null allele of a flowering repressor gene VERNALIZATION 2 (VRN2). As a result, the exe3 mutant has both WPCL1 and VRN2 loss-of-function mutations. Analysis of plant development in a growth chamber showed that vernalization treatment accelerated flowering time in the exe3 mutant under short day (SD) as well as long day (LD) conditions, and the early-flowering phenotype was correlated with the earlier up-regulation of VRN1. The deletion of WPCL1 affects the SD-specific expression patterns of some clock-related genes, clock downstream genes and photoperiod pathway genes, suggesting that the exe3 mutant causes a disordered SD response. The present study indicates that VRN1 expression is associated with the biological clock and the VRN1 up-regulation is not influenced by the presence or absence of VRN2.

Sugar beet (Beta vulgaris) is a biennial crop that accounts for 30% sugar production of the world. Vernalization is an essential factor for sugar beet reproductative growth under long days. Although genes association with bolting and flowering were well explored, the difference of proteomics in the two growth stages were still poorly understood. To address the molecular mechanism at the level of proteins, an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomics approach was employed to the three different growth stages (germination, bolting, flowering) of vernalized samples and the corresponding stage germination (17W weeks), 19W and 20W of nonvernalized samples. A total of 1110 peptides, 842 unique peptides and 570 proteins were identified. Most of them were assigned to phenylpropanoid biosynthesis, hormone metabolism and protein processing pathway. IAA and Gibberellins (GA3) promoted growth and development in a threshold manner at growth stage germination after vernalization. A novel discovery was that IAA biosynthetic pathway of sugar beet was the Trp-dependent. In addition, two predominant pathways of protein processing association with vernalization were also identified in sugar beet at growth stage flowering. This study provided an in-depth understanding of the molecular mechanism of vernalization at the level of proteomics.

DNA J HOMOLOG 3 (J3) is a special transcriptional regulator in flowering time control, but the molecular mechanism of J3 in regulating flowering time has not been thoroughly revealed in B. juncea which is one important oilseed and vegetable crop. In this study, J3 gene was cloned from B. juncea (BjuJ3). Phylogenetic relationship analysis showed that the BjuJ3 had high amino acid sequence similarity (>93%) with other Brassica plants. The BjuJ3-transgenic tobacco plants exhibited early flowering, suggesting that BjuJ3 was an activator of flowering time. The qRT-PCR analysis found that BjuJ3 could be ubiquitously induced by the long-day and vernalization treatments in all the tissues of B. juncea. Yeast two-hybrid assays and GST pull-down experiments revealed that BjuJ3 could not directly interact with BjuSOC1, BjuSVP and BjuAGL24. Whereas, yeast one-hybrid and Dual-Glo® Luciferase assays found that BjuJ3 could not interact with BjuAGL24 promoter but could specifically bind to BjuSOC1-1 which is one of truncated fragments of BjuSOC1 promoter. Our research will provide valuable information for unraveling regulatory mechanisms of flowering time in B. juncea.

This paper reviews climate change impacts on the production, physiology, yield, and product quality of vegetables affected by shifting CO2 and O3 concentrations, precipitation and temperature conditions, as well as subjected to extreme weather events. The emphasis is on the temperate cool climate of Western Europe. Physiological processes such as respiration and photosynthesis can acclimate to increasing atmospheric CO2 and temperatures. The effect of increased CO2 on vegetables is mostly beneficial for production, but may alter internal product quality, or result in photosynthetic down-regulation. Heat stress reduces fruit set of fruiting vegetables, and speeds up development of determinate vegetables, shortening their time for photoassimilation. In both cases, yield losses result with an impaired product quality, thereby increasing production waste. A longer growing season, arising from warmer temperatures, allows a greater number of plantings to be cultivated, contributing to greater annual yields. However, some vegetables need a period of cold accumulation to produce a harvest. Despite the increasing potential for winter cultivation in the future, perennials like asparagus might increasingly suffer from a lack of winter chilling. In cauliflower, higher temperatures will likely cause insufficient vernalization delaying head induction. This review may contribute in improving the adaptation strategies of vegetable production to climate change for a sustainable horticulture due to an effective risk management by meeting the problems of possible waste increase; breeding of new heat, drought and pest tolerant cultivars; secure water resources; increase the use of renewable energy sources; stimulating new ideas in innovative technologies; development of new approaches to secure stable yields and improve the product quality of vegetables for a cleaner production. © Elsevier. All rights.

Camelina sativa is a promising oilseed and industrial crop that benefits sustainable food, feed and fuel industries. Early flowering is critical for local adaptation as well as maximizing yield in Camelina sativa. Even though the preliminary data indicated wide variation in flowering time in the spring camelina germplasm, our understanding of underlying genes and their roles in regulating flower development is still limited. The current study combined genotypic data and flowering time from the spring panel, followed by genome-wide association study (GWAS) and whole-genome prediction to identify significant trait-associated markers and evaluate the predictive capability of the entire marker set. The analysis of phenotypic data showed significant genotypic and environmental effects on flowering time. A high heritability of 0.893 in flowering time suggests effectiveness of breeding early flowering camelina varieties. The GWAS analysis identified 20 significant trait-associated single nucleotide polymorphisms (SNPs) that colocalized within/or near a variety of transcription factors (e.g. SUPPRESSOR of PHYA-1/SPA1, BES1-INTERACTING MYC-LIKE 1/BIM1) or protein families containing specific functional domains (e.g. CCCH zinc finger protein family and B3-DNA binding domain containing protein family). These transcription factors were known to interact with key regulatory genes in the four major pathways (i.e. photoperiod, autonomous, vernalization and gibberellic acid pathways) to cooperatively regulate floral transition in arabidopsis. Whole-genome prediction showed a low-to-moderate predictive ability (0.559) to improve early flowering trait in camelina. This study is the first step for future in-depth exploration and genetic improvements of flower development and timing in camelina for breeding.

