Disease resistance and genetic diversity analysis in selected populations ofMacrobrachium rosenbergii

Abstract

16 selected populations were injected with bacteria(Vibrio alginolyticus) suspension to know deeply about disease resistance of Macrobrachium rosenbergii. Bacterial challenge experiments demonstrated that there were big differences in disease resistance among the 16 selected populations. Some families exhibited strong disease resistance to bacterial infection,while some families were not resistant to bacterial challenge. Among the 16 selected populations,3 populations( population SCR11-6,SCR11-11 and SCR1116) with strong disease resistance with a survival rate of 80% were identified,7 populations with secondly strong disease resistance,4 populations with normal disease resistance with a survival rate of 65%-70%, and 2 populations with low disease resistance with a survival rate of 49.53% and 35.0% were identified. The genetic structure of 16 selected populations was analyzed assessed by 8 microsatellite markers. The results showed that the number of total alleles was 53. The numbers of allele at each locus ranged from 5 to 9 with an average of 6.625,and polymorphic information content(PIC) was 0.6294- 0.8294,and the average was 0.7323. The mean polymorphism information content in 16 selected populations was 0.4932- 0.6956. The average observed and expected heterozygosity of the 16 selected populations varied from 0.5062 to 0.6513 and from 0.5519 to 0.7332,respectively,and the average genetic similarity coefficient and genetic distance between them was 0.6552 and 0.4344,respectively. Besides,after PCR amplification on the individuals of DP and SP populations,differential bands were calculated and the correlation betw een growth trait and microsatellite loci was established. The results showed that 5 loci were correlated with disease resistant trait,of which MRMB11 had extreme significance of 0.282. These results indicated that 4 of 16 selected populations had strong disease resistance and high genetic diversity. The development of these 8 populations lays foundation for selective breeding of M. rosenbergii with disease resistance.