Ethylene-induced aerenchyma and stem hypertrophy in flooded tomato plants

VIDOZ, M.L.; DE PEDRO, F.; MIGNOLLI, F.

Corrientes

Congreso; Reunión Argentina de Fisiología Vegetal; 2016

Tomato plants form a new adventitious root system in response to flooding and subsequent death of the original roots. Normal functioning of adventitious roots depends on the diffusion of oxygen from the atmosphere into submerged tissues, which is facilitated by aerenchyma development. We studied the involvement of ethylene in aerenchyma formation and stem hypertrophy of flooded tomato plants. Microscopic studies revealed that stem aerenchyma production, associated with cortex cell expansion, was evident after 24h from the onset of flooding. Both aerenchyma development and stem hypertrophy were effectively blocked by an ethylene action inhibitor (AgNO3). Concomitantly, stem porosity was reduced by limiting ethylene action. The role of ethylene was confirmed by using the Never ripe mutant, which is partially insensitive to ethylene and developed less porosity when flooded in comparison to its wild-type. We also analyzed the expression level of genes involved in cell wall loosening (LeEXPA1, LeEXPA2, Cel7 y SlXTH1) in stems from control, flooded and AgNO3-treated flooded plants. Our data suggest that ethylene causes the early induction of these genes, leading to stem hypertrophy in flooded plants. In conclusion, ethylene evolution in flooded tomato plants seems to be the trigger of these adaptive responses that result in plant survival.