Autophagy as an energy regulator? Its impact on the growth and development of P. patens

LIBERATORE F; PETTINARI G; SCHENFELD E; SAAVEDRA LAURA

Rosario

Congreso; . Sociedad Argentina de Fisiologia Vegetal; 2024

Autophagy is a crucial cellular process responsible for the degradation and recycling of cellular components. In plants it plays a key role in the modulation of growth and development, as well as in stress responses, providing both pro-life and pro-death functions. Even in optimal conditions, the metabolic state of the cell is known to affect and be affected by autophagy. The bryophyte Physcomitrium patens represents an ideal model to study this process in relation to apical growth and the transition of 2D to 3D growth. In this plant, autophagy is activated by darkness during the night, and it is known that loss of autophagic function mutants such as atg5 and atg7 show accelerated senescence and impaired growth, effects which are exacerbated under nutrient insufficient conditions.We set out to gauge the metabolic state of these mutants during their normal day-night cycle by measuring their starch, sugar, and adenylate content in comparison to the wild-type. We found that the autophagic mutants show a lower amount of starch, but, surprisingly, a higher ATP:ADP ratio than the WT, while the sugar content differed according to each kind of sugar. We also studied the effects of different sugars on the growth and development of these lines, and found that glucose delayed the transition to 3D growth and reverted the senescent phenotype of atg5, effects which were not replicated by sucrose. Furthermore, glucose and sucrose had distinctive effects on autophagic activity during the night. Further research is ongoing to dissect the origin of the senescence shown by atg mutants, by analyzing their redox state and the cell death pattern observed along pronotema filaments.Our results provide clues that autophagy is an important process for maintaining the metabolic and energetic status of plants during the diurnal cycle, and that different sources of energy can regulate this process in distinct ways, impacting on the modulation of plant growth and development