ROLE OF CHLOROPLAST-GENERATED REACTIVE OXYGEN SPECIES IN THE PLANTS-NECROTROPHIC FUNGI INTERACTION

BISARO, FABIANA; ROSSI, FRANCO; MAIALE, SANTIAGO; PIECKENSTAIN, FERNANDO; CARRILLO, NESTOR; KRAPP, ADRIANA

Rosario

Congreso; 50 Reunion anual de la sociedad argentina de investigaciones en bioquimica y biologia molecula; 2014

Plant pathogenic fungi have evolved two main infection strategies. Biotrophs proliferate within living plant tissues causing minimal damage. Necrotrophic fungi, on the other hand, kill host cells with lytic enzymes and toxins, and  induce processes indicative of programmed cell death in host tissues. There is strong evidence of an oxidative burst at the host-fungal interface, localized cell death and redox-related signaling events. The role of chloroplast-generated reactive oxygen species (ROS) in this process was evaluated in transgenic tobacco plants expressing a plastid-targeted flavodoxin (Fld) and exposed to the necrotrophic fungus Botrytis cinerea. Fld acts as a general antioxidant specific for chloroplasts. Phenotypic, biochemical and microscopic studies were carried out to evaluate the plant-fungus interaction. ROS were visualized with a specific fluorescent probe by confocal microscopy. Leaf necrosis and ROS accumulation caused by fungal infection were reduced in Fld plants, as compared to the wild type. Estimation of photosynthetic parameters showed that Fld lines were less affected by the pathogen, resulting in reduced sensitivity to B. cinerea. Other aspects of the defense response were also analyzed. This study shed light on the role of chloroplast-generated ROS in plant responses to infection by necrotrophic fungi.