Vegetative cell wall protein OsGP1 regulates cell wall mediated soda saline-alkali stress in rice.

Plant growth and development are inhibited by the high levels of ions and pH due to soda saline-alkali soil, and the cell wall serves as a crucial barrier against external stresses in plant cells. Proteins in the cell wall play important roles in plant cell growth, morphogenesis, pathogen infection and environmental response. In the current study, the full-length coding sequence of the vegetative cell wall protein gene OsGP1 was characterized from Lj11 (Oryza sativa longjing11), it contained 660 bp nucleotides encoding 219 amino acids. Protein-protein interaction network analysis revealed possible interaction between CESA1, TUBB8, and OsJ_01535 proteins, which are related to plant growth and cell wall synthesis. OsGP1 was found to be localized in the cell membrane and cell wall. Furthermore, overexpression of OsGP1 leads to increase in plant height and fresh weight, showing enhanced resistance to saline-alkali stress. The ROS (reactive oxygen species) scavengers were regulated by OsGP1 protein, peroxidase and superoxide dismutase activities were significantly higher, while malondialdehyde was lower in the overexpression line under stress. These results suggest that OsGP1 improves saline-alkali stress tolerance of rice possibly through cell wall-mediated intracellular environmental homeostasis.

OsSAP6 Positively Regulates Soda Saline-Alkaline Stress Tolerance in Rice.

BACKGROUND: Soil salinization is a worldwide environmental problem, especially in the arid and semiarid regions of northeastern China, which are heavily affected by soda saline-alkaline stress. At present, there is an urgent need to improve the soda saline-alkaline stress tolerance of rice. RESULTS: Stress-associated proteins are involved in regulating the abiotic stresses in plants. There are 18 members of the rice stress-associated protein (OsSAP) gene family. In this study, the expression levels of OsSAP6 in leaves and roots were upregulated with increasing NaHCO3 stress duration. OsSAP6 was located in nucleus and cytoplasm. The bud length and total root length of OsSAP6 overexpression rice were significantly longer than those of Lj11 (Oryza sativa longjing11) during germination stage, and the survival rates, plant height and malondialdehyde content at the seedling stage showed tolerance growth of saline-alkaline stress. The expression of OsCu/Zn-SOD, OsAPX2, and OsCAT1 in transgenic lines was increased significantly under SAE (soda saline-alkali soil eluent) stress. OsSAP6 interacts with OsPK5 according to yeast two-hybrid screening and luciferase complementation experiments. The expression of OsPK5 increased under NaHCO3 and H2O2 stress, and the overexpression of OsPK5 in rice improved soda saline-alkaline tolerance. CONCLUSION: Overexpression of OsSAP6 in rice significantly enhanced saline-alkaline tolerance compared with the wild type. It is speculated that OsSAP6 responds to soda salinity stress and interacts with OsPK5 to positively regulate soda saline-alkaline tolerance through ROS homeostasis. This study revealed the features of OsSAP6 involved in response to soda saline-alkaline stress and the interaction with OsPK5, which provided resources for breeding aimed at improving the soda saline-alkaline stress tolerance of rice.

Drought resistance of tobacco overexpressing the AfNAC1 gene of Amorpha fruticosa Linn.

Plants are often adversely affected by abiotic stresses such as drought, low temperature, and salinity during growth, and plant NAC-like transcription factors are involved in regulating growth and developmental processes in response to stresses such as drought and salinity. In this study, to investigate the function of AfNAC1, a co-expression network of AfNAC1 genes was constructed using gene expression data from the Chinese legume deciduous shrub, Amorpha fruticosa Linn. A 576 bp NAC transcription factor (AfNAC1 gene, MN180266) encoding 191 amino acids was isolated from Amorpha fruticosa seedlings by RT-PCR. qRT-PCR showed that the AfNAC1 gene was expressed in the roots, stems, leaves, and flowers of Amorpha fruticosa. However, drought stress significantly increased root expression, and the AfNAC1 protein was localized in the nucleus by green fluorescence detection. This study analyzed the drought resistance of overexpressing tobacco in depth. Under natural drought stress, the chlorophyll and antioxidant enzyme activities of overexpressing plants were significantly higher than those of wild-type (WT) plants, but the MDA content was lower than that of WT; after rehydration the Fv/Fm values of AfNAC1-overexpressing tobacco recovered faster than those of wild-type tobacco and rapidly reached the control levels; AfNAC1 may be involved in the regulation of the photosystem and indirectly in the regulation of the plant in response to drought stress.