Tagging, mapping and identification of the QTLs associated with phosphorous utilization for phosphorous- limiting soils in tropical maize

Abstract

Phosphorus (P) deficiency is one of the major abiotic constraints leading to low maize productivity. Twenty- four SSR markers sequence information was obtained from maize databases (MaizeGDB). These SSRs were selected from targeted regions of the maize genome linked to Quantitative Trait Loci (QTLs) for Phosphorus utilization efficiency. The mapping population consisting 67 F 2 maize plants, were obtained from advancing a bi- parental cross between an efficient line (L354) and an in-efficient maize line (L585). Out of 24 SSRs five identified polymorphic SSR markers were subsequently used for genotyping the 67 tagged F 2 plants. Sixty seven F 2:3 maize families were used for QTL localization. Inclusive composite interval mapping (ICIM) analysis identified seven QTLs associated with phosphorus utilization on chromosome 5. All the mapped QTLs were more than 5 cM from the nearest molecular marker utilized in the study. The closest mapped QTL, PeSB-5, 7 associated with shoot biomass was at 11.7 cM, from the nearest marker umc2136 on chromosome 5. Therefore, there is need to saturate the map which may prove useful to identify and test several markers near the mapped QTLs. The identified markers could serve as potential SSR markers for QTLs associated with phosphorous utilization for phosphorous- limiting soils in tropical maize.