Physio-biochemical and molecular characterization of a rice drought-insensitive TILLING line 1 (ditl1) mutant

Drought stress is a major abiotic stress that limits rice yield. Therefore, the development of new varieties tolerant to drought stress is a high priority in breeding programs. In this study, 150 rice M-10 mutant lines, previously developed using gamma-ray irradiation, were used, and a drought-insensitive rice mutant (ditl1) was selected by drought stress screening. The ditl1 mutant exhibited significantly decreased water loss, leaf curling, and H2O2 accumulation under drought stress. Chlorophyll leaching assay and toluidine blue staining suggested lower cuticle permeability in ditl1 mutants than in wild-type (WT) plants. In addition, transmission electron microscopy revealed that ditl1 plants accumulated more cuticular wax on the epidermal surface. Whole-genome resequencing analysis suggested that the deletion of a single nucleotide on the LOC_Os05g48260 gene, a putative ortholog of WSD1 (wax ester synthase/diacylglycerol O-acyltransferase in Arabidopsis), maybe be the gene responsible for the drought insensitive phenotype of ditl1. The ditl1 mutant will be a valuable breeding resource for developing drought stress tolerant rice cultivar.

Automated summary

This study identified a drought-insensitive rice mutant through screening, which exhibited reduced water loss and leaf curling under drought stress, indicating good drought tolerance. The mutant also accumulated more cuticular wax on the surface, potentially contributing to enhanced drought resistance in rice.