The differential expression of HvCO9, a member of the CONSTANS-like gene family, contributes to the control of flowering under short-day conditions in barley

The spring-type near isogenic line (NIL) of the winter-type barley (Hordeum vulgare ssp. vulgare) var. Hayakiso 2 (HK2) was developed by introducing VERNALIZATION-H1 (Vrn-H1) for spring growth habit from the spring-type var. Indo Omugi. Contrary to expectations, the spring-type NIL flowered later than winter-type HK2. This phenotypic difference was controlled by a single gene, which cosegregated only with phytochrome C (HvPhyC) among three candidates around the Vrn-H1 region (Vrn-H1, HvPhyC, and CASEIN KINASE IIa), indicating that HvPhyC was the most likely candidate gene. Compared with the late-flowering allele HvPhyC-l from the NIL, the early-flowering allele HvPhyC-e from HK2 had a single nucleotide polymorphism T1139C in exon 1, which caused a nonsynonymous amino acid substitution of phenylalanine at position 380 by serine in the functionally essential GAF (39, 59-cyclic-GMP phosphodiesterase, adenylate cyclase, formate hydrogen lyase activator protein) domain. Functional assay using a rice (Oryza sativa) phyA phyC double mutant line showed that both of the HvPhyC alleles are functional, but HvPhyC-e may have a hyperfunction. Expression analysis using NILs carrying HvPhyC-e and HvPhyC-l (NIL [HvPhyC-e] and NIL [HvPhyC-l], respectively) showed that HvPhyC-e up-regulated only the flowering promoter FLOWERING LOCUS T1 by bypassing the circadian clock genes and flowering integrator CONSTANS1 under a long photoperiod. Consistent with the up-regulation, NIL (HvPhyC-e) flowered earlier than NIL (HvPhyC-l) under long photoperiods. These results implied that HvPhyC is a key factor to control long-day flowering directly.

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“…The expression level was higher under short than long photoperiod conditions. This was consistent with the observation by Kikuchi et al (2012).…”

Section: Expression Analysis Of the Flowering Pathway Genessupporting

confidence: 94%

“…We analyzed the expression of other photoperiodic response genes, Ppd-H2 (HvFT3) and HvCO9, which control flowering time under short photoperiods (Kikuchi et al, , 2012. There were no clear differences in either gene between the NILs (Fig.…”

Section: Expression Analysis Of the Flowering Pathway Genesmentioning

confidence: 99%

Phytochrome C Is A Key Factor Controlling Long-Day Flowering in Barley

et al. 2013

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“…Similar to many subtropical grasses, rice is a short-day plant, and the requirement for short days to flower in rice is augmented by the long-day repression conferred by Ghd7 (Xue et al, 2008;Weng et al, 2014). Although little is known about members of the VRN2/Ghd7 sister CO9 clade, barley CO9 has also been shown to prevent precocious flowering, but in this case under noninductive short-day conditions that accompany winter (Kikuchi et al, 2012). Thus, we infer that the ancestor of VRN2/Ghd7 and CO9 clades repressed flowering but that photoperiod regulation of these genes evolved following their duplication.…”

Section: Conservation Of Vrn2 As a Flowering Repressormentioning

confidence: 99%

Evolution of VRN2/Ghd7-Like Genes in Vernalization-Mediated Repression of Grass Flowering

et al. 2016

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Flowering of many plant species is coordinated with seasonal environmental cues such as temperature and photoperiod. Vernalization provides competence to flower after prolonged cold exposure, and a vernalization requirement prevents flowering from occurring prior to winter. In winter wheat (Triticum aestivum) and barley (Hordeum vulgare), three genes VRN1, VRN2, and FT form a regulatory loop that regulates the initiation of flowering. Prior to cold exposure, VRN2 represses FT. During cold, VRN1 expression increases, resulting in the repression of VRN2, which in turn allows activation of FT during long days to induce flowering. Here, we test whether the circuitry of this regulatory loop is conserved across Pooideae, consistent with their niche transition from the tropics to the temperate zone. Our phylogenetic analyses of VRN2-like genes reveal a duplication event occurred before the diversification of the grasses that gave rise to a CO9 and VRN2/Ghd7 clade and support orthology between wheat/barley VRN2 and rice (Oryza sativa) Ghd7. Our Brachypodium distachyon VRN1 and VRN2 knockdown and overexpression experiments demonstrate functional conservation of grass VRN1 and VRN2 in the promotion and repression of flowering, respectively. However, expression analyses in a range of pooids demonstrate that the cold repression of VRN2 is unique to core Pooideae such as wheat and barley. Furthermore, VRN1 knockdown in B. distachyon demonstrates that the VRN1-mediated suppression of VRN2 is not conserved. Thus, the VRN1-VRN2 feature of the regulatory loop appears to have evolved late in the diversification of temperate grasses.The initiation of flowering is a major developmental transition in the plant life cycle. When flowering initiates, shoot apical meristems shift from forming vegetative organs such as leaves to forming flowers. In many plant species, flowering occurs at a particular time of year in response to the sensing of seasonal cues such as changes in day length and temperature. In some plants adapted to temperate climates, exposure to the prolonged cold of winter (vernalization) results in the ability to flower in the next growing season (Chouard, 1960;Amasino, 2010). Although vernalization ultimately enables flowering, vernalization responsiveness is typically an adaptation to ensure that flowering does not occur prematurely in the fall season. This has obvious adaptive value; for example, many vernalization-responsive plants become established in the fall season (during which flowering would not lead to successful reproduction) and then rapidly flower in the spring when conditions for reproduction and seed maturation are optimal.The grass family (Poaceae) originated approximately 70 million years ago as part of the tropical forest understory. However, grasses have since diversified across the globe occupying a variety of ecological niches (Kellogg, 2001). Exemplifying this, the ;3,800 species of grass subfamily Pooideae, including the economically important cereals wheat (Triticum aestivum, Triticeae), barley (...

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“…For example, stress could stimulate blossom that has been found correlating to CO-like (COL) gene (Higgins et al, 2010;Kikuchi et al, 2012;Kitagawa et al, 2012). Treatment with ultrasound stress could stimulate bacterial growth (Pitt and Ross, 2003).…”

Section: Dear Editormentioning

confidence: 99%