Genetic dissection of QTL against phosphate deficiency in the hybrid rice ‘Xieyou9308’

Phosphate (Pi) plays important roles in plant development and architecture. With the goal of identifying genomic regions that influence tolerance to Pi deficiency (TPDE) in hybrid rice (Oryza sativa L.), quantitative trait loci (QTL) were mapped using recombinant inbred lines (RILs) that were derived from a cross between tolerant ‘XieqingzaoB’ (XB) and susceptible ‘Zhonghui9308’. Six TPDE-related traits, including the root length, root dry weight, tillers number, shoot dry weight, total plant dry weight and root-to-shoot ratio, were evaluated for QTL analysis during both the tillering and heading stages. A correlation analysis showed that most of the traits were correlated with each other. Twenty-one additive QTL were detected and jointly explained between 10–49% of the trait variance, tending to cluster on chromosomes 4, 6, 10 and 11. Three QTL, qTPDE4 XB , qTPDE10 XB and qTPDE11.3 XB , were validated by the phenotypic evaluation using near isogenic lines (NILs, BC4F3) during the seedling stage. qTPDE4 XB showed the most stable tolerance against Pi deficiency. These QTL will enrich the genetic resources and accelerate hybrid rice breeding against Pi deficiency.