Vernalization Requirement Research Articles

A single haplotype hyposensitive to light and requiring strong vernalization dominates Arabidopsis thaliana populations in Patagonia, Argentina

The growing collection of sequenced or genotyped Arabidopsis thaliana accessions includes mostly individuals from the native Eurasian and N. African range and introduced North American populations. Here, we describe the genetic and phenotypic diversity, along with habitats and life history, of A.thaliana plants collected at the southernmost end of its worldwide distribution. Seed samples were harvested from plants growing in four sites within a ~3500-km2 -area in Patagonia, Argentina, and represent the first germplasm to be collected in South America for this species. Whole-genome resequencing revealed that plants from the four sites and a Patagonia herbarium specimen collected in 1967 formed a single haplogroup (Pat), indicating that the phenotypic variation observed in the field reflected plastic responses to the environment. admixture and principal components analyses suggest that the ancestor of the Pat haplogroup either came from Italy or the Balkan/Caucasus regions of Eurasia. In the laboratory, plants from the Pat haplogroup were hyposensitive to continuous red (Rc) and shade light, with corresponding changes in the expression of phytochrome signalling genes. Pat had higher PIF3 and PIF5 and lower HY5 expression under Rc light; and lower expression of PIL1, ATHB2 and HFR1 under shade compared to Col-0. In addition, Pat plants had a strong vernalization requirement associated with high levels of FLC expression. We conclude that including Pat in studies of natural variation and in comparison with other introduced populations will provide additional information for association studies and allow for a more detailed assessment of the demographic events following colonization.

FLC expression is down-regulated by cold treatment in Diplotaxis tenuifolia (wild rocket), but flowering time is unaffected

Wild rocket (Diplotaxis tenuifolia) has become a very popular salad leaf due to its peppery taste. It is part of the Brassicaceae family and thus has a high level of homology at the DNA level to other Brassica species including Arabidopsis thaliana. The vernalization and photoperiodic requirements of wild rocket have not been reported to date. Photoperiodic experiments described here demonstrate that rocket is a facultative long day plant. To investigate the vernalization requirement, both seed and young plants were given vernalization treatments at 4°C for different lengths of time. A rocket homologue of FLOWERING LOCUS C (DtFLC) was isolated and shown to functionally complement the Arabidopsis FRI+flc3 null mutant. Whilst the expression of DtFLC was significantly reduced after just one week of cold treatment, cold treatments of two to eight weeks had no significant effect on bolting time of wild rocket indicating that rocket does not have a vernalization requirement. These findings illustrate that important fundamental differences can exist between model and crop plant species, such as in this case where down-regulation of DtFLC expression does not enable earlier flowering in wild rocket as it does in Arabidopsis and many other Brassica species.

Adaptation response surfaces for managing wheat under perturbed climate and CO2 in a Mediterranean environment

Adaptation of crops to climate change has to be addressed locally due to the variability of soil, climate and the specific socio-economic settings influencing farm management decisions. Adaptation of rainfed cropping systems in the Mediterranean is especially challenging due to the projected decline in precipitation in the coming decades, which will increase the risk of droughts. Methods that can help explore uncertainties in climate projections and crop modelling, such as impact response surfaces (IRSs) and ensemble modelling, can then be valuable for identifying effective adaptations. Here, an ensemble of 17 crop models was used to simulate a total of 54 adaptation options for rainfed winter wheat (Triticum aestivum) at Lleida (NE Spain). To support the ensemble building, an ex post quality check of model simulations based on several criteria was performed. Those criteria were based on the “According to Our Current Knowledge” (AOCK) concept, which has been formalized here. Adaptations were based on changes in cultivars and management regarding phenology, vernalization, sowing date and irrigation. The effects of adaptation options under changed precipitation (P), temperature (T), [CO2] and soil type were analysed by constructing response surfaces, which we termed, in accordance with their specific purpose, adaptation response surfaces (ARSs). These were created to assess the effect of adaptations through a range of plausible P, T and [CO2] perturbations. The results indicated that impacts of altered climate were predominantly negative. No single adaptation was capable of overcoming the detrimental effect of the complex interactions imposed by the P, T and [CO2] perturbations except for supplementary irrigation (sI), which reduced the potential impacts under most of the perturbations. Yet, a combination of adaptations for dealing with climate change demonstrated that effective adaptation is possible at Lleida. Combinations based on a cultivar without vernalization requirements showed good and wide adaptation potential. Few combined adaptation options performed well under rainfed conditions. However, a single sI was sufficient to develop a high adaptation potential, including options mainly based on spring wheat, current cycle duration and early sowing date. Depending on local environment (e.g. soil type), many of these adaptations can maintain current yield levels under moderate changes in T and P, and some also under strong changes. We conclude that ARSs can offer a useful tool for supporting planning of field level adaptation under conditions of high uncertainty.

