GOLGI APPARATUS INVOLVEMENT IN CHLOROPLAST DISMANTLING DURING SENESCENCE.

KRUEGER FALCO; LAUFF DIANA; GUIAMET JUAN J; CARRIÓN CRISTIAN A; SCHUMACHER KARIN

Corrientes

Congreso; XXXI REUNIÓN ARGENTINA DE FISIOLOGÍ A VEGETAL; 2016

Sociedad Argentina de Fisiologia Vegetal

Leaf senescence is associated with nutrient remobilization from leaves to other parts of plants (e.g.seeds, roots). Breakdown of chloroplasts is the main process during leaf senescence, and Senescence-Associated Vacuoles (SAVs) appear to be responsible for the degradation of some photosyntheticproteins. However, the biogenesis of these vacuoles is unknown. These experiments aimed todetermine the involvement of the Golgi apparatus in the biogenesis of SAVs. In senescent Arabidopsisplants expressing the cis-golgi marker ManI domain fused to YFP it was observed that part of this signallocalized to SAVs. Using a line of Arabidopsis expressing VHA-a1:RFP (trans-golgi network marker),partial colocalization with chlorophyll and R6502 (a cysteine protease activity marker) was detected inSAVs. The H + -ATPase inhibitor Concanamicin A (ConcA, 1 μM) blocked the appearance in SAVs of thesenescence specific cysteine peptidase SAG12:GFP after 20 h of treatment. ConcA is known not onlyto inhibit the acidification but also the release of some post-golgi vesicles. With a similar effect, theapplication of 20 μM of Wortmannin, an inhibitor of some Golgi-Vacuole pathways, during 20 h produceda significant decrease of SAVs. These results suggest that the Golgi Apparatus could be involved inSAVs biogenesis, providing the lytic and acidification potential needed for the extraplastidial degradationof stromal proteins