Level of <i>VERNALIZATION 1</i> expression is correlated with earliness in <i>extra early-flowering</i> mutant wheat lines

Abstract

Four extra early-flowering mutants, named extra early-flowering1 (exe1), exe2, exe3, and exe4, were identified in Triticum monococcum strain KU104-1 following heavy-ion beam mutagenesis. The four exe mutants fell into two groups, namely Type I (moderately extra early-flowering type; exe1 and exe3) and Type II (extremely extra early-flowering type; exe2 and exe4). Analysis of plant development in a growth chamber showed that the speed of leaf emergence was accelerated in exe mutants at the reproductive stage compared to wild-type (WT) plants. The speed of leaf emergence was faster in Type II than Type I plants. Analysis of VERNALIZATION 1 (VRN1), a flowering promoter gene, showed that it was more highly expressed in seedlings at early developmental stages in Type II mutants than Type I mutants. These findings indicate that the difference in earliness between Type I and Type II mutants is associated with the level of VRN1 expression. The original KU104-1 is an einkorn wheat strain that carries a null allele of the VRN2 gene, a repressor of flowering. Thus, our results indicate that the level of VRN1 expression controls earliness in exe mutants independently of VRN2.

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

“…Since the transcript abundance of Vrn-1 and WFT are often correlated with heading time in wheat [7], we examined the expression of these genes in ‘Chogokuwase’ and its parental cultivars. Vrn-1 transcript levels were significantly higher in ‘Chogokuwase’ than in the parental cultivars at all 4L stages under V0-LD, V21-LD and V21-SD conditions (Fig 2).…”

“…All of the early heading F 2 plants in the MG population had the dominant VRN-D1 allele (Fig 6). Our preceding experiment demonstrated that Vrn-1 expression levels in leaves were associated with earliness [7]. Therefore, VRN-D1 might be a candidate gene that confers early heading in ‘Chogokuwase’, a hypothesis that remains to be tested.…”

“…Recessive alleles at all Vrn-1 homoeoloci confer a winter growth habit (vernalization sensitive), whereas one or more dominant alleles at Vrn-1 homoeoloci results in a spring growth habit (vernalization insensitive). The expression levels of Vrn-1 in leaves are associated with earliness, suggesting that Vrn-1 determines the flowering time [7]. Recently, Vrn-D4 was identified as a duplicated copy of Vrn-A1 [8].…”

Identification of Earliness Per Se Flowering Time Locus in Spring Wheat through a Genome‐Wide Association Study

“…It can survive extreme temperatures through the vegetative (-35°C) to grain filling (40°C) phases and is grown under different climatic conditions from Australia to Canada (Reynolds et al, 2009;Kamran et al, 2013). Vernalization (VRN) and photoperiod (PPD) are the (very wellstudied) major gene systems that control flowering time in wheat (Yan et al, 2003;Li et al, 2011;Chen and Dubcovsky, 2012;;Zheng et al, 2013;Eagles et al, 2014;Guedira et al, 2014;Nishiura et al, 2014). Vernalization (VRN) and photoperiod (PPD) are the (very wellstudied) major gene systems that control flowering time in wheat (Yan et al, 2003;Li et al, 2011;Chen and Dubcovsky, 2012;;Zheng et al, 2013;Eagles et al, 2014;Guedira et al, 2014;Nishiura et al, 2014).…”

Direct interaction between VRN1 protein and the promoter region of the wheat <i>FT</i> gene

“…VRN1 encodes an APETALA1 (AP1)/FRUIT-FULL-like MADS box transcription factor that is upregulated by vernalization (Danyluk et al, 2003;Murai et al, 2003;Trevaskis et al, 2003;Yan et al, 2003). The level of VRN1 expression is correlated with the level of expression of the wheat florigen gene Wheat FLOWERING LOCUS T (WFT, which is identical to VRN3) (Shimada et al, 2009;Nishiura et al, 2014). Expression of VRN1 gradually increases during the seedling growth stage without vernalization (Nishiura et al, 2014), suggesting that the expression of VRN1 is also controlled by internal signals such as aging.…”