Characterization of an A. thaliana null mutant lacking a cytosolic glyceraldehyde-3P dehydrogenase

RIUS, S.; CASATI, P.; IGLESIAS, A.; DIEGO FABIAN GOMEZ CASATI

Rosario

Congreso; XLII Reunión SAIB; 2006

The cytosolic enzyme phosphorylating glyceraldehyde-3P dehydrogenase (NAD-GAPDH; At3g04120) catalyzes the conversion of Ga3P to 1,3BPG in the payoff phase of glycolysis. To further characterize the function of this enzyme, we analyze an homozygous T-DNA null mutant of A. thaliana (SALK_010839). The absence of NAD-GAPDH has direct effect on ATP levels and respiration rate compared with wt. Activities of several enzymes of carbon metabolism such as PEPC, NADP-ME, G6PDH and NAD-MDH were also affected. These results are in agreement with microarray data. Furthermore, a decrease of CO2 fixation and a down-regulation of the mRNA of rubisco activase were observed. Redox system was analyzed showing an increase of CAT1, CAT3 and GST6 mRNAs. An overproduction of ROS in trichomes was revealed using H2DCFDA probe in spite of higher activity of catalase in leaves. nad-gapdh plants present a delay in growth. Moreover, the absence of NAD-GAPDH activity alters siliques production and embryo development, but had no effects on pollen viability. These results suggest that the lack of cytosolic NAD-GAPDH alters carbohydrate metabolism, resulting in decreased levels of ATP and respiration and alteration of redox metabolism, affecting embryo and seeds development.