Characterization of Arabidopsis Lines Deficient in GAPC-1, a Cytosolic NAD-Dependent Glyceraldehyde-3-Phosphate Dehydrogenase.

SEBASTIÁN P. RIUS; PAULA CASATI; ALBERTO A. IGLESIAS; DIEGO F. GÓMEZ-CASATI

Plant Physiology

American Society of Plant Phys

Lugar: American Society of Plant Phys; Año: 2008 vol. 148 p. 1655 - 1667

0032-0889

The phosphorylating glyceraldehyde 3-phosphate dehydrogenase (GAPC-1) is a highly conserved cytosolic enzyme that catalyzes the conversion of glyceraldehyde-3-P to 1,3-bis-phosphoglycerate; besides its participation in glycolysis, it is thought to be involved in additional cellular functions. To reach an integrative view on the many roles played by this enzyme, we characterized a homozygous gapc-1 null mutant and an as-GAPC1 line of Arabidopsis thaliana. Both mutant plant lines show a delay in growth, morphological alterations in siliques and low seed number. Embryo development was altered showing abortions and empty embryonic sacs in basal and apical siliques, respectively. gapc-1 shows a 25% decrease in ATP levels and 40% reduction of the respiratory rate. Furthermore, both lines exhibit a decrease in the expression and activity of mitochondrial enzymes, aconitase and SDH, and reduced levels of pyruvate and several TCA cycle intermediates, as well as increased reactive oxygen species levels, indicating that GAPC-1 deficiency results in mitochondrial dysfunction. Concurrently, transcriptome analysis of the gapc-1 mutants unveil a differential accumulation of transcripts encoding for enzymes involved in carbon partitioning. According to these studies, some enzymes involved in carbon flux decreased (PEPC, NAD-ME, G6PDH) or increased (NAD-MDH) their activities compared to the wt line. Taken together, our data indicate that a deficiency in the cytosolic GAPC activity results in modifications of carbon flux, decreased levels of ATP and respiratory rate, and an alteration of plant and embryo development with decreased number of seeds, indicating that GAPC-1 is essential for normal fertility in Arabidopsis plants.