A Lobularia maritima LmSAP protein modulates gibberellic acid homeostasis via its A20 domain under abiotic stress conditions.

ABSTRACT: Stress-associated proteins (SAPs) are favorable targets to improve stress tolerance in plants, owing to their roles in developmental processes and stress responses. However, the role of SAPs and the molecular mechanisms by which they regulate plant stress responses remain poorly understood. Previously, it was reported that LmSAP expression was upregulated by various abiotic stressors in Lobularia maritima, and that transgenic tobacco lines with constitutively expressed LmSAP?A20 and LmSAP?A20-?AN1 showed dwarf phenotypes due to the deficiency of cell elongation under salt and osmotic stresses. In this study, we examined the function of A20 domain in the GA pathway in response to abiotic stresses. Transient expression of acGFP-LmSAP?A20 and acGFP-LmSAP?A20-?AN1 in onion epidermal cells demonstrated that these fused proteins were localized in the nucleo-cytoplasm. However, the truncated form acGFP-LmSAP?AN1 was localized in the nucleus. Moreover, comparison of native and truncated LmSAP showed dramatic structural changes caused by the deletion of the A20 domain, leading to loss of function and localization. Interestingly, overexpression LmSAP and truncated LmSAP?AN1 led to up-regulation of GA biosynthetic genes and increased total gibberellins (GAs) content, corresponding with accelerated development in transgenic tobacco plants. Moreover, the dwarf phenotype of the transgenic lines that express LmSAP?A20 and LmSAP?A20-?AN1 under stress conditions was fully restored by the application of exogenous GA3. These findings improve our understanding of the role of LmSAP in regulating GA homeostasis, which is important for regulating plant development under abiotic stress conditions.

SUBMITTER: Ben Saad R 

PROVIDER: S-EPMC7237032 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature