QTLs and epistasis underlying activity of acid phosphatase under phosphorus sufficient and deficient condition in rice (Oryza sativa L.)

Eighty-four selected lines from a recombinant inbred (RI) line population o f 284 lines derived from a cross between the indica varieties IR20 and IR55 178-3B-9-3 were used in a hydroponic culture experiment with sufficient P s upply (10 mg P L-1) and P-deficient stress (0.05 mg P L-1). After 2 weeks, the activity of acid phosphatase (AAP) in roots of each parent and each lin e from both normal culture and P-deficient stress was determined. QTLs for AAP, P-deficiency stress induced AAP (Psi-AAP) and relative AAP (RAAP) were detected using 178 molecular markers mapped on all 12 chromosomes based on single marker analysis and interval mapping. One QTL for AAP and three QTL s for Psi-AAP were detected on chromosome 1, 6 and 12, respectively. Two QT Ls for RAAP were identical with these for Psi-AAP on chromosome 6 and 12. T he results in this case indicated that the genetic system for Psi-AAP was d ifferent with that for AAP under normal culture. The AAP was mainly influen ced by interaction among muti-factors, while Psi-AAP was controlled by a Ps i genetic system.