Abstract

Twenty-one Nigerian rice landraces were screened for tolerance to phosphate deficiency in nutrient medium using selected morphological indices from which Phosphate Deficiency Tolerance Index (PDTI) was evaluated. All landraces were analyzed for the presence of four phosphate uptake 1 (Pup-1) gene-linked markers while relative expression levels of two Pup-1 genes were evaluated in selected landraces under zero, normal and excess phosphate. PDTI analysis grouped the landraces into negative, low positive or high positive PDTI categories depending on whether performance at zero P was better than normal P, comparable to normal P, or less than normal P, respectively. However, irrespective of PDTI grouping, each landrace had at least one Pup-1 gene marker. Under zero P, Phillipine landrace showed no superior expression of OsPupK05-1 and OsPupK04-1 genes despite belonging to negative PDTI group. Thus, PDTI-based characterization of the landraces was not completely consonant with the presence or expression levels of the Pup-1 genes, suggesting a possible influence of other P deficiency tolerant genes. However, with a combination of negative PDTI, superior performance in root and shoot traits under zero P, and possession of at least 3 Pup 1 genes, Dantala Mass, Ankulyan, and Variety 44 may be regarded as P tolerant landraces.

Key words: Oryza sativa, phosphate deficiency tolerance index, RT-PCR, Pup genes.