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

COWPER COLES, PATRICIO; MIGNOLLI, FRANCESCO; VIDOZ, MARIA L.

Córdoba

Congreso; 32° REUNIÓN ARGENTINA E FISIOLOGÍA VEGETAL; 2019

Flooding is one of the most frequent and extensive abioticstresses that negatively influence terrestrial plant growthand productivity and may result in plant death. In tomato,aerenchyma formation enables oxygen (O2) to move towards hypoxic hypocotyls of flooded plants restoring normal internal O2 concentration. Conversely, silver nitrate(AgNO3) treated plants failed to develop aerenchyma andO2 levels were maintained markedly below than in controlplants. We then asked whether internal aeration was ableto restore respiration in submerged hypocotyls. Surprisingly, rate of carbon dioxide (CO2) evolution was constantly higher in flooded and in flooded AgNO3-treatedhypocotyls with respect to normoxic controls. O2 uptakewas also enhanced in flooded and in flooded AgNO3-treated hypocotyls in comparison with controls. Triphenyl tetrazolium chloride (TTC) is a redox indicator used to markcellular respiration. In fact, when hypocotyl slices are simultaneously incubated with TTC and potassium cyanide,which inhibits mitochondrial cytochrome c oxidase activity, TTC reduction is impaired. Interestingly, in slices offlooded and flooded AgNO3-treated hypocotyls, TTC dyeingwas more intense than in controls. In conclusion, respiratory metabolism in tomato hypocotyls appears unexpectedly exacerbated in the hypoxic environment and,although aerenchyma improves oxygenation in submerged hypocotyls, it does not affect respiration.