| This research covered two subjects related to drought tolerance of rice. One was the construction of core collection from 335 varieties of upland rice. The other was the location of DT related QTLs.1). Diversity analysis was conducted on all collected upland rice which include 335 varieties from China, Africa, South America, South-East Asia and some other countries. Most Chinese varieties came from Yunnan province and Hainan province. Total 38 traits, including morphological, agronomic and yield traits, had been investigated. In whole collection, there are 266 indica and 69 japonica varieties. Among these materials, 107 varieties have short growth durations while 63 varieties have long ones.There are 111 dwarf rice, 18 rice with large panicle (> 250 spikelets per panicle), 69 rice with large grain (>30g/1000-grain) and 30 varieties with color seed capsule. In core collection, there are 58 indica and 28 japonica varieties. Among these materials, 1 5 varieties have short growth durations while 31 varieties have long ones. There are 33 dwarf rice, only one rice varietie with large panicle, 19 rice with large grain, and 10 varieties with color seed capsule. All these results could be used in the further research and breeding programs.2). All materials were divided into 7 groups according to their origin. The sampling strategies to construct upland rice core collection were studied at three levels, i.e. sampling proportion within groups, sampling scale in whole collection and sampling method from each group. Sampling proportions in each group were logarithm, square root and index of genetic diversity proportion. Sampling scale in whole collection were 5%, 10%, 15%, 20%, 25% and 30%. Random and clustering sampling was carried out in each group. Four parameters, ratio of phenotype retained (RPR), variation of phenotypic frequency (VPF), index of genetic diversity (H) and coefficient of variation (CV) were used to evaluate different sampling strategies.Results showed that the better sampling proportion was index of genetic diversity proportion. Six overall sampling scales were significantly different from each other, and the multicomparison showed that 25% sampling scale was optimal to represent the genetic diversity of the whole resources. The comparison of the value of 4 test parameters and variance analysis showed that clustering sampling was better than randomly sampling. Therefore, the best sampling strategies to construct core collection of these 335 upland rice varieties was the combine of the index of genetic diversity sampling proportion, 25% sampling scale and clustering sampling method.3). The comparison of the index of genetic diversity (H) showed that 6 groups in core has obviously higher H than that in whole collection. Only materials from Africa had similar H between the core and the whole resources. For 68 phenotypes of 20 quality traits, only two rare phenotypes of color rice were not included in core. The representation of 18 quantitative traits were tested by the comparison of 6 values including Max, Min, Range, Mean, SD, CV. Result showed that the values of these 6 parameters of both core and whole recourses were similar. The coincidence rate of SD in 2002 and 2003 were 88.45% and 89.61%. The coincidence rate of Range in 2002 and 2003 were 92.67% and 91.59%. And the coincidence rate of MEAN in the two years was 92.85% and 91.02%. These results indicated that the whole recourses were well covered by the core collection. Furthermore, the result of the structure comparison showed that clustering sampling method could avoid abundance and improve uniformity of genetic variation in the core collection.4). A complete and well-distributed molecular linkage map with 213 SSR markers was constructed using a set of recombinant inbred (RI) lines (F9) derived from the cross of Zhenshan97B (indica, lowland rice)/IRAT109 (japonica, upland rice). The genetic map spanned 1825.0cM and covered all of 12 rice chromosomes with an average distance of 8.6cM between adjacent markers. The X2 test of the markers and lin...
|
PDF Full Text Request