Hormonal control on ascorbic acid synthesis and its interaction with respiration

LUIS MIGUEL MAZORRA; MARÍA EUGENIA SENN; GUSTAVO GERGOFF; DIEGO DARÍO FANELLO; CRISTIAN CARRIÓN; MIRIAM NÚÑEZ; GERAR J. BISHOP

Rosario

Congreso; 8th International Conference for Plant Mitochondrial Biology (ICPMB 2013); 2013

The ICPMB 2013 Organizing Team

Ascorbic acid (AA) regulates photosynthesis, stomata closure, cell growth and plays an important role in the detoxification of reactive oxygen species. The last step of AA biosynthesis in plants is catalysed by the mitochondrial flavoenzyme L-galactono-1,4-lactone dehydrogenase (L-GalLDH). Brassinosteroids (BR) are plant steroid hormones that control cell elongation, growth and photosynthesis but their participation in mitochondria activity remains to be studied. Similarly, the hormonal control on AA levels is still largely unknown. The aim of this work is to study the participation of hormones in L-GalLDH activity and its interaction with respiration. The experiments were carried out using BR deficient (dx) or BR over-accumulating tomato plants, in combination with exogenous BR application. In addition, since dx leaves presented increased ethylene production the application of 1-methylcyclopropene was used to inhibit ethylene sensitivity. The results presented here show antagonistic effects of BR and ethylene on leaf AA synthesis, displayed by isolated mitochondria or whole leaf tissues. The BR/ethylene level ratio regulating plant mitochondria metabolism will be discussed.