PUTATIVE ROLE FOR A CALCIUM DEPENDENT PROTEIN KINASE ON FRUCTAN SYNTHESIS INITIATION MEDIATED BY SUGARS IN WHEAT LEAVES

MARTÍNEZ-NOËL G; TOGNETTI J; PONTIS H

Cordoba, Argentina

Congreso; SAIB; 2001

SAIB

Fructan synthesis initiation is associated with increased sugar concentration in leaves of temperate cereals, as verified in experiments using detached leaf blades immersed with their cut ends in sugar solutions. Previous experiments with the addition of specific inhibitors of protein kinases such as W7 (calmodulin antagonist) and staurosporine (Ser/Thr protein kinase inhibitor) suggested both the need for protein phosphorilation and the involvement of Ca+2 ions in the signaling pathway that ends in the induction of sucrose:fructan fructosyl transferase (6-SFT), the enzyme responsible for the initiation of fructan synthesis. The participation of calcium in this process was also suggested by the addition of chelating agents such as EDTA and EGTA that led to the inhibition of the 6-SFT induction mediated by sugars. The same result was obtained with a highly selective Ca+2 chelating agent, BAPTA. Taken together our results indicate that a calcium dependent protein kinase may be involved in the induction of fructan synthesis initiation mediated by sugars. Finally, a fragment of 200 bp corresponding to a wheat CDPK was cloned with degenerated primers using RT-PCR. Northern blot analysis using the cloned fragment as a probe are being performed to test the possibility that CDPK expression is associated with this sugar signaling pathway. Supported by ANPCyT. +2 ions in the signaling pathway that ends in the induction of sucrose:fructan fructosyl transferase (6-SFT), the enzyme responsible for the initiation of fructan synthesis. The participation of calcium in this process was also suggested by the addition of chelating agents such as EDTA and EGTA that led to the inhibition of the 6-SFT induction mediated by sugars. The same result was obtained with a highly selective Ca+2 chelating agent, BAPTA. Taken together our results indicate that a calcium dependent protein kinase may be involved in the induction of fructan synthesis initiation mediated by sugars. Finally, a fragment of 200 bp corresponding to a wheat CDPK was cloned with degenerated primers using RT-PCR. Northern blot analysis using the cloned fragment as a probe are being performed to test the possibility that CDPK expression is associated with this sugar signaling pathway. Supported by ANPCyT.