Regulation by phosphorylation of carbon metabolism in seeds

PIATTONI, CLAUDIA V.; FERRERO, DANISA ML; IGLESIAS, ALBERTO A.

Mar del Plata

Congreso; XXX REUNION ANUAL DE LA SOCIEDAD ARGENTINA DE FISIOLOGÍA VEGETAL; 2014

Sociedad Argentina de Fisiología Vegetal

Seed development is genetically programmed but many posttranslational signals are involved in switching from pre-storage to storage/maturation phases. Protein kinases (CDPK and SnRK1) are critically involved in such a transition. Herein, we report changes in phosphorylation of ADP-glucose pyrophosphorylase (ADP-GlcPPase) and glyceraldehyde-3P dehydrogenase (Ga3PDHase), two enzymes involved in carbon metabolism along development of seeds mainly storing starch (wheat) or oil (castor bean). In wheat: 1. ADP-GlcPPase phosphorylation occurred during maturation; a phase where the enzyme activity and starch contents increase. 2. Ga3PDHase was constantly phosphorylated. Instead, in castor bean: 1. ADP-GlcPPase was not found phosphorylated. 2. Ga3PDHase activity and phosphorylation increased during proliferation and transition, but activity and protein amount are increasingly reduced in the following phases, being almost undetectable during maturation. Protein stability analysis showed that in castor bean Ga3PDHase degradation was associated to phosphorylation, which was avoided by a proteasome inhibitor reagent. Activity profiles along development were opposed in both seeds. Phosphorylation of castor bean Ga3PDHase and wheat ADP GlcPPase seems related with the switch from the pre-storage to the storage/maturation phase and it would modulate carbon partitioning. The results provide insights into the regulation of enzymes involved in critical steps of carbon metabolism during seed development.