Inhibition of gibberellic acid-induced starch mobilization by salicylhydroxamic acid in Avena fatua L. seed

• Published in: Annals of botany 1987-03, Vol.59 (3), p.265-268
• Main Author: Upadhyaya, M.K
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; alpha-amylase; Avena fatua; Avena fatua L; Biological and medical sciences; Economic plant physiology; Endosperm; enzyme activity; Enzymes; Fundamental and applied biological sciences. Psychology; gibberellic acid; inhibitors; Metabolism; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); Nutrition. Photosynthesis. Respiration. Metabolism; Photosynthesis, respiration. Anabolism, catabolism; Plant physiology; Plant physiology and development; Plants; Respiration; salicylhydroxamic acid; seed; Seed dormancy; Seedling growth; Seeds; starch; Starches; Sugars; wild oat; α-amylase
• ISSN: 0305-7364; 1095-8290
• DOI: 10.1093/oxfordjournals.aob.a087314

Inhibition of GA3-induced endosperm mobilization in Avena fatua L. by salicylhydroxamic acid (SHAM), a widely used alternative respiration inhibitor, was studied. SHAM strongly inhibited the GA3-induced release of reducing sugars in the incubation medium by 3 mm de-embryonated endosperm segments; at 4 mM SHAM, GA3-induced sugar release was inhibited by 66–79 per cent. Extracts prepared from segments incubated in 0.05 mM GA3 with 2, 5 and 10 mM SHAM showed 30, 53 and 71 per cent lower α-amylase activity, respectively, compared to the GA3-alone treatment. Addition of SHAM (0.5–5 mM) during the enzyme assay had no effect on the activity of α-amylase. Thus, the inhibition of starch mobilization in endosperm by SHAM is due to inhibition of the production and not the activity of α-amylase. The inhibition of Avena fatua seedling growth by SHAM reported earlier may, in part, be due to its effect on endosperm mobilization. Since (1) Avena fatua seeds have been shown to have little or no SHAM-sensitive respiration, and (2) concentrations of SHAM necessary for inhibiting endosperm mobilization were significantly higher than those generally necessary for inhibiting alternative respiration, the inhibition of endosperm mobilization by this compound does not appear to involve its effect on alternative respiration.