Lilium × formolongi, a facultative long-day (LD) plant, has precocious flowering characteristics, as it can flower within one year from seeds without the need for vernalization. Under normal LD conditions, the seedlings entered the flowering induction phase and bolted with 9−10 rosette leaves at 6 months after sowing. High temperature, especially at the root zone, inhibited bolting of the seedlings in LDs, accompanied by changes in plant shape and rapid expansion of underground bulbs. Low temperature in the natural environment could rapidly reverse the inhibition caused by high temperature, and promote bolting even under non-induced short days. The circadian clock and photoperiod pathways were disturbed at the transcriptional level by high temperature in both leaves and bulbs, such as LfCCA1, LfCRY, LfCOP1, LfFKF1, LfCOLs and LfPIFs. Thus, the flowering integrators LfFT1 and LfSOC1 were suppressed by high temperature. To determine the flowering inhibitors induced by high temperature in the root zone, the metabolome was analyzed under different conditions. ABA and ACC accumulation in the leaves and bulbs respectively during high temperature, was crucial to flowering inhibition possibly via interaction with the circadian clock and photoperiod-dependent pathways. Additionally, under high temperature conditions, D-allose, pentose and glucuronate interconversions and glutathione metabolism in the leaves were significantly activated. After cold exposure, TCA cycle was suppressed and SA, JA and some sugar (D-mannose, D-fructose, D-arabinose and maltotriose) levels were upregulated in the leaves, simultaneously with the vigorous fatty acid metabolism in the bulbs. These metabolic regulations were crucial to the phase transition under different conditions.

International audience; During the past few years, milder autumn and winter seasons have caused severe problems to cauliflower harvest of Brittany region in France, mainly due to curd deformation. Consequently, cauliflower breeders are working on breeding new varieties that are more robust to climate change to stabilize the quality of cauliflower production. The aim of this study was to identify at which stage of the curd formation, significant difference can be detected between healthy and stressed cauliflower. A non-invasive classification based on Magnetic Resonance Imaging (MRI) images for cauliflower phenotyping was proposed. Plants exposed to vernalization stress were sampled at different times around primary meristem stage, then both MRI imaged and apex dissected. A work flow was developped to extract features from MRI images. A classification on phenotype was learned by LDA, QDA, PLSDA and CNN binary classification between two groups: healthy and stressed cauliflower. Promising F1 score and MCC up to 95% were achieved. Curd deformation is the main cause for cauliflower’s later physiological disorders when reaching maturity. Therefore, the cauliflowers with deformation could be removed at the earliest, e.g., screening for plant breeding. At the same time, the healthy cauliflowers are not destroyed and continue their life cycle

The vernalization of wheat is one of the important factors that determine the planting region, introduction and cultivation techniques of wheat. However, the known vernalization genes (molecular marker) cannot precisely distinguish the vernalization requirement of winter wheat cultivars. Therefore, it is important to explore new vernalization genes and elucidate the mechanism of vernalization regulation. To explore the gene network in the vernalization pathway, we screened TaIRI9 (ice recrystallization inhibitor protein) gene associated with the expression profile of vernalization treatment of winter wheat Jing 841. Overexpression of TaIRI9 in wild type wheat resulted in reduced plant height, increased tiller number and delayed heading days. After 4 °C vernalization treatment for 30, 35, 45 or 50 days, TaIRI9 overexpression lines showed increased vernalization requirement and delayed heading time than wild type, indicating that TaIRI9 may affect vernalization process of wheat. In addition, the expression of the TaIRI9 genes were analyzed in winter Jing 841, strong winter wheat cultivar Xindong 18 and ten recombinant inbred lines (RILs, Hussar × Yanzhan1). The data showed that the expression of TaIRI9 was positively associated with the requirement of vernalization. These results indicated that TaIRI9 regulates heading and flowering time in wheat by promoting VRN2 and inhibiting flowering promoter VRN1 and VRN3 and may be involved in wheat vernalization regulation pathway.

The hybrid production of winter rapeseed is limited by the difficult vernalization processes. Thus, floral regulation of winter rapeseed parental lines cannot be executed through selection of sowing time during hybrid production. Therefore, in this study, strong winter rapeseed was used as the material to analyse the floral transition mechanism of germinating seed vernalization. Results demonstrated that germinating seeds could sense low temperatures and complete vernalization following a low temperature treatment for 56.5 d with a 100 % vernalization rate. The regression equation between vernalization rate (y) and vernalization treatment days (x) was determined as y = 0.019x - 0.0765 (R² = 0.8529). When the vernalization treatment time was prolonged, the vernalization rate and fruiting ability increased rapidly, and variations were observed in the membrane lipid oxidation and physiological characteristics. Furthermore, at the prolonged treatment time of 10-50 d, the salicylic acid (SA) content continued to decrease, with values significantly lower than those of the control. SA content is significantly positively correlated with the level of BrFLC transcription and a significantly negatively correlated with the vernalization rate of germinating seeds. Moreover, the expressions of genes associated with SA biosynthesis, SA signal transduction, the flowering key negative regulators were suppressed and that of positive regulators were promoted during vernalization. These results suggest that SA as a floral repressor is involved in the regulation of the vernalization process of winter rapeseed germination seeds. In addition, SA may be related to the counting dosage of vernalization.

