OsMDH12: A Peroxisomal Malate Dehydrogenase Regulating Tiller Number and Salt Tolerance in Rice

Abstract

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 OsMDH12 was determined, revealing its involvement in regulating tiller number and salt tolerance in rice. OsMDH12 localises in the peroxisome and is expressed across various organs. In vitro analysis confirmed that OsMDH12 converts OAA to malate. Seedlings of OsMDH12-overexpressing (OE) plants had shorter shoot lengths and lower fresh weights than wild-type (WT) plants, while osmdh12 mutants displayed the opposite. At maturity, OsMDH12-OE plants had fewer tillers than WT, whereas osmdh12 mutants had more, suggesting OsMDH12’s role in tiller number regulation. Moreover, OsMDH12-OE plants were sensitive to salt stress, but osmdh12 mutants showed enhanced salt tolerance. The Na+/K+ content ratio increased in OsMDH12-OE plants and decreased in osmdh12 mutants, suggesting that OsMDH12 might negatively affect salt tolerance through influencing the Na+/K+ balance. These findings hint at OsMDH12’s potential as a genetic tool to enhance rice growth and salt tolerance.

Physiological and Cellular Ultrastructural Responses of Isatis indigotica Fort. under Salt Stress

“…Biomass and plant morphology are some of the most direct indicators for assessing the degree of salt stress and plant resistance [ 28 ]. Salt stress also leads to a decrease in the number of tillers of plants.…”

Genome-Wide Identification and Expression Analysis of Malate Dehydrogenase Gene Family in Sweet Potato and Its Two Diploid Relatives

“…The rice plastidial NAD-MDH1 negatively regulated salt treatment by reducing the vitamin B6 content [49]. The functional characterizations indicated that the MDH genes were linked to plant salt tolerance [28,29,32]. The sweet potato MDH genes in the stems and leaves may play important roles in regulating salt and drought stresses, as shown in Figure 10.…”

“…In apples, MdcyMDH overexpression enhances the tolerance to cold and salt stresses by producing more reductive redox states and increasing the salicylic acid level [30,31]. Overexpressing OsMDH12 rice is susceptible to salt stress, but the OsMDH12 mutant exhibits enhanced salt endurance [32]. MDH genes responding to salt stress are also found in tomato [16] and poplar [19].…”