The colonization of land by ancestors of embryophyte plants was one of the most significant evolutionary events in the history of life on earth. The lack of a buffering aquatic environment necessitated adaptations for coping with novel abiotic challenges, particularly high light intensities and desiccation as well as the formation of novel anchoring structures.
Bryophytes mark the transition from freshwater to terrestrial habitats and form adaptive features such as rhizoids for soil contact and water uptake, devices for gas exchange along with protective and repellent surface layers. The amphibious liverwort Riccia fluitans can grow as a land form LF or water form WF and was employed to analyze these critical traits in two different habitats. Stable transgenic R. Morphological studies demonstrated that the R.
However, these pores are arrested at an early four cell stage and do not develop further into open pores that could mediate gas exchange. Similarly, also arrested rhizoid initial cells are formed in the WF, which exhibit a distinctive morphology compared to other ventral epidermal cells.
Furthermore, we detected that the LF thallus has a reduced surface permeability compared to the WF, likely mediated by formation of thicker LF cell walls and a distinct cuticle compared to the WF. Our R. Terrestrial colonization is one of the most significant evolutionary episodes in Earth history. Land plants evolved from an ancestral freshwater streptophycean alga and the origin of extant land plant lineages dates back ca MYA de Vries and Archibald, ; Morris et al.
Colonization of land by plants transformed our planet Earth and also changed the evolutionary trajectories of other lineages of life. Novel ecological niches were formed, necessitating morphological and metabolic plant adaptations for a life, lacking buffering aquatic capacities Delwiche and Cooper, ; Rensing, By the early Silurian, land plants had evolved a series of crucial innovations such as adaptative devices for gas exchange, water and nutrient uptake as well as protective cell surface layers Morris et al.
