Cytochrome c deficiency alters plant growth, developmental transitions and carbon metabolism in Arabidopsis thaliana.

RACCA S,; GONZALEZ DH,; WELCHEN E.

Congreso; 11th International Congress of Plant Molecular Biology; 2015

Cytochrome c (CYTc) is a heme protein of the mitochondrial intermembrane space that mediates electron transfer between Complexes III and IV of the respiratory chain. CYTc has other important functions, like regulation of apoptosis in mammals and ascorbate synthesis in plants. To study the role of CYTc in plants, we obtained knock-down double mutants (called ab1 and ab4) in the two genes encoding CYTc in Arabidopsis thaliana. We observed that mutants have lower biomass and shorter roots compared to wild-type (WT) plants. In addition, ab1 and ab4 exhibit delayed flowering and senescence. On the other hand, a decrease in CYTc levels produces alterations in carbon metabolism, with accumulation of higher levels of starch and glucose during the diurnal cycle, indicating that mutants accumulate sugars instead of using them for growth. Remodeling of plant metabolism and development is supported by gene expression analysis. Several genes related to sugar metabolism, photosynthesis, flowering and the circadian clock show altered expression in mutant plants. Treatment of mutant plants with gibberellins (GA) partially revert the phenotype, suggesting the existence of an alteration in GA synthesis and/or metabolism. The results indicate that CYTc links mitochondrial respiration, sugar metabolism and plant growth.