Flowering time is an important trait for productivity in legumes, which include many food and fodder plants. Medicago truncatula (Medicago) is a model temperate legume used to study flowering time pathways. Like Arabidopsis thaliana (Arabidopsis), its flowering is promoted by extended periods of cold (vernalization, V), followed by warm long day (LD) photoperiods. However, Arabidopsis flowering-time genes such as the FLOWERING LOCUS C (FLC)/ MADS AFFECTING FLOWERING (MAF) clade are missing and CONSTANS-LIKE (CO-LIKE) genes do not appear to have a role in Medicago or Pisum sativum (pea). Another photoperiodic regulator, the red/far red photoreceptor PHYTOCHROME A (PHYA), promotes Arabidopsis flowering by stabilizing the CO protein in LD. Interestingly, despite the absence of CO-LIKE function in pea, PsPHYA plays a key role in promoting LD photoperiodic flowering and plant architecture. Medicago has one homolog of PHYA, MtPHYA, but its function is not known. Genetic analysis of two MtPHYA Tnt1 insertion mutant alleles indicates that MtPHYA has an important role in promoting Medicago flowering and primary stem elongation in VLD and LD and in perception of far-red wavelengths in seedlings. MtPHYA positively regulates the expression of MtE1-like (MtE1L), a homologue of an important legume-specific flowering time gene, E1 in soybean and other Medicago LD-regulated flowering-time gene homologues, including the three FLOWERING LOCUS T-LIKE (FT-LIKE) genes, MtFTa1, MtFTb1 and MtFTb2 and the two FRUITFULL-LIKE (FUL-LIKE) genes MtFULa and MtFULb. MtPHYA also modulates the expression of the circadian clock genes, GIGANTEA (GI) and TIMING OF CAB EXPRESSION 1a (TOC1a). Genetic analyses indicate that Mtphya-1 Mte1l double mutants flowered at the same time as the single mutants. However, Mtphya-1 Mtfta1 double mutants had a weak additive effect in delaying flowering and in reduction of primary axis lengths beyond what was conferred by either of the single mutants. MtPHYA has an important role in LD photoperiodic control of flowering, plant architecture and seedling de-etiolation under far-red wavelengths in Medicago. It promotes the expression of LD-induced flowering time genes and modulates clock-related genes. In addition to MtFTa1, MtPHYA likely regulates other targets during LD floral induction in Medicago.

中文翻译：

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Medicago PHYA可以长时间促进开花，初生茎伸长和开花时间基因的表达。

开花时间是豆科植物（包括许多粮食和饲料植物）生产力的重要特征。紫花苜蓿（Medicago truncatula（Medicago））是一种模型性的温带豆科植物，用于研究开花时间途径。像拟南芥（Arabidopsis）一样，长时间的寒冷（春化，V）继之以温暖的长日（LD）光周期促进了其开花。但是，缺少拟南芥开花期基因，例如FLOWERING LOCUS C（FLC）/ MADS影响FLOWERING（MAF）进化枝，CONSTANS-LIKE（CO-LIKE）基因似乎在紫花苜蓿或豌豆中没有作用）。另一个光周期调节剂，红色/远红色感光体PHYTOCHROME A（PHYA），通过稳定LD中的CO蛋白来促进拟南芥开花。有趣的是，尽管豌豆缺乏CO-LIKE功能，PsPHYA在促进LD光周期开花和植物结构中起关键作用。紫花苜蓿具有PHYA的一个同系物MtPHYA，但其功能尚不清楚。对两个MtPHYA Tnt1插入突变等位基因的遗传分析表明，MtPHYA在促进紫花苜蓿开花和VLD和LD中的初生茎伸长以及幼苗的远红波长方面具有重要作用。MtPHYA在大豆和其他Medicago LD调节的开花时间基因同源物中积极调控MtE1样（MtE1L）（一种重要的豆科植物特定开花时间基因E1的同源物）的表达，包括三个FLOWERING LOCUS T-LIKE（FT -LIKE）基因，MtFTa1，MtFTb1和MtFTb2以及两个FRUITFULL-LIKE（FUL-LIKE）基因MtFULa和MtFULb。MtPHYA还调节昼夜节律基因的表达，巨型（GI）和CAB表达1a（TOC1a）的时间安排。遗传分析表明，Mtphya-1 Mte11双突变体与单突变体同时开花。但是，Mtphya-1 Mtfta1双突变体在延迟开花和减少主轴长度（超过任一单个突变体所赋予的长度）方面具有较弱的累加作用。MtPHYA在紫花苜蓿的LD光周期控制开花，植物结构和幼苗去黄化中起着重要作用。它促进LD诱导的开花时间基因的表达并调节与时钟相关的基因。除MtFTa1外，MtPHYA还可能在苜蓿的LD花诱导过程中调控其他靶标。Mtphya-1 Mtfta1双突变体在延缓开花和减少主轴长度（超过任一单个突变体所赋予的长度）方面具有较弱的累加作用。MtPHYA在紫花苜蓿的LD光周期控制开花，植物结构和幼苗去黄化中起着重要作用。它促进LD诱导的开花时间基因的表达并调节与时钟相关的基因。除MtFTa1外，MtPHYA还可能在苜蓿的LD花诱导过程中调控其他靶标。Mtphya-1 Mtfta1双突变体在延缓开花和减少主轴长度（超过任一单个突变体所赋予的长度）方面具有较弱的累加作用。MtPHYA在紫花苜蓿的LD光周期控制开花，植物结构和幼苗去黄化中起着重要作用。它促进LD诱导的开花时间基因的表达并调节与时钟相关的基因。除MtFTa1外，MtPHYA还可能在苜蓿的LD花诱导过程中调控其他靶标。它促进LD诱导的开花时间基因的表达并调节与时钟相关的基因。除MtFTa1外，MtPHYA还可能在苜蓿的LD花诱导过程中调控其他靶标。它促进LD诱导的开花时间基因的表达并调节与时钟相关的基因。除MtFTa1外，MtPHYA还可能在苜蓿的LD花诱导过程中调控其他靶标。