Modifications on root mitochondria during dark-induced senescence

CARLOS GUILLERMO BARTOLI; DIEGO DARÍO FANELLO; JUAN JOSÉ GUIAMET

Rosario

Congreso; 8th International Conference for Plant Mitochondrial Biology (ICPMB 2013); 2013

The ICPMB 2013 Organizing Team

Senescence traditionally refers to degradative processes in leaves and mainly in chloroplast. Studies about modifications in plant root metabolism and mitochondrial associated activities during senescence are scarce. The experiments of this work are attempted to study mitochondria modifications during plant development. Arabidopsis thaliana plants with a targeting signal to mitochondria fused to YFP were used. This plant were cultivated in a hydroponic system at 22°C, 150 µmole m-2 s-1 (PPFD) and de 8/16 h light/darkness photoperiod. Seven weeks-old plants were induced to senesces under darkness for 10 days. Roots of darkened plant showed a detention of growth whereas control plants under light continued growing. Respiration rate was 70% less in roots of darkened plants compared with those of control plants. Epiflorescence and confocal images showed a remarkable decrease (46%) in the total pool of mitochondria (YFP labeled mitochondria) and even highest decrease (92%) in the active pool of mitochondria (Mitotracker red labeled mitochondria). Moreover, size distribution changed with senescence since roots of darkened plants presented increased proportion of larger mitochondria with decreased in the proportion of small ones compare with control plants. Western blot analysis showed lower mitochondrial protein in darkened plants compared with control plants. These results suggest a declining of activity and structural changes in root chondriome during senescence.