Genetic Diversity Of Genitic Marker Of DNA And Isozyme Of Three Populations Of Grass Carp(Ctenopharyngodon Idellus) Collected From The Yangtze River

PCR-RFLP of D-loop regions on mitochondrial DNA, RAPD and isozyme were used tostudying the genetic differentiation among grass carp (Ctenopharyngodon idellus) naturalpopulations from the Yangtze River. The technologies were also used to compare the geneticdiversity of different natural populations.1. The D-loop regions of 141 grass carp from 3 populations (Jianli in Hubei Province,Jiujiang in Jiangxi Province and Hanjiang in Jiangsu Province) were amplified and digestedwith 12 restriction endonucleases. The results showed that the length of the D-loop regionsamplified in 140 samples were 1.6kbp, while the D-loop region of one sample in the Jianlipopulation was 1.8kbp, which revealed the length variation. Restriction sites were observedwith six enzymes, and two haplotypes were detected. The one sample having lengthvariation belonged to one haplotype, while the remaining 140 samples belonged to the other.The haplotype diversity index and nucleotide diversity index within the Jiujiang and theHanjiang populations were both 0, respectively, but within Jianli population they were0.0465 and 0.00180, respectively. The Rogers' distance between the Jianli population andthe Jiujiang (or Hanjiang) population was 0.0403. Based on the genetic distances, The x~2 testshowed that there was no significant variance among three populations (P＞0.05). As a result,the genetic diversity in the mtDNA D-loop regions of grass carps was quite low.2. Twelve random primers were used to performing RAPD analysis of three grasscarp natural populations from the Yangtze River (Hanjiang in Jiangsu Province, Jiujiang inJiangxi Province and Jianli in Hubei Province). The intrapopulation BSI were 0.9713,0.9855, 0.9560, respectively. Meanwhile, the intrapopulation genetic variation of Jianli wasthe highest, Jiujiang population was in the middle, and Hanjiang was the lowest. Theinterpopulation BSI was 0.9547, 0.9527, and 0.9511. The average genetic distance amongthree grass carp populations was 0.0472. As a result, the genetic diversity was quite lowamong three grass carp populations.3. From the results of isozyme electrophoresis, we analyzed the basic electrophoreticpatterns of eight isozymes of 84 specimens. There were two polymorphic loci in 12 loci wehave tested, a-GPD~* and GPI-2~* were polymorphic loci in Hanjiang population; GPI-2~* waspolymorphic locus in Jiujiang population. The proportion of polymorphic loci was 0.167,0.083 in Hanjiang and Jiujiang population, respectively. The mean heterozygote observedwere 0.0204, 0.0064 in Hanging population; the mean heterozygote expected were 0.0192, 0.0062 in Jiujiang population, respectively. So, the genetic variation of Hanjiang populationwas higher than Jiujiang's. By the way of x~2, genotypes of polymorphic loci were consistentwith Hardy-Weinberg equilibrium in Jiujiang population. Otherwise, Hanjiang's wereinconsistent with Hardy-Weinberg equilibrium. By the way of x~2 of interpopulation, weconcluded that there was no significant variance at GPI-2~*, there was significant differenceat a-GPD~*. The genetic identity was 0.99928; the Nei's genetic distance was 0.00072between two populations. It indicated that there was no significant variance between twopopulations.