| Aflatoxin contamination in peanut(Arachis hypogaea L.) is an important factor affecting food safety and industry development. Breeding and planting peanut varieties with suitable resistance to aflatoxin is the most cost-effective approach for managing contamination. Hence, it is highly necessary to create novel peanut germplasm and develop Marker-Assisted Selection(MAS) techniques that could promote genetic improvement of aflatoxin resistance in this crop. In this study, recombinant inbred lines(RILs) derived from Zhonghua 10 and ICG 12625 with different levels in resistance to Aspergillus flavus were tested for their reaction to fungi infection and aflatoxin production by artificial inoculation. Inheritance of resistance to Aspergillus infection and to aflatoxin contamination in peanut has been studied. Meanwhile, a peanut genetic linkage map based on SSR has been constructed. QTL mapping has been implementated based on the constructed genetic linkage map analysis and resistance identification.1. The resistance components to A. flavus infection and aflatoxin production were quantitatively inherited. Obvious segregation of resistance was detected in the RILs and extra-heterosis was observed in some lines. Results of genetic analysis showed that the two resistance components were controlled by two major genes as well as polygenes with minor effectes. The correlation between the resistance to fungi invasion and resistance to aflatoxin production was not significant. One RIL line(QT401) with low infection index and 4 lines including QT344, QT389, QT477 and QT483 with low aflatoxin production were identified through resistance evaluation in the RILs.2. A peanut genetic linkage map covering 1261.93 cM with 20 linkage groups was constructed by using Joinmap 3.0. A total of 656 SSR loci were anchored on the map, and the length of 20 linkage groups varied from 29.96 cM to 106.87 cM. The number of markers of individual linkage group varied from 18 to 54, with an average genetic distance of 1.93 cM. Compared with the previously published single genetic maps for cultivated peanut by various reserachers, the map constructed in this study covered more loci, and the marker density was higher. Compared to the integrated map of Shirasawa(2013), the two genetic maps showed good colinearity relationship, hence it was regarded as a desirable genetic map with high density and accuracy.3. Composite interval mapping(CIM) was implemented by using WincartQTL 2.0 and 14 QTLs for resistance to invasion of A. flavus and 8 for resistance to aflatoxin production were identified, explaining 5.44% to12.35% phenotypic variation respectively. Three QTLs(qAFI-1-1, qAFI-9-3 and qAFI-14-2), with phenotypic variation more than 10.00% and LOD greater than 3, were regarded as main effect QTLs related to resistance to fungi invasion. The three QTLS, qAFQ-8-1, qAFQ-2-2 and qAFQ-15-2, were main effect QTLs related to resistance to aflatoxin production. Furthermore, three QTLs(qAFI-9-1, qAFI-9-2, and qAFI-9-3)related to resistance to fungi invasion were in an overlap section, explaining 11.45%, 9.90%, and 10.34% phenotypic variation respectively. In addition, a QTL related to resistance to aflatoxin production, qAFQ-17-1, was close to two molecular markers(pPGPseq16H08, pPGPseq2D12B) linked with resistance to A. flavus(Hong et al, 2009; Huang et al, 2012) indicating that it was a reliable QTL for the resistance. |
PDF Full Text Request