Analysis of the VERNALIZATION-A1 exon-4 polymorphism in polyploid wheat

One of the key genes, which influence on adaptability of wheat to environments and yield are the VRN1 genes. In recent studies the association of the missense mutations within VERNALIZATION-A1 exon-4 with modulation of quantitative values of such agronomically valuable traits as frost tolerance, vernalization requirement duration and flowering time of wheat was shown. However these investigations were carried out exclusively in varieties of T. aestivum and has not covered of other species of polyploid wheat and the different VRN-A1 alleles. The earlier studies not supposed more than one copy of VRN-A1 per genome. Furthermore only recently it was shown that only several SNPs distinguish the VRN-D4 and VRN-A1 genes. In present study polymorphism of the VRN-A1 exon-4 was investigated in 158 accessions of 6 tetraploid and 5 hexaploid wheat species, carrying the different VRN-A1 alleles. To identification of the VRN-A1 exon-4 haplotypes the co-dominant marker was designed, based on modulation of curvature of the DNA molecule. Polymorphism of the VRN-A1 exon-4 was revealed only in accessions of hexaploid wheat and was associated with the presence of noless than two copies of VRN-A1 per genome. With the exception of one accession the mutant type of exon-4 was identified only in combination with the wild type. Furthermore the allele-specific primers were designed to identification of the VRN-D4 gene or in order to exclude its impact on the results during analysis of the VRN-A1 haplotypes. In the result of expand of analyzed region the additional haplotypes, which are associated with polymorphism of adenine tract within intron-4 were identified. The splitting at haplotype was obtained among accessions carrying only intact exon-4 VRN-A1 and among dominant alleles of this gene. Finally, based on revealed associations between the VRN-A1 alleles and haplotypes the new putative dominant VRN-A1 allele (designated Vrn-A1k), carrying 42 bp insertion within promoter region, was identified in tetraploid wheat of Triticum dicoccum.

Winter wheat cultivars in Australian farming systems: a review

Winter wheat cultivars are defined as those that have an obligate vernalisation requirement that must be met before they will progress from the vegetative to reproductive phase of development i.e. they must experience a true winter before they will flower. Historically, very little breeding effort has been applied to the selection of winter cultivars suited to southern Australia, with the notable exception of the New South Wales Agriculture breeding program based in Wagga and Temora that ran from the 1960s until 2002. A shift by growers to earlier sowing, increased usage of dual-purpose cereals, and research highlighting the whole-farm benefits of winter cultivars to average farm wheat yield has increased grower interest and demand for winter cultivars. Three major wheat breeding companies operating in southern Australia have responded by commencing selection for milling quality winter cultivars, the first of which was released in 2017. Existing research relating to winter wheats in southern Australian farming systems is reviewed here, including interactions with agronomic management, environment and weeds and disease. It is concluded that winter wheats can offer significant production and farming system benefits to growers by allowing earlier establishment, which increases water-limited potential yield (PYw) by ~15% relative to later sown spring wheats, and makes forage available for dual-purpose grazing during vegetative development. Winter wheats sown early require agronomic management different to that of later sown spring wheats, including greater attention to control of grass weeds and certain diseases. There are significant research gaps that will prevent growers from maximising the opportunities from new winter cultivars once they are released. The first of these is a well-defined establishment window for winter cultivars, particularly in medium-low rainfall environments of South Australia, Victoria and Western Australia that have not historically grown them. There is circumstantial evidence that the yield advantage of early established winter wheats over later sown spring wheats is greatest when stored soil water is present at establishment, or the soil profile fills during the growing season. Explicit confirmation of this would allow growers to identify situations where the yield advantage of winter wheats will be maximised. Given the imminent release of several new winter wheat cultivars and the increases in PYw that they embody, it is critical to experimentally define the management and environmental conditions under which performance of these new genotypes are optimised, before their release and availability to growers. Optimising the genotype × environmental × management interactions possible with these cultivars will empower growers to make the best use of the technology and better realise the gains in water limited potential yield possible with these genotypes.

