Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects.We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives. Geosphere-Biosphere Program (IGBP) and DIVERSITAS, the TRY database (TRY-not an acronym, rather a statement of sentiment; https ://www.try-db.org; Kattge et al., 2011) was proposed with the explicit assignment to improve the availability and accessibility of plant trait data for ecology and earth system sciences. The Max Planck Institute for Biogeochemistry (MPI-BGC) offered to host the database and the different groups joined forces for this community-driven program. Two factors were key to the success of TRY: the support and trust of leaders in the field of functional plant ecology submitting large databases and the long-term funding by the Max Planck Society, the MPI-BGC and the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, which has enabled the continuous development of the TRY database.

Nearly two-thirds of extant bromeliads belong to two large radiations: the core tillandsioids, originating in the Andes ca. 14.2 Ma, and the Brazilian Shield bromelioids, originating in the Serro do Mar and adjacent regions ca. 9.1 Ma.

Summary Stable carbon isotope ratios (δ13C) of terrestrial plants are employed across a diverse range of applications in environmental and plant sciences; however, the kind of information that is desired from the δ13C signal often differs. At the extremes, it ranges between purely environmental and purely biological. Here, we review environmental drivers of variation in carbon isotope discrimination (Δ) in terrestrial plants, and the biological processes that can either damp or amplify the response. For C3 plants, where Δ is primarily controlled by the ratio of intercellular to ambient CO2 concentrations (ci/ca), coordination between stomatal conductance and photosynthesis and leaf area adjustment tends to constrain the potential environmentally driven range of Δ. For C4 plants, variation in bundle‐sheath leakiness to CO2 can either damp or amplify the effects of ci/ca on Δ. For plants with crassulacean acid metabolism (CAM), Δ varies over a relatively large range as a function of the proportion of daytime to night‐time CO2 fixation. This range can be substantially broadened by environmental effects on Δ when carbon uptake takes place primarily during the day. The effective use of Δ across its full range of applications will require a holistic view of the interplay between environmental control and physiological modulation of the environmental signal.

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The large Neotropical family Bromeliaceae presents an outstanding example of adaptive radiation in plants, containing a wide range of terrestrial and epiphytic life-forms occupying many distinct habitats. Diversification in bromeliads has been linked to several key innovations, including water-and nutrient-impounding phytotelmata, absorptive epidermal trichomes, and the water-conserving mode of photosynthesis known as crassulacean acid metabolism (CAM). To clarify the origins of CAM and the epiphytic habit, we conducted a phylogenetic analysis of nucleotide sequences for 51 bromeliad taxa by using the plastid loci matK and the rps16 intron, combined with a survey of photosynthetic pathway determined by carbon-isotope ratios for 1,873 species representing 65% of the family. Optimization of character-states onto the strict consensus tree indicated that the last common ancestor of Bromeliaceae was a terrestrial C 3 mesophyte, probably adapted to moist, exposed, nutrient-poor habitats. Both CAM photosynthesis and the epiphytic habit evolved a minimum of three times in the family, most likely in response to geological and climatic changes in the late Tertiary. The great majority of epiphytic forms are now found in two lineages: in subfamily Tillandsioideae, in which C 3 photosynthesis was the ancestral state and CAM developed later in the most extreme epiphytes, and in subfamily Bromelioideae, in which CAM photosynthesis predated the appearance of epiphytism. Subsequent radiation of the bromelioid line into less xeric habitats has led to reversion to C 3 photosynthesis in some taxa, showing that both gain and loss of CAM have occurred in the complex evolutionary history of this family. The Bromeliaceae are frequently celebrated as an outstanding example of adaptive radiation in vascular plants (1, 2). They represent one of the largest families with a Neotropical distribution (3), comprising 2,885 species in 56 genera (4, 5), with an ecological range that encompasses extremes of moisture availability (from rain forests to hyperarid coastal sands), elevation (from sea level to Ͼ4,000 m), and exposure (fully exposed sites to shaded forest understories). The family contains a correspondingly rich diversity of life-forms, from soil-rooted terrestrial plants, through rosulate ''tank'' epiphytes with water-and nutrient-impounding phytotelmata, to extreme epiphytes completely independent of their substratum for nutrition. The evolutionary transition from terrestrial to epiphytic life-forms appears to have been closely linked to elaboration of the absorptive epidermal trichomes characteristic of the family (1, 6, 7). Indeed, about half of all bromeliads are epiphytic, and they constitute one of the most distinctive components of the Neotropical forest canopy (8, 9).In addition to morphological specializations, another key innovation associated with the success of bromeliads in more arid habitats is the form of photosynthesis known as crassulacean acid metabolism (CAM) (10-13). In typical CAM plants, CO 2 is taken up at night ...