Vernalization, the acquisition of competence to flower after extended cold treatment, has puzzled researchers throughout the last century. Great progress in understanding the molecular mechanisms of vernalization in Arabidopsis has been made in the course of the last 20 years, placing the flowering repressor-encoding gene FLOWERING LOCUS C (FLC) in the limelight (Bouche et al., 2017). In vernalization-dependent accessions, FRIGIDA (FRI) ensures strong expression of FLC that delays flowering, and extended exposure to low temperatures such as during winter leads to stable repression of FLC, which in turn clears the way for induction of flowering.

International audience; Intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey) is being developed for use as a new perennial grain crop through breeding and agronomic research. However, progress has been hampered by lack of understanding of environmental requirements for flowering and grain production. Therefore, we developed a phenology model for IWG adapted from the STICS soil-crop model. The model was compliant with experimental results (relative root mean square error = 0.03). The optimal vernalizing temperature was between 4 and 5 • C, optimal daylength between 13 and 14h, while daylength below 11h slowed reproductive development. Vernalization requirement was found to be a constraining inductive process. Including a photoperiod limitation to the model with temperature improved its ability to predict induction at various latitudes. Therefore, timing and duration of vegetative vs. reproductive growth may differ between environments and change reproductive tiller elongation earliness, weed competitiveness, management timing, and stress conditions during phases critical to grain yield. Accurate phenology models will enable optimal field management and inform future breeding strategies. However, plasticity may lead to divergent ideotypes under various agroecosystems.

Rapeseed (Brassica napus L.) has winter and semi-winter ecotypes which need vernalization in the development process. Leaf development coincides with vernalization, and the leaf petiole angle (LPA) is associated with cold environmental adaptation during the overwintering period in rapeseed. In the present study, a genome-wide association study (GWAS) using a Brassica 60 K SNP array for LPA identified 45 significantly associated quantitative trait loci (QTLs) and 3525 candidate genes. Moreover, two rapeseed accessions (T193, winter type and T268, semi-winter type) with significantly different LPA degrees were used for RNA sequencing (RNA-seq). And transcriptome analysis revealed that most of the differentially expressed genes (DEGs) were involved in auxin, brassinosteroid (BR) and ethylene signaling pathways as well as the cell division pathway. Using integration of GWAS and RNA-seq analysis, several promising candidate genes, including BZR1, IAA7, IAA15, PIN3 and SPL orthologs were prioritized for further research. Quantitative real time PCR (qRT-PCR) also validated the differential expression patterns of nine candidate genes between T193 and T268. Through regulating differential cell division of the abaxial and adaxial petiole for small LPA, auxin signaling genes could be involved in the adaptation of rapeseed seedlings to low temperature conditions. These findings provide insights into the molecular mechanism of environmental adaptation at the seedling stage and provide valuable information for facilitating marker-based breeding in B. napus.

Winter survival in wheat requires programmed potential modulations to develop low temperature (LT) acclimation for its growth and yield. The purpose of the present study was to understand the relationships between developmental regulations and metabolic changes during LT acclimation and vernalization under field conditions. Six wheat recombinant inbred lines (RILs) of F8 generation resulted from cross Mironovskaya 808 (winter-habit parent) and Pishtaz (spring-habit parent) with different vernalization requirements and reproductive development, whose growth habits were determined by Vrn-1 loci, were cultivated under greenhouse and field conditions. Plants were sampled on three dates (Dec. 12, Jan. 11, and Feb. 10) as different phenological development stages. Early and rapid transition from vegetative to reproductive phase measured by double ridge (DR) formation and final leaf number (FLN) occurred in spring genotypes, including Pishtaz parent and RILs 4006 and 4014. They also had the lowest enzymatic antioxidants activity and contents of anthocyanins, total phenols, flavonoids, lignin, proline and carotenoids and the highest damage indices (H2O2 and MDA) among genotypes. RILs 4012 and 4016 had higher FLN than Pishtaz and remained in vegetative phase longer and showed higher tolerance (LT50 and metabolites) as compared to spring genotypes. In contrast, Mironovskaya 808 parent and RILs 4005 and 4003 spent the longest time in the vegetative phase and showed the highest level of LT tolerance (confirmed by LT50, damage indices and pigment contents). The highest level of LT tolerance in all genotypes, obtained at the vegetative/reproductive transition, significantly decreased with the onset of the reproductive phase. Our results suggested that LT tolerance was established from developmental regulations and potential metabolic networks following longer vegetative phase in wheat.

Madonna lily (Lilium candidum) is a flowering geophyte growing wild in Israel and in the neighboring region. In view of its holly character in the Christian culture, L. candidum has a great commercial potential as an ornamental crop. However, knowledge regarding its cultivation and the control of its flowering time is very limited. In this study, we aimed to define external factors affecting L. candidum flowering and characterized the developmental stages of the shoot apical meristem (SAM), under different temperature and photoperiod regimes. We found that in most cases, bulb or plant exposure to low temperature (4 °C, forcing) hastened floral transition and flowering in a quantitative manner, whereas day length had a negligible effect on these traits. These results suggest that vernalization is a major pathway regulating flowering time in L. candidum. We also characterized a novel phenomenon in which exposure of the bulb to low temperature led to a delay in bolting and flowering until the following season. We showed that the ability of a bulb to perceive cold exposure as signal for flowering hastening or as a delay was dependent on the SAM's developmental stage and was related to the season. During the summer, cold exposure applied to the SAM at the juvenile phase results in growth inhibition, while from the fall onward, when the meristem has reached its vegetative adult phase, cold exposure promotes bolting and flowering, according to the classic vernalization response. Exposure of the juvenile bulb to 12 °C promotes the transition of the SAM from juvenile to vegetative adult. In conclusion, we showed cold exposure of bulbs at the juvenile phase induced the inhibition of the bolting and flowering, while bulb cold exposure of bulbs at the vegetative adult stage promoted flowering. This study sheds light on the development and flowering physiology of L. candidum and can have applied outcomes for its cultivation as a cut flower crop.