Vernalization requirements of bread winter wheat varieties

Aim. To study the peculiarities of vernalization requirement in set of bread winter wheat varieties.Material and methods. The duration of vernalization requirement in bread winter wheat varieties was determined at spring sowing winter wheat with preliminary vernalization of seeds in Petri dishes for 10 to 60 days at temperature of 1–2°C. Vernalized seeds were sown in the soil to5 cm depth (80 seeds per linear meter). In each variant, field germination was determined (%), heading date was noted, number of productive stems was counted at the time of harvesting. To determine the possible additional vernalization in the field, sprouted, but not vernalized seeds of each variety were also sown. Period of vernalization was considered to be sufficient for the variety if most of the plants formed ear.Results. Data obtained show that 51% of varieties had vernalization requirement of 10 to 30 days. Fewer varieties (31%) needed vernalization during 30-40 days and only 18% needed more than 40 days. We have identified the varieties with high vernalization requirement (over 40 days), including Myrleben, Monotyp, Ekspromt, Myronivska 66, Myronivska 28, Volodarka, Khurtovyna, Bohdana, Smuhlianka, Slavna, Dostatok.It has been established that with increasing exposure of the germinating seeds in a refrigerator to 60 days the field germination significantly decreases. At the same time, significant varietal differences were also revealed. Therefore, when sowing in late terms, it is necessary to take into account these peculiarities and to choose varieties which germinating seeds, if left in the soil for a prolonged period, reduce the field germination less.The longest vernalization period (over 60 days) for the years of research was revealed in the variety Monotyp. The variety Voloshkova being created by means of multiple individual selection from plant population obtained by changing growth habit of spring wheat Flambard (France) into winter wheat has low vernalization requirement and high winter hardiness (8 points). Such properties allow using Voloshkova variety for sowing in permissible and late calendar periods. Seeds of varieties Voloshkova, Remeslivna, Pamiyati Remesla, Kolos Mironivshchyny, Lehenda Myronivska, Myrliena, Yuviliar Myronivskyi significantly less reduce the field germination when vernalized within 50–60 days.Conclusions. To assess varieties more objectively along with index of frost resistance, in their characteristics it is expedient to indicate the vernalization requirement. When sowing winter wheat in acceptable and late calendar periods, it is necessary to use varieties with a short vernalization period and frost resistance of at least 7–8 points.

A Flowering Locus C Homolog Is a Vernalization-Regulated Repressor in Brachypodium and Is Cold Regulated in Wheat.

Winter cereals require prolonged cold to transition from vegetative to reproductive development. This process, referred to as vernalization, has been extensively studied in Arabidopsis (Arabidopsis thaliana). In Arabidopsis, a key flowering repressor called FLOWERING LOCUS C (FLC) quantitatively controls the vernalization requirement. By contrast, in cereals, the vernalization response is mainly regulated by the VERNALIZATION genes, VRN1 and VRN2 Here, we characterize ODDSOC2, a recently identified FLC ortholog in monocots, knowing that it belongs to the FLC lineage. By studying its expression in a diverse set of Brachypodium accessions, we find that it is a good predictor of the vernalization requirement. Analyses of transgenics demonstrated that BdODDSOC2 functions as a vernalization-regulated flowering repressor. In most Brachypodium accessions BdODDSOC2 is down-regulated by cold, and in one of the winter accessions in which this down-regulation was evident, BdODDSOC2 responded to cold before BdVRN1. When stably down-regulated, the mechanism is associated with spreading H3K27me3 modifications at the BdODDSOC2 chromatin. Finally, homoeolog-specific gene expression analyses identify TaAGL33 and its splice variant TaAGL22 as the FLC orthologs in wheat (Triticum aestivum) behaving most similar to Brachypodium ODDSOC2 Overall, our study suggests that ODDSOC2 is not only phylogenetically related to FLC in eudicots but also functions as a flowering repressor in the vernalization pathway of Brachypodium and likely other temperate grasses. These insights could prove useful in breeding efforts to refine the vernalization requirement of temperate cereals and adapt varieties to changing climates.

