Mapping Of A Rice Dominant Male Sterile Mutant Of OsDMS-2

Rice is one of the most important food crops in the world. In China, rice planting area accounts for more than a quarter of the total area of grain crops, and rice grain output accounts for 39% of the total food crops. Use of heterosis is one of the main ways to improve the yield and quality of rice. Dominant genic male sterility gene as a hybrid tool has incomparable advantages. Currently found only 6 Rice Dominant genic male sterile material, finding more new dominant genic male sterile rice material has important implications to male sterility mechanism understanding and rice molecular breeding.In the present study, OsDMS-2(Dominant Male Sterility), found in an indica restorer line 8B1390, exhibited stable male sterility in both Chongqing and Hainan with different conditions of daylenth and temperature. We investigated the sterile characters by using light microscope and scanning electron microscope, and mapped OsDMS-2 mutant by using molecular marker analysis. 1. The OsDMS-2 fertility sensitivity to light and temperatureOsDMS-2 showing consistent stertility both in Chongqing(long daylenth and low temperature) and Hainan(short daylenth and high temperature) indicated the sterility of OsDMS-2 is not sensitive to daylenth and temperature change. 2. The effects of the mutation in OsDMS-2 on agronomic traitsQualitative observation showed no obvious differences on the agronomic traits such as tiller number, grain numbers per panicle, and 1000-grain weight, was found between the mutant and wild type. The mutant heading time was slightly late compared to the wild type, and the mutant plant was a little shorter than wild type. The seed setting did not occur when mutant OsDMS-2 selfing and the seed setting ratios were less than 20% when crossed as female. These results indicated that the mutation had no effect on agronomic traits, while had adverse effects on female fertility. 3. Characters of male sterility OsDMS-2Between the wild type and mutant, there were no apparent differences in the morphology of the panicle and glume. However, although the mutant anthers protruded normally, no pollen was released from the mutant anthers. The anthers of OsDMS-2 dominant male sterile mutant were shorter and whiter than the wild-type anthers. Pollen abundance was lower in mutant anthers than in wild-type anthers. And most of the mutant pollen grains were small and malformed. And most of the mutant pollen failed to accumulating starch, which resulted in non-staining in iodine solution; On the inner surface of OsDMS-2, the ubish bodies developed normally as the wild type. The normall anther surface development in mutant indicated that the mutation had no effects on the anther surface structure. The semi-section results indicated the mutation of OsDMS-2 destroyed the synthesis of the inclusions of pollen. 4. Mapping of OsDMS-2Two loci of OsDMS-2A(on chromosome 2) and OsDMS-2B(on chromosome 8) were found to be related with this dominant sterility after mapping with a same backcross population. The nearest flanking markers of OsDMS-2A are In Del Markers C2D11 and C2D12, whose genetic distances were 0.66 cM and 0.33 cM, respectively; The distances of the flanking makers(C8D3 and C8D7) of OsDMS-2B were 1.32 cM and 2.32 cM respectively.