In order to study the effect of duration of the vegetative period (sowing to floral initiation) on potential yield, sister spring wheat semi-dwarf cultivars, Yecora and Cajeme, the latter having an extra vernalization sensitive allele (Vrn-A1v) and a photoperiod sensitive one (Ppd-D1b), were grown at 4–5 sowing dates over 5 years under irrigation and high fertility in northwest Mexico (latitude 27°N). In the earliest sowings (late Oct-early Nov) Cajeme had a 20 day longer vegetative period; this delay decreased steadily to 8 days in the latest sowings (mid-late January); anthesis date for Cajeme was, respectively, 17 and 6 days later. Relationships to minimum temperature levels in the vegetative phase strongly suggest that this sowing date by cultivar interaction arises largely because of the difference in vernalization alleles in an environment where there is limited vernalizing cold. Cajeme produced a greater maximum number of shoots, more spikelet nodes per spike, greater green area index, and greater above ground dry matter at anthesis and at physiological maturity. However Cajeme yielded no more than Yecora, even when yield was plotted against anthesis date, tending to have fewer grains/m 2 . A similar conclusion was reached when grains/m 2 were related to preanthesis photothermal quotient, and grain weight to grain filling mean temperature: both cultivars responded similarly although Cajeme had slightly fewer grains/m 2 and heavier kernels, thus weather around flowering dominated determination of these yield components. Some other yield components were also slightly, but significantly, affected by cultivar in a manner independent of flowering date and weather. Thus Cajeme had a significantly higher spike dry matter at anthesis and a significantly lower fruiting efficiency of Cajeme (73.8 versus 84.2 grains/g spike dry matter). It is suggested that the latter was a consequence of the longer vegetative period leading to greater tillering, poorer tiller survival and a more competitive preanthesis canopy, causing poorer floret survival in grain-bearing spikes. The excessive tillering may have been exaggerated by supplying all nitrogen fertilizer at sowing.

Wheat phenological modelling literature suggests final leaf number (FLN) targets of wheat (Triticum aestivum) will be set only once daylight is perceived and will be based upon environmental and cultivar-specific genetics at that time. Development is thought to proceed relative to thermal time regardless of light perception prior to emergence. Modelled predictions of final leaf number (FLN) and thence anthesis are based on this mechanism. Results did not support this hypothesis, and we suggest and alternative hypothesis based on molecular interactions between vernalization genes Vrn1, Vrn2 and Vrn3.

An understanding of genotype × environment (G × E) interactions for phenological adaptation in crops can help identify traits that facilitate genetic improvement and cultivar selection. Such understanding is also necessary to identify environments that facilitate identification of cultivars with better environmental adaptation. Process-based crop simulation models including APSIM are valuable tools to investigate G × E interactions and traits conferring adaption to particular conditions. However cultivar parameters relating to crop phenology in crop model are difficult to determine directly through field experiments. Within this paper, we present a simulation study to explore the environmental and genotypic control of time to flowering and maturity in lupin and its grain yield, by using the APSIM model. In the model, lupin cultivar parameters were optimized by combining prior knowledge and PEST (Parameter ESTimation), a model-independent parameter optimiser. The parameterisation was for nine lupin cultivars with contrasting maturity (early vs late) and vernalization requirement (non-responsive vs responsive) across 13 sites × years across Australia. We showed that phenological differences among the cultivars were well explained by the optimized set of parameters, mainly reflected in vernalization response and photoperiodic sensitivity before flowering. Simulated flowering days and grain yield agreed well with the observations, with RMSEs (root mean squared error) of 4 days and 0.34 t ha−1 for all cultivars together. The simulation results showed that lupin yield was significantly affected by temperature and water availability. An early-maturity cultivar would yield better than the late-maturity one at the warm and low rainfall region, while at high rainfall or long-season regions, cultivar types should be chosen tactically based on the climatic conditions for that season. Thus, lupin breeding in Australia should therefore focus on temperature regimes and rainfall gradients. These results indicate that the parameter-optimized APSIM model could be used to explore the adaptation of genotypes to a particular environment to provide guidance for a more efficient breeding program and develop optimal agronomic management practices.

In sub-tropics, most sweetpotato genotypes do not flower at all. The aim of this study was to develop methods of inducing flowering based on the application of 2.4-dichlorophenoxyacetic acid (2.4D) and grafting of non-flowering genotypes on rootstocks of genotypes that flower. The first experiment was a 3 * 4 * 2 factorial experiment repeated in summer and winter seasons. Four levels of 2.4D (0, 40, 80 and 120 ppm) were applied at two levels (once and twice) on three sweetpotato genotypes. The second experiment involved grafting scions of two genotypes on rootstocks of flowering genotype. During summer season there were significant differences ( P

Information concerning to regulation of vegetative phase and floral initiation in herbaceous perennial plants has been limited to a few plant species. To know and compare flowering regulation in a wider range of plant species, we identified and characterized SHORT VEGETATIVE PHASE (SVP)-like genes (GtSVP-L1 and GtSVP-L2) from herbaceous perennial gentian (Gentiana triflora). Apple latent spherical virus (ALSV)-mediated silencing of the GtSVP-L1 in G. triflora seedlings resulted in early flowering and shortened vegetative phase by about one-third period of time, without vernalization. This indicated that GtSVP-L1 acts as a negative regulator of flowering and vegetative phase. Seasonal change in the expression of GtSVP was monitored in the overwinter buds (OWBs) of G. triflora. It was found that the levels of GtSVP-L1 mRNA in OWBs increased concomitantly with induction and/or maintenance of dormancy, then decreased toward release from dormancy, while that of GtSVP-L2 mRNA remained low and unchanged. These results implied that, in herbaceous perennial plants, SVP ortholog might concern to activity-dormancy control, as well as negative regulation in flowering. Practically, these results can be applicable to non-time-consuming technologies for breeding.