Characterising genes associated with flowering time in carrot (Daucus carota L.) using transcriptome analysis.

Carrot is generally regarded as a biennial plant with an obligatory vernalization requirement. Early spring cultivation makes plants vulnerable to premature bolting, which results in a loss of commercial value. However, our knowledge of flowering time genes and flowering mechanisms in carrot remain limited. Bolting behavior of D. carota ssp. carota 'Songzi', a wild species sensitive to flower induction by vernalization and photoperiod, and orange cultivar 'Amsterdam forcing', and their offspring were investigated in different growing conditions. We performed RNA-seq to identify the flowering time genes, and digital gene expression (DGE) analysis to examine their expression levels. The circadian patterns of related genes were identified by qPCR. The results showed bolting behavior of carrot was influenced by low temperature, illumination intensity and photoperiod. A total of 45 flowering time-related unigenes were identified, which were classified into five categories including photoperiod, vernalization, autonomous and gibberellin pathway, and floral integrators. Homologs of LATE ELONGATED HYPOCOTYL (LHY) and CONSTANS-LIKE 2 (COL2) were more highly expressed under short day condition than under long day condition. Homologs of COL2, CONSTANS-LIKE 5 (COL5), SUPPRESSION OF OVEREXPRESSION OF CONSTANS 1 (SOC1), FLOWERING LOCUS C (FLC) and GIBBERELLIC ACID INSENSITIVE (GAI) were differentially expressed between 'Songzi' and 'Amsterdam forcing'. The homolog of COL2 (Dct43207) was repressed by light, but that of COL5 (Dct20940) was induced. A preliminary model of genetic network controlling flowering time was constructed by associating the results of DGE analysis with correlation coefficients between genes. This study provides useful information for further investigating the genetic mechanism of flowering in carrot.

The occurrence of spring forms in tetraploid Timopheevi wheat is associated with variation in the first intron of the VRN-A1 gene.

Background Triticum araraticum and Triticum timopheevii are tetraploid species of the Timopheevi group. The former includes both winter and spring forms with a predominance of winter forms, whereas T. timopheevii is considered a spring species. In order to clarify the origin of the spring growth habit in T. timopheevii, allelic variability of the VRN-1 gene was investigated in a set of accessions of both tetraploid species, together with the diploid species Ae. speltoides, presumed donor of the G genome to these tetraploids.ResultsThe promoter region of the VRN-A1 locus in all studied tetraploid accessions of both T. araraticum and T. timopheevii represents the previously described allele VRN-A1f with a 50 bp deletion near the start codon. Three additional alleles were identified namely, VRN-A1f-del, VRN-A1f-ins and VRN-A1f-del/ins, which contained large mutations in the first (1st) intron of VRN-A1. The first allele, carrying a deletion of 2.7 kb in a central part of intron 1, occurred in a few accessions of T. araraticum and no accessions of T. timopheevii. The VRN-A1f-ins allele, containing the insertion of a 0.4 kb MITE element about 0.4 kb upstream from the start of intron 1, and allele VRN-A1f-del/ins having this insertion coupled with a deletion of 2.7 kb are characteristic only for T. timopheevii. Allelic variation at the VRN-G1 locus includes the previously described allele VRN-G1a (with the insertion of a 0.2 kb MITE in the promoter) found in a few accessions of both tetraploid species. We showed that alleles VRN-A1f-del and VRN-G1a have no association with the spring growth habit, while in all accessions of T. timopheevii this habit was associated with the dominant VRN-A1f-ins and VRN-A1f-del/ins alleles. None of the Ae. speltoides accessions included in this study had changes in the promoter or 1st intron regions of VRN-1 which might confer a spring growth habit. The VRN-1 promoter sequences analyzed herein and downloaded from databases have been used to construct a phylogram to assess the time of divergence of Ae. speltoides in relation to other wheat species.ConclusionsAmong accessions of T. araraticum, the preferentially winter predecessor of T. timopheevii, two large mutations were found in both VRN-A1 and VRN-G1 loci (VRN-A1f-del and VRN-G1a) that were found to have no effect on vernalization requirements. Spring tetraploid T. timopheevii had one VRN-1 allele in common for two species (VRN-G1a), and two that were specific (VRN-A1f-ins, VRN-A1f-del/ins). The latter alleles include mutations in the 1st intron of VRN-A1 and also share a 0.4 kb MITE insertion near the start of intron 1. We suggested that this insertion resulted in a spring growth habit in a progenitor of T. timopheevii which has probably been selected during subsequent domestication. The phylogram constructed on the basis of the VRN-1 promoter sequences confirmed the early divergence (~3.5 MYA) of the ancestor(s) of the B/G genomes from Ae. speltoides.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0925-y) contains supplementary material, which is available to authorized users.

