Tolerance of Oryza sativa to low phosphate is associated with adaptive changes in root architecture and metabolic exudates

Abstract

The optimum usage of fertilizers is key for the sustainable agriculture. Among nutrients, phosphorus (P) is critical for plant growth and development. Due to complete reliance on natural resources (rock phosphate) for P, the availability of P fertilizers is emerging as a global challenge for crop cultivation. Moreover, the excess application of P fertilizers in rice, mostly grown under flooded conditions, leads to water pollution called eutrophication. In this study, we employed a mutagenesis approach for developing and characterizing rice EMS (ethyl methanesulfonate) mutants with better adaptation to low soil P conditions. One such mutant of rice cultivar Nagina 22, named NH4824, was characterized comprehensively at seedling and reproductive growth stages under hydroponic and field conditions. The mutant exhibits low soil P tolerance due to combined adaptive changes in root system architecture, anatomy, organic acid exudates, plasma membrane (PM) H⁺-ATPase activity, induced expression of P transporter genes, and efficient mobilization and partitioning of P in different plant tissues. The activity of antioxidant enzymes and better photosynthesis suggested relatively less stress experienced by NH4824 than N22 under low soil P conditions. These insights are highly useful to develop P use efficient crop cultivars through breeding or genome editing approaches.