Comparative Genomics Study On The Evolution Of Different Ploidy Genomes In Peanut

Peanut(Arachis hypogaea L.)is the important oil crops in the legume.Several peanuts have been sequenced,which provides a data base for understanding the structural variation and evolution of peanut from the molecular level.Through comparative genomics analyses of eight peanuts,progress had been made in the evolution of peanut genome structure,illegitimate recombination,and representative important functional genes:(1)We identified chromosomal rearrangement events occurred during the evolution of different ploidy peanuts,and found the frequency of events occurring in diploid wild species AA genomes higher than BB,and the rearrangement in tetraploid peanut originated from diploid peanut,providing a new perspective inferring the origin of tetraploid peanut.(2)We constructed a table of homologous genes related to polyploidy and species divergence in peanut,it was found that chromosomal rearrangements may affect gene loss and evolution,higher gene loss rates and evolutionary rates in the BB genome than AA.(3)We identified the scale and patterns of gene conversion between duplicated genes generated by LCT and PRT in peanut,gene conversion accelerated differences in the peanut.Distribution of genes on chromosomes(physical location,length of the duplicated region),and gene family size were important factors affecting the frequency of conversion.(4)NBS-LRR disease resistance and HSP70 genes were identified in different ploidy peanuts.Artificial selection might contribute to higher number of disease resistance genes in cultivars peanut than wild.For 48.21%～79.42% of NBS-LRR genes distributed on gene clusters,chromosome inversion might disrupt the gene clusters.Tandem duplications might be an important reason for HSP70 family expansion.This research can deepen the understanding of structural evolution and illegitimate recombination between homologous chromosome after polyploidy in peanut,and provide a comparative genomic basis for the study of peanut resistance genes,which are important for the sustainable development of peanut industry.Figure 22;Table 16;Reference 96...