Differential response of rice plants to low-phosphorus stress and its physiological adaptive mechanism

Two rice genotypes, JX17 (Oryza sativa ssp. japonica) and ZYQ8 (Oryza sativa ssp. indica), which had been the parents of the 127-line double haploid (DH) population for construction of molecular linkage map, were chosen to study their response to low phosphorus (P) stress. The results indicated that JX17 had advantages over ZYQ8 on some traits associated with phosphorus uptake efficiency, such as root dry weight, root-exuded acid phosphatase activity, root-exuded organic acids and proton. Consequently, JX17 had higher relative total dry weight and was regarded as the non-sensitive genotype to low phosphorus stress. Physiological response of the two genotypes to P deficiency was studied in monoculture and in mixed culture. The results showed that, compared with monoculture, JX17 absorbed more P and had higher biomass in mixed culture condition under P stress. ZYQ8, by contrast, suffered from P stress to a much greater extent, with lower P uptake and biomass. JX17 had a higher P uptake rate expressed as P amount per root length which is suggested to be the main reason for its insensitivity to low P stress.