Physcomitrium patens: an emerging model for autophagy study.

Physcomitrium patens (formerly Physcomitrella patens), a model moss species, has emerged as an invaluable system for studying autophagy in plants. This review highlights the unique advantages of P. patens for autophagy research, including its efficient homologous recombination in mitotic cells, simple body plan, haploid-presiding life cycle, and accessibility to microscopic observation. I discuss recent advances in understanding autophagy mechanisms in P. patens, particularly focusing on the role of core autophagy-related (ATG) genes in growth, development, stress responses, and cell death. The characterization of autophagy-deficient mutants revealed unexpected roles of autophagy in promoting cell death under oxidative stress and desiccation, in contrast with classical survival functions. I also examine the conservation and divergence of the autophagy machinery between mosses and vascular plants, emphasizing how P. patens bridges evolutionary gaps in our understanding of plant autophagy. Finally, I outline future perspectives on the use of this model system to address fundamental questions about selective autophagy, autophagosome dynamics, and the integration of autophagy with developmental programs.