QTL Mapping of Phosphorus Deficiency Tolerance in Soybean(Glycine max L.) during Seedling Stage

Phosphorus(P) deficiency is a major abiotic stress that limits productivity of crops such as soybean throughout the world.In the present investigation,151 recombinant inbred line(RIL) families derived from a cross between Bogao and Nannong 94-156(low phosphorus tolerant germplasm) and their genetic maps were used to detect quantitative trait locus(QTL) associated with P deficiency tolerance by pot culture of soybean seedlings with two treatments of minus-P and plus-P.After six weeks of seeding,the relative total dry weight(RTDW),relative phosphorus uptake per plant(RPU),relative phosphorus use efficiency(RPUE),and relative root to shoot ratio(RR/S) were measured as indices for tolerance to phosphorus deficiency.The primary results showed that total dry weight under P-minus condition was determined by phosphorus uptake per plant,and no correlation between phosphorus use efficiency and total dry weight.Phosphorus uptake per plant was significantly and positively correlated with root dry weight and root efficiency(P uptake per unit weight of root),and 76.2% of variance of phosphorus uptake per plant came from root efficiency.Root/shoot ratio under P-minus condition was increased significantly because of no significant change of shoot dry weight and significant increase of root dry weight.Seven QTLs associated with phosphorus deficiency tolerance were detected and mapped on the linkage groups of D1b+W,F,G,N,and O.Each QTL explained 4.8%-17.0% of phenotypic variance,positive alleles of five QTLs among them were from female parent 'Bogao',and those of the other QTLs from male parent 'Nannong 94-156'.Three of seven QTLs were mapped!on linkage group G,among them one major QTL for RTDW explained more than 10% of the phenotypic variance was detected between sat-203 and sat-185 on LG-G by using CIM and MIM methods.