大豆FT同源基因GmFT2a/5a和GmFT1a/4突变体创制及其遗传效应解析

Soybean (Glycine max (L.) Merr.) is an important crop that provides abundant protein and oil for food production and animal feed. Soybean is a typical short-day plant and is sensitive to seasonal changes in day length. Day length has an important influence on flowering and growth habit in soybean and responses to photoperiod sensitivity limits soybean cultivars geographical range of cultivation. Selecting cultivars with a flowering response that fits the proposed region is a prerequisite to reach breeding goals. Thus investigating the photoperiod response in flowering induction has great significance in soybean regional introduction and domestication. .Molecular biological studies in Arabidopsis thaliana and rice have shown that FLOWER LOCUS T (FT) encodes florigen and plays an important role in flowering pathways as an integrator. FT gene is considered to be the most important signal integrator of photoperiod flowering pathway. In soybean, at least 10 FT homologs have been identified. GmFT2a and 5a were found to be strictly photoperiod-regulated, and overexpression has been shown to promote flowering in Arabidopsis and soybean. Ectopic expression of GmFT2b, 3a, 3b and 5b also promote flowering in Arabidopsis, but GmFT4 represses flowering. Overexpression of GmFT1a delayed flowering and maturation in soybean, confirming that GmFT1a functions as a flowering inhibitor. The results suggest that FTs have functionally diverged in soybean. On the other hand, CRISPR/Cas9-mediated targeted homozygous mutants of GmFT2a exhibited late flowering in soybean. But the genetic effect is obviously lower than the overexpressed research results. The findings suggest the results are not comprehensive obtained by ectopic expression in Arabidopsis or overexpression in soybean. The development and application of CRISPR/Cas9-mediated targeted mutation technique offers new tools for research on FTs genetic effects and serve as new germplasm in soybean breeding. .In this program, the established systems of soybean transformation and CRISPR/Cas9 mediated soybean genome editing in our laboratory will be applied. For flowering promoter GmFT2a/5a and inhibitor GmFT1a/4, the targeted mutagenesis and overexpressed lines with the same genotype will be obtained. By the analysis on the phenotypic characterization and the gene expression of these lines, the genetic effects of GmFT2a, 5a, 1a, and 4 will be analyzed and the degree of their influence on soybean flowering and mature period will be clear. Meanwhile, we will analyze the expression pattern of the other soybean FT homologous genes and the photoperiod-related genes in these lines. The double genes mutagenesis lines will be created through genetic recombination, and the interaction relationship will be analyzed among GmFT2a, 5a, 1a, and 4. These special materials will serve as new germplasm for soybean breeding. These results will be explored a new way that to expand regional adaptability of soybean varieties.

大豆富含蛋白质和油脂，是重要的粮油兼用作物。作为典型的短日植物，光周期反应敏感是影响大豆品种区域适应性的重要因素。FT基因被认为是最重要的光周期反应信号整合因子，对大豆开花和生长发育产生重要影响。本研究拟在前期研究基础上，利用成功建立的大豆转基因技术平台和CRISPR/Cas9介导的大豆基因组编辑技术体系，重点针对大豆FT同源基因中具有开花促进作用的GmFT2a、GmFT5a和具有开花抑制作用的GmFT1a、GmFT4，创制遗传背景一致的定点敲除突变体，与对应的过量表达转基因大豆材料相结合，通过表型鉴定和基因表达分析等手段，系统评价其遗传效应，明确其对大豆开花期和成熟期影响的程度，揭示其与其它大豆FT同源基因、大豆光周期途径重要相关基因表达的关系。并进一步通过杂交重组，明确它们之间的互作或互补效应，获得新的基因重组特殊材料，为大豆育种提供特异新种质，为拓展大豆品种区域适应性探索新途径。

大豆富含蛋白质和油脂，是重要的粮油饲兼用作物。作为典型的短日植物，光周期反应敏感是影响大豆品种区域适应性的重要因素，适时开花成熟是大豆区域适应性的先决条件和重要育种目标，研究大豆开花诱导过程中的光周期响应对大豆跨区域引种和驯化也具有重要意义。FT基因被认为是最重要的光周期反应信号整合因子，对大豆开花和生长发育产生重要影响。在大豆中，已鉴定出至少10个FT同源基因，并且存在功能分化，有针对性的调控FT基因的表达，可为大豆育种提供了新的种质资源。.本项目按计划创制了大豆GmFT2a、GmFT5a、GmFT1a、GmFT4基因编辑定点敲除纯合系和过量表达大豆转基因纯合系。同时，还创制出GmFT2b、GmFT3b、GmFT5b、GmFT1b等其它大豆FT同源基因的基因编辑定点敲除纯合系及过量表达转基因大豆纯合系。优化了大豆基因编辑载体系统，率先建立了大豆单碱基替换基因编辑技术体系，创制出GmFT2a和GmFT4基因单碱基替换突变体。系统分析了上述8个大豆FT同源基因的单基因遗传效应，评价了其对大豆花期、熟期影响的方式和程度，以及对其它大豆光周期途径重要相关基因表达的影响和可能存在的互作、互补或基因冗余关系。创制了GmFT2a、GmFT5a、GmFT1a、GmFT4基因的双突变体材料，系统分析了双基因突变的遗传效应，评价了双基因突变对花期、熟期影响的方式和程度，以及对其它大豆光周期途径重要相关基因表达的影响，分析了相互间可能存在的互作或互补关系。.本项目明确了上述8个大豆FT同源基因对大豆花期、熟期影响的遗传效应及对其它大豆光周期途径重要相关基因表达的影响，获得了基因编辑定点敲除突变体纯合系和对应的过量表达大豆转基因纯合系，创制出新种质、明确了育种应用策略。获得了GmFT2a/5a/1a/4双基因突变体材料，明确了双基因突变组合对大豆花期熟期影响的方式和程度、相互间的互作或互补效应，明确了育种应用策略、创制出新种质。该研究为大豆育种提供了特异新种质，为拓展大豆品种区域适应性探索了新途径。