|MANJUNATH, SIVALINGANNA - U OF ILL, URBANA
Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/1996
Publication Date: N/A
Interpretive Summary: 1) Rationale: The goal was to determine how root glyceraldehyde-3-phosphate dehydrogenase (an enzyme involved in glucose metabolism) is regulated during flooding in maize. 2) Accomplishments: It was determined that root glyceraldehyde-3-phosphate dehydrogenase is encoded by four genes. Expression of two genes was turned on in response to flooding, the other two genes are on all the time (including during non-flooding conditions). 3) Significance: The understanding of the role of root glyceraldehyde-3-phosphate dehydrogenase in a plant's response to low oxygen-stress conditions will allow greater understanding of how a plant can cope under flooding conditions, and may allow development of effective methods to produce crop plants that are tolerant to flooding.
Technical Abstract: Maize cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) has been identified as one of the anaerobic polypeptides and mRNA levels corresponding to a member of the gpc multi-gene family, gpc3, increase under anaerobiosis (Russell and Sachs, 1989, 1992). Further analysis of full length cDNA clones of GAPC2, GAPC3 and GAPC4 revealed that the deduced amino acid sequence of GAPC4 has 99.4% identity with that of GAPC3 as compared to only 81% with either GAPC1 or GAPC2 amino acid sequence. Northern blot analysis indicated ~20 fold increase in gpc4 mRNAs after 24 h anoxia. However, heat shock, cold and salt stress treatments did not induce the expression of gpc3 or gpc4. Analysis of the upstream regions of gpc2 and gpc4 revealed that they have typical eukaryotic promoter features and their transcription start points (TSP) are at 76 and 68 bp upstream of their respective translation initiation sites, respectively. Transient expression analysis of gpc4 promoter driven (uidA) constructs in maize suspension culture cells showed an induced expression of approximately three fold above the aerobic control, during anaerobiosis. 5'-unidirectional deletion analysis of the gpc4 upstream region demonstrated that a critical region required for induced expression lies between -290 and -157 bp. The critical region identified here has regulatory elements like a G-box and a GC-motif, similar to the previously defined maize adh1 and Arabidopsis adh regulatory elements as well as the sequences found in other environmentally inducible genes.