拟南芥TSB1协调植物生长与抗逆的机制研究

A varieties of abiotic stresses affect plant growth and development, and plants has evolved sophisticated strategies in response to these adverse environmental conditions. Therefore, it is important for us to understand how plants regulate the trade-off between growth and abiotic-stress responses. Our previous work showed that the expression of tryptophan synthase unnit 1（TSB1）is decreased in Arabidopsis subjected to salt or drought treatment. Also, trp2-13, a loss-of-function mutant of TSB1, shows reduced growth rate and has decreased IAA level, but enhanced tolerance to salt or drought stress with increased ABA level compared with those in the wild type. Further，TSB1 interacts with TIP1, an enzyme that can catalyze the release of ABA from the substrate ABA-GE. In this project, we plan to carry out further experiments to demonstrate TSB1 as a key factor to regulate trade-off between plant growth and tolerance to abiotic stresses. Thus, We will analyze the changes of IAA/ABA levels and tolerance to the abiotic stress in the mutant subjected to the stresses; confirm the interaction between TSB1 and TIP1; assay the TSB1-mediated regulation of TIP1 enzymatic activity; determine the genetic relationship of TSB1 and TIP1; assess the expression of the genes involved in plant growth and responses to abiotic stress and their role in these processes. Our research will show that TSB1 acts as a key factor regulating the trade-off between plant growth and tolerance to abiotic stress, and also illustrate this underlying mechanism.

植物在生长过程中常遭遇逆境，长期进化使得植物能根据环境变化，调整其生长来应对逆境。但是目前还没有鉴定出能协调植物生长和抵抗非生物胁迫的关键调节因子。因此，对其深入研究有重要的理论意义和潜在应用价值。我们的研究发现，在干旱和高盐胁迫下，植物下调在IAA合成中起重要作用的色氨酸合成酶β亚基（TSB1）基因的表达。TSB1功能缺失突变体trp2-13的IAA含量下降，生长受到抑制；但ABA积累增加，干旱和高盐的耐受力得到提高。TSB1还可同TIP1互作，而TIP1能水解ABA-GE为ABA以增加ABA含量。因此，计划深入分析相关突变体逆境耐受力和IAA和ABA积累；明确TSB1表达抑制不仅会影响IAA的积累，还可通过互作影响TIP1的酶活，进而调控ABA含量变化；分析生长和抗逆相关基因的表达状况及可能作用。上述研究将证明TSB1通过调控生长激素IAA和逆境应答激素ABA，协调植物生长与抗逆应答。

植物在生长过程中常遭遇逆境，而植物能依据环境变化调整其生长来应对逆境。近期研究已揭示植物调节生长和抗病之间平衡的分子机制，但是对于植物如何协调调控生长和抵抗非生物逆境胁迫间的平衡，目前并不清楚。通过研究，我们深入分析了功能缺失突变体tsb1(trp2-13 和amiR-TSB1)在干旱和高盐胁迫条件下对逆境的耐受力以及对IAA和ABA积累的影响；证明了TSB1通过与BG1相互作用抑制BG1的酶活性从而减少ABA的积累；进一步获得trp2-13 bg1-1双突变，分析其ABA含量和胁迫耐受力的变化而明晰了TSB1与BG1的遗传关系；最后利用转录组测序了解了相关突变体在胁迫条件下基因表达变化差异并完成其在植物生长与抗逆中的作用的分析。因此，我们的研究首次明确证明 TSB1 为协调植物生长和抗逆的关键因子。其调控机制为：植物通过下调TSB1 的表达并降低 IAA 的积累来感受干旱和高盐胁迫和延缓植物生长；而 TSB1 的下调又能减轻其对BG1的抑制，进而通过促进 BA-GE 水解提升ABA 积累，从而提高植物对非生物胁迫的耐受力。我们研究明确证明TSB1通过调控生长激素IAA和逆境应答激素ABA来协调植物生长与抗逆应答，对我们深入理解植物如何协调生长和抗逆具有重要意义。