New insights into the role of the root system of epiphytic bromeliads: comparison of root and leaf trichome functions in acquisition of water and nutrients.

Background: In epiphytic bromeliads, the roots were previously considered to be poorly functional organs in the processes of absorption and metabolization of water and nutrients, while the leaves were considered to always act as protagonists in both functions. More recent discoveries have been changing this old view of the root system.

Scope: In this review, we address previous ideas regarding the function performed by the roots of epiphytic bromeliads (mere holdfast structures with low physiological activity) and the importance of a reduced or lack of a root system for the emergence of epiphytism.

Transcriptomic and Biochemical Analysis Reveal Integrative Pathways Between Carbon and Nitrogen Metabolism in (Bromeliaceae) Under Drought.

Most epiphytes are found in low-nutrient environments with an intermittent water supply. To deal with water limitation, many bromeliads perform crassulacean acid metabolism (CAM), such as , which shifts from C to CAM and can recycle CO from the respiration while stomata remain closed during daytime and nighttime (CAM-idling mode). Since the absorbing leaf trichomes can be in contact with organic (urea) and inorganic nutrients (NO , NH ) and the urea hydrolysis releases NH and CO, we hypothesized that urea can integrate the N and C metabolism during periods of severe drought.

What does the RuBisCO activity tell us about a C-CAM plant?

Plants that perform the Crassulacean acid metabolism (CAM), which obtain CO overnight and convert it mainly in malic acid, successfully grow in environments with water and nutrient shortages, that is partly associated with their higher water- and nitrogen-use efficiencies. Water and nutrient limitations can impair photosynthesis through the reduction of RuBisCO and increment of photorespiration, disturbing the plant carbon balance. In this context, we conducted a controlled experiment with the epiphytic C-CAM bromeliad Guzmania monostachia to investigate how the combined water and nutritional deficits affect the activity of RuBisCO and its activation state (RAS), and to evaluate the efficiency of photosynthesis during the transition from C to CAM.

Transcriptional foliar profile of the C3-CAM bromeliad Guzmania monostachia.

Guzmania monostachia is an epiphytic tank bromeliad that displays the inducible CAM photosynthesis under stressful conditions and had the highest stomata density in the leaf apex, while the base portion has the highest density of trichomes, which are specialized structures used to acquire water and nutrients from the tank solution. In order to correlate the genetic factors behind these morpho-physiological characteristics along the leaf blade of G. monostachia, a comparative transcriptome analysis was performed to identify the functional enriched pathways and unigenes that could play a role in the apical, middle and basal leaf portions.

Involvement of aquaporins on nitrogen-acquisition strategies of juvenile and adult plants of an epiphytic tank-forming bromeliad.

Depending on the N source and plant ontogenetic state, the epiphytic tank-forming bromeliad Vriesea gigantea can modulate aquaporin expression to maximize the absorption of the most available nitrogen source. Epiphytic bromeliads frequently present a structure formed by the overlapping of leaf bases where water and nutrients can be accumulated and absorbed, called tank. However, this structure is not present during the juvenile ontogenetic phase, leading to differences in nutrient acquisition strategies.

Antioxidant capacity along the leaf blade of the C-CAM facultative bromeliad Guzmania monostachia under water deficit conditions.

Guzmania monostachia (L.) Rusby ex Mez is an epiphytic, rosette-shaped bromeliad that displays variable degrees of crassulacean acid metabolism (CAM) along the leaf under water deficit. The aim of our study was to evaluate whether the production-scavenging system of reactive oxygen species (ROS) along the leaf length of G.

Ammonium intensifies CAM photosynthesis and counteracts drought effects by increasing malate transport and antioxidant capacity in Guzmania monostachia.

Guzmania monostachia (Bromeliaceae) is a tropical epiphyte capable of up-regulating crassulacean acid metabolism (CAM) in its photosynthetic tissues in response to changing nutrient and water availability. Previous studies have shown that under drought there is a gradient of increasing CAM expression from the basal (youngest) to the apical (oldest) portion of the leaves, and additionally that nitrogen deficiency can further increase CAM intensity in the leaf apex of this bromeliad. The present study investigated the inter-relationships between nitrogen source (nitrate and/or ammonium) and water deficit in regulating CAM expression in G.

The contribution of weak CAM to the photosynthetic metabolic activities of a bromeliad species under water deficit.

The Crassulacean acid metabolism (CAM) can be a transitory strategy for saving water during unfavourable conditions, like a dry season. In some cases, CAM can also contribute to the maintenance of photosynthetic integrity, even if carbon gain and growth are impaired. CAM occurs in different intensities, being stronger or weaker depending on the degree of nocturnal malic acid accumulation.

