利用 Lea 第四群基因族探討大豆屬物種之親緣系統及分子演化關係

Abstract

Taiwan is the southernmost region of the distribution for annual wild soybean species and the northernmost region of the distribution of the perennial ones. In this study, we used GmPM16 and GmPM28 gene families, which belong to the fourth group of late embryogenesis abundant (LEA) proteins of soybean, as the genetic markers to assess the molecular relationships of the genus Glycine. We surveyed sequence variations in the cultivated soybean, wild soybean, and thirteen accessions of the perennial soybean relatives. The PCR primers were designed based on the soybean cDNA sequences. We examined the phylogenetic relationships by total sequences, introns and open reading frame (ORF) using the neighbor-joining and minimum spanning network methods. In the present study, SDS-PAGE analysis of the seed proteins from many Glycine species suggested that each species had unique protein profiles that varied in the total number of bands and their relative motilities. However, the results of western blot with GmPM16 and GmPM28 antibodies indicated no significant difference among them. According to total sequences of the 2 soybean seed gene families, the genetic diversities were higher in the perennial soybean relative accessions than those of the annual soybeans. The value of Ks/Ka also suggested the evolutionary forces of these two gene families were deviated from the neutrality hypothesis. Furthermore, the species, based on the sequences of those two gene families, were with lowerπ(nucleotide diversity) values and higher Hd (haplotype diversity) values. The results suggested that these populations were expanded after a period of low effective population size; rapid population growth enhanved the retention of new mutations. The evolutionary relationship among the entries was inconsistent as indicated in phylogenetic trees and minimum spanning network, which were constructed based on total sequences, introns, or ORFs. This indicated that the two gene families had their unique coalescence time scale in the phylogenetic trees. On the basis of clustering results, we proposed that the genome of tom039 collected in eastern Taiwan has a close relationship to the Australian-originated genomes DDD3D3, AAB’B’, and AA.