Loss-of-Function Mutations in Three Homoeologous PHYTOCLOCK 1 Genes in Common Wheat Are Associated with the Extra-Early Flowering Phenotype.

Triticum aestivum L. cv ‘Chogokuwase’ is an extra-early flowering common wheat cultivar that is insensitive to photoperiod conferred by the photoperiod insensitive alleles at the Photoperiod-B1 (Ppd-B1) and Ppd-D1loci, and does not require vernalization for flowering. This reduced vernalization requirement is likely due to the spring habitat allele Vrn-D1 at the VERNALIZATION-D1 locus. Genotypes of the Ppd-1 loci that determine photoperiod sensitivity do not fully explain the insensitivity to photoperiod seen in ‘Chogokuwase’. We detected altered expression patterns of clock and clock-output genes including Ppd-1 in ‘Chogokuwase’ that were similar to those in an einkorn wheat mutant that lacks the clock-gene homologue, wheat PHYTOCLOCK 1 (WPCL1). Presumptive loss-of-function mutations in all WPCL1 homoeologous genes were found in ‘Chogokuwase’ and ‘Geurumil’, one of the parental cultivars. Segregation analysis of the two intervarietal F2 populations revealed that all the examined F2 plants that headed as early as ‘Chogokuwase’ had the loss-of-function wpcl1 alleles at all three homoeoloci. Some F2 plants carrying the wpcl1 alleles at three homoeoloci headed later than ‘Chogokuwase’, suggesting the presence of other loci influencing heading date. Flowering repressor Vrn-2 was up-regulated in ‘Chogokuwase’ and ‘Geurumil’ that had the triple recessive wpcl1 alleles. An elevated transcript abundance of Vrn-2 could explain the observation that ‘Geurumil’ and some F2 plants carrying the three recessive wpcl1 homeoealleles headed later than ‘Chogokuwase’. In spite of the up-regulation of Vrn-2, ‘Chogokuwase’ may have headed earlier due to unidentified earliness genes. Our observations indicated that loss-of-function mutations in the clock gene wpcl1 are necessary but are not sufficient to explain the extra-early heading of ‘Chogokuwase’.

Allelic variation at the VERNALIZATION-A1, VRN-B1, VRN-B3, and PHOTOPERIOD-A1 genes in cultivars of Triticum durum Desf.

The durum wheat varieties from Ukraine, Russia, and Kazakhstan are characterized by the specific allelic composition of the VRN genes that sharply distinguish them from the Triticum durum varieties from other countries. For numerous varieties, the VRN alleles which previously were not found in tetraploid wheat were identified. The ability of wheat to adapt to a wide range of environmental conditions is mostly determined by the allelic diversity within genes regulating the vernalization requirement (VRN) and photoperiod response (PPD). In the present study, allelic variation in the VRN1, VRN3, and PPD-A1 genes was investigated for 134 varieties of Triticum durum from different eco-geographic areas. It was shown that varieties from Russia and Ukraine have a specific allelic composition at the VRN genes, which in quantity and quality differed from European and American cultivars. A large number of varieties of T. durum from Russia carry the dominant Vrn-A1a.1 allele, previously identified mainly in hexaploid wheat. For some varieties from Eastern Europe and Asia, Vrn-A1i and vrn-A1b.3 recently revealed in wheat were also identified. Polymorphism of the VRN-B1 promoter region, distinguishing all three variants of this sequence (VRN-B1.f, VRN-B1.s, and VRN-B1.m), was detected. It was found that the dominant Vrn-B1c allele is commonly found in varieties of T. durum from Russia and Ukraine, but not Europe or USA. Furthermore, many Ukrainian and Russian varieties carry the dominant alleles of the both VRN-A1 and VRN-B1 genes simultaneously, while varieties from Europe and America carry the dominant allele of VRN-A1 alone. Finally, a high frequency of the Vrn-B3a allele, which previously was found only in some accessions of hexaploid wheat, was observed for varieties from Ukraine and Russia. It was revealed that the Ukrainian pool of T. durum varieties is currently the largest genetic source of the dominant Vrn-B3a allele in wheat in the worldwide.

