Comparative physiological and transcriptomic characterization of rice (Oryza Sativa L.) root seedlings under phosphorus deficiency

Phosphorus (P) is essential for optimal growth, development, and metabolic functioning in rice. In this research study, we compared the physiologies and transcriptomes of root seedlings of two rice varieties, upland rice (LH1) and lowland rice (IR26), under the treatments of normal P application (NP: 300 mu M) and low P application (LP: 10 mu M). The results demonstrated that the plant biomass of LH1 and IR26 was reduced by 10.0% and 27.8% in the LP treatment compared to the NP treatment (control), respectively. The P deficiency substantially affected the enzymatic activities in the roots of LH1 and IR26, which are vital for carbon and energy metabolism. Transcriptomic results identified 24,193 genes in all samples, and over 5000 differentially expressed genes (DEGs) were identified in both varieties under LP compared with their controls. KEGG analysis showed the functional categories for DEGs, which mainly included phenylpropanoid biosynthesis, glutathione metabolism, plant hormone signal transduction, photosynthesis, and carbon fixation in photosynthetic organisms. The DEGs involved in the glutathione metabolism, carbon fixation, and photosynthesis in photosynthetic pathways were downregulated by P deficiency. The DEGs involved in the metabolism of plant hormone signal transduction and carbohydrate transition for LH1 and IR26 exhibited different defense responses to the P deficiency in upland and lowland rice. The genes engaged in plant hormone signal transduction and carbohydrate fixation are anticipated to play key roles in improving the upland and lowland rice adaptation to P-deficient conditions. The results of this investigation have established a theoretical basis for strengthening our insight into the P tolerance mechanism in lowland and upland rice.