摘要：

Part I: Since the late of 1970s, a total of 2.8 billion tons of hybrid rice seeds have been produced, accounting for about 60% of the China's total rice output. It can be produced in such a large scale with 20% higher yields thanks mainly to the development of the Wild Abortive (WA) type of cytoplasmic male sterility (CMS) system. We have isolated a gene WA352 conferring this type of CMS in rice. WA352 originated from complex recombination events in th mitochondrial genome.  This CMS effect appears general as shown by introducing the transgene into rice and Arabidopsis. Further study on the evolutionary dynamics of this CMS locus provides new insight into the evolution of rice.

Part II:  Asian cultivated rice (Oryza sativa L.) has differentiated into two major subspecies, indica and japonica. The two subspecies are reproductively isolated by various degrees of male and female sterilities in their hybrids. Here we show that, in the indica-japonica hybrids, the indica allele of a hybrid sterility gene in the Sa locus, OsSaM^-i that encodes a Mms21 domain containing protein, functions in a gametophytic manner to cause the selective abortion of male gametes carrying the diverged japonica allele (OsSaM^-j ). Further genetic and molecular analyses revealed that an F-box gene of the indica allele OsSaF^-ilocating adjacently to OsSaM^-i is required for this allele-specific male sterility, by a sporophytic interaction between OsSaF^-i and OsSaM