水稻单核苷酸多态性及其应用现状

单核苷酸多态性（single nucleotide polymorphisms, SNPs）在水稻中数量多，分布密度高，遗传稳定性高。水稻SNPs的发现方法主要有对样本DNA的PCR产物直接测序、从SSR区段检测SNPs和从基因组序列直接搜索等。目前已有多种基因分型技术运用到了水稻SNPs检测，SNPs检测的高度自动化使水稻SNPs基因分型非常方便。单核苷酸多态性在水稻遗传图谱的构建、基因克隆和功能基因组学研究、标记辅助选择育种、遗传资源分类及物种进化等方面的应用具有巨大潜力。

Single Nucleotide Polymorphism (SNP) and Its Application in Rice

Single nucleotide polymorphisms(SNPs) distribute numerously and high-density throughout rice(Oryza sativa L.) genome.A total of 80 127 SNP sites were identified in rice genome,and one SNP every 154 bp was found between two rice subspecies indica and japonica.The SNP rate is 0.65%.SNPs also are very considerable among within-subspecies cultivars,even it can be found between closely related cultivars,in which it has been difficult to find polymorphic sites by conventional methods.The frequency of SNPs in rice genome varied between chromosomes,moreover it showed uneven distribution of polymorphism-rich and-poor regions along each chromosome.Several routes have been used for identification of SNP in rice,such as sequencing PCR products of DNA samples,screening SNPs in SSR fragments,and searching for SNPs through the rice genome sequences and EST database.A number of genotyping systems have been developed to identify SNPs in rice genome.High automation in SNPs identification has become a very convenient operation by the automatized systems.SNPs can be converted to CAPS(cleaved amplified polymorphic sequence) or dCAPS(derived-CAPS),and allele-specific PCR markers.SNP has shown huge potential in establishing rice genetic maps,genes cloning and functional genomics,MAS(marker assisted selection) in rice breeding,and studying on classification and evolution of germplasm.