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Poster: Environmental physiology

Abs # P01025: Carbohydrate mobilization in germinating tomato seeds under allelopathic stress

Presenter: Lara-Nunez, Aurora       Contact Presenter
AuthorsLara-Nunez, Aurora  (A)   Gutierrez-Najera, Nora A (A)   Sanchez-Nieto, Sobeida  (B)   Anaya, A-L.  (A)   Cruz-Ortega, Rocio  (A)  
Affiliations: (A): Instituto de Ecologia-UNAM
(B): Facultad de Quimica-UNAM
Web Site:http://www.ecologia.unam.mx/

Sicyos deppei (Cucurbitaceae) has a strong allelopathic effect on Lycopersicon esculentum germination. Previous studies have shown that allelochemical stress produced by S. deppei aqueous leachate on tomato seeds caused inhibitory effects on H+ATPase activity and an oxidative damage, evidenced by membrane lipid peroxidation and a raise in ROS. In this study we analyzed the effects on carbohydrate mobilization in germinating seeds exposed of S. deppei aqueous leachate at different times. We evaluated the concentration of starch, sucrose, glucose and fructose, and the activity of carbohydrate-related enzymes. No difference is observed in all tested carbohydrate concentration among control and treatment at early germination times (3-24h) but at longer times (36 & 48h) there is an imbalance in glucose, starch and fructose. An earlier inactivation of α-amilase, a degrading starch enzyme, at 12h-treated seeds may account for the imbalance in starch at further germination times. A similar effect was observed in sucrose phosphate synthase, in acidic and neutral invertase activities and in sucrose synthase activity, all of them involved in sucrose metabolism. Currently, we are analyzing the activity of enzymes related to cell wall synthesis and degradation, such as β-1, 3- glucanase, endo β-mannanase, β-mannosidase, α-galactosidase and exo-poligalacturonase. In conclusion, there is an imbalance in the carbohydrate metabolism in germinating seeds exposed to allelochemical stress produced by S. deppei aqueous leachate on tomato seeds.

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