Initial Study on Sichuan Apomixis Rice (SAR-1)

SAR-1 is a new germplasm which was discovered in the breeding material of southern multiplication in spring, 1988. The material showing high sterility of pollens is able to set seeds spontaneously. Under isolation, the seed-setting highest rate may reach 55.33%. The florets emasculated by clipping spikelet and lukewarm water still set seeds at certain rates. The completely sterile florets, after being emasculated and checked under microscope one by one, still set seeds, and the highest setting rate is 41.80%. Cytoembryological research indicates that the egg of SAR-1, without fertilization, divides independently into an embryo, which follows the normal process to maturity. Adventitious embryos originate from ovary wall cells. Therefore, it is deduced that SAR-1 has multiple mechanisms of apomixis, and the unfertilized polar nuclei fuse and develop into endosperm cells. The endosperm provids the embryo with nutrient for development. The automatic formation of the endosperm is an obvious feature of SAR-1.