StMAPKK5 Positively Regulates Response to Drought and Salt Stress in Potato

Abstract

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 StMAPKK5 is responsive to drought and salt stress. To further investigate the function and regulatory mechanism of StMAPKK5 in potato stress response, potato variety ‘Atlantic’ was subjected to drought and NaCl treatments, and the expression of the StMAPKK5 gene was detected by qRT-PCR. StMAPKK5 overexpression and RNA interference-mediated StMAPKK5 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 StMAPKK5 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 StMAPKK5 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 StMAPKK5 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 StMAPKK5 is crucial for potato growth, development, and response to adversity.

StMAPKK5 responds to heat stress by regulating potato growth, photosynthesis, and antioxidant defenses

“…In order to better assess the location of StMAPKK5 protein, we examined by tagging StMAPKK5 protein with GFP and dissecting the green fluorescence, with the red autofluorescence of chlorophyll as a location reference. The green fluorescence is evenly distributed in the nucleus, cytoplasm and cytomembrane ( Figure 4C ), which was consistent with our previous result ( Luo et al., 2024 ). In comparison with the NT plants, StMAPKK5 overexpression significantly enhanced the thermotolerance of potato plants as evidenced by the increases in plant height, dry weight, dry root weight, fresh weight, and root fresh weight, under normal and heat stress conditions after 4 weeks of cultivation ( p < 0.001) ( Figures 4D, E ).…”

Transcription Factor McHB7 Improves Ice Plant Drought Tolerance through ABA Signaling Pathway

“…For example, SOD can convert superoxide radical to O 2 , APX can catalyze the conversion of H 2 O 2 to H 2 O and O 2 [40], and CAT also decomposes H 2 O 2 to H 2 O and O 2 [38]. POD can catalyze the process of H 2 O 2 reduction by phenolic compounds, specialized metabolites, or other substrates [41]. MDA is cytotoxic and is associated with premature senescence, which can cause the crosslinking of macromolecules such as proteins and nucleic acids [42].…”

“…Each sample had four biological replicates. The physiological parameters included superoxide dismutase (SOD), peroxidase (POD), and malondialdehyde (MDA), which were assayed as previously described [41]. For ascorbate peroxidase (APX) measurement, 0.1 g of the leaf sample was homogenized in liquid nitrogen and transferred to a tube with 3 mL 50 mM cold PBS buffer (1 M K 2 HPO 4 and 1 M KH 2 PO 4 , pH 7.8) with 0.4% (w/v) polyvinyl pyrrolidone, then placed on an agitator at 4 • C for 1 h. The samples were centrifuged at 5000 rpm at 4 • C for 10 min and the supernatant was the crude enzyme solution.…”