Genotype × environment interactions for phenological adaptation in narrow-leafed lupin: A simulation study with a parameter optimized model

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 4days and 0.34tha−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.

Alternative Energy Resources: Brassica Napus for Biofuel Production

Submit Manuscript | http://medcraveonline.com could be able to partly decrease the depth by using oil crops as base for biodiesel production. Brassica napus, widely known as rapeseed, is the most productive oil crops Europe mainly uses for biodiesel production in fact almost 65% of biodiesel production in Europe comes from rapeseed feedstock. Feed stocks for biofuel production can result from plants cultivated directly for this use or from crops parts. In this case plants are being cultivated for feed or any other use, while their wastes are being used for biofuel production. Furthermore, oil crops can be use as alternatives to petroleum-based substances in order to reduce the fossil fuel use, nevertheless, chemical composition of these fuels is highly leveled. Brassica napus, B. rapa, B. juncea Brassica’s commercial supply is dominated by two species, Brassica napus L. and B. rapa L. Both contain spring and winter forms that are distinguished by vernalization requirement. Seeds of these species contain 40 % or more oil. In 2013/2014 rape seed holds ca. 14 % of the world production of major oil crops [1,2]. According to FAO statistics (2014), rapeseed ranked number 14 in agricultural commodity production in Europe in 2012. Although many farmers still have doubts about cultivating crops for biodiesel production thinking of it as a risky action, agriculturists assure that oil crops cultivation is similar to any other one they may be used to. Brassica for example grows excellent in temperature not beyond 30 degrees while some species resist under -20 degrees. The plant does not have any specific need as for the soil structure, it grows well in any type of soil from 5, 5 up to 8,3 Ph levels, as soon as there is not poor natural internal drainage so as for the crop root to be adequate aerationed. Crop’s yield is 120-210 kg per acre while from this amount 4070 kg oil could be extracted (almost 50 % oil production). Oil can be extracted by crushing the seed and sqeezing the oil out. This oil tranfesterified to make biodiesel. The prices are usually specified under contracts between the farmer and the oil production company, however according to farmer prices range between 4045 Euros per kilo. In addition to Brassica napus, many other plants produce oil which could be used as biodiesel. Soybean, canola, mustard, camelina, safflower, and tropical oilseed trees like palm tree and coconut are already being used for this purpose. Yet, researches are being held about three more oilseed crops that could be used as biodiesel feedstock, lesquerella, pennycress and hazelnuts might help us increase our future biofuel production. References

Nucleotide polymorphism affecting FLC expression underpins heading date variation in horticultural brassicas.

SummaryVariation in flowering time and response to overwintering has been exploited to breed brassica vegetables that can be harvested year‐round. Our knowledge of flowering time control now enables the investigation of the molecular basis of this important variation. Here, we show that a major determinant of heading date variation in Brassica oleracea is from variation in vernalization response through allelic variation at FLOWERING LOCUS C.C2 (BoFLC4). We characterize two alleles of BoFLC.C2 that are both functional and confer a requirement for vernalization, but they show distinct expression dynamics in response to cold. Complementation experiments in Arabidopsis thaliana revealed that the allelic variation results from cis polymorphism at BoFLC.C2, which quantitatively influences the degree of cold‐induced epigenetic silencing. This results in one allelic variant conferring consistently later heading under both glasshouse and field conditions through reduced environmental sensitivity. Our results suggest that breeding of brassica varieties for commercially valuable variation in heading date has been achieved through the selection of cis polymorphism at FLC, similar to that underpinning natural variation in A. thaliana. This understanding will allow for the selection of alleles with distinct sensitivities to cold and robust heading dates under variable climatic conditions, and will facilitate the breeding of varieties more resistant to climate change.

The loss of vernalization requirement in narrow-leafed lupin is associated with a deletion in the promoter and de-repressed expression of a Flowering Locus T (FT) homologue.

