Charlotte Steelheart1, Matías Leonel Alegre1, Pierre Baldet2, Christophe Rothan2, Cecile Bres2, Daniel Just2, Yoshihiro Okabe3,4, Hiroshi Ezura3,4, Inti Ganganelli1, Gustavo Esteban Gergoff Grozeff1, Carlos Guillermo Bartoli5. 1. INFIVE, Facultades de Ciencias Agrarias y Forestales y Ciencias Naturales y Museo, Universidad Nacional de La Plata, CCT CONICET, La Plata, Argentina. 2. Institut National de la Recherche Agronomique (INRAE), Université de Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, 33140, Villenave d'Ornon, France. 3. Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan. 4. Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan. 5. INFIVE, Facultades de Ciencias Agrarias y Forestales y Ciencias Naturales y Museo, Universidad Nacional de La Plata, CCT CONICET, La Plata, Argentina. carlos.bartoli@agro.unlp.edu.ar.
Abstract
MAIN CONCLUSION: The oxidant/antioxidant balance affects the ripening time of tomato fruit. Ripening of tomato fruit is associated with several modifications such as loss of cell wall firmness and transformation of chloroplasts to chromoplasts. Besides a peak in H2O2, reactive oxygen species (ROS) are observed at the transition stage. However, the role of different components of oxidative stress metabolism in fruit ripening has been scarcely addressed. Two GDP-L-galactose phosphorylase (GGP) Solanum lycopersicum L. cv Micro-Tom mutants which have fruit with low ascorbic acid content (30% of wild type) were used in this work to unravel the participation of ascorbic acid and H2O2 in fruit maturation. Both GGP mutants show delayed fruit maturation with no peak of H2O2; treatment with ascorbic acid increases its own concentration and accelerates ripening only in mutants to become like wild type plants. Unexpectedly, the treatment with ascorbic acid increases H2O2 synthesis in both mutants resembling what is observed in wild type fruit. Exogenous supplementation with H2O2 decreases its own synthesis delaying fruit maturation in plants with low ascorbic acid content. The site of ROS production is localized in the chloroplasts of fruit of all genotypes as determined by confocal microscopy analysis. The results presented here demonstrate that both ascorbic acid and H2O2 actively participate in tomato fruit ripening.
MAIN CONCLUSION: The oxidant/antioxidant balance affects the ripening time of tomato fruit. Ripening of tomato fruit is associated with several modifications such as loss of cell wall firmness and transformation of chloroplasts to chromoplasts. Besides a peak in H2O2, reactive oxygen species (ROS) are observed at the transition stage. However, the role of different components of oxidative stress metabolism in fruit ripening has been scarcely addressed. Two GDP-L-galactose phosphorylase (GGP) Solanum lycopersicum L. cv Micro-Tom mutants which have fruit with low ascorbic acid content (30% of wild type) were used in this work to unravel the participation of ascorbic acid and H2O2 in fruit maturation. Both GGP mutants show delayed fruit maturation with no peak of H2O2; treatment with ascorbic acid increases its own concentration and accelerates ripening only in mutants to become like wild type plants. Unexpectedly, the treatment with ascorbic acid increases H2O2 synthesis in both mutants resembling what is observed in wild type fruit. Exogenous supplementation with H2O2 decreases its own synthesis delaying fruit maturation in plants with low ascorbic acid content. The site of ROS production is localized in the chloroplasts of fruit of all genotypes as determined by confocal microscopy analysis. The results presented here demonstrate that both ascorbic acid and H2O2 actively participate in tomato fruit ripening.