Mapping Quantitative Trait Loci and Domestication Analysis for Seed Size and Shape Traits in Soybean (Glycine Maxl.Merr.)
|School||Nanjing Agricultural College|
|Keywords||soybean yield seed size seed shape QTL multi-QTL joint analysis domestication|
Seed size and shape traits in soybean are playing a critical role in breeding because these traits are closely related to both seed yield and appearance quality. Especially, the size and shape traits have a significant change in the process of soybean domestication from wild soybean to cultivated soybean and the related genetic study could enhance our understanding to the domestication mechanism.The purpose of this study is to dissect the genetic mechanism of seed size and shape traits and to investigate the patterns of the above traits in soybean domestication process. To perform the first objective of this study, an attempt was made to detect quantitative trait loci (QTL) for the size and shape traits (seed length, width, thickness, length-to-width, length-to-thickness, width-to-thickness and 100-seed weight) in F2:3, F2:4 and F2:5 populations from the direct and reciprocal crosses of Lishuizhongzihuangdou with Nannong 493-1, using multi-QTL joint analysis (MJA) and composite interval mapping (CIM). To make clear the second objective of this study, the aforementioned segregation populations and three kinds of cultivar populations in soybean domestication process that consist of wild soybean, cultivated landrace and released cultivar, respectively, were used to investigate the patterns of the above traits in soybean domestication process, using partial correlation analysis and factor analysis. The main results are as follows:1. A total of 157 main-effect QTL (M-QTL),6 cytoplasmic effects and 103 cytoplasm-by-QTL interactions,7 environmental effects and 12 environment-by-QTL interactions were detected by the MJA while eighty-two M-QTL were detected by CIM. Sixty-three common M-QTL across MJA and CIM,24 common M-QTL in more than two populations,5 stable M-QTL (qSW-6-1、qSLW-10-2、qSLW-13-1、qSLW-17-5 and qSWT-20-1) in all three populations showed the stability of the results, and 5 M-QTL (qSL-14-1、qSW-14-2、qST-5-2、qSLW-10-2 and qSWT-3-2) had higher heritability, greater than 20%. In addition,34 cytoplasm-by-QTL in the MJA were confirmed by CIM, qSL-10-3、qSLW-10-2 and qSLW-X3 were detected simultaneously in the direct and reciprocal crosses but had different effects and heritabilities and the others were detected only in the direct or reciprocal cross.4 environment-by-QTL interactions identified by the MJA were confirmed by CIM, but the four QTL were all mapped only in one environment.All the common M-QTL between the above two approaches were placed on 16 chromosomes. Note that half of the common M-QTL was clustered in eight marker intervals in 7 chromosomes and three or more than three M-QTL were identified in each of the eight marker intervals. This may explain the phenotypic correlation between the above traits.2. In the study of soybean domestication mechanism, we adopted two kinds of analyses. One is to detect QTL for seed size and shape traits in the aforementioned segregating populations and the other is to carry out partial correlation analysis and factor analysis in four kinds of populations, i.e., wild soybean, cultivated landrace, released landrace and the segregating populations. Results from the above two analyses showed that 100-seed weight is highly correlated with seed size traits but not with seed shape traits, and 100-seed weight and seed length-to-width ratio are the representative traits for seed size and shape traits in soybean domestication process, respectively.