| The genomes of two Salicaceae plants(willow or Salix sinopurpurea and poplar or Populus trichocarpa)have been sequenced and revealed a tetraploid ancestor.To understand more of their genome structure and evolution,here we selected grape genome as the reference.By revealing collinear genes between genomes and within a genome,the homologous gene pairs with colinearity are found out,and the homologous structure dot map with visual analysis function is constructed.In addition to the whole-genome triplication of dicotyledons,Salicaceae plants experienced a whole-genome duplication(SWD).Here,by revealing correspondence between Saliceae chromosomes,we deduced that there were eight ancestral chromosomes before the SWD.By searching and analyzing homologous fragments and comparing genomes of different species,we constructed a multi-genome alignment map with the grape genome as a reference.Moreover,we analyzed the genome evolution process of Salicaceae plants from the perspective of gene loss and retention.Also,we classified colinear genes associated with different events.By comparing the loss rate of colinear gene pairs,we find that the loss rate of colinear gene is higher,the number of colinear gene pairs is fewer and the Ks value is higher in willow than those in poplar.These data all suggest that willows undergo more genetic changes,showing that willow has evolved faster than poplar.We also deduced that the SWD to have occurred about 25-30 million years ago,and the speciation between poplar and willow occurred about 15-20 million years ago.What’s more,we compared and analyzed the two sets of subgenomes produced by SWD of poplar through gene expression,gene family and gene function GO enrichment analysis.We found that there was no significant difference in gene expression,gene family,and gene function between the two sets of subgenomes.The present analysis provided more evidence that the ancestral whole-genome duplication is caused by autotetraploidization.Figure 17;Table 4;Reference 52... |
