| Channa argus, belongs to Channidae, is widely distributed in various main river systems in China and has become an important species for aquaculture. In recent years, as a consequence of overfishing and environmental change, wild C. argus population size has declined substantially. To conserve and rationally utilize natural populations and genetic resources of this species, novel microsatellite markers were developed and were used to evaluate genetic diversity and population genetic structure for nine wild populations of C. argus. The main results are as follows:1. Development and screening of microsatellites for C. argus(1) FIASCO protocol were used to construct (AGAT)6-microsatellite enriched libraries, a total of 100 positive clones were sequenced, among which sixty-two contained microsatellite repeats.42 primer pairs were designed to test their polymorphism in population of Poyang Lake,18 were polymorphic loci including 1 dinucleotide SSR and 17 tetranucleotide SSR.(2) Newly developed microsatellite loci were assessed using 42 individuals of C. argus collected from Poyang Lake. The number of alleles and effective alleles per locus ranged from 5 to 18 and from 2.649 to 11.344, respectively. The observed and expected heterozygosities ranged from 0.214 to 1.000 and from 0.630 to 0.923, respectively. Six out of 18 loci were significantly deviated from Hardy-Weinberg Equilibrium (HWE) after Bonferroni correction (P< 0.05). All of the loci showed high levels of polymorphism.(3) 68684 unigenes were constructed from the trascriptome database of C. argus, among which 26498 sequences contained microsatellite repeats,10 primer pairs were designed and only 1 pair was polymorphic.2. Genetic diversity of nine wild populations for C. argus(1) Nine wild populations of C. argus were collected from Huang Lake (HL) and Shuijia Lake (SJL) in Anhui Province, Liangzi Lake (LZL) and Zhijiang (ZJ) in Hubei Province, Lixian (LX) in Hunan Province, Minggang (MG) and Zhongmou (ZM) in Henan Province, Poyang Lake (PYL) in Jiangxi Province and Nansi Lake (NSL) in Shandong Pro vice. Genetic diversity of nine populations of C. argus were evaluated using 14 microsatellites.337 alleles were amplified with a range of 78-430 bp. The average number of alleles and effective alleles ranged from 6.071 to 14.643 and from 3.413 to 8.175, respectively.17 specific alleles were identified in the population PYL whereas only two were identified in the population ZM.(2) The observed and expected heterozygosities as well as Shannon diversity index of nine populations ranged from 0.612 to 0.818, from 0.664 to 0.846 and from 1.337 to 2.219, respectively. The populations from the NSL, ZJ, LX, SJL and HL showed relatively high level of genetic diversity while the population ZM had a relatively low one.(3) Fifty-four out of 126 tests were significantly deviated from HWE, null alleles were detected among these loci. Specifically, the populations from the LX, PYL, NSL were balanced at all loci whereas the population LZL was found to be deviated from HWE at all loci.3. Genetic structure of nine wild populations for C. argus(1) Nei's genetic distance (DA) of nine populations ranged from 0.162 to 0.596. Genetic differentiation was relatively low among populations along the Yangtze drainage except the population PYL, obvious genetic differentiation was detected among other populations. FST/(1-FST) had no significant correlation with geographic distances among populations (r=0.2747, P> 0.05).(2) Cluster analysis of UPGMA, NJ and FCA revealed that nine populations can be divided into 3 groups, five populations (HL, LX, ZJ, LZL, PYL) sampled along the Yangtze River was closely related to each other, two populations SJL and NSL as well as two populations MG and ZM were clustered as a group, respectively. The results of AMOVA showed that 88.93% of the genetic variation occurred within populations while 11.07% among populations, indicating a significant genetic differentiation among nine populations (P< 0.001). While three groups were divided, AMOVA showed that 87.21% of the genetic variation occurred within populations,6.18% among groups and 6.61% among populations within groups, indicating significant genetic differentiations among populations within groups and within populations (P<0.001).(3) Structure analysis showed that nine populations were divided into three genetic groups in theory. In addition, the genetic structure of six populations from the HL, SJL, LX, MG, PYL, NSL were relatively independent, whereas infiltration may exist among the populations from the LZL, ZJ and ZM. |
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