PAT1与COL13基因互作调控芥菜分枝与开花机制

Branching is a major vegetative organ that determines yield in Xuecai variety of Brassica juncea. Shoot branching is controlled by complex interactions between phytohormonal, developmental and environmental factors. Phytochrome A signal transduction 1 (PAT1) is a positive regulator of phytochrome A signal transduction in response to light spectrum, but the involvement of PAT1 underlying shoot branching remains unknown. Previously, we mapped a PAT1 (Phytochrome A signal transduction 1) gene that negatively controls shoot branching in B. juncea using associated study. Moreover, we found that PAT1 can interact with COL13 (CONSTANS-like 13), a flowering regulator using yeast-two-hybridization. Based on these findings, we supposed that interaction of PAT1 and COL13 coordinately regulate shoot branching and flowering in leafy B. juncea. In this proposal, we plan to confirm the functions of interactions of PAT1 and COL13 in regulating shooting branching and flowering via gene editing and protein-protein interaction. And we are going to study the functions of SNPs of PAT1 in regulating shooting branching and flowering through TILLING (Targeting Induced Local Lesions In Genomes). Our objective is to reveal the mechanism on PAT1 and COL13 coordinately orchestrating shoot branching and flowering transition in leafy Brassica juncea and to provide theoretical basis and gene resourse for breeding new cultivars with high yield and quality in B. juncea.

分枝是芥菜（雪菜）产品器官和产量形成的决定因素，受激素、发育和环境因子协调调控，但迄今未发现PhyA信号途径与分枝有关。我们前期定位到控制芥菜分枝的基因PAT1（Phytochrome A signal transduction 1），初步验证了PAT1负调控芥菜分枝，发现PAT1可与开花调控基因COL13（CONSTANS-like 13）互作，据此提出PAT1与COL13互作调控芥菜分枝与与开花的可能机制。本项目拟采用基因编辑、蛋白互作、TILLING等手段，对PAT1和COL13基因互作调控分枝和开花功能进行研究，探索PAT1基因SNPs在分枝和开花调控中的作用。最终目标是解析PAT1与COL13互作调控芥菜分枝与与开花机制，为选育高产优质芥菜新品种提供基因资源和理论依据。

芥菜类蔬菜作物表型变异丰富，其中叶用芥菜（雪菜）分枝性强，分枝是其营养产品器官和产量形成的决定因素。本研究通过遗传分离群体结合BSA、重测序和关联分析方法，鉴定到一个与芥菜分枝形成相关的基因PAT1（Phytochrome A signal transduction 1），属于GRAS转录因子家族。基于基因分型、沉默表达、互补表达和回交基因型与表型关联分析等方法，证实了PAT1负调控芥菜分枝形成的生物学功能，PAT1与BRC1互作表明 PAT1调控分枝形成依赖于BRC1（BRANCHED 1）途径。同时，发现PAT1可以响应红光/远红光信号从而调控分枝形成，当PAT1基因表达沉默后，可解除低比例红光/远红光抑制分枝形成，并且这一调控过程发生在芽原基分化形成之后。进一步研究发现，PAT1与COL13（CONSTANS-like 13）基因互作，PAT1沉默表达后开花时间提前，COL13沉默表达后分枝数目增加，表明PAT1与COL13基因互作调控分枝（营养生长）与开花（生殖生长）的转换。分枝调控相关基因PAT1的挖掘与调控机制解析，可为早熟、高产芥菜类蔬菜作物种质创新提供新的基因资源。