Expression of a single gene encoding microbody NAD-malate dehydrogenase during glyoxysome and peroxisome development in cucumber

• Published in: Plant molecular biology 1994-12, Vol.26 (6), p.1833-1841
• Main Authors: Kim, D.J. (Edinburgh Univ. (United Kingdom). Inst. of Cell and Molecular Biology), Smith, S.M
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Base Sequence; Carbohydrate Dehydrogenases - biosynthesis; Carbohydrate Dehydrogenases - genetics; CODE GENETIQUE; CODIGO GENETICO; Cotyledon - enzymology; Cotyledon - growth & development; CUCUMIS SATIVUS; Cucumis sativus - enzymology; Cucumis sativus - genetics; DNA, Complementary - genetics; DNA, Plant - genetics; EXPRESION GENICA; EXPRESSION DES GENES; GENE EXPRESSION; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Gene Library; GENETIC CODE; Glyoxylates - metabolism; Isocitrate Lyase - biosynthesis; Isocitrate Lyase - genetics; MALATE DEHYDROGENASE; Malate Dehydrogenase - biosynthesis; Malate Dehydrogenase - genetics; MALATE DESHYDROGENASE; Malate Synthase - biosynthesis; Malate Synthase - genetics; MALATO DESHIDROGENASA; Microbodies - enzymology; Molecular Sequence Data; Nucleic Acid Hybridization; RNA, Plant - genetics
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/BF00019496

A full-length cDNA clone encoding microbody NAD(+)-dependent malate dehydrogenase (MDH) of cucumber has been isolated. The deduced amino acid sequence is 97% identical to glyoxysomal MDH (gMDH) of watermelon, including the amino terminal putative transit peptide. The cucumber genome contains only a single copy of this gene. Expression of this mdh gene increases dramatically in cotyledons during the few days immediately following seed imbibition, in parallel with genes encoding isocitrate lyase (ICL) and malate synthase (MS), two glyoxylate cycle enzymes. The level of MDH, ICL and MS mRNAs then declines, but then MDH mRNA increases again together with that of peroxisomal NAD(+)-dependent hydroxypyruvate reductase (HPR). The mdh gene is also expressed during cotyledon senescence, together with hpr, icl and ms genes. These results indicate that a single gene encodes MDH which functions in both glyoxysomes and peroxisomes. In contrast to icl and ms genes, expression of the mdh gene is not activated by incubating detached green cotyledons in the dark, nor is it affected by exogenous sucrose in the incubation medium. The function of this microbody MDH and the regulation of its synthesis are discussed.