MAPPING QTLS AND DETERMINING RELATIONSHIPS AMONG RESISTANCES TO MULTIPLE FOLIAR PATHOGENS OF MAIZE (Zea mays L.)
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Date
2014-12-12
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University of Agricultural Sciences GKVK, Bangalore
Abstract
Foliar diseases of Maize viz., northern corn leaf blight (NCLB), sorghum downy mildew (SDM) and southern corn rust (SCR) are the most persistent and destructive biotic constraints in India and worldwide. An investigation was carried out to unravel the genetics of resistance to NCLB and SCR through six generation mean analysis in two crosses of maize viz., CM212 × SKV50 and HKI162 × SKV50 during Kharif 2013 and to identify QTLs conferring resistance to foliar diseasesand co-localization of QTLs for resistance to three foliar diseases using194 polymorphic SNPs in 344 F2:3progenies derived from the cross CML153 (susceptible) × SKV50 (resistant)during Kharif 2012 and Kharif 2013 at Mandya.Generation mean analysis revealed significance of additive, dominance and additive × additive gene effects, duplicate gene interaction and partial dominance in the inheritance of NCLB and SCR in both the crosses.Using GMendel 2.0 linkage analysis computer program, 194 polymorphic markers were assigned to ten chromosomes of maizewith thresholdLOD of 3 spanning 2143.02cM with average distance interval length between markers of 10.77 cM.A total of nineteen QTLswere detected for resistance to NCLB, SDM and SCR using composite interval mapping. Two QTLs on chromosome bins 5.04-5.05 and 8.06 explained the total phenotypic variation of 26.58%for NCLB resistance; three QTLs on bin locations 3.04 and 8.06 collectively explained 44.13% variation for SDM resistance and a major QTL on bin location 10.03 with phenotypic variation of 18.59% was detectedfor SCR resistance. Significant pairwise association observed between NCLB, SDM and SCR indicated the presence of multiple disease resistant loci in the F2:3population studied. Co-localization of QTLs for resistance to three foliar diseases viz., NCLB (one QTL), SDM (two QTLs) and SCR (two QTLs) were located on bin location 8.03 with common adjacent marker MZA2487-6 which can be used to transfer multiple resistance alleles to susceptible lines through Marker Assisted Selection.
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