Effect of Singlet Oxygen on the Stomatal and Cell Wall of Rice Seedling Under Different Stresses.

Singlet oxygen (O), a reactive oxygen species, can oxidize lipids, proteins, and DNA at high concentrations, leading to cell death. Despite its extremely short half-life (10 s), O acts as a critical signaling molecule, triggering a retrograde pathway from chloroplasts to the nucleus to regulate nuclear gene expression. In this study, rice seeds were treated with 0, 5, 20 and 80 μM Rose Bengal (RB, a photosensitizer) under moderate light for 3 days to induce O generation. Treatment with 20 μM RB reduced stomatal density by approximately 25% in three-leaf-stage rice seedlings, while increasing the contents of pectin, hemicellulose, and cellulose in root cell walls by 30-40%. Under drought, salinity, or shading stress, 20 μM RB treatment significantly improved rice tolerance, as evidenced by higher relative water contents (49-58%) and chlorophyll contents (60-76%) and lower malondialdehyde (37-43%) and electrolyte leakage (29-37%) compared to the control. Moreover, RT-qPCR analysis revealed that the significant up-regulation of stomatal development genes ( and ) and cell wall biosynthesis genes ( and ) was associated with RB-induced O production. Thus, under controlled environmental conditions, O may regulate stomatal development and cell wall remodeling to enhance rice tolerance to multiple abiotic stresses. These results provide new perspectives for the improvement of rice stress tolerance.