Expression of predicted salt tolerant gene in rice Oryza sativa l. And characterization of OsBTBZ1 gene

Abstract

Rice (Oryza sativa L.) holds significant importance as a primary food source globally. In Asia, the production of rice plays a crucial role in enhancing food security. Salinity poses a substantial constraint on plants like rice, leading to a reduction in their growth and overall productivity. The advancement of transcriptomics in agriculture has provided a powerful tool for understanding the molecular processes in crops, contributing to the development of more resilient, productive, and sustainable agricultural systems. The transcriptomic approach in rice using two rice lines with close genetic relationships, but different salt tolerance ability, CSSL16 and KDML105 combined with single nucleotide polymorphism (SNP) gives the new insight in identifying the salt-tolerant genes and produces 9 candidates genes. LOC_Os01g64870, OsBTBZ1, OsERD4, LOC_01g73110, and OsSub34 consistently showing the increment trend of gene expression in both early (0 – 48 h after stress) and late (0 – 9 d after stress) response during salt stress.

OsBTBZ1 was chosen to validate its involvement in salt tolerance through the creation of revertant lines, REV1 and REV2, in the Atbt3 Arabidopsis mutant. Additionally, overexpressed lines, OE1 and OE2, were generated in the wildtype lines to investigate the impact of elevated OsBTBZ1 expression on salt tolerance. The phenotyping under salt stress (150 mM NaCl), ABA 1 µM, and mannitol 150 mM were conducted. The germination, root length, fresh weight, Chl a, Chl b and carotenoid contents were chosen to describe the function of OsBTBZ1. Under salt and ABA treatment, the Atbt3 mutant exhibits the highest reduction in all examined parameters, which were counteracted by OsBTBZ1 expression. In addition, the exposure in mannitol resulted a comparable decrease in weight, root length, and photosynthetic pigment content across all tested lines. Furthermore, the expression of OsBTBZ1 in both the WT and Atbt3 mutant backgrounds demonstrated enhanced tolerance to abiotic stress, specifically under salt and ABA stress condition. Based on these data, OsBTBZ1 is more responsible for the tolerance in salt stress rather than osmotic stress. The observed restoration of phenotypes in the mutant line upon introducing OsBTBZ1 expression also occurred under ABA treatment, pointing to the involvement of the ABA-dependent pathway in OsBTBZ1 function.