Adaptation of Lupinus angustifolius (narrow-leafed lupin) to cropping in southern Australian and northern Europe was transformed by a dominant mutation (Ku) that removed vernalization requirement for flowering. The Ku mutation is now widely used in lupin breeding to confer early flowering and maturity. We report here the identity of the Ku mutation. We used a range of genetic, genomic and gene expression approaches to determine whether Flowering Locus T (FT) homologues are associated with the Ku locus. One of four FT homologues present in the narrow-leafed lupin genome, LanFTc1, perfectly co-segregated with the Ku locus in a reference mapping population. Expression of LanFTc1 in the ku (late-flowering) parent was strongly induced by vernalization, in contrast to the Ku (early-flowering) parent, which showed constitutively high LanFTc1 expression. Co-segregation of this expression phenotype with the LanFTc1 genotype indicated that the Ku mutation impairs cis-regulation of LanFTc1. Sequencing of LanFTc1 revealed a 1.4-kb deletion in the promoter region, which was perfectly predictive of vernalization response in 216 wild and domesticated accessions. Linkage disequilibrium rapidly decayed around LanFTc1, suggesting that this deletion caused the loss of vernalization response. This is the first time a legume FTc subclade gene has been implicated in the vernalization response.

Heading Date QTL in Winter Wheat (Triticum aestivum L.) Coincide with Major Developmental Genes VERNALIZATION1 and PHOTOPERIOD1.

In wheat (Triticum aestivum L.), time from planting to spike emergence is influenced by genes controlling vernalization requirement and photoperiod response. Characterizing the available genetic diversity of known and novel alleles of VERNALIZATION1 (VRN1) and PHOTOPERIOD1 (PPD1) in winter wheat can inform approaches for breeding climate resilient cultivars. This study identified QTL for heading date (HD) associated with multiple VRN1 and PPD1 loci in a population developed from a cross between two early flowering winter wheat cultivars. When the population was grown in the greenhouse after partial vernalization treatment, major heading date QTLs co-located with the VRN-A1 and VRN-B1 loci. Copy number variation at the VRN-A1 locus influenced HD such that RIL having three copies required longer cold exposure to transition to flowering than RIL having two VRN-A1 copies. Sequencing vrn-B1 winter alleles of the parents revealed multiple polymorphisms in the first intron that were the basis of mapping a major HD QTL coinciding with VRN-B1. A 36 bp deletion in the first intron of VRN-B1 was associated with earlier HD after partial vernalization in lines having either two or three haploid copies of VRN-A1. The VRN1 loci interacted significantly and influenced time to heading in field experiments in Louisiana, Georgia and North Carolina. The PPD1 loci were significant determinants of heading date in the fully vernalized treatment in the greenhouse and in all field environments. Heading date QTL were associated with alleles having large deletions in the upstream regions of PPD-A1 and PPD-D1 and with copy number variants at the PPD-B1 locus. The PPD-D1 locus was determined to have the largest genetic effect, followed by PPD-A1 and PPD-B1. Our results demonstrate that VRN1 and PPD1 alleles of varying strength allow fine tuning of flowering time in diverse winter wheat growing environments.

Comparative Transcriptomics Indicates a Role for SHORT VEGETATIVE PHASE (SVP) Genes in Mimulus guttatus Vernalization Response.

The timing of reproduction in response to variable environmental conditions is critical to plant fitness, and is a major driver of taxon differentiation. In the yellow monkey flower, Mimulus guttatus, geographically distinct North American populations vary in their photoperiod and chilling (vernalization) requirements for flowering, suggesting strong local adaptation to their surroundings. Previous analyses revealed quantitative trait loci (QTL) underlying short-day mediated vernalization responsiveness using two annual M. guttatus populations that differed in their vernalization response. To narrow down candidate genes responsible for this variation, and to reveal potential downstream genes, we conducted comparative transcriptomics and quantitative PCR (qPCR) in shoot apices of parental vernalization responsive IM62, and unresponsive LMC24 inbred lines grown under different photoperiods and temperatures. Our study identified several metabolic, hormone signaling, photosynthetic, stress response, and flowering time genes that are differentially expressed between treatments, suggesting a role for their protein products in short-day-mediated vernalization responsiveness. Only a small subset of these genes intersected with candidate genes from the previous QTL study, and, of the main candidates tested with qPCR under nonpermissive conditions, only SHORT VEGETATIVE PHASE (SVP) gene expression met predictions for a population-specific short-day-repressor of flowering that is repressed by cold.

