QTL mapping for traits related to P-deficient tolerance using three related RIL populations in wheat

Phosphorus (P) deficiency is one of the major constraints to wheat production worldwide. In this study, conditional and unconditional quantitative trait locus (QTL) analyses for 12 traits of wheat seedlings under P-normal and P-deficient conditions were conducted using three F-9 recombinant inbred line (RIL) populations with a common female parent in wheat. Of the total 110 QTLs identified by unconditional QTL analysis, 29 were detected in multiple populations or under different P treatment, with 28 major QTLs. Notably, QRPU-4B on chromosome 4B in interval wPt-3608-wPt-667817 was detected in two populations and at two P levels, accounting for 44.08 % average value of phenotypic variance. Of 49 specific QTLs related to P-deficient tolerance detected by conditional QTL analysis, only nine were detected by unconditional QTL mapping under P-deficient condition, indicating that most QTLs directly concerned with P-deficient tolerance could be detected only by conditional QTL analysis. Eighteen important QTL clusters were mapped on 12 chromosomes 1D, 2A, 2B, 3A, 3B, 4B, 4D, 5A, 5D, 6A, 6B, and 7B, involving 85 QTLs that accounted for 53.4 % of total numbers of QTLs detected by unconditional and conditional mapping. Of these 18 QTL clusters, 14 were detected in multiple populations and 11 were detected by both unconditional and conditional analyses. Thus, these chromosome intervals were important areas controlling the expression of seedling traits related to P-deficient tolerance.