In the Pacific Northwest, USA, pathogenic Fusarium spp. are common in agricultural soils but rare in forest soils. We hypothesized that regional forest soils possess indigenous Fusarium- suppressive microbes, which may enter into novel associations with introduced crop plants, potentially contributing to suppressive soils. To test this hypothesis, we inoculated winter wheat with regional forest litter microbial communities and rhizosphere fungi and challenged plants with pathogenic Fusarium culmorum from regional agricultural fields. We also challenged plants with drought and low-temperature stress, which may augment disease severity. A forest litter microbiome improved survival of Fusarium -infected wheat three-fold and increased growth by 67%. Seedlings inoculated with individual forest fungi developed larger root systems during vernalization. Penicillium sp. doubled yield of Fusarium -infected winter wheat exposed to drought conditions. Indigenous microbes from native plant communities of the interior Northwest mitigate abiotic stresses and may contribute to suppression of a soil-borne wheat disease via novel symbioses.

In many bulbous plant species that require vernalization, including garlic, the age of the plant and a period of low temperature are important for complete vernalization. However, the response of garlic to vernalization treatment, which regulates development, remains poorly understood. In this study, the effects of vernalization and plant age on garlic growth and development were assessed. Garlic cultivar cv. G064 (bolting type), which is widely cultivated in China, was grown in a plastic tunnel for three different durations (A65, A45 or A25: 65, 45 or 25 days after planting) and then exposed to four vernalization temperatures [T5–0: 5 °C/0 °C, T10–5: 10 °C/5 °C, T15–10: 15 °C/10 °C, T20–15: 20 °C/15 °C (day/night)] for 40 days in growth chambers. To evaluate the bolting rate, plant growth, and endogenous physiological indexes, leaf and pseudostem samples were taken from all plants after 20 days of treatment and from A25 plants after 40 days of treatment. The results indicate that the response to vernalization varied among garlic plants of different ages, although the patterns were similar among the treatments. In general, vernalization treatment significantly increased the bolting rate in plants at all ages tested, with the youngest plants having the highest bolting rates at 10 °C/5 °C (28.6%, 40.1% and 50.0% for the A65, A45, and A25 plants, respectively), inhibited vegetative growth (with reductions in plant height observed in all plants except for A65 plants, pseudostem diameter, and green leaf number, especially for the T5–10 treatment) and promoted peroxidase (E.C. 1.15.1.7) and superoxide dismutase (E.C. 1.15.1.1) activities compared with the results observed in the control. The lowest temperature induced the strongest enhancing effect. It seems that a curved parabolic relationship might exist between the vernalization conditions and successful vernalization. Furthermore, the regulation of growth and bolting of plants requiring green-plant vernalization is achievable through the control of plant age (sowing dates) and growth temperature.

Litchi (Litchi chinensis) is an important subtropical evergreen fruit crop with high commercial value due to its high nutritional values and favorable tastes. However, irregular bearing attributed to unstable flowering is a major ongoing problem for litchi producers. There is a need to better understand the genetic and molecular mechanisms underlying the reproductive process in litchi. In a previous study, our laboratory had analyzed the transcriptome of litchi leaves before and after low-temperature treatment with RNA-seq technology. Herein, we demonstrated that litchi flowering was induced by low-temperature and identified two FLOWERING LOCUS T (FT) homologue genes named LcFT1 and LcFT2, respectively. We found that low-temperature could only induce LcFT1 expression in leaves, but could not induce LcFT2 expression. Heterologous expression of LcFT1 in transgenic tobacco and Arabidopsis plants induced their precocious flowering. These results indicate that LcFT1 plays a pivotal role in litchi floral induction by low-temperature. In addition, we found that two types of LcFT1 promoter existed in different litchi cultivars. The LcFT1 promoters in the early-flowering cultivars belonged to one type whereas LcFT1 promoters in the late-flowering belonged to another one. LcFT1 promoter in the early-flowering cultivars was more sensitive to low-temperature than that of the late-flowering cultivars was, which may be caused by the different cis-acting elements, including MYC, MYB, ABRE, and WRKY cis-acting elements, which were found to be present in the LcFT1 promoter sequences of the early-flowering cultivars. This difference may be responsible for the different requirements of low-temperature for floral induction in the early- and late-flowering cultivars of litchi. Taken together, the difference in LcFT1 promoter sequences may be one of the leading cause for the natural variation of flowering timing in different litchi cultivars. Our study has provided valuable genetic basis for cross-breeding of litchi cultivars to generate new litchi cultivars for overcoming the problem of unstable flowering for litchi producers.

The successful transition from vegetative to reproductive growth directly influences plant biomass and fitness. The regulation of flowering time has been investigated for over two decades, with several molecular modules having been characterized, functioning in the photoperiod, vernalization, autonomous, aging, or phytohormone pathways. Although the upstream components of these flowering pathways differ among plant species, most endogenous and external cues are ultimately integrated to control a highly conserved protein, FLOWERING LOCUS T (FT), to ensure that flowering is initiated at an appropriate time.

