Phosphorus Starvation Tolerance in Rice Through Combined Physiological, Biochemical, and Proteome Analyses
V. Prathap, Suresh Kumar, Nand Lal Meena, Chirag Maheshwari, Monika Dalal, Aruna Tyagi
Abstract
Phosphorus (P) deficiency limits the growth, development and productivity of rice. To better understand the underlying mechanisms in P-deficiency tolerance and the role of Pup1 QTL in enhancing P use efficiency (PUE) for the development of P-efficient rice cultivars, a pair of contrasting rice genotypes (Pusa-44 and NIL-23) was used to investigate the morpho-physio-biochemical and proteomic changes under P-starvation stress. The rice genotypes were grown hydroponically in a PusaRich medium with adequate P (16 mg/kg, +P) or without P (0 mg/kg, -P) for 30 d. P-starvation manifested a significant reductions in root and shoot biomass, shoot length, leaf area, total chlorophyll, and phosphorus, nitrogen and starch contents as well as protein kinase activity. The stress increased root-to-shoot biomass ratio, root length, sucrose content and acid phosphatase activity, particularly in the tolerant genotype (NIL-23). Comparative proteome analysis revealed several P metabolism-associated proteins (including OsCDPKs, OsMAPKs, OsCPKs, OsLecRK2 and OsSAPks) to be expressed in shoot of NIL-23, indicating that multiple protein kinases were involved in P-starvation/deficiency tolerance. Moreover, the up-regulated expression of OsrbcL, OsABCG32, OsSUS5, OsPolI-like B and ClpC2 proteins in the shoot, and OsACA9, OsACA8, OsSPS2F, OsPP2C15 and OsBiP3 in the root of NIL-23 indicated their role in P-starvation stress control through Pup1 QTL. Thus, our findings indicated that -P stress-responsive proteins, in conjugation with morpho-physio-biochemical modulations, improve PUE and make NIL-23 a P-deficiency tolerant genotype due to the introgression of Pup1 QTL in Pusa-44 background.