ISSR Analysis Of Genetic Diversity Of Zizania Latifolia Germplasm Resources In China

Zizania latifolia is a perennial aquatic herb of the genus Gramineae(Zizania).It is the most primitive species of the four species of Brassica,distributed in East Asia.The other three species of the Zizania,such as Zizania texana,Zizania aquatica and Zizania palustris,are located in North America.According to the latest survey results,China is one of the important distribution areas of Zizania latifolia germplasm resources,especially in the middle and lower reaches of the Yangtze River and the Huaihe River Basin.There is a high degree of collinearity between the Zizania latifolia genome and the rice genome,and it has a very high value of gene resource utilization,which is increasingly valued by breeders.Due to the phenomenon of self-crossing degradation,heterosexual tendency,easy-to-grain,and difficult to collect seeds,the Zizania latifolia gene has hindered the deep exploration of its genetic evolution law.Therefore,this paper takes the Zizania latifolia sample material in East China as an example,and screens out the optimal electrophoresis detection method for ISSR-PCR amplification products,and applies the labeling and detection methods to 381 of 25 Zizania latifolia in four major regions of China.Genetic diversity analysis of materials explores the genetic variation between Zizania latifolia populations.The main findings are as follows:(1)Optimum electrophoresis detection method: compare the effects of two detection methods of 2% agarose and 5% polyacrylamide gel electrophoresis on the genetic diversity of Zizania latifolia in East China.The results show that the polyacrylamide method can better reflecting the genetic diversity of Zizania latifolia in East China,the agarose method failed to effectively separate PCR products due to its low resolution,resulting in low genetic diversity.Therefore,the polyacrylamide method is superior to the agarose gel method.(2)Genetic polymorphism analysis: 13 primers were selected to PCR the genomic DNA of 381 materials from 25 Zizania latifolia populations in China.The products were detected by 5 % non-denaturing polyacrylamide gel electrophoresis.A total of 244 bands were amplified by 13 ISSR primers,including 218 polymorphic bands,and the percentage of polymorphic loci(PPB)was 89.34%.(3)Genetic diversity analysis: POPGENE 1.32 software analysis showed that Zizania latifolia have rich genetic diversity: Nei's gene diversity index(He=0.2222),Shannon's diversity information index(I=0.3518);inter-population genes The flow(Nm=0.3799<1)indicates that genetic drift becomes the main factor affecting the genetic structure of the population.The genetic differentiation among populations(Gst=0.5682>0.25)was high,suggesting that the variation between populations was slightly higher than that within the population.(4)Analysis of clustering relationship: Clustering results showed that the genetic similarity coefficient(Gs)and genetic distance(Gd)of each population were between0.7349~0.9851 and 0.0150~0.3080;Cixi(CX)and Hangzhou(HZ)had the highest genetic similarity coefficient.The distance is the smallest and the kinship is the closest;Beijing(BJ)and Shaoguan(SG)have the smallest genetic similarity coefficient,the largest genetic distance and the closest relationship;The genetic distance and geographical distance analysis showed that r=0.8429 and p=0.001(p<0.01),indicating that the genetic distance between Zizania latifolia populations was significantly positively correlated with the geographical distance index.(5)Analysis of genetic structure: The phylogenetic analysis of MEGA software and the principal component analysis(PCA)of MVSP software show that Chinese Zizania latifolia is divided into two by common ancestors in genetic structure,including 20 population in East China,Central South and Southwest China(including Dalian population),the northern five populations belong to another branch,although there is a small amount of genetic confounding(genetic communication phenomenon)between the groups,but there is still obvious differentiation.Conclusion: The ISSR-labeled 5% polyacrylamide gel electrophoresis method is superior to the agarose gel method;Zizania latifolia has rich genetic diversity;The genetic distance between populations is significantly positively correlated with geographical distance.