Proton and anion transport across the tonoplast vesicles in bromeliad species.

Crassulacean acid metabolism (CAM) is one of the key innovations in the Neotropical family Bromeliaceae that has enabled many of its species to occupy seasonally water-limited terrestrial environments or microclimatically arid epiphytic niches. However, the relationship between CAM activity and the transport processes responsible for vacuolar organic-acid accumulation at night has not been systematically explored in this family. In the present investigation, ATP- and PPi-dependent proton transport rates were studied in tonoplast membrane vesicles isolated from leaves of six CAM and one C3 species of bromeliads.

Nitrate enhancement of CAM activity in two Kalanchoë species is associated with increased vacuolar proton transport capacity.

Among species that perform CAM photosynthesis, members of the genus Kalanchoë have been studied frequently to investigate the effect of environmental factors on the magnitude of CAM activity. In particular, different nitrogen sources have been shown to influence the rate of nocturnal CO fixation and organic-acid accumulation in several species of Kalanchoë. However, there has been little investigation of the interrelationship between nitrogen source (nitrate versus ammonium), concentration and the activity of the vacuolar proton pumps responsible for driving nocturnal organic-acid accumulation in these species.

Alternative fluorimetric-based method to detect and compare total S-nitrosothiols in plants.

Nitric oxide (NO) is an important signaling molecule occurring in virtually all organisms, whose mechanism of action relies mainly on its interaction with proteins or peptides by nitrosylation, forming compounds such as S-nitrosothiols (SNO). The Saville reaction and the ozone-based chemiluminescence method are the main techniques used for nitrosylated protein quantification. While the Saville assay is not very sensitive, the ozone-based chemiluminescence is expensive and time-consuming.

Adjustments in CAM and enzymatic scavenging of HO in juvenile plants of the epiphytic bromeliad Guzmania monostachia as affected by drought and rewatering.

Juvenile plants of epiphytes such as bromeliads are highly prone to dehydration under drought conditions. It is likely that young epiphytes evolved mostly metabolic strategies to resist drought, which may include the plastic modulation of the enzymatic antioxidant system and crassulacean acid metabolism (CAM). Few studies have investigated such strategies in juvenile epiphytes, although such research is important to understand how these plants might face drought intensification derived from potential climatic alterations.

Trade-off between soluble protein production and nutritional storage in Bromeliaceae.

Background And Aims: Bromeliads are able to occupy some of the most nutrient-poor environments especially because they possess absorptive leaf trichomes, leaves organized in rosettes, distinct photosynthetic pathways [C, Crassulacean acid metabolism (CAM) or facultative C-CAM], and may present an epiphytic habit. The more derived features related to these traits are described for the Tillandsioideae subfamily. In this context, the aims of this study were to evaluate how terrestrial predators contribute to the nutrition and performance of bromeliad species, subfamilies and ecophysiological types, whether these species differ in their ecophysiological traits and whether the physiological outcomes are consistent among subfamilies and types (e.

Implications of leaf ontogeny on drought-induced gradients of CAM expression and ABA levels in rosettes of the epiphytic tank bromeliad Guzmania monostachia.

Guzmania monostachia is an epiphytic heteroblastic bromeliad that exhibits rosette leaves forming water-holding tanks at maturity. Different portions along its leaf blades can display variable degrees of crassulacean acid metabolism (CAM) up-regulation under drought. Since abscisic acid (ABA) can act as an important long-distance signal, we conducted a joint investigation of ontogenetic and drought impacts on CAM intensity and ABA levels in different leaf groups within the G.

Spatial patterns of photosynthesis in thin- and thick-leaved epiphytic orchids: unravelling C3-CAM plasticity in an organ-compartmented way.

Background And Aims: A positive correlation between tissue thickness and crassulacean acid metabolism (CAM) expression has been frequently suggested. Therefore, this study addressed the question of whether water availability modulates photosynthetic plasticity in different organs of two epiphytic orchids with distinct leaf thickness.

Methods: Tissue morphology and photosynthetic mode (C3 and/or CAM) were examined in leaves, pseudobulbs and roots of a thick-leaved (Cattleya walkeriana) and a thin-leaved (Oncidium 'Aloha') epiphytic orchid.

Spatial division of phosphoenolpyruvate carboxylase and nitrate reductase activity and its regulation by cytokinins in CAM-induced leaves of Guzmania monostachia (Bromeliaceae).

Crassulacean acid metabolism (CAM) is a physiological adaptation of plants that live in stress environment conditions. A good model of CAM modulation is the epiphytic bromeliad, Guzmania monostachia, which switches between two photosynthetic pathways (C3-CAM) in response to different environmental conditions, such as light stress and water availability. Along the leaf length a gradient of acidity can be observed when G.