This work aims to investigate the effects of two pathways using artificial vernalization for the production of cuttings of globe artichoke cultivar “Violet d’Hyeres” on yield, earliness and marketable traits. The cultivation was set up and followed for two production seasons (2016/2018). The first pathway has targeted the production and the cool chilling (5 °C) of field’s ovoli for 2 and 3 weeks under darkness represented respectively by treatments F1 and F2 with the control treatment F0 (field’s ovoli without cold treatment). The second pathway was designed for the production of nursery’s ovoli as follows; T0 (nursery’s ovoli without cold treatment), T1 (nursery’s ovoli kept at a temperature of 5 °C for two weeks in the dark), T2 (nursery’s ovoli kept at a temperature of 5 °C for two weeks with a photoperiod of 14 h of light), T3 (nursery’s ovoli kept at a temperature of 5 °C for three weeks in the dark), T4 (nursery’s ovoli kept at a temperature of 5 °C for three weeks with a photoperiod of 14 h of light). Results have shown that the cold treatment under darkness especially for a period of three weeks has enhanced the vegetative development of plants derived from both field and nursery’s ovoli compared to their control treatments. For over two years, the highest rate in early yield was obtained in T3 for nursery’s ovoli and it was about 17 % from the total production whereas for field’s ovoli it was less than 14 % for treatment F2. For the total yield, vernalized nursery’s ovoli have recorded the best values ranging from 20.10 t ha−1 to 24.91 t ha−1, then followed by vernalized field’s ovoli with a maximum yield of 19.13 t ha−1. The lowest values in all parameters were often found in non- vernalized treatments T0 and F0. Traits of marketable heads such as head diameter and head weight were influenced significantly by treatments and varied according to the harvest period. These results lead us to conclude that dark-chilling has improved the development potential of cuttings which was after that reflected on yield, earliness and on commercial characteristics of the production.

The developmental transition to flowering in many plants is timed by changing seasons, which enables plants to flower at a season that is favorable for seed production. Many plants grown at high latitudes perceive the seasonal cues of changing day length and/or winter cold (prolonged cold exposure), to regulate the expression of flowering-regulatory genes through the photoperiod pathway and/or vernalization pathway, and thus align flowering with a particular season. Recent studies in the model flowering plant Arabidopsis thaliana have revealed that diverse transcription factors engage various chromatin modifiers to regulate several key flowering-regulatory genes including FLOWERING LOCUS C (FLC) and FLOWERING LOCUS T (FT) in response to seasonal signals. Here, we summarize the current understanding of molecular and chromatin-regulatory or epigenetic mechanisms underlying the vernalization response and photoperiodic control of flowering in Arabidopsis. Moreover, the conservation and divergence of regulatory mechanisms for seasonal flowering in crops and other plants are briefly discussed., Higher plants sense seasonal changes in day length and growth temperature and often align the timing of flower development with a particular season favorable for reproduction. This review summarizes the genetic and epigenetic understanding of the timing of flowering in response to day-length changes and prolonged cold exposure (winter cold) and highlights the broad applications of the obtained knowledge in agricultural production, including development of crops with wide geographic adaptation and maximization of reproductive success to increase crop yields.

Summary Plants with winter annual life history germinate in summer or autumn and require a period of prolonged winter cold to initiate flowering, known as vernalization. In the Brassicaceae, the requirement for vernalization is conferred by high expression of orthologs of the FLOWERING LOCUS C (FLC) gene, the expression of which is known to be silenced by prolonged exposure to winter-like temperatures [1]. Based on a wealth of vernalization experiments, typically carried out in the range of 5°C–10°C, we would expect field environments during winter to induce flowering in crops with winter annual life history. Here, we show that, in the case of winter oilseed rape, expression of multiple FLC orthologs declines not during winter but predominantly during October when the average air temperature is 10°C–15°C. We further demonstrate that plants proceed through the floral transition in early November and overwinter as inflorescence meristems, which complete floral development in spring. To validate the importance of pre-winter temperatures in flowering time control, we artificially simulated climate warming in field trial plots in October. We found that increasing the temperature by 5°C in October results in raised FLC expression and delays the floral transition by 3 weeks but only has a mild effect on flowering date the following spring. Our work shows that winter annuals overwinter as a floral bud in a manner that resembles perennials and highlights the importance of studying signaling events in the field for understanding how plants transition to flowering under real environmental conditions., Highlights • Levels of the key floral repressor FLC fall during October rather than during winter • Warming field plots in October delays flowering in spring • Plants overwinter as an inflorescence meristem in a manner resembling perennials, Vernalization has been traditionally understood as a response of plants to prolonged winter temperatures, which enable plants to flower. However, here, O’Neill et al. use a plot warming system to show that vernalization is an autumn phenomenon in the field.

Treating cereals as a dual-purpose crop (grazing and grain production) can modify the timing of anthesis, but which among the main determinants of the timing of anthesis – namely leaf number, the phyllochron and the length of the flag leaf emergence to anthesis interval – are affected is unclear. Eight field experiments conducted in triticale, designed to vary both sowing date (October through January), growth habit (vernalization requiring vs non-requiring) and to simulate grazing by clipping at the terminal spikelet stage (TS), were performed to monitor plant development. Clipping delayed anthesis by 2–7 days in four cultivar/environment combinations. The slower rate of leaf emergence after clipping delayed the appearance of the flag leaf ligule (FLA). When a delayed FLA was not accompanied by a proportional reduction in the duration of the FLA-anthesis interval, anthesis occurred later. The impact of an increase in the phyllochron can be expected to be wider than just a delay to anthesis. A higher phyllochron can also result in a slower recovery of leaf area, with a knock-on effect on the duration of the most critical period for grain number determination.

