In order to clarify the regulating mechanism of rice spikelet development , a spikelet-rudimentary rice mu-tant (spd-ph7 3) was obtained from the offspring of hp 73 mutated by60Coγradiation.Genetic analysis and gene map-ping indicated that the phenotype was controlled by a single recessive gene , named as spd-hp73, and the spd-hp73 lo-cus was mapped to the long arm of chromosome 4 between SSR marker RM 471 and RM273 .In the present study , we observed the spike development dynamic of both wild type ( WT) and mutant by stereomicroscope and scanning elec-tron microscope .The results showed that:there was no significant difference in the morphology of spikelet between mutant and hp73 in the early stage.But the morphology of inflorescence changed during the pistil and stamen forma -tion.In this stage , the spikelet number of mutant was significantly reduced , and almost all the spikelets on primary branch and secondary branch were degradated .This result indicated that the main function of spd-hp73 gene was pos-sibly to control spikelet number during the spikelet (or floret) primordium differentiation.%为了深入研究水稻幼穗形成和发育调控机理，经60 Co γ射线诱变处理和筛选，获得了一小穗退化突变体spd-hp73，经遗传分析和基因定位分析，spd-hp73小穗退化突变性状受一对隐性基因控制（暂命名为spd-hp73），该基因位于第4染色体长臂RM471和RM273之间。在本研究中，利用扫描电镜及体视显微镜对该突变基因控制下的幼穗发育过程进行跟踪观察，结果发现，与野生型hp73相比，该突变体幼穗在发育的早期生长形态非常正常，随着穗的继续发育在雌雄蕊原基形成的过程中，小穗数量显著减少，一次枝梗及二次枝梗上的小穗几乎全部退化。因而推测该突变基因spd-hp73的作用机理主要是对小穗（或颖花）原基分化期的小穗（或颖花）数量进行调控。
展开▼
