#100-102 The SALT HYPERSENSITIVE MUTANT 2 plays a negative role in ABA biosynthesis in Arabidopsis

Abscisic acid (ABA) plays a pivotal role in regulating plant growth and response to abiotic stress. However, the regulation of ABA biosynthesis, particularly negative regulators, largely remains unknown. In this study, we genetically isolated Arabidopsis salt hypersensitive mutant 2 (sahy2), which exhibits post-germination developmental arrest under normal and salt stress. Through map-based cloning, we have confirmed that SAHY2corresponds to At1G28100, which has been assumed to be involved in neoxanthin biosynthesis. Nevertheless, the late germination phenotype of sahy2 can be rescued by exogenous application of ABA biosynthesis inhibitor fluridone, reflecting that the germination delay of sahy2 might be due to the higher ABA content than the wild-type. Supporting evidence indicates that the sahy2 mutants and SAHY2 over-expressors confer drought and salt tolerance and sensitivity, respectively. It is noteworthy that the SAHY2 protein is more stable and localizes at the cytoplasm and peroxisome under salt stress. Taken together, our study sheds light on the negative role of SAHY2 in ABA biosynthesis and its influence on plant growth and development during salt stress.

Keywords: salt stress, drought stress, negative regulator, abscisic acid (ABA) biosynthesis, Arabidopsis thaliana.