Garlic ( Allium sativum L.) has been long favored as a seasoning and as a seasonal vegetable all over the world. However, the production of fresh garlic scapes and bulbs is extremely limited by the climate and region, especially the temperature and photoperiod, under natural production conditions, and the uncertainty of the vernalization characteristic of garlic has been a key restriction to the developmental regulation of bolting and bulbing. A thorough understanding of the vernalization conditions for garlic growth should improve our knowledge of the bolting and bulbing processes. This research was conducted to assess the response of the clove to chilling treatment and further demonstrate whether chilling treatment on garlic clove could substitute the vernalization requirements for garlic plant. Before planting, the cloves (cv. G064) were subjected to low temperature (5 °C, 10 °C, 15 °C) for different durations (20 days, 40 days or 60 days) for chilling treatment. The control cloves or plants remained in the 20–22 °C regime throughout. Then, the plant growth, bolting and garlic yield were evaluated during field growing. The results indicate that pre-plant chilling treatment significantly affects garlic plant growth and development, and could act as the vernalization and enable the garlic plant to bolt without undergoing chilling during plant growth. Lower temperatures and longer treatment durations significantly enhanced the leaf elongation, shortened the growth period (5 °C or 60 days), promoted the rate of one-clove bulbs (5 °C or 40 days), stimulated bolting and increased the bolting rate (10 °C) compared with the control. However, the bolting rate and low-temperature treatment did not follow a simple linear relation, as lower temperatures (5 °C) or higher temperatures (15 °C) were not beneficial to garlic bolting. It was found that garlic plants subjected to a treatment of 10 °C for 20/40 days or 5 °C for 20 days had comparatively higher bolting rates. Nevertheless, the garlic bulb yield and mean bulb weight decreased significantly as a function of the increasing period of the chilling treatment compared with the control. The treatment of 5 °C for 20 days had the greatest yield among all the treatments, second only to the control. These findings provide strong evidence for the potential cultivation of garlic of various cultivars in various climates or seasons, making off-season cultivation possible. Other researchers could use a similar methodology to shorten the period needed until harvest or even produce desirable scapes and bulbs in the warm season.

The flowering time of wheat is strongly controlled by temperature and is potentially highly sensitive to climate change. In this study, we analysed the occurrence of last frost (days with minimum temperature under 2 °C) and first heat (days with maximum temperatures exceeding 30 °C) events of the year to determine the optimum flowering date in the wheat belt of New South Wales (NSW), eastern Australia. We used statistically downscaled daily maximum and minimum temperature data from 19 Global Climate Models (GCMs) with a vernalizing–photothermal model in order to simulate future flowering dates and the changes in frost and hot days occurrence at flowering date (± 7 days) for two future scenarios for atmospheric greenhouse gas concentrations (RCP4.5 and RCP8.5) in 2040s (2021–2060) and 2080s (2061–2100). Relative to the 1961–2000 period, the GCMs projected increased daily maximum and minimum temperatures for these future periods, accompanied by reduced frost occurrence and increased heat stress incidence. As a consequence, by the 2080s, simulations suggest a general advance in spring wheat flowering date by, on average, 10.2 days for RCP4.5 and 17.8 days for RCP8.5 across the NSW wheat belt. Winter wheat flowering dates were delayed by an average of 2.4 days for RCP4.5 and 14.3 days for RCP8.5 in the warmest parts of the region (the northwest) due to reduced cumulative vernalization days (requiring cool conditions). In the cooler regions (the northeast, southeast and southwest), flowering date occurred earlier by 6.2 days for RCP4.5 and 6.7 days for RCP8.5 on average. Moreover, in the western parts of the wheat belt the delay of winter wheat flowering date was about 9.5 days longer than that in the eastern parts. As a result of phenological responses to increasing temperatures, current wheat varieties may not be suitable for future climate conditions, despite reduced frost risk. In the future, it may be necessary to use longer-season wheat varieties and varieties with increased heat-stress resistance.

Responsing to environmental signals, Vernalization Insensitive 3 (VIN3) family proteins are involved in plant development control by repressing the target genes epigenecticly together with Polycomb Repressive Complex 2 (PRC2) complex. BdVIL4 is a VIN3 like gene in Brachypodium distachyon, preferentially expressed in young tissues spatially. The RNAi plants were constructed to study the function of BdVIL4 on the development process. The plants with BdVIL4 RNA interferenced (BdVIL4 RNAi plants) had no obvious difference from the wild at 23 °C, but flowered significantly later and had more branches than the control at l6 °C. In BdVIL4 RNAi plants the expression of miR156 were upregulated, and much more at low temperature (l6 °C). Coincidentally, similar to the BdVIL4 RNAi plants, the miR156 overexpressors also showed late flowering and more branches, and the late flowering phynotype just only performanced at lower temperature. The results suggested that BdVIL4 are involved in the regulation of branching and flowering responsing to the ambient temperature by repressing the expression of miR156.

Brassinosteroids (BRs), known as a kind of phytohormones, play essential roles in plant growth and development. Although the studies on the BR biosynthesis and signaling are extensive in Arabidopsis, little is known in temperate cereals. In this study, bdbrd1-1, a T-DNA insertion mutant from Brachypodium distachyon, was isolated and characterized in details. The bdbrd1-1 mutant showed lots of cellular and morphogenetic defects, including shortened cell shapes, severe dwarfing, twisted leaves and sterile spikes. Sequencing the flanking fragment of the T-DNA and complementation by genomic DNA in the mutant, confirmed that the developmental defects are caused by the T-DNA insertion in BdBRD1, a possible brassinosteroid C-6 oxidase gene. Application of 24-epicastasterone could partly rescue the bdbrd1-1 dwarfing phenotype. Expression analysis of BdBRD1 suggested that bdbrd1-1 is probably a null mutant and its wild type transcript is expressed in various tissues and highest in the leaf sheaths. Meanwhile, measurements on leaf numbers of the main stems or days to the emergence of the inflorescences suggested that bdbrd1-1 is late-flowering. The late-flowering phenotype could be converted by vernalization treatment, although there lacks a typical FLC gene in B. distachyon. The current data provide an insight into the relationship between BRs biosynthesis and individual development in B. distachyon, an emerging model plant for the temperate cereals.

