PRELIMINARY STUDIES ON THE CORRELATION BETWEEN MICROSATELLITE|MARKERS AND GROWTH TRAITS IN CHINESE MITTEN CRAB (ERIOCHEIR|SINENSIS)
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Abstract
Chinese mitten crab (Eriocheir sinensis), belong to order Brachyura, family Grapsiodea, is one of the mostimportant species for aquaculture in China with an annual cultured production of about 518357 tons, especially in theYangtze River valley. Chinese mitten crab has three main strains in China, including Yangtze River strain, Liaohe Riverstrain and Oujiang River strain. The strain of Yangtze River exhibited excellent economical characters and is the beststrain for aquaculture. However, genetic degeneration, such as low growth rate, small body size, weak disease-resistance,etc., emerged in Chinese mitten crab with the rapid development of its farming scale. Microsatellite marker is a veryusefu1 and powerful molecular marker due to its highly polymorphism, stable and co-dominance and it was widely applicatedin researches of genetic diversity, kin discrimination, strain identification, genetic linkage map construction,trait-related marker screening, genetic evaluation, molecular taxonomy and so on. In this paper, Chinese mitten crabs ofthe Yangtze River strain were cultured in a 0.5 ha pond and 100 individuals were sampled at the same time in November.The growth traits of all individuals, including body weight, body width and body height, were measured separately. Theresults indicated that the growth traits were quantitative traits with the characteristic of continuous variation and compliedwith normal distribution according to the Kolmogorov-Smiromov normality test. Two extreme groups were chosenaccording to their body weight and used for primary screening of trait-related loci. The 15 individuals weighing morethan 155g were selected as “maximal group” and another 15 individuals weighing less than 69 g were selected as“minimal group”. Thirty microsatellite loci were used to analyse the differences between maximal and minimal groups.The results of Chi-Square test showed that 4 out of 30 loci showed significant variances of genotypes between groups.Loci ESIN33, ESC29 and ESC57 showed extremely significant difference in genotypes (P0.01) and locus ESC65showed significant difference in genotypes (P0.05) between “maximal group” and “minimal group”. The above fourmicrosatellite loci were applied in analysis of all 100 samples. Statistical analysis showed ESIN33, ESC29 and ESC57had an extremely significant impact on body weight, body width and body height (P0.01) while ESC65 had an extremelysignificant impact on body width and height (P0.01) and a significant impact on body weight (P0.05) accordingto General linear model (GLM) and Duncan Correlation analysis. The results of multi-comparison of differentgenotypes indicated that AC at locus ESIN33, DD at locus ESC29 and BB at locus ESC65 had a positive correlationwith body weight, body width and body height, and they were the most advantageous genotypes for growth traits(P0.05). Genotype DE at locus ESC29 had a negative correlation with body weight, body width and body height. Theresults also suggested that the growth traits should be determined by more than one loci which was conformed to thetheory on quantitative genetics. This work investigated the correlation between microsatellite markers and growth traitsin Chinese mitten crab and obtained trait-related microsatellite loci for the first time and the results would be valuablefor marker-assisted breeding in Chinese mitten crab.
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