RAPD And ISSR Analysis Of Genetic Diversity Of Suaeda Salsa

Suaeda salsa, belonging to Suaeda of Chenopodiaceae, is an annual herb. S. salsa has strong stress resistance, especially prominent salinity resistance. It can survive in 4.3% sea water. It richly contains the nutrition and the medicine ingredient. Researches about S. salsa on stresses, especially on salinity resistance have developed to molecular level. Whereas the conservative and using work of S. salsa is lack of the supporting of the theoretical guidance on genetic diversity research. This study selected 120 individuals of 8 populations of S. salsa which natural distributed in different salinity soil in Dongying, Shandong and adopted RAPD and ISSR as the molecular markers to detect the genetic diversity and the genetic variation, genetic structure among and within the populations. It indicated that there existed the correlations between genetic differentiation and geographic distance in S. salsa population. An understanding of both genetic diversity and population structure of S.salsa provides insight for the conservation and management of S. salsa. This study obtained the conclusion thereinafter:1. An optimized PCR reaction system for RAPD and ISSR was established: RAPD-PCR was performed in a 25uL reaction mixture with 30～50ng DNA, 1.0umol/L primer, 10×PCR Buffer, 0.2mmol/L dNTPs, and 1U Taq polymerase. ISSR-PCR was performed in a 25uL reaction mixture with about 50ng DNA, 1.0umol/L primer, 10×PCR Buffer, 0.2mmol/L dNTPs, and 1U Taq polymerase. The temperature profile used for RAPD-PCR was 94℃for 2 min; followed by 45 cycles of 94℃for l min; 36℃for l min; and 72℃for 2 min; and was terminated with a 10 min DNA extension step at 72℃. The temperature profile used for ISSR-PCR was 94℃for 2 min, followed by 35 cycles of 94℃for 50 sec; 50℃for 45 sec; and 72℃for 1.5 min; and was terminated with a 5 min DNA extension step at 72℃; stored at 4℃.2. The genetic diversity of S. salsa revealed by RAPD and ISSR on species level: The percentage of polymorphic bands (P) was 89.43% for RAPD, 86.76% for ISSR respectively. The Nei's genetic diversity index (H) was 0.3264 for RAPD, 0.2815 for ISSR. The Shannon diversity information index (I) was 0.4854, for RAPD and 0.4291 for ISSR. All of these two molecular markers are the suitable one to test the genetic diversity of S. salsa.3. The genetic variation among the natural populations of S. salsa revealed by Nei's analysis and Analysis of Molecular Variation showed a certain genetic differentiation had occurred among eight populations. Genetic variation mainly existed between populations ( Gst: 0.2359 for RAPD and 0.2811 for ISSR ). The gene flow of S. salsa was high ( Nm: 1.6196 for RAPD, 1.2789 for ISSR ), indicating certain genetic intercourse among populations.4. The analysis of genetic identity ( I: 0.7855～0.9276 for RAPD, average 0.8826; 0.7879～0.9583 for ISSR, average 0.8868 ) and genetic distance ( D: 0.0752～0.2414 for RAPD, average 0.1536;0.0426～0.2384 for ISSR, average 0.1226 ) showed high genetic identity among eight populations and a certain genetic differentiation. The genetic distance according with the geographic distance, HS population and other seven populations had the longest genetic distance. The cluster analysis demonstrated that the populations with near geo-graphical distribution were clustered together.It indicated that there existed the correlations between genetic differentiation and geographic distance in S. salsa populations.