The evolution of robust DNA repair mechanisms was a prerequisite for the conquest of land by plants, a transition that exposed them to harsh new environmental stressors. The poly (ADP-ribose) polymerase (PARP) family is central to this adaptation, as it orchestrates DNA repair and stress signaling pathways essential for coping with the elevated UV radiation and desiccation of terrestrial environments. Yet its early evolutionary origins are unknown. Here, we present a comprehensive reconstruction of the PARP family’s history across the plant kingdom. Our phylogenomic analysis reveals that PARP evolution ignited during the bryophyte radiation, expanding from a single ancestral algal gene into three distinct subfamilies (PARP1, PARP2, and PARP3). This diversification was driven by structural innovations in DNA-binding domains and a rewiring of transcriptional networks to respond to terrestrial challenges. We provide direct experimental support for this hypothesis through functional analysis of PARPs from the extremotolerant moss Syntrichia caninervis. We show that its PARP proteins provide multifaceted protection against UV radiation, heat, and genotoxic agents, and that recently duplicated PARP2 genes are already diverging in function. Our work pinpoints the molecular adaptations in a key DNA repair family that enabled the greening of Earth and uncovers novel genetic targets for enhancing crop resilience.

Halostachys caspica is a salt-tolerant shrub widely distributed on saline-alkali soils in Xinjiang, but research on its salt-tolerance mechanisms has been limited by the lack of reliable regeneration and transformation protocols. We optimized seed germination on 1/2 MS medium with 45 g/L sucrose, significantly raising rates from 8.7% to 70.3% and providing adequate explant material. For regeneration, we developed two complementary protocols: a conventional route using seedling-derived assimilation branches, with optimal adventitious bud induction on medium containing 100 mM NaCl and 1 mg/L 6-BA, followed by transfer to proliferation medium (100 mM NaCl, 0.8 mg/L 6-BA, 0.5 mg/L IBA) that resulted in simultaneous proliferation, elongation, and rooting; and an accelerated protocol using regenerated plantlet assimilation branches, which produced complete plantlets within 35 days on medium with 1 mg/L IBA and 100 mM NaCl, establishing an effective rapid propagation system. Using these explants, we optimized Agrobacterium-mediated transformation parameters, achieving over 90% transient transformation efficiency. Together, this regeneration and transformation platform will facilitate functional dissection of stress-responsive genes and regulatory networks, while the rapid propagation protocol provides reliable planting material and may serve as a reference for other woody plants and halophytes lacking established regeneration systems.