| Distant hybridization generally refers to crosses between distant species in contrast to close hybridization between varieties of the same species or subspecies,provides a way to combine diverged genomes into one nucleus.Wide hybridization is an important driving force for the formation of new species and diversity,survival of offspring usually showed heterosis,so it has an important role in agricultural breeding.Hybrids contain two or more different genomes,usually accompanied by the occurrence of genome incompatibility and transcriptome shock phenomenon,which results in changes in genotypes and phenotypes of the progenies.The bisexual fertile allodiploid hybrid offspring lines group is obtained by using MegaJobrama amblycephala((?))× Erythroculter ilishaeformis((?)).The experiment is based on the whole genome of Megalobrama amblycephala and Erythroculter Ilishaeformis and their hybrid offsprings liver transcriptome sequencing data,to reveal the interaction between the two subgenomes of allodiploid offspring(F1,F2),causing the offsprings to show a hybrid advantage in fecundity and growth.1.We have selected 10 genes from blunt snout bream(BSB)and Topmouth red culter(TC)genome database—Apob、Asxl、Ccr4、EIF2、Foxa、Hnrpn、Igfals、noct、Nrld、Slc43a;and Selected 4 genes form metabolism related genes which selected from transcriptome sequencing of the database—Dhcr7、Idi1、G6pc、GPat.The partial DNA sequence of the chimeric gene and the partial cDNA sequence of metabolism related genes were gained by cloning technology,We analyzed the recombination of parents(BSB,TC)and hybrids(F1,F2)at the level of genomic and transcriptome.In this study,we investigated the genetic structure changes caused by the genomic incompatibility associated with distant hybridization from the aspects of length comparison of clonal sequences,similarity and recombination signal analysis,inheritance or mutation of SNPs loci,and phylogenetic relationships of four fishes.The results showed that at the genomic level,8(Apob,Asxl,Foxa,Hnrpn,Igfals,Noct,Nrld,Slc43a)(80%)of the 10 genes were found to have recombination at the genomic level,and 2(Ccr4,ElF2)(20%)of the chimeric genes were not reorganized.There were a total of 296 hybrid progeny sequences,of which 214(72.2%)were reconstructed and 82(27.7%)without recombination signals;At the transcriptome level,4(100%)metabolic genes were found recombined in the progeny.There were a total of 104 hybrid progeny sequences,of which 69(66.3%)were reconstructed and 35(33.7%)without recombination signals;.The type of progeny sequence had the paternal-biased type、the maternal-biased type、the parents-biased alternate type、progeny-variations type.This suggests that recombination is a common phenomenon in distant hybrid lines,and genomics leads to changes in genomic structure that provide a molecular basis for species genetic evolution and diversity.2.Based on the sequencing of transcriptome,the expression characteristics of the metabolic genes in cyprinidae lines were studied,and the differences between the progeny and the parents were compared.From the hot map of 145 metabolic genes,There may be significant differences in the expression level of different species of fish in the same metabolism;Some genes are not only associated with a metabolic pathway.The result of non-additive gene analysis showed that more than 60%of hybrids genes were nonadditively expressed genes.Only less than 30%of the differential expressed genes in Fi and F2 showed expression additivity.In addition,From hybrid Fi to F2,the amount of nonadditively expressed genes increased.We also analyzed the expression characteristics of Dhcrl,Idil,G6pc and GPat genes in cyprinidae lines by RT-PCR,the results showed that Dhcr7 and Idil genes showed the parental expression level dominance,while G6pc was the typical ELD-BSB expression pattem.All the results showed that transcriptome shock in distant hybridization could cause changes of expression leve,so that the metabolic function of hybrids shows a hybridization advantage. |
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