Genetic Diversity Of Lowland And Upland Rice Landraces In China

In recent day, because of narrow genetic base and a little difference of genetic background in current rice cultivar, the productivity of rice has been stagnant in China. There are wealthy of rice landraces in China, which contain a large number of excellent genes. Lacking a detailed understanding of the genetic diversity, which limited the excellent rice germplasms effective management and utilization to rice breeding. Detected the genetic diversity of lowland and upland rice landraces in China is great significance for upland rice be used in rice breeding.The genetic diversity, genetic difference and cluster of 165 lowland rice and 159 upland rice landraces from China were discussed using 70 pairs of SSR markers. The results were summarized as follow:1. A total of 572 alleles were detected from all tested 324 accessions with 70 SSR markers, and the alleles per pair of primers were ranged from 2 to 21 with the mean value of 8.171. The effective number of alleles (Ne) were 244.297, and varied from 1.035—9.195 with the average was 3.490. Shannon's Information index (I) were changed from 0.104—2.432, and the average was 1.343. Among the SSR markers, RM72,RM232,RM219,RM241,RM224 and RM3 showed high polymorphism than the others, so they were fit for assessment the genetic diversity of rice germplasm resources.2. A total 502 alleles were identified from 187 Japonica rice landraces, there were 83 alleles which were only appeared in Japonica rice, accounting for 16.53%. The mean value of alleles per loci was 7.171, the effective number of alleles (Ne) per loci was 2.902, and the average of Shannon's Information index (I) was 1.120. In the lowland rice, a total of 434 alleles were assessed, there were 53 alleles which only appeared in lowland rice, accounting for 12.21%, the mean value of Na,Ne and I were 6.200,2.599 and 1.034 in Japonica lowland rice; In the upland rice, a total of 449 alleles were assessed, there were 68 alleles only present in upland rice, accounting for 15.14%, the average of Na,Ne and I were 6.414,2.884 and 1.100 in Japonica upland rice.3. A total 489 alleles were detected from 137 Indica rice landraces, there were 70 alleles which were only present in Indica rice, accounting for 14.31%, with an average of alleles per loci was 6.986 , the effective number of alleles (Ne) per loci was 3.030 , and the mean value of Shannon's Information index (I) was 1.201. In the lowland rice, a total of 397 alleles were identified, there were 61 alleles only appeared in lowland rice, accounting for 5.37%, the average of Na,Ne and I were 5.671,2.617 and 1.019 in Indica lowland rice; In the upland rice, a total of 428 alleles were detected, there were 92 alleles only appeared in upland rice, accounting for 21.50%, the mean value of Na,Ne and I were 6.114,3.195 and 1.245 in Indica upland rice.4. In Japonica and Indica rice landraces, test of significance on the mean of alleles of the SSR loci showed that there were no significant difference between the upland and lowland rice, while the upland rice was more the effective number of alleles (Ne) and shannon's Information index (I) than lowland rice, so in the same geographical origins, upland rice landraces were more genetic diversity than lowland rice.5. In Japonica rice landraces, the most genetically diverse of district was Yunnan province in lowland rice, but Guangxi, Yunnan and Taiwan for upland rice; In Indica rice landraces, the most genetically diverse of region was Guizhou province in lowland rice, but Guizhou, Guangxi, Yunnan and Hainan for upland rice.6. The mean value of genetic distance (GD) indices for Japonica rice landraces from different region were 0.315 in lowland rice, but 0.300 in upland rice, so the relationship among upland rice is more closer. The average of genetic distance indices for Indica rice from different area were 0.244 in lowland rice, but 0.356 in upland rice, so the relationship among lowland rice is more closer.7. The japonica lowland and upland rice landraces from the different provinces which had the more geographical or climate proximity had the small genetic distance index, the contrary has also set up. However the correlated relation was not distinct in indica lowland and upland rice landraces, so it needed further study in indica rice.8. Cluster and genetic structure of lowland and upland rice landraces showed that there are some differences in the distribution among the groups. So it's necessary to detect the genetic difference between lowland and upland rice.In addition, a total of 232 alleles were assessed in 20 germplasm resources from Brazil with 70 SSR markers, with the mean value of Na,Ne and I were 3.314,2.043 and 0.783.