Using a Candidate Gene-Based Genetic Linkage Map to Identify QTL for Winter Survival in Perennial Ryegrass.

Important agronomical traits in perennial ryegrass (Lolium perenne) breeding programs such as winter survival and heading date, are quantitative traits that are generally controlled by multiple loci. Individually, these loci have relatively small effects. The aim of this study was to develop a candidate gene based Illumina GoldenGate 1,536-plex assay, containing single nucleotide polymorphism markers designed from transcripts involved in response to cold acclimation, vernalization, and induction of flowering. The assay was used to genotype a mapping population that we have also phenotyped for winter survival to complement the heading date trait previously mapped in this population. A positive correlation was observed between strong vernalization requirement and winter survival, and some QTL for winter survival and heading date overlapped on the genetic map. Candidate genes were located in clusters along the genetic map, some of which co-localized with QTL for winter survival and heading date. These clusters of candidate genes may be used in candidate gene based association studies to identify alleles associated with winter survival and heading date.

Developmental regulation of metabolites and low temperature tolerance in lines of crosses between spring and winter wheat

Low temperature (LT) tolerance in cereals needs developmental regulation of metabolites, a process which is associated with vernalization requirement. This study was initiated to investigate the relationships among stage of phenological development, final leaf number (FLN), the activities superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase and polyphenol oxidase, the contents of proline, photosynthetic pigments, and hydrogen peroxide (H2O2) during vernalization and LT acclimation in spring and winter wheat. Six genotypes with different vernalization requirements were grown under greenhouse and field conditions. The spring-habit parent, “Pishtaz” and line 4021, rapidly entered the reproductive phase and had a limited capacities to LT acclimate. They also had the lowest antioxidative activities and accumulation of proline among genotypes. Lines 4002 and 4014, with a short vernalization requirement and higher FLN, remained in the early stages of phenological development longer and developed a higher level of LT tolerance and metabolites compared to spring habit genotypes. In contrast, the winter habit “Norstar” and line 4023 spent a longer time in the vegetative stage and accumulated higher levels of metabolites. Maximum LT tolerance and metabolite accumulations occurred near the vegetative/reproductive transition in all genotypes. The longer periods of vernalization and increased FLN that happened along with increased defense mechanisms and decreased damage indices (H2O2 content and LT50) ensured LT tolerance in wheat. These results demonstrate that both genetic and environmental factors via developmental regulation of metabolites play important roles in creating LT tolerance in long mild winters of Iran. Significant correlations coefficients for many of the metabolites considered in this study and Lethal temperature 50 (LT50) also suggest that they could be useful as indirect measures of plant LT tolerance potential in wheat breeding programs.

Strong genetic differentiation in the invasive annual grass Bromus tectorum across the Mojave–Great Basin ecological transition zone

Bromus tectorum, an inbreeding annual grass, is a dominant invader in sagebrush steppe habitat in North America. It is also common in warm and salt deserts, displaying a larger environmental tolerance than most native species. We tested the hypothesis that a suite of habitat-specific B. tectorum lineages dominates warm desert habitats. We sampled 30 B. tectorum Mojave Desert and desert fringe populations and genotyped 10–26 individuals per population using 69 single nucleotide polymorphic (SNP) markers. We compared these populations to 11 Great Basin steppe and salt desert populations. Populations from warm desert habitats were dominated by members of two haplogroups (87 % of individuals) that were distinct from haplogroups common in Great Basin habitats. We conducted common garden studies comparing adaptive traits and field performance among haplogroups typically found in different habitats. In contrast to the haplogroup abundant in sagebrush steppe, warm desert haplogroups generally lacked a vernalization requirement for flowering. The most widespread warm desert haplogroup (Warm Desert 1) also had larger seeds and a higher root:shoot ratio than other haplogroups. In the field, performance of warm desert haplogroups was dramatically lower than the sagebrush steppe haplogroup at one steppe site, but one warm desert haplogroup performed as well as the steppe haplogroup under drought conditions at the other site. Our results suggest that B. tectorum succeeds in widely disparate environments through ecotypic variation displayed by distinct lineages of plants. Accounting for this ecotypic variation is essential in modeling its future distribution in response to climate change.