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Abstract
The plant cell wall provides the structural basis upon which the morphogenesis of plant cells, tissues, and organs rests. Pectin, a major wall component, is a family of polysaccharides that provides many of the biochemical properties that define cell wall form and function. Regulation of enzymes that synthesize wall components could potentially be altered to affect wall formation and therefore modify the growth and development of the plant. A specific family of enzymes involved in pectin biosynthesis known as Galacturonosyltransferases (GalATs) catalyze the transfer of galactosyluronic acid (GalA) residues from uridine diphosphate-GalA (UDP-GalA) to the growing pectic polysaccharide chain. The first gene that encodes a pectin GalAT in Arabidopsis thaliana, known as GAlactUronosylTransferase1 (GAUT1), was previously identified and BLAST analyses indicated a gene superfamily with high-sequence similarity. To understand the biological significance of GAUT1 and GAUT7, transcriptional expression was analyzed using a -Glucuronidase (GUS) reporter gene system. The GAUT promoters were amplified, fused to the GUS gene, and transformed into Arabidopsis plants. The activities of the promoter:GUS constructs were assayed to reveal spatial and temporal expression patterns. This data shows that GAUT1 and GAUT7 are expressed heavily in meristematic regions, vascular tissues, and pollen, suggesting a role in primary and secondary wall growth. Extensive overlap of expression provides evidence that these proteins work in a complex. This study provides new insight to guide the design of future studies on GAUT function in pectin synthesis and can be used with other evidence to further elucidate the physiological relevance of these genes.