| The cultivated soybean (Glycine max (L.) Merrill) belongs to the genus Glycine subgenus Soja inthe family Leguminosae subfamily Papilionatae. Soybean seeds contain about40%protein and20%fat,which makes it one of the most important crops for food, oil, stock feed and also industrial material, andtherefore widely grown in the globe. The subgenus Soja also includes another species, the annual wildsoybean (Glycine soja Sieb. et Zucc.), the wild progenitor of cultivated soybean. Soybean KunitzTrypsin Inhibitor (SKTI) is a kind of serine proteinase inhibitor in the seed storage protein of soybean,which can inhibit trypsin specifically. SKTI extensively exists in the cultivated and wild soybeans andhas many kinds of variants, and is often used as a genetic marker for studying the origin anddissemination of soybeans.In this study,10131Chinese soybean landrace accessions were identified for SKTI types and a setof representative sample of187soybean landraces was analyzed to assess the genetic diversity andrelationships of different SKTI type accessions using20nuclear SSR markers and5chloroplast SSRmarkers. The results were as follows:1. In the10131soybean landraces, a total of41Tib type accessions,2Tic type accessions and1Tidtype accession were identified. The frequencies of Tia, Tib, Tic and Tid alleles were99.57%,0.40%,0.02%and0.01%respectively. The Tib allele was detected in8provinces and the frequency distribution(from high to low) was shown: Gansu (21accessions,7.320%), Heilongjiang (5accessions,1.044%),Jilin (7accessions,0.906%), Yunnan (2accessions,0.680%), Liaoning (3accessions,0.441%), Fujian(1accession,0.386%), Shandong (1accession,0.344%) and Jiangsu (1accession,0.173%). The Ticallele was detected in two accessions from Dalian and Dandong, Liaoning Province. The only one Tidtype accession detected was from Wen county, Gansu Province.Through sequencing of SKTI genes,Tibi7type was first detected in Chinese cultivated soybeans. Because Tibi7had already been found inChinese wild soybeans, thus, this study undoubtedly confirmed that soybean domestication events hadonce occurred in China.2. At the nuclear DNA level, the genetic diversity of the Tib type accessions was lower than that ofthe Tia type, but the genetic diversity at the chloroplast DNA level was just opposite, suggesting the Tibtype accessions could have descended from more wild soybean ancestors in the domestication process.The cluster analysis showed that the Tib accessions from different regions tended to cluster togetherpreferentially, indicating a close relationship among those Tib accessions. The Tib type soybeanlandraces in Gansu Province were rich in diversity of chloroplast haplotypes, and were principallycomprised of type â…¡ and â…¢. The soybean landraces with chloroplast haplotype â…¡ in Gansu mightbe the main source of the soybeans with the same type from other provinces. Based on the fact that Tibtype soybean landraces in Gansu Province had a higher genetic diversity and a close relationship withthose from other provinces, Gansu Province might be a center of the origin for Tib type soybeans inChina.3. In the representative sample of187accessions, the soybean landraces from Huang-Huai region (especially the southeastern part of Gansu) had the highest level of genetic diversity, followed by SouthChina Region, while the Northeastern region was the least. As for the different eco-types, the HHSu(Huang-Huai Summer soybean) type had the highest genetic diversity at the nuclear DNA level, whilethe NSp (North Spring soybean) type had the highest diversity at the chloroplast DNA level. The clusteranalysis showed that different defined groups of soybeans were mainly clustered according to thegeographic differentiation, supplemented by the eco-type differentiation. At the chloroplast DNA level,the NESp (Northeast Spring soybean) type had a closer relationship with SSp (South Spring soybean)type; the SSu (South Summer soybean) type was closer to both the HHSu and NSp types. |
PDF Full Text Request