Abstract:

Globular stink bug [Megacota cribraria (Fabricius)] is one of the important pests for soybean [Glycine max (L.) Merr.] in the central and southern China. However, very few reports on soybean resistant to M. cribraria were found in the literature. The objectives of the present study were to find QTLs associated with resistance to M. cribraria in soybean and to analyze the stability of mapped QTLs among years by using two RIL populations, NJRIKY (or KY) and NJRIWT (or WT) derived from the crosses of Kefeng 1 × Nannong 1138-2 and Wan 82-178 × Tongshanbopihuangdoujia, respectively. The 184 lines of KY and 142 lines of WT were tested and the percentage of black mildew on stem and purple spots on leaves was used as indicator to evaluate their resistance to M. cribraria under natural infestation during 2004–2006. There existed significant differences among lines in the two RIL populations during the three years, with heritability of 66.5%–88.8% in KY and 61.3%–84.8% in WT. The composite interval mapping (CIM) of the software Windows QTL Cartographer Version 2.5 was used to map QTLs. The linkage group D1a and C2 in KY and the linkage group H and D1b in WT were found to be related with resistance to L. indicata. The QTL qRMC-d1a-1 on Linkage group D1a was detected consistently associated with reaction to M. cribraria in KY during the three years, which accounted for 7.6%–31.4% of phenotypic variation; the QTL qRMC-c2-1 on linkage group C2 was detected in 2005–2006, which accounted for less phenotypic variation than the former one; the resistance alleles were from Nannong 1138-2. There appeared significant interactions between qRMC-d1a-1 and qRMC-h-1 in KY in 2005 and 2006. The QTL qRMC-h-1 on linkage group H was detected also consistently associated with reaction to M. cribraria in WT during the three years, which accounted for 16.3%–36.2% of phenotypic variation; the QTL qRMC-d1b-2 on linkage group D1b was detected in 2004-2005, which accounted for less phenotypic variation than the former one; the resistant alleles were from Tongshanbopihuangdoujia. Therefore, different QTLs conferred resistance to M. cribraria in KY and WT basically although the two QTLs in the latter population were also identified in one year in the former population. The fact that the QTLs were repeatedly detected in different environments indicated the resistance was controlled stably by the main QTLs. Based on the results, it is inferred that the markers linked to the detected QTLs should be useful for marker-assisted selection for resistance to M. cribraria in soybean.

Key words: Soybean [Glycine max (L.) Merr, Globular stink bug [Megacota cribraria (Fabricius)], Resistance to insects, QTL Mapping