外源CTK与IAA调控小麦分蘖芽生长的作用机制研究

The regulation of the tillering occurrence is important for enhancing wheat yield potential. Tillers develop from tiller buds, and the growth of tiller buds can directly determine the tillering occurrence. Numerous studies have also shown that exogenous hormones that the plants are exposed to can regulate the growth of tiller buds by altering the levels of the endogenous hormones CTK and IAA. But the relationship between the synthesis and accumulation of endogenous CTK and IAA hormones and the growth of wheat tiller buds remains unclear, especially regarding how exogenous hormones influence CTK/IAA levels and tiller bud growth. Here, the difference in tillering capacity of wheat cultivars are used to study (1) the characteristics of the synthesis and accumulation of the endogenous CTK and IAA, and the relationship between these hormones and the growth of tiller buds; and (2) the regulatory effects of exogenous CTK and IAA on the synthesis and accumulation of the endogenous CTK and IAA, and its effect on the growth of tiller buds. Our aim is to further understand the regulatory mechanism of exogenous CTK and IAA on the growth of wheat tiller buds. The results can enrich the tiller bud regulation theory and provide a theoretical basis for directional regulation of the tillering occurrence in wheat.

调控分蘖发生以增强群体质量是提升小麦产量的重要途径。分蘖由分蘖芽生长而成，其生长状况直接决定分蘖能否正常发生。研究表明，分蘖芽生长过程与植株内源激素含量和激素间平衡关系密切，外源激素通过影响内源激素调节分蘖芽生长，且内源细胞分裂素（CTK）和生长素（IAA）在小麦分蘖芽生长调控中起主导作用。然而，关于小麦内源CTK和IAA合成及其作用部位激素积累与分蘖芽生长的关系，以及外源激素如何调节内源CTK和IAA合成积累、影响分蘖芽生长，迄今认识尚少。为此本项目以分蘖力差异显著的小麦品种为材料，研究（1）小麦内源CTK和IAA合成积累的特征及其与分蘖芽生长的关系、（2）外源CTK、IAA处理对内源CTK和IAA合成积累及分蘖芽生长的调节效应，进而阐明外源CTK与IAA调控分蘖芽生长的机制。研究结果将进一步丰富和完善分蘖芽生长调控理论，为定向调控小麦分蘖发生提供依据。

在确保小麦群体数量的基础上提高群体质量以实现成穗结实整齐度高是小麦高产高效栽培理论的重要研究方向。小麦个体由主茎和一系列分蘖构成，抑制弱势、无效分蘖发生有利于提高群体整齐度。分蘖由分蘖芽生长而成，分蘖芽与植株内源激素积累密切相关，且易受外源激素影响。明确外源CTK与IAA调控小麦分蘖芽生长的效应及其作用机制，构建小麦分蘖芽定向调控途径，对小麦高产高效栽培具有重要的理论意义与实践价值。本项目以分蘖力差异显著的小麦品种为材料，研究了小麦内源CTK和IAA合成及其作用部位激素积累与分蘖芽生长的关系，以及外源激素调节内源CTK和IAA积累、影响分蘖芽生长的效应。结果表明，Z（玉米素，细胞分裂素类）在调控分蘖芽生长中起着直接作用，外源激素通过影响Z含量以调控小麦分蘖芽的生长。其中，外源IAA通过影响植株内源IAA分布及数量降低内源Z积累，抑制分蘖芽生长；而外源Z可在逆境（低氮）下提高植株内源Z含量，促进分蘖芽生长。并基于室内试验，经过田间验证，提出了外源激素定向调控分蘖发生的技术途径。综上所述，项目对外源激素调控分蘖芽生长进行了系统深入的研究。研究结果为调控分蘖芽生长以定向调控小麦分蘖发生提供了一定的理论依据。