Abscisic acid and nitric oxide signaling in two different portions of detached leaves of Guzmania monostachia with CAM up-regulated by drought.

Guzmania monostachia is an epiphyte tank bromeliad capable of up-regulating crassulacean acid metabolism (CAM) in response to several environmental stimuli, including drought and light stress. In other plant species, abscisic acid (ABA) and nitric oxide (NO) seem to be involved in CAM induction. Because the leaves of tank bromeliads perform different functions along their length, this study attempted to investigate whether ABA and NO are involved in regulation of CAM expression in this species by quantifying these compounds in apical and basal portions of the leaf, and whether there would be differences in this event for each leaf portion.

Spider-fed bromeliads: seasonal and interspecific variation in plant performance.

Background And Aims: Several animals that live on bromeliads can contribute to plant nutrition through nitrogen provisioning (digestive mutualism). The bromeliad-living spider Psecas chapoda (Salticidae) inhabits and breeds on Bromelia balansae in regions of South America, but in specific regions can also appear on Ananas comosus (pineapple) plantations and Aechmea distichantha.

Methods: Using isotopic and physiological methods in greenhouse experiments, the role of labelled ((15)N) spider faeces and Drosophila melanogaster flies in the nutrition and growth of each host plant was evaluated, as well as seasonal variation in the importance of this digestive mutualism.

Nitrogen metabolism in leaves of a tank epiphytic bromeliad: characterization of a spatial and functional division.

The leaf is considered the most important vegetative organ of tank epiphytic bromeliads due to its ability to absorb and assimilate nutrients. However, little is known about the physiological characteristics of nutrient uptake and assimilation. In order to better understand the mechanisms utilized by some tank epiphytic bromeliads to optimize the nitrogen acquisition and assimilation, a study was proposed to verify the existence of a differential capacity to assimilate nitrogen in different leaf portions.

Correlation between citric acid and nitrate metabolisms during CAM cycle in the atmospheric bromeliad Tillandsia pohliana.

Crassulacean acid metabolism (CAM) confers crucial adaptations for plants living under frequent environmental stresses. A wide metabolic plasticity can be found among CAM species regarding the type of storage carbohydrate, organic acid accumulated at night and decarboxylating system. Consequently, many aspects of the CAM pathway control are still elusive while the impact of this photosynthetic adaptation on nitrogen metabolism has remained largely unexplored.

Nitric oxide mediates the hormonal control of Crassulacean acid metabolism expression in young pineapple plants.

Genotypic, developmental, and environmental factors converge to determine the degree of Crassulacean acid metabolism (CAM) expression. To characterize the signaling events controlling CAM expression in young pineapple (Ananas comosus) plants, this photosynthetic pathway was modulated through manipulations in water availability. Rapid, intense, and completely reversible up-regulation in CAM expression was triggered by water deficit, as indicated by the rise in nocturnal malate accumulation and in the expression and activity of important CAM enzymes.

Nitrogen fluxes from treefrogs to tank epiphytic bromeliads: an isotopic and physiological approach.

Diverse invertebrate and vertebrate species live in association with plants of the large Neotropical family Bromeliaceae. Although previous studies have assumed that debris of associated organisms improves plant nutrition, so far little evidence supports this assumption. In this study we used isotopic ((15)N) and physiological methods to investigate if the treefrog Scinax hayii, which uses the tank epiphytic bromeliad Vriesea bituminosa as a diurnal shelter, contributes to host plant nutrition.

Specific leaf areas of the tank bromeliad Guzmania monostachia perform distinct functions in response to water shortage.

Leaves comprise most of the vegetative body of tank bromeliads and are usually subjected to strong longitudinal gradients. For instance, while the leaf base is in contact with the water accumulated in the tank, the more light-exposed middle and upper leaf sections have no direct access to this water reservoir. Therefore, the present study attempted to investigate whether different leaf portions of Guzmania monostachia, a tank-forming C(3)-CAM bromeliad, play distinct physiological roles in response to water shortage, which is a major abiotic constraint in the epiphytic habitat.

Thermoperiod affects the diurnal cycle of nitrate reductase expression and activity in pineapple plants by modulating the endogenous levels of cytokinins.

Nitrate reductase (NR, EC 1.6.6.

Detection of urease in the cell wall and membranes from leaf tissues of bromeliad species.

Urea is an important nitrogen source for some bromeliad species, and in nature it is derived from the excretion of amphibians, which visit or live inside the tank water. Its assimilation is dependent on the hydrolysis by urease (EC: 3.5.