水稻株高及分蘖调控因子DTL1的分离及功能分析

Plant height and tillering are two major factors in determining of the rice architecture and yield production. Although a few genes controlling of tillering and plant height had been cloned, however, the regulation mechanisms of plant height and tillering is still poor understanding due to the complexity of agronomic traits. To further explore the regulation mechanism of rice tillering and plant height, we identified a mutant with reduced plant height and tillering number( dtl1) under mutagenesis screening, and delimited DTL1 onto chromosome 12 within a physical distance of 150-kb. To verify the target gene is indeed DTL1, several experiments will be performed, such as the functional complementation and over-expression assay. The DTL1 promoter-driven GUS transgene and in-situ hybridization studies should be applied to determine the expression pattern of DTL1. RNA-seq and yeast two-hybrid technologies will also be utilized to find the downstream genes and its interacting proteins. Furthermore, by constructing double mutant of dtl1 with known reduced-tillering and dwarf mutants and exogenous hormones treatment with Gibberellin and strigolactone etc, the function of DTL1 in determining of plant height and tiller number mediated by hormones will be explored. The completement of this project should significantly improve our knowledge in regulation mechanism of plant height and tillering, and will also provide a theoretical basis for rice high-yield breeding via architecture improvement.

株高和分蘖数目是决定水稻株型的主要因素，是影响水稻产量的重要农艺性状。虽然株高和分蘖数目形成的分子机理已被广泛研究，然而由于其调控机制复杂性，目前仅有几个同时控制分蘖和株高基因被克隆，因而人们对于水稻株高和分蘖调控机理认识还十分有限。本研究通过分离一个水稻株高和分蘖数目同时减少突变体dtl1，以图位克隆方法克隆该基因，并通过功能互补实验验证其功能；通过转基因及原位杂交等技术研究DTL1基因表达模式；利用RNA-seq技术筛选DTL1的下游基因；利用酵母双杂交筛选与DTL1相互作用蛋白；通过与gid1等矮秆或少分蘖材料杂交鉴定DTL1与现有株高和少分蘖基因的遗传学关系；通过激素外施实验，探讨DTL1在激素调控分蘖数目和株高过程中的重要角色。本项目研究不仅对阐明植物株高和分蘖调控机制有重要的理论价值，还将为农业生产中利用水稻株型改良提高水稻产量提供理论依据。

水稻株型和分蘖数是影响其产量的主要因素，然而，影响这些农艺性状的分子机理，目前还不十分清楚。通过基因工程技术，得到一个水稻株高和分蘖减少突变体，经典遗传研究表明该性状由一对隐性核基因控制（dtl1）。通过图位克隆的方法，我们构建了dtl1突变体的高饱合的遗传图谱和精细物理图谱并鉴定突变座位及其等位基因，研究鉴定该基因功能及其调控机制。实验结果表明，DTL1编码一个formin蛋白，参与调控叶绿体发育和微丝形成，并最终影响细胞伸长。在dtl1突变体中，由于DTL1基因的功能丧失，从而导致微丝形成过程及细胞伸长受阻。这一基因克隆，将为理解微丝结构在水稻株高和分蘖形成过程中发挥的重要作用奠定坚实基础，也为指导育种实践，培育高产水稻品种具有重要指导意义。