Spermidine synthase as affected by osmotic stress in oat leaves
Osmotically-induced putrescine (Put) accumulation in cereals could result not only from the activation of the arginine decarboxylase pathway, but also from the inhibition of spermidine synthase, the enzyme which catalyzes the transformation of Put to spermidine (Spd). To test the latter possibility, they evaluated Spd synthase activity in oat leaves as affected by osmotic stress. They developed a new assay for Spd synthase activity by adding S-adenosylmethionine, C/sup 14/-Put and pyridoxal phosphate to the assay mixture. Incorporation of the C/sup 14/-label into Spd can be detected after 45 min of incubation at 37/sup 0/C. Labelled Spd is separated from labelled Put or spermine by elution with HCl in Dowex 50 W-H/sup +/ columns. In peeled oat leaves floated in the dark over 0.6 M sorbitol in 1mM PO/sub 4/ buffer (pH 5.8) for 6 and 136 h. Spd synthase activity is reduced by 24 and 53%, respectively, as compared with controls. The results suggest that the activity of this enzyme is inhibited by osmotic stress, and could partially account for the accumulation of Put.
- Research Organization:
- Yale Univ., New Haven, CT
- OSTI ID:
- 5019396
- Journal Information:
- Plant Physiol., Suppl.; (United States), Journal Name: Plant Physiol., Suppl.; (United States) Vol. 80:4; ISSN PPYSA
- Country of Publication:
- United States
- Language:
- English
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