The trihelix transcription factor OsGT gamma-2 is involved adaption to salt stress in rice

摘要

Key message OsGT gamma-2, a trihelix transcription factor, is a positive regulator of rice responses to salt stress by regulating the expression of ion transporters. Salinity stress seriously restricts rice growth and yield. Trihelix transcription factors (GT factors) specifically bind to GT elements and play a diverse role in plant morphological development and responses to abiotic stresses. In our previous study, we found that the GT-1 element (GAAAAA) is a key element in the salinity-induced OsRAV2 promoter. Here, we identified a rice OsGT gamma family member, OsGT gamma-2, which directly interacted with the GT-1 element in the OsRAV2 promoter. OsGT gamma-2 specifically targeted the nucleus, was mainly expressed in roots, sheathes, stems and seeds, and was induced by salinity, osmotic and oxidative stresses and abscisic acid (ABA). The seed germination rate, seedling growth and survival rate under salinity stress was improved in OsGT gamma-2 overexpressing lines (P-ZmUbi::OsGT gamma-2). In contrast, CRISPR/Cas9-mediated OsGT gamma-2 knockout lines (osgt gamma-2) showed salt-hypersensitive phenotypes. In response to salt stress, different Na+ and K+ acclamation patterns were observed in P-ZmUbi::OsGT gamma-2 lines and osgt gamma-2 plants were observed. The molecular mechanism of OsGT gamma-2 in rice salt adaptation was also investigated. Several major genes responsible for ion transporting, such as the OsHKT2; 1, OsHKT1; 3 and OsNHX1 were transcriptionally regulated by OsGT gamma-2. A subsequent yeast one-hybrid assay and EMSA indicated that OsGT gamma-2 directly interacted with the promoters of OsHKT2; 1, OsNHX1 and OsHKT1; 3. Taken together, these results suggest that OsGT gamma-2 is an important positive regulator involved in rice responses to salt stress and suggest a potential role for OsGT gamma-2 in regulating salinity adaptation in rice.