Molecular marker and phenotypic analyses for low phosphorus stress tolerance in cultivars and landraces of upland rice under irrigated and drought situations

Low available phosphorous (P) is a major problem for upland rice cultivation. Pup1, a major QTL responsible for efficient P uptake is very important for upland rice. The present investigation aimed to identify rice genotypes having Pup1 QTL, thereby showing better P use efficiency. Ninety six upland rice cultivars and landraces were screened of which 46.88% showed presence of the Pup1 QTL. Seventy six genotypes accounting for 79.17% of total population showed probable presence of PSTOL1 gene. The cluster analysis distinguished the irrigated, upland and aerobic genotypes forming different sub-branches. The genotypes Dinoroda, N22, Bowdel, Tepiboro, Bamawpyan, Karni, Lalsankari, Hazaridhan, Surjamukhi and Kalinga 3 being positive for all the molecular markers considered in the study formed a distinct branch in the tree. The phenotyping study also confirmed the usefulness of the Pup1 positive genotypes. The Pup1 positive genotypes showed better Puptake than the Pup1 negative genotypes. More P-uptake was observed in the genotypes Bowdel, Lalsankari, Karni, N22, Tepiboro, Dular and Surjamukhi as compared to Kasalath taken as the positive check. But the genotypes that showed promisingly/significant better uptake than Kasalath were Surjamukhi (irrigated P normal); Karni (irrigated P deficient); Lalsankari (drought P normal); Tepiboro, N22, Karni and Lalsankari (drought P deficient). A general correspondence of irrigated situation showed decreasing trend of P-uptake in P-deficient condition as compared to P-sufficient condition. The genotypes Surjamukhi, Karni, Lalsankari, Tepiboro, N22 and Bowdel can be considered as donors to be used in marker-assisted breeding programs for incorporation of Pup1 QTL into high yielding popular varieties to increase their phosphorus uptake efficiency.