Identification Of Genus Megalobrama And Their F₁Generation Based On Morphology And Microsatellite Markers

The genus Megabobrama belongs to the subfamily Cultrinae of the family Cyprinidea, which is very economically important in the Chinese freshwater polyculture system. According to several latest studies which based on morphological data, the Megalobrama genus includes four valid species, M. amblycephala, M. pellegrini, M. terminalis and M. skolkovii. As the meat of these species is tender, juicy and very delicious, they are very popular with consumers and the breeding work is being started one step by step. In this study, we have done some researches on the morphological analysis of these four species based on single factor variance analysis and principal component analysis. We also development microsatellite makers using cross-species amplification method and some application practice have been done in the identification of self-bred progenies and hybrids of these four species. We hope our research could find identification method to F1progenies. Overall, all of these basic research works we have done will be useful in breeding and provide theortical reference for production of genus Megabobrama.1. The morphological analysis of genus MegabobramaTo investigate the difference among4species in genus Megalobrama,23morphometric characters and24meristic characters were measured from340wild individuals of the genus Megalobrama by using single factor variance analysis and principal component analysis. The result showed that significant differences (P<0.05) in the morphological characters(lateral line scales, caudal vertebrae and total vertebrae) and meristic characters (mouth width/head length、length of spine in ventral fin/head length、4-7/body length、6-8/body length、7-8/body length、the second swim bladder length/the first swim bladder length) among4species which can be used to distinguish the species among the genus Megalobrama. According to the principalcomponent analysis (PCA) of the morphometric characters (the meristic characters), three principal components were extracted and the related contribution ratios were32.43%(24.43%)、14.70%(11.34%) and10.06%(9.57%), respectively, with the cumulative contribution ratio of57.19%(45.34%). Scatterplots of scores of principle components show:four species of the genus Megalobrama forms4clusters, M. hoffmanni is clearly separated from M. amblycephala. The results also indicate that there are a greater change in meristic characters than in morphometric characters in the same species. So the morphometric characters may be choosen to distinguish the species.2. Cross-species amplification of microsatellites in genera MegalobramaOur research development microsatellite markers of genus Megalobrama using microsatellite markers of M. amblycephala based on cross-species amplification method. And the result shows high success rate of cross-species amplification(90.93%in M. pellegrini,93.75%in M. terminalisand96.88%in M. skolkovii.). At the same time,13microsatellite markers have been chosen for interspecific polymorphism analysis. The number of alleles ranged from1to12with an average of4.2. The average PIC values is0.60.The observed heterozygosity ranged from0.067to1.000, and the expected heterozygosity ranged from0.278to0.843, the PIC values for the microsatellite loci ranged from0.4407to0.6377.3. The application of microsatellite marker in genus Megalobrama F1progeniesAccording to the repeated units and amplification differences,12microsatellite markers of M. amblycephala and M. pellegrini were chosen to tested in genus Megalobrama F1progenies (selfing groups:M. amblycephala♀×M. amblycephala♂, M. terminalis♀×M. terminalis♂, M. pellegrini♀×M. pellegrini♂,M. skolkovii♀×M. skolkovii♂; hybrid groups:M. amblycephala♀×M. pellegrini♂,M. pellegrini♀×M. amblycephala♂,M. amblycephala♀×M. terminalis♂,M. terminalis♀×M. amblycephala♂, M. amblycephala♀×M. skolkovii♂, M. skolkovii♀×M. amblycephala♂). The result found that four microsatellite loci (Mam_EST46, TTF01, MP01, MP26) showed obvious difference in different Fi groups and these four micosatllite markers could identify these F1groups except for the self-breeding of the progeny of M. pellegrini and M. amblycephala♀×M. terminalis♂.