The Fine Evolution Analysis Of Genome Structure And Function In Cucurbitaceae

Cucurbitaceae plants are of considerable biological and economic importance,and genomes of cucumber,watermelon,and melon have been sequenced.However,its genome structure and functional evolution need further study.This study has made a fine comparison of the genome structure of Cucurbitaceae plants based on statistics and comparative genomics and found that there was a common tetraploidy ancestor.Comparing the duplicated genes associated with different doubling events with the genomes of the cucurbit,a set of duplicated genes produced by different doubling events,and the direct homologous relationship between the genomes was obtained.A multi-genome homologous linear list associated with polyploidy is constructed.In addition,we analyze the loss of duplicated genes in different stages of species genome evolution and set up a comprehensive statistical decision algorithm.The nature of the doubling event in Cucurbit was identified.It is presumed that the total doubling of cucurbit may be a heterogenous polyploid event.A cascade algorithm of kernel density-gaussian mixture model is proposed in this paper.In order to redetermine the happened time of evolutionary events accurately and efficiently,it was inferred that the cucurbit-common tetraploidization occurred about 0.9-1.02 billion years ago.Watermelons were differentiated from the Cucurbitaceae about 22-25 million years ago.Melons and cucumbers were divided 14-16 million years ago.At the same time,the evolution law of important genes and gene families affected by polyploidy is analyzed,which revealed the variation of gene copy number after different gene doubling events.The results of this study will provide a wide and valuable resource for the structure and function related research for the cucurbit crop genome.The proposed comprehensive statistical decision algorithm and kernel density-gaussian mixture model cascade algorithm will become an important means to resolve the complex genome structure.This is of great significance to the study of cucurbit crops genome.It provides an important genomics support for expanding the genetic basis of the molecular biology of the Cucurbit germplasm innovation.