MOLECULAR CHARACTERIZATION OF SELECTED RICE GENOTYPES FOR THE MAJOR QTL PHOSPHORUS UPTAKE ONE (PUP1)

Abstract

Marker-assisted breeding is a very useful instrument for breeders but still needs much research work because information on the effect of quantitative trait loci (QTLs) in different genetic backgrounds is uncertain and ideal molecular markers are unavailable. Therefore, some research efforts toward the investigation and validation of the major rice QTL Phosphate uptake 1 (Pup1) that confers tolerance of phosphorus (P) deficiency in rice (Oryza sativa L.) have been made throughout assessing the effect of the presence of the Pup1 allele on growth parameters of selected genotypes. Six markers were selected that target firstly putative genes that are partially conserved in the Nipponbare reference genome and secondly Kasalath-specific genes that are located in a large insertion-deletion (INDEL) region that is absent in Nipponbare. Testing these markers in 30 diverse rice genotypes showed that those genotypes possess Kasalath alleles at all analysed loci, apart from Kasalath, were Azucena, Black Gora, FR 13A, IAC 165 and IAC 25. Genotypes that partially possessed Kasalath alleles were only three (Dular, Li-Jiang-Xin-Tuan-Hei-Gu and M 202) while the other genotypes lacked Kasalath alleles at all loci analysed. These contrasting Pup1 genotypes were subsequently grown in two different P-deficient soils and environments. Whether P applied in liquid form as Yoshida’s nutrient solution (YNS) or solid form as rock phosphate added either homogenously or in 10 cm shallow layer, genotypes with the Kasalath alleles in Pup1 locus maintained significantly higher shoot dry weight (SDW) plant-1 under P deprivation in comparison with intolerant genotypes with the Nipponbare alleles in this locus. Overall, the data provide evidence that Pup1 has the potential to improve SDW in P-deficient conditions and in diverse genetic backgrounds.