INCREASED RESPIRATION IN FLOODED TOMATO HYPOCOTYLS DOES NOT DEPEND ON AERENCHYMA-PROMOTED INTERNAL AERATION

MIGNOLLI, FRANCESCO; BARONE, JAVIER ORLANDO; VIDOZ, MARÍA LAURA

Congreso; 32 Reunión Argentina de Fisiología Vegetal; 2018

Flooding is one of the most frequent and extensive abiotic stresses that negatively influence terrestrial plant growth and productivity and mayresult in plant death. In tomato, aerenchyma formation enables oxygen (O2) to move towards hypoxic hypocotyls of flooded plants restoringnormal internal O2 concentration. Conversely, silver nitrate (AgNO3) treated plants failed to develop aerenchyma and O2 levels weremaintained markedly below than in control plants. We then asked whether internal aeration was able to restore respiration in submergedhypocotyls. Surprisingly, rate of carbon dioxide (CO2) evolution was constantly higher in flooded and in flooded AgNO3-treated hypocotylswith respect to normoxic controls. O2 uptake was also enhanced in flooded and in flooded AgNO3-treated hypocotyls in comparison withcontrols. Triphenyl tetrazolium chloride (TTC) is a redox indicator used to mark cellular respiration. In fact, when hypocotyl slices aresimultaneously incubated with TTC and potassium cyanide, which inhibits mitochondrial cytochrome c oxidase activity, TTC reduction isimpaired. Interestingly, in slices of flooded and flooded AgNO3-treated hypocotyls, TTC dyeing was more intense than in controls. Inconclusion, respiratory metabolism in tomato hypocotyls appears unexpectedly exacerbated in the hypoxic environment and, althoughaerenchyma improves oxygenation in submerged hypocotyls, it does not affect respiration