Positively Regulates Response to Drought and Salt Stress in Potato.

MAPKKs, as one of the main members of the mitogen-activated protein kinase (MAPK) cascade pathway, are located in the middle of the cascade and are involved in many physiological processes of plant growth and development, as well as stress tolerance. Previous studies have found that is responsive to drought and salt stress. To further investigate the function and regulatory mechanism of in potato stress response, potato variety 'Atlantic' was subjected to drought and NaCl treatments, and the expression of the gene was detected by qRT-PCR. overexpression and RNA interference-mediated knockdown potato plants were constructed. The relative water content, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities, as well as proline (Pro) and malondialdehyde (MDA) contents of plant leaves, were also assayed under drought and NaCl stress. The StMAPKK5 interacting proteins were identified and validated by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC). The results showed that the expression of was significantly up-regulated under drought and NaCl stress conditions. The StMAPKK5 protein was localized in the nucleus, cytoplasm, and cell membrane. The expression of affected the relative water content, the enzymatic activities of SOD, CAT, and POD, and the proline and MDA contents of potatoes under drought and salt stress conditions. These results suggest that plays a significant role in regulating drought and salt tolerance in potato crop. Yeast two-hybrid (Y2H) screening identified four interacting proteins: StMYB19, StZFP8, StPUB-like, and StSKIP19. BiFC confirmed the authenticity of the interactions. These findings suggest that is crucial for potato growth, development, and response to adversity.