AUTHOR=Zhu Xi , Li Wei , Zhang Ning , Jin Hui , Duan Huimin , Chen Zhuo , Chen Shu , Wang Qihua , Tang Jinghua , Zhou Jiannan , Zhang Yu , Si Huaijun 

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

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1392425

DOI=10.3389/fpls.2024.1392425

ISSN=1664-462X

ABSTRACT=<sec><title>Backgrounds</title><p>As a conserved signaling pathway, mitogen-activated protein kinase (MAPK) cascade regulates cellular signaling in response to abiotic stress. High temperature may contribute to a significant decrease in economic yield. However, research into the expression patterns of <italic>StMAPKK</italic> family genes under high temperature is limited and lacks experimental validation regarding their role in supporting potato plant growth.</p></sec><sec><title>Methods</title><p>To trigger heat stress responses, potato plants were grown at 35°C. qRT-PCR was conducted to analyze the expression pattern of <italic>StMAPKK</italic> family genes in potato plants. Plant with <italic>StMAPKK5</italic> loss-of-function and gain-of-function were developed. Potato growth and morphological features were assessed through measures of plant height, dry weight, and fresh weight. The antioxidant ability of <italic>StMAPKK5</italic> was indicated by antioxidant enzyme activity and H<sub>2</sub>O<sub>2</sub> content. Cell membrane integrity and permeability were suggested by relative electrical conductivity (REC), and contents of MDA and proline. Photosynthetic capacity was next determined. Further, mRNA expression of heat stress-responsive genes and antioxidant enzyme genes was examined.</p></sec><sec><title>Results</title><p>In reaction to heat stress, the expression profiles of <italic>StMAPKK</italic> family genes were changed. The StMAPKK5 protein is located to the nucleus, cytoplasm and cytomembrane, playing a role in controlling the height and weight of potato plants under heat stress conditions. <italic>StMAPKK5</italic> over-expression promoted photosynthesis and maintained cell membrane integrity, while inhibited transpiration and stomatal conductance under heat stress. Overexpression of <italic>StMAPKK5</italic> triggered biochemical defenses in potato plant against heat stress, modulating the levels of H<sub>2</sub>O<sub>2</sub>, MDA and proline, as well as the antioxidant activities of CAT, SOD and POD. Overexpression of <italic>StMAPKK5</italic> elicited genetic responses in potato plants to heat stress, affecting heat stress-responsive genes and genes encoding antioxidant enzymes.</p></sec><sec><title>Conclusion</title><p><italic>StMAPKK5</italic> can improve the resilience of potato plants to heat stress-induced damage, offering a promising approach for engineering potatoes with enhanced adaptability to challenging heat stress conditions.</p></sec>