Roles of autophagy in growth and development under optimal and nutrient-deprived conditions in the moss P. patens

PETTINARI G; GONZALEZ CLAUDIO; FINELLO J; LASCANO R; ROBERT G; SAAVEDRA L

Santa Fé

Congreso; XXXIII Argentinian meeting of Plant Physiology (RAFV2021); 2021

Sociedad Argentina de Fisiología Vegetal

Roles of autophagy in growth and development under optimal and nutrient-deprived conditions in the moss P. patensPettinari G1, Finello J2, Robert G1; González C2; Lascano,1,2; Saavedra L11Unidad de Estudios Agropecuarios (UDEA), INTA-CONICET; 2FCEFyN-Uiversidad Nacional de Córdoba; Córdoba, ArgentinaEmail: geor.pettinari@gmail.com; laura.saavedra@conicet.gov.arAutophagy (ATG) is an evolutionarily conserved cellular process that involves sequestration, degradation, and recycling of cytoplasmic components, thus constituting a fundamental mechanism for the maintenance of cellular homeostasis in eukaryotic organisms. Most knowledge and major contributions in the field of plant autophagy arise from studies in seed plants. However, our research is focused on bryophytes, the earliest diverging group of terrestrial flora, using the moss Physcomitrium patens as a model system that allows us to dive into evolutionary aspects regarding the autophagic process and specie-specific roles of this mechanism.In this study, we explore the involvement of autophagy in growth and development under optimal and nutrient-deprived conditions (carbon and nitrogen starvation) in P. patens. We describe the autophagic response of wild type, atg5, and atg7 knock-out lines by phenotypic characterization, PpATG8a-f gene expression analysis, combined with autophagic flux assay and visualization of autophagic vesicles using a PpATG8b::GFP-PpATGb reporter line. Both atg lines showed accelerated senescence under both carbon and nitrogen deficiencies and optimal growth conditions, highlighting that the protective role of autophagy is conserved in P. patens. In addition, atg mutants are characterized by shorter protonemata cells and impaired apical caulonema cell growth rate, and the spread of the colony through protonema growth is prioritized at the expense of a reduction in buds and gametophore development. Taken together, our results show that autophagy highly contributes to the progression of P. patens life cycle in optimal and nutrient-deprived conditions and suggests a role in sustaining the growth of caulonema cell type.