Abstract
Ferns are one of the oldest vascular plants in existence and they are the second most diverse group of vascular plants followed to angiosperms. To unravel fern success has focused on the eco-physiological power and stress tolerance of their sporophyte and the gametophyte generations. In this context, those insightsencompass plant water relations, as well as the tolerance to and recovery from drought or desiccation stresses in the fern life cycle are reviewed. Lack of secondary xylem in ferns is compensated by selection for efficient primary xylem composed of large, closely arranged tracheids with permeable pit membranes.Protection from drought-induced hydraulic failure appears to arise from a combination of pit membrane traits and the arrangement of vascular bundles. Features such as tracheid-based xylem and variously sized megaphylls are shared between ferns and more derived lineages, and offer an opportunity to compare convergent and divergent hydraulic strategies critical to the success of xylem-bearing plants. Similarly the synthesis and accumulation of sugar, proline and stress proteins along with the production of pool of polyphenols add strength to desiccation stress. Thus, it can possible to suggest that selection acted on the physiology in a synchronous manner that is consistent with selection for drought tolerance in the epiphytic niche, and the increasingly diverse habitats of the mid to late Cenozoic.
Highlights
Phylogenetic analysis reveals that land plants evolved from simple aquatic algal progenitors (Bennici, 2008)
Some land plants relied on the radical mechanism of survival from desiccation: by desiccation tolerance (DT) i.e., those that which can lose from their vegetative structures all internal water and enter into, and recover from, anhydrobiosis, the cessation of metabolic activity as a result of low intracellular water content (Bewley, 1979)
There is good reason to suspect that physiological and morphological traits in the ferns are in a coordinated manner that was consistent with the Cenozoic diversification of the fern epiphytic flora, and possibly other fern radiations across the post-Eocene landscape
Summary
Phylogenetic analysis reveals that land plants evolved from simple aquatic algal progenitors (Bennici, 2008). The radiation of once aquatic species on to dry terrestrial habitat required the evolution of adaptive features suites that permitted life in land To accommodate in this habitat, plants have developed critically two modes of surviving desiccating conditions. Desiccation tolerance requires the complex and organized shut-down of metabolism and the occurrence of DT in many distantly related lineages and life stages indicates that there may be significant variation in the mechanisms behind this phenomenon (Alpert and Oliver, 2002). The sporophyte, the primary stage for dispersal, has a well-developed vascular system and a waxy cuticle complete with stomata These differences alone result in unique life-cycle-mediated ecological strategies, especially as they relate to water relations and demography (Watkins et al, 2007). Because of the well-known resurrection fern like Selaginella sp, the presence of DT in the vascular sporophytes of ferns has been reported to be more common than in other vascular plants. Proctor and Pence (2002) recorded that 64 species of ferns exhibited DT and estimated that less than 1% of all ferns possess such ability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
