An Overview of Water and Nutrient Uptake by Epiphytic Bromeliads: New Insights into the Absorptive Capability of Leaf Trichomes and Roots

Abstract

AbstractThe presence of specific morphological structures, such as the formation of a tank and the presence of leaf absorbing trichomes, together with peculiar adaptive strategies to capture resources in the epiphytic environment, can be considered one of the most important characteristics that explain the occupational success of several species of bromeliads in the forest canopy. In view of the great importance that specialized nutrition represents for epiphytic bromeliads, this chapter gathers the most recent findings regarding the strong influence that ontogenetic stages and some abiotic factors, such as nitrogen nutrition, can exert on the anatomical formation, absorptive capability and distribution of trichomes present on the leaf surface. Studies showing the existence of water inward transport systems involving high- and low-affinity membrane transport proteins and aquaporins are also discussed. Furthermore, we present new discoveries about how the process of water uptake occurs through the entire anatomical structure of the trichome, highlighting the relevance of the wing cells of the shield. Important advances in recent studies regarding the physiological function of the roots of epiphytic bromeliads are also highlighted. Contrary to what was believed in the past regarding the roots of these plants, considering them no more than holdfast structures, the roots of some species of epiphytic tank-forming bromeliads have shown to play an important role in the processes of absorption and metabolization of resources. The new findings related to (1) the influence of developmental stages on the absorptive capability of the roots of epiphytic tank-forming bromeliads, (2) the independence of the absorption mechanisms exerted by the trichomes and roots, and (3) the synergy between the processes of resource uptake carried out by the root system and leaf absorbing trichomes are also presented and discussed in this chapter.