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Cloning and expression of a hypoxic and nitrogen inducible maize alanine aminotransferase gene
Author(s) -
Muench Douglas G.,
Christopher Mary E.,
Good Allen G.
Publication year - 1998
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1998.1030409.x
Subject(s) - panicum miliaceum , biology , hordeum vulgare , gene , complementary dna , gene expression , abscisic acid , botany , microbiology and biotechnology , poaceae , biochemistry
Alanine aminotransferase (ALT, EC 2.6.1.2) is regulated by hypoxia in the roots of several plant species, and by light and nitrogen stress in the leaves of the C 4 plant, broomcorn millet ( Panicum miliaceum ). In order to more fully characterize the regulation of ALT, we isolated a maize alt genomic clone that has high sequence homology to the coding regions of both the barley ( Hordeum vulgare ) and P. miliaceum alt cDNA clones. This is the first plant alt gene isolated to date. The alt gene consists of 15 exons, and has regions of the promoter that are similar to the maize Anaerobic Responsive Element, and to the maize 27‐kDa zein promoter. ALT activity increased 2.1‐fold in roots after 96 h of hypoxic stress, but did not increase significantly in either root or leaf tissue when the plant was subjected to anaerobic conditions. Northern analysis of hypoxic root tissue showed an 18‐fold increase in a single alt mRNA band after 8 h of hypoxic stress, followed by a continual decline in mRNA levels. ALT activity and mRNA levels were also found to increase in root tissue after recovery from nitrogen stress but not after salt, cold or heat stress conditions. These interesting patterns of ALT expression in maize roots as a result of exposure to hypoxia and nitrogen stress are discussed.