Studies On Genetic Diversity Of Germplasm Resources Of Zizania Latifolia (Griseb.) Trucz. Based On ISSR And SSR Markers

Zizania latifolia (Griseb.), also called wild rice, is a perennial grass belonging to thetribe Oryzeae, and is thus related to rice (Oryza sativa L.). Zizania latifolia is one of thefour Zizania species distributes in East Asia, while the other three Zizanias in NorthAmerica. Z. latifolia can both grow in water or wetland widely in China and possessesnumerous traits valuable for rice breeding, such as broad resistance to pathogens, cold andflood tolerance, and high grain quality. Given that, the rice breeders see Z.latifolia a goodsource of excellent genes for rice breeding. However, the basic information, such the statusof wild populations, gene diversity, gene transfer between populations etc, is till obscure.Genetic diversity and structure of wild rice populations of Zizania latifolia collected fromthe Poyang Lake valley was investigated using SSR and ISSR markers in this study. Now,we have the information of genetic diversity and genetic relationship of these wildpopulations. The important information and results we got will facilitated the utilizationand protection of this wild resources. The main results of this thesis are as follow:1we established an optimized ISSR-PCR reaction system for genotyping of Z. latifolia.20μL reaction system with composition concentration as follows:0.5mM dNTPs,3.0mMMg2+(10×Buffer),0.24U μL-1Taq polymerase,1.0μM primer,1.5ng μL-1DNA template.2Using14informative ISSR primers, a total of83bands were generated from80sampleswhich collected from30wild Zizania latifolia populations. The average PPB was78.29%.The primer’ polymorphism information content (PIC) range from0.07～0.49, with anaverage0.25. Popgeng software analysis showed that the genetic distance (GD) rangedfrom0.0658～0.4868, with an average0.2763. The average index of Nei’s genetic diversity(He) and Shannon’s information (I*) were0.2386and0.4174, respectively. Cluster analysisshowed that30wild populations of Z. latifolia classified into three groups at the thresholdof0.728based on ISSR genotypes using the UPGMA method. Similarity coefficient matrixbased on Mantel test has significantly correlations (r=0.6782) with the clustering results.The relationship of the30populations on account of principal coordinate analysis weremore intuitive and nuanced than that based on UPGMA method analysis. Principalcoordinate analysis divided all the30populations into4groups at two dimensional level,and more elaborate into2groups at the third coordinate direction.3A total of276bands were generated from19pairs of informative SSR primers we pickedfrom1113pairs SSR primers for Oryza sativa. In the276bands amplified265werepolymorphic, the percentage of polymorphic bands (PPB) was91.67%. Average bands perprimer was13.32and the primer’ polymorphism information content (PIC) range from0.16～0.44, with an average0.28. Popgeng software analysis showed that the geneticdistance (GD) ranged from0.1632～0.4410, with an average0.3021. The average index ofNei’s genetic diversity (He) and Shannon’s information (I*) were0.2712and0.4144, respectively. Cluster analysis showed that30wild populations of Z. latifolia classified intothree groups at the threshold of0.698based on SSR genotypes using the UPGMA method.Similarity coefficient matrix based on Mantel test has significantly correlations(r=0.6664)with the clustering results. The principal coordinate analysis results were moreintuitive and nuanced than that based on UPGMA method analysis. Principal coordinateanalysis divided all the30populations into4groups at two dimensional leve l, and moreelaborate into2groups at the third coordinate direction, slightly different from the clusteranalysis results.4The correlation coefficient of similarity coefficient matrix of the two kinds of markerswas0.3378, that means a poor matching between ISSR and SSR data. The polymorphismsratio and information content from SSR primers are higher than that from ISSR primers.For better explanation of the genetic relationship between these populations, data fromISSR and SSR should takes into account together.30wild populations of Z. latifolia wereclustered into three groups at the threshold of0.706based on data integration using theUPGMA analysis method from NTSYS software. Similarity coefficient matrix based onMantel test has significantly correlations (r=0.6715)with the clustering results, show thatthe clustering results well reflect the genetic relationship between the wild Z. latifoliapopulations.