Abstract: Switchgrass is a perennial gramineous plant.It is studied widely and applied as an energy crop because of its huge biomass to produce fuel ethanol. Tillering is the main factor that directly affects the biomass of gramineous plants. The production of tillers is determined by the development of tiller buds,which is regulated by many factors including plant hormones and external environment. A tiller-deficient mutant lt induced by EMS was studied in physiological,biochemical and molecular mechanisms. The results showed that the number of tillers and elongation rate of axillary buds of mutant lt decreased. And the shoot of lt responded to gravity weakly,the contents of auxin,abscisic acid and strigolactones in lt increased. At the same time,the expression level of genes involved in strigolactones pathway in lt mutant increased. These results indicated that the tillering development of switchgrass mutant lt was regulated by auxin,abscisic acid and strigolactones. These results could provide theoretical direction for increasing biomass yield of switchgrass.

Key words: Switchgrass, Tillering, Plant hormones, Strigolactones

摘要： 柳枝稷是多年生禾本科植物，因生物量巨大可生产燃料乙醇而作为能源作物被广泛研究和应用。分蘖是直接影响禾本科植物生物量的主要因素，分蘖的数量由分蘖芽的分化和伸长共同决定。分蘖芽的分化和伸长过程受植物激素和外界环境等多种内在和外界因素共同调控。本研究对一个由EMS诱变获得的少分蘖突变体lt进行生理生化和分子机理研究。结果表明，与对照相比，突变体lt分蘖数目减少，腋芽伸长速度减缓；lt地上部分对重力响应减弱；lt体内生长素、脱落酸和独脚金内酯的含量增加；同时，lt突变体中独脚金内酯途径的基因表达水平增加。由此说明柳枝稷突变体lt分蘖发育的过程中受到了生长素、脱落酸和独脚金内酯的共同调控。该研究可为提高柳枝稷生物产量提供理论基础。

关键词: 柳枝稷, 分蘖, 植物激素, 独脚金内酯