Research On Thermo Sensitive Male Sterile Line SP2S In Rapifseed (Brassica Napusl)

Photoperiod and/or thermo-sensitive male sterility is a new way for heterosis utilizationbesides cytoplasmic male sterility, genic male sterility and chemical hybriding agents.Hybrid production based on photoperiod and/or thermo-sensitive male sterility is aneconomical and effective pollination control system. It is easy to develop high yielding hybridusing less time because this male sterility has a superior cross combinations and its sterilitywas controlled by the nucleus gene. SP2S is a new thermo-sensitive male sterility found byour group. We studied the inheritance of male sterile by the field experiment. The fertilityconversion temperature of SP2S was detected in growth chamber. We discovered the periodand characteristic of the pollen abortion through microscopical and ultrastructural observation.We used the SRAP molecule marker to find the marker which linked to the male sterile gene.The main results are as following:（1）SP2S was sensitive to temperature change but the photoperiod had no obviouseffect on it. SP2S became male sterile in high-temperature. The temperature of fertilityconversion was between13℃and16℃; The thermo-sensitive stage was13~14days beforeflowering.（2）SP2S was genic male sterility line, the fertility of SP2S was controlled bythermo-sensitive gene and male sterility gene, and the sterility gene might be one or tworecessive gene.（3）The result showed the anther abortion occurred at the early stage of micropsoremother cell, and finally degradated at the uni-nuclear microspore stage, which had an obviousdifference with other reported photoperiod and/or thermo-sensitive male sterility. The tapetalcells were already highly vacuolated and enlarged at the stage of micropsore mother cell. Thecytoplasm, without typical mitochondria, was decayed gradually. Without secretory function,the tapetal cells can not secrete callose synthase which was function on the callose. As a result,the micropsores can not be released and adhesion with each other. The microspores didn’t form the extine normally because of the absence of sporopollenin and some other material.The cytoplasm of pollen cells decayed gradually and at last became empty. These evidencesstated clearly that the abnormal PCD process of the tapetal cell was the main reason of thepollen abortion.（4）We found six SSR primer combinations that linked to male sterile gene. They hadpolymorphism between sterile and fertile DNA pool.