Differential expression and sequence analysis of the maize glyceraldehyde-3-phosphate dehydrogenase gene family.

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Abstract
Two cDNA clones for maize cytosolic glyceraldehyde-3-phosphate dehydrogenase are described. One is about 97% similar in coding capacity to a previously published clone [Brinkmann et al. (1987). J. Mol. Evol. 26, 320-328], while the other shows only 88% similarity. Evidence points toward the three cDNAs being the products of three genes, to be called Gpc1, Gpc2, and Gpc3. When the least similar clone, corresponding to Gpc3, was used to analyze RNA gel blots, anaerobic treatment for 6 hours induced RNA accumulation in the shoots 15.6-fold, while a 1-hour shift from 28 degrees C to 40 degrees C increased accumulation 5.1-fold. Roots had a higher basal level of expression, leading to a 6.0-fold anaerobic induction, and a 2.4-fold heat stress induction. RNA gel blot analysis using the clone corresponding to Gpc2 showed decreased RNA accumulation within 6 hours of anaerobiosis, while analysis with the previously published clone, corresponding to Gpc1, showed a decrease within 24 hours. Neither Gpc1 nor Gpc2 showed heat stress induction, while some other known anaerobic genes did. Through the use of hybrid selection, in vitro translation, and immune precipitation, the relative expression of the three genes is shown. The role of the observed changes in gene expression is discussed in relation to stress physiology.