Open AccessTissue-Specific and Light-Mediated Expression of the C4 Photosynthetic NAD-Dependent Malic Enzyme of Amaranth Mitochondria
Author(s) -
John F. Long,
James O. Berry
Publication year - 1996
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.112.2.473
Subject(s) - amaranth , nad+ kinase , biology , c4 photosynthesis , amaranthus hypochondriacus , photosynthesis , biochemistry , plastid , protein subunit , gene expression , chloroplast , malic enzyme , arabidopsis , microbiology and biotechnology , enzyme , gene , dehydrogenase , mutant
In the C4 dicotyledonous grain plant amaranth (Amaranthus hypochondriacus), a mitochondrial NAD-dependent malic enzyme (NAD-ME; EC 1.1.1.39) serves a specialized and essential role in photosynthetic carbon fixation. In this study we have examined specialized photosynthetic gene expression patterns for the NAD-ME [alpha] subunit. We show here that the [alpha] subunit gene is preferentially expressed in leaves and cotyledons (the most photosynthetically active tissues), and this expression is specific to the bundle-sheath cells of these tissues from the earliest stages of development. Synthesis of the [alpha] subunit polypeptide and accumulation of its corresponding mRNA are strongly light-dependent, but this regulation is also influenced by seedling development. In addition, light-dependent accumulation of the [alpha] subunit mRNA is regulated at transcriptional as well as posttranscriptional levels. Our findings demonstrate that the NAD-ME of amaranth has acquired numerous complex tissue-specific and light-mediated regulation patterns that define its specialized function as a key enzyme in the C4 photosynthetic pathway.