OsMDH12: A Peroxisomal Malate Dehydrogenase Regulating Tiller Number and Salt Tolerance in Rice
2023
Yuheng Shi | Jiahui Feng | Liping Wang | Yanchen Liu | Dujun He | Yangyang Sun | Yuehua Luo | Cheng Jin | Yuanyuan Zhang
Salinity is an important environmental factor influencing crop growth and yield. Malate dehydrogenase (MDH) catalyses the reversible conversion of oxaloacetate (OAA) to malate. While many MDHs have been identified in various plants, the biochemical function of MDH in rice remains uncharacterised, and its role in growth and salt stress response is largely unexplored. In this study, the biochemical function of <i>OsMDH12</i> was determined, revealing its involvement in regulating tiller number and salt tolerance in rice. <i>OsMDH12</i> localises in the peroxisome and is expressed across various organs. In vitro analysis confirmed that <i>OsMDH12</i> converts OAA to malate. Seedlings of <i>OsMDH12</i>-overexpressing (<i>OE</i>) plants had shorter shoot lengths and lower fresh weights than wild-type (WT) plants, while <i>osmdh12</i> mutants displayed the opposite. At maturity, <i>OsMDH12</i>-<i>OE</i> plants had fewer tillers than WT, whereas <i>osmdh12</i> mutants had more, suggesting <i>OsMDH12</i>’s role in tiller number regulation. Moreover, <i>OsMDH12</i>-<i>OE</i> plants were sensitive to salt stress, but <i>osmdh12</i> mutants showed enhanced salt tolerance. The Na<sup>+</sup>/K<sup>+</sup> content ratio increased in <i>OsMDH12</i>-<i>OE</i> plants and decreased in <i>osmdh12</i> mutants, suggesting that <i>OsMDH12</i> might negatively affect salt tolerance through influencing the Na<sup>+</sup>/K<sup>+</sup> balance. These findings hint at <i>OsMDH12</i>’s potential as a genetic tool to enhance rice growth and salt tolerance.
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