The Evolutionarily Conserved Jasmonate Pathway Positively Affects Desiccation Tolerance on Syntrichia caninervis by Boosting Antioxidant Capacity

Syntrichia caninervis ( S. caninervis ) serves as a model organism for desiccation tolerance research because of its exceptional capacity to withstand 98% cellular water loss. Although jasmonic acid (JA) biosynthesis and signaling genes have been well characterized in vascular plants, their functional and evolutionary roles in bryophytes remain poorly understood. This study demonstrated that exogenous JA treatment significantly delayed the reduction in absolute water content (AWC) and the optimal photochemical efficiency of photosystem II ( Fv/Fm ) during dehydration in S. caninervis , while mitigating reactive oxygen species (ROS) accumulation through enhanced antioxidant enzyme activity. Multi‐omics analyses revealed the upregulation of JA pathway genes during early dehydration, coinciding with JA pathway protein accumulation. Notably, the genes involved in JA biosynthesis undergo phosphorylation and acetylation during dehydration. Genome‐wide analysis identified 34 JA pathway genes in S. caninervis that were uniformly distributed across chromosomes without sex chromosome association. Collinearity analysis confirmed the conservation of the JA pathway genes between S. caninervis and Physcomitrella patens ( P. patens ). Multiple stress‐ and phytohormone‐responsive cis‐elements were enriched in JA pathway genes, highlighting their regulatory adaptation to environmental stresses. In addition, RT‐qPCR analysis revealed that JA pathway genes responded to dehydration, salt, cold, and heat stress. Overall, these findings provide compelling evidence for the evolutionary conservation of JA pathway in terrestrial plants and advance our understanding of their functional mechanisms in desiccation tolerance.