Characteristics of a Novel Monodehydroascorbate Reductase Gene in Corn (Zea mays L.) and Its Role in the Response to Stress

Corn plants Zea mays L. are sensitive to many stress factors that cause excessive formation of reactive oxygen species, the elimination mechanism of which includes the monodehydroascorbate reductase (MDHAR; EC 1.6.5.4), which catalyzes the reduction of monodehydroascorbic acid to ascorbate. There are four known genes in the maize genome, ZmMDHAR1–ZmMDHAR4, differing in the intracellular localization of the encoded MDHAR proteins. In this work, a novel gene of the family was identified, ZmMDHAR5 (Zm00001d017786; LOC100193942), encoding a close structural homolog of peroxisomal ZmMDHAR3. It has been assumed that ZmMDHAR5 may function similarly to chloroplast-mitochondrial MDHARs. Differential expression of ZmMDHAR1–ZmMDHAR5 genes in maize seedlings in response to various stress factors also suggested the important role of ZmMDHAR4 and ZmMDHAR5 in response to exogenous abscisic acid, low temperature, and dehydration; ZmMDHAR1 and ZmMDHAR3 to salt stress; and ZmMDHAR2 to salt and water stresses.