Elevated CO 2 (eCO 2) experiments provide critical information to quantify the effects of rising CO 2 on vegetation 1,2,3,4,5,6. Many eCO 2 experiments suggest that nutrient limitations modulate the local magnitude of the eCO 2 effect on plant biomass 1,3,5 , but the global extent of these limitations has not been empirically quantified, complicating projections of the capacity of plants to take up CO 2 7,8. Here, we present a data-driven global quantification of the eCO 2 effect on biomass based on 138 eCO 2 experiments. The strength of CO 2 fertilization is primarily driven by nitrogen (N) in ~65% of global vegetation and by phosphorus (P) in ~25% of global vegetation, with Nor Plimitation modulated by mycorrhizal association. Our approach suggests that CO 2 levels expected by 2100 can potentially enhance plant biomass by 12 ± 3% above current values, equivalent to 59 ± 13 PgC. The global-scale response to eCO 2 we derive from experiments is similar to past changes in greenness 9 and biomass 10 with rising CO 2 , suggesting that CO 2 will continue to stimulate plant biomass in the future despite the constraining effect of soil nutrients. Our research reconciles conflicting evidence on CO 2 fertilization across scales and provides an empirical estimate of the biomass sensitivity to eCO 2 that may help to constrain climate projections.

Crassulacean acid metabolism (CAM) is a water-use efficient adaptation of photosynthesis that has evolved independently many times in diverse lineages of flowering plants. We hypothesize that convergent evolution of protein sequence and temporal gene expression underpins the independent emergences of CAM from C3 photosynthesis. To test this hypothesis, we generate a de novo genome assembly and genome-wide transcript expression data for Kalanchoë fedtschenkoi, an obligate CAM species within the core eudicots with a relatively small genome (~260 Mb). Our comparative analyses identify signatures of convergence in protein sequence and re-scheduling of diel transcript expression of genes involved in nocturnal CO2 fixation, stomatal movement, heat tolerance, circadian clock, and carbohydrate metabolism in K. fedtschenkoi and other CAM species in comparison with non-CAM species. These findings provide new insights into molecular convergence and building blocks of CAM and will facilitate CAM-into-C3 photosynthesis engineering to enhance water-use efficiency in crops.

Comparative studies of chlorophyll a fluorescence, measured with a pulse amplitude modulated fluorometer, and of the pigment composition of leaves, suggest a specific role of zeaxanthin, a carotenoid formed in the xanthophyll cycle, in protecting the photosynthetic apparatus aginst the adverse effects of excessive light. This conclusion is based on the following fmdings: (a) (7), photoinhibitory damage to PSII reaction centers, i.e. a decrease in the rate constant for PSII photochemistry, leads to a rise in initial fluorescence at open PSII traps, F0,3 whereas an increase in the rate constant ofnonradiative energy dissipation leads to a decrease in both initial fluorescence, FO, and maximum fluorescence at closed PSII traps, FM. Such an increase in thermal de-excitation could function as an overflow valve to allow for nondestructive dissipation of excess excitation energy and may therefore be viewed as a potentially protective process rather than as an indication of damage, e.g. to proteins (10) of the thylakoid membrane. Increased nonradiative energy dissipation, as indicated by Chl 77 K fluorescence characteristics, was shown to occur under conditions of excess excitation in low light (in 2% 02 and the absence of C02) with no evidence for simultaneous photoinhibitory damage to the PSII reaction centers, as well as at high light levels where there was evidence for simultaneous damage (4). This paper presents a striking parallel between the occurrence of conditions, at both high and low light levels, under which increased nonradiative energy dissipation is observed, and the accumulation of the carotenoid zeaxanthin in leaves exposed to such conditions. Zeaxanthin is known to be formed by deepoxidation of violaxanthin in the so-called violaxanthin or xanthophyll cycle which is present in thylakoid membranes and which is fine-tuned to respond to the balance of electron transport reactions and CO2 uptake (6, 23). The function of this cycle has been unknown thus far. We propose that the formation of zeaxanthin under photoinhibitory conditions is indicative of a specific function of this particular carotenoid compound in the prevention of photoinhibitory damage.