Enhanced tolerance to salinity stress and ABA is regulated by Oryza sativa STRESS ASSOCIATED PROTEIN 8 (OsSAP8)

Increased tolerance to multiple abiotic stresses in plants is a key target for food security.OsSAP8 is a member of the stress-associated protein (SAP) gene family in rice and is characterized by the presence of two zinc finger domains, A20 and AN1.In this research, we aim to understand the regulatory mechanism of OsSAP8 in response to multiple stresses for rice survival.We used the Arabidopsis transformation system to understand the gene's function.Two Arabidopsis lines were used; OsSAP8 overexpression line and Arabidopsis atsap2 knockout loss-of-function mutation in comparison to wild type Columbia-0 (Col-0).The protein sequence of Arabidopsis atsap2 has been shown to be highly identical to the OsSAP8.An atsap2 knockout showed a sensitive phenotype to high concentration of NaCl and PEG with reduced germination percentage.OsSAP8 overexpression showed a tolerance phenotype to 150 mM NaCl and 20% PEG compared to atsap2.OsSAP8 also showed an insensitive germination phenotype to high concentration of ABA compared to Col-0 and atsap2.The insensitive phenotype of OsSAP8 on the high concentration of ABA (12 µM) and the sensitive phenotype of its orthologue atsap2 in Arabidopsis suggests that OsSAP8 may have a role in part through ABA signaling as a putative transcriptional regulator for ABA during stress response.