Studies On Core Collection Of Rice Germplasm Resources And Establishment Of The Framework Of Its Information Processing System

In this research, studies on three aspects about core collection were carried out, including sampling a core collection, studying the genetic diversity and evolution of rice; establishing a framework of information processing system of core collection of rice germplasm resources. The main contents and results were as follow:It firstly studied the genetic structure of a rice population estimated by different number of loci with different polymorphisms, and genetic diversity and genetic structure in core collections sampled according to different number of loci with different polymorphisms. The results showed that different strategies on selection of SSRs maker should be determined for different research aim and object. The efficiency of esitmating genetic diveristy and sampling core collections was related to the number of loci rather than the number of alleles. To precisly estimate the genetic structure of rice landraces and sample a representative core collection, for SSRs marker, randomly selected 18 to 24 loci could be recommended.Using two sets of populations, one of which was gotten by simulation and one of which was sampled from a core collection, the relationship of variation retention with parameters of population and with those of sampling were analysed. Correlation and path analysis showed that, among different sampling parameters, sampling scale was the determinative parameter; the sampling scale was determined according to the expected retention of variation and the situation of rare alleles in the initial population.Fifty-three core sets were sampled from a population with 1527 accessions by different sampling approches and methods. The comparison of diversity index, retention of variation and variation range, coefficient of variation and variance in different core sets showed that stepwise sampling could help to retain more variation and remove more genetic redundancy. And it also showed that, even though no much information could be gotten at the beginning in the parental population from which a core collection will be sampled, the representative core collection could be sampled by stepwise sampling, in the process of which sampling scale decreased stepwise and data information increased stepwise.Using the core collection of Yunnan rice landraces and 20 SSRs loci, gentic diveristy and evolution of rice in Yunnan were studied. The results showed that the area covering Simao, Lincang and Xishuangbanna in southwest Yunnan was the center of gentic diversity of rice in Yunnan and japonica was evolved from wild rice earlier than indica in Yunnan. Then it analyzed the sequences features in 20 SSRs loci in three varieties belonging to indica and japonica respectively, and the correlation between the inter-/intra-subspecific sequence polymorphisms in three varieties and the amplified SSRs polymorphisms in core collection of landrace rice in Yunnan. It showed that the inter-subspecies variations mostly came from the repeat region in the SSRs locus and mainly insertion/deletion variations; however some of the intra-subspecies variations came from non-repeat region in the SSRslocus except for from the repeat region, and considerable intra-subspecies variations were transition/transversion. Transition/transversion variations in SSRs loci promoted the differentiation between indica and japonica, it may be explained as transition/transversion variations caused two subspecies different adaptability to evironment.Finally, the framework of information processing system of core collection of rice germplasm resources (1PS-CCRGR) was designed. It aimed at data assembly and maintanence, information query and analysis, core collection sampling and decision of application and management of core collection. Some of its main models were programmed.