Chloroplast dismantling during leaf senescence: mechanism and impact on crop yield

GUIAMET JJ

Córdoba

Congreso; XXXII Reunión Argentina de Fisiología Vegetal - XVI Congreso Latinoamericano de Fisiología Vegetal; 2018

Asociación Sociedad Argentina de Fisiología Vegetal

Senescence is the last phase in leaf development, priorto leaf death. The main symptom of senescence is thedismantling of the photosynthetic machinery, whichcauses photosynthesis and other assimilatory processes to decline. This has led to the proposal that a delayin leaf senescence might increase C assimilation bycrops, thereby increasing potential grain yield.In recent years, several extra-chloroplastic pathwaysinvolved in chloroplast protein degradation have beendescribed, including Rubisco-Containing Bodies, Senescence-Associated Vacuoles (SAVs), CV-ContainingVesicles and ATI-PS Bodies.Whether these vesicularstructures are different entities, or they represent thesame structure visualized and studied with differentprobes is an unresolved question. In any event, theSAG12 protease, localized to SAVs, is starting to emergeas an important player in Rubisco degradation.Finally, experiments with field crops challenge the common assumption that delaying senescence might boostgrain yield. Instead, the study of delayed-senescencegenotypes underscores a complex interaction with environmental conditions, and potential trade-offs between yield and grain quality.