In Lilium longiflorum, vernalization is both an obligatory requirement and the major factor affecting flowering time, however, little is known about the molecular regulation of this mechanism in Lilium and other flowering bulbs. Exposure of L. longiflorum bulbs to 9 weeks at 4 °C greatly promoted stem elongation within the bulb, floral transition and flowering. Subtraction libraries of vernalized (V) and non-vernalized (NV) bulb meristems were constructed. 671 and 479 genes were sequenced, from which 72 and 82 proteins were inferred for the NV–V and the V–NV libraries, respectively. Much lower transcription levels and putative gene functions were recorded in the NV–V libraries compared the V–NV libraries. However, a large number of genes annotated to transposable elements (TEs), represented more than 20% of the sequenced cDNA were expressed in the NV–V libraries, as opposed to less than 2% in the V–NV libraries. The expression profile of several genes potentially involved in the vernalization pathway was assessed. Expression of LlSOC1, the lily homologue of SUPPRESSOR OF OVER-EXPRESSION OF CO1 (SOC1), an important flowering gene in several plant species, found in the V–NV library, was highly up-regulated during bulb meristem cold exposure. The subtraction libraries provided a fast tool for relevant gene isolation.

Local climate conditions and sowing time are very important to the vernalization and summer reproduction of the wheat. Xundian County is located in Yunnan Province of China, at latitude 25.56° north and longitude 103.25° east. Xundian County is situated 1 873 m above sea level, and is conducive for the summer reproduction of the wheat. To investigate the optimal sowing time, 11 spring wheat cultivars and one semi-winter wheat cultivar were sown 10 times at an interval of five days from May 26, 2012, and the strong winter wheat Suyin 10 was treated in a vernalization room at 2°C with different concentrations of the gibberellin and 5-azacytidine. The results showed that Suyin 10 should be vernalized at 2°C for 30 days in summer, and the growth periods of strong winter wheat plants could been shortened if treated with a specific concentration of the gibberellin and 5-azacytidine at a low temperature. The growth period of the spring wheat in summer reproduction was delayed, and their agronomic traits gradually decreased with the passage of the sowing time. Thus, spring wheat should be sown at the earliest time possible for better yield. June 25 should be the latest date for summer reproduction of the wheat, but the semi-winter wheat cultivars in Xundian County should be added generation in summer after being treated at 2°C for 10 days. Xundian County is a suitable location for summer reproduction of the wheat in China.

It is well established that a period of exposure to low temperature is required in order for temperate plants to achieve maximum freezing tolerance. During the cold acclimation process a large number of biophysical, biochemical and molecular changes occur that enable the plant to survive at below freezing temperatures. These include the alteration of carbohydrate and protein accumulation profiles, resulting large quantities of soluble sugars and cold induced stress proteins (dehydrins) thought to function in a cryoprotective role. When fully cold acclimated plants are exposed to warm temperatures (de-acclimation) a rapid turnover of these carbohydrates and proteins occurs, resulting in a plant that no longer possesses an elevated level of freezing tolerance. In certain species, re-exposure to cold acclimating temperatures (re-acclimation) results in re-accumulation of carbohydrates and proteins with a synergistic impact on freezing tolerance. In canola (Brassica napus L.), a full recovery of freezing tolerance is observed upon re-acclimation in both spring and winter cultivars. In contrast, the re-acclimation of winter wheat (Triticum aestivum L.) results in only a 39% recovery of freezing tolerance. Upon further analysis it was revealed that wheat does not accumulate carbohydrates during the re-acclimation period. While certain dehydrins also accumulate during re-acclimation, there is no clear relationship with freezing tolerance and we suggest it is the interaction of these proteins with soluble carbohydrates that is responsible for the development of freezing tolerance during re-acclimation. The role of vernalization in these processes is also discussed.

Vernalization requirement maintains winter annuals in a cold hardy vegetative state during the winter. Vernalization saturation has been shown to be followed by a loss of freezing tolerance under controlled experimental conditions. The objective of this study was to determine a possible relationship between vernalization saturation and the maintenance of cultivar specific freezing tolerance levels in winter rapeseed (Brassica napus L.) under field conditions. Two cultivars, ‘Banjo’ and ‘Californium’, with differing vernalization requirements were chosen after a screening of 18 cultivars under controlled conditions. Vernalization response and freezing tolerance of the two cultivars grown under field conditions were compared on five different dates throughout the winter of 2010/11 at Apelsvoll Research Station, Norway (60° 42′ N, 10° 52′ E, 250 m a.s.l.). ‘Californium’ reached vernalization saturation on 11 Oct. whereas ‘Banjo’ did 13 days later. Maximum freezing tolerance of both cultivars was attained in early December and it was maintained for 31 days in ‘Californium’ and 67 days in ‘Banjo’. Our results indicate that there is no simple relationship between freezing tolerance and saturation of vernalization. Increasing contents of water, d -glucose and d -fructose and decreasing sucrose and starch levels in the shoot apex from mid to late winter were significantly correlated with a decrease in freezing tolerance (LT50) and shoot regrowth following a −12 °C low temperature treatment and so these parameters may be good predictors of plant survival and vitality in the spring.