Is monodehydroascorbate reductase activity in leaf tissue critical for the maintenance of yield in tomato?

Vincent Truffault (1, 2) , Gisele Riqueau (3) , Cecile Garchery (1) , Hélène Gautier (2) , Rebecca Stevens (1)

1 GAFL - Génétique et Amélioration des Fruits et Légumes
2 PSH - Unité de recherche Plantes et Systèmes de Culture Horticoles
3 SQPOV - Sécurité et Qualité des Produits d'Origine Végétale

Ascorbate redox metabolism and growth have been shown to be linked and related to the activity of enzymes that produce or remove the radical monodehydroascorbate, the semi-oxidized form of ascorbate (ascorbate oxidase or peroxidase and monodehydroascorbate reductase respectively). Previous work in cherry tomato has revealed correlations between monodehydroascorbate reductase and ascorbate oxidase activity and fruit yield: decreased whole plant MDHAR activity decreases yield while decreased whole plant ascorbate oxidase activity increases yield under unfavourable environmental conditions. We aimed to investigate if similar effects on yield are obtained in a large-fruited variety of tomato, Moneymaker. Furthermore we wished to establish whether previously observed effects on yield in cherry tomato following changes in whole plant enzyme activity could be reproduced by reducing MDHAR activity in fruit only by using a fruit-specific promoter in cherry tomato (West Virginia 106). In Moneymaker, RNAi lines for monodehydroascorbate reductase did not show significant yield decrease compared to control lines when plants were grown under optimal or non-optimal conditions of carbon stress generated by mature leaf removal. In addition, we show that a decrease in monodehydroascorbate reductase activity in fruit of cherry tomato had no effect on yield compared to a reduction in whole-plant monodehydroascorbate reductase activity: we therefore show that whole plant MDHAR activity is necessary to maintain yield in cherry tomato, suggesting that the carbon source in autotrophic tissue is more important than fruit sink activity. The present data also revealed differences between cherry and large fruited tomato that could be linked to a source of genetic variability in the response to monodehydroascorbate metabolism in tomato: maybe the domestication of tomato towards large-fruited lines could have affected the importance of MDHAR in yield maintenance.

Mots clés: carbon limitation; ascorbate redox; Solanum lycopersicum; genetic background; yield; tomato

Mots clés: déshydroascorbate; ascorbate peroxydase; déhydroascorbate réductase; tissu foliaire; tomate

Domaines: Biologie végétale

Vincent Truffault, Gisele Riqueau, Cecile Garchery, Hélène Gautier, Rebecca Stevens. Is monodehydroascorbate reductase activity in leaf tissue critical for the maintenance of yield in tomato?. Journal of Plant Physiology, 2017, 222, pp.1-28. ⟨10.1016/j.jplph.2017.12.012⟩. ⟨hal-01669403⟩