Chloroplast-generated reactive oxygen species play a role in leaf development and senescence

MARTÍN MAYTA; NÉSTOR CARRILLO; ANABELLA F. LODEYRO

Rosario

Congreso; L Reunión Anual de SAIB; 2014

Socieda Argentina de Investigacipon en Bioquímica y Biología Molecular

Leaf development can be divided in several processes: i) initiation of primordia, ii) cell proliferation, iii) cell expansion, and iv) senescence. Reactive oxygen species (ROS) are involved in both the early steps of leaf development, and leaf senescence. Noteworthy, the onsets of cell expansion and senescence represent extreme stages of leaf development with a feature in common, an imperfectly assembled photosynthetic electron transport (PET) chain, which is in the process of full assembly in the first case and of collapse in the second. Non-functional PET leads to runaway ROS production. A plastid-targeted flavodoxin (Fld) can increase tolerance to multiple stresses in plants by acting as a general antioxidant specific for chloroplasts preventing ROS accumulation in these organelles. Therefore Fld-expressing lines can be used as tools to probe the role played by chloroplast-generated ROS in different processes undergone by plants. In plants grown under controlled conditions, leaves of the Fld transformants showed a decrease in leaf size caused by a repression of cell expansion. Likewise, Fld expression significantly delayed senescence. The ?stay-green? phenotype was reflected by extended preservation of leaf pigments and photosynthetic activity. Taken together, the results indicate that chloroplast-generated ROS are involved in leaf development and senescence.