Strategic roadmap to assess forest vulnerability under air pollution and climate change

Although it is an integral part of global change, most of the research addressing the effects of climate change on forests have overlooked the role of environmental pollution. Similarly, most studies investigating the effects of air pollutants on forests have generally neglected the impacts of climate change. We review the current knowledge on combined air pollution and climate change effects on global forest ecosystems and identify several key research priorities as a roadmap for the future. Specifically, we recommend (1) the establishment of much denser array of monitoring sites, particularly in the South Hemisphere; (2) further integration of ground and satellite monitoring; (3) generation of flux-based standards and critical levels taking into account the sensitivity of dominant forest tree species; (4) long-term monitoring of N, S, P cycles and base cations deposition together at global scale; (5) intensification of experimental studies, addressing the combined effects of different abiotic factors on forests by assuring a better representation of taxonomic and functional diversity across the similar to 73,000 tree species on Earth; (6) more experimental focus on phenomics and genomics; (7) improved knowledge on key processes regulating the dynamics of radionuclides in forest systems; and (8) development of models integrating air pollution and climate change data from long-term monitoring programs.</p

Hexose Kinases and Their Role in Sugar-Sensing and Plant Development

Hexose sugars, such as glucose and fructose produced in plants, are ubiquitous in most organisms and are the origin of most of the organic matter found in nature. To be utilized, hexose sugars must first be phosphorylated. The central role of hexose-phosphorylating enzymes has attracted the attention of many researchers, leading to novel discoveries. Only two families of enzymes capable of phosphorylating glucose and fructose have been identified in plants; hexokinases (HXKs), and fructokinases (FRKs). Intensive investigations of these two families in numerous plant species have yielded a wealth of knowledge regarding the genes number, enzymatic characterization, intracellular localization, and developmental and physiological roles of several HXKs and FRKs. The emerging picture indicates that HXK and FRK enzymes found at specific intracellular locations play distinct roles in plant metabolism and development. Individual HXKs were shown for the first time to be dual-function enzymes – sensing sugar levels independent of their catalytic activity and controlling gene expression and major developmental pathways, as well as hormonal interactions. FRK, on the other hand, seems to play a central metabolic role in vascular tissues, controlling the amounts of sugars allocated for vascular development. While a clearer picture of the roles of these two types of enzymes is emerging, many questions remain unsolved, such as the specific tissues and types of cells in which these enzymes function, the roles of individual HXK and FRK genes, and how these enzymes interact with hormones in the regulation of developmental processes. It is anticipated that ongoing efforts will broaden our knowledge of these important plant enzymes and their potential uses in the modification of plant traits

LYRATE Is a Key Regulator of Leaflet Initiation and Lamina Outgrowth in Tomato[C][W][OA]

Development of the flattened laminar structure in plant leaves requires highly regulated cell division and expansion patterns. Although tight regulation of these processes is essential during leaf development, leaf shape is highly diverse across the plant kingdom, implying that patterning of growth must be amenable to evolutionary change. Here, we describe the molecular identification of the classical tomato (Solanum lycopersicum) mutant lyrate, which is impaired in outgrowth of leaflet primodia and laminar tissues during compound leaf development. We found that the lyrate phenotype results from a loss-of-function mutation of the tomato JAGGED homolog, a well-described positive regulator of cell division in lateral organs. We demonstrate that LYRATE coordinates lateral outgrowth in the compound leaves of tomato by interacting with both the KNOX and auxin transcriptional networks and suggest that evolutionary changes in LYRATE expression may contribute to the fundamental difference between compound and simple leaves

The effect of climate on wood density:What provenance trials tell us?

Wood density, considered a heritable trait, is often associated with drought tolerance and can be a useful trait for tree breeders to select drought-tolerant provenances. Provenance trials are a useful tool to disentangle genetic variation from plasticity of adaptive traits among populations within the same species. If wood density is a strongly heritable trait selected by climatic conditions, we hypothesize that its variation in provenance trials should be shaped by the provenance climatic variables. To test our hypothesis we collected wood density data of provenance trials from the literature. We used thirty publications published between 1966 and 2015 including 25 species (13 angiosperms and 12 gymnosperms). At the intraspecific level, eight species showed significant positive correlations between wood density and drought conditions of the provenance, two species showed the opposite trend and the remaining 15 species showed no correlation with the climatic conditions of the provenances. For the 10 species with wood density strongly linked to the climatic conditions of the provenance, such relationship reflects a strong genetic determinism and a theoretical fitness optimum. For the other 15 species, wood density does not seem to be the main selection target of drought. This information is critical in the frame of breeding programs for selecting provenances more adaptable to different climate change scenarios

Sucrose-induced stomatal closure is conserved across evolution.

As plants evolved to function on land, they developed stomata for effective gas exchange, for photosynthesis and for controlling water loss. We have recently shown that sugars, as the end product of photosynthesis, close the stomata of various angiosperm species, to coordinate sugar production with water loss. In the current study, we examined the sugar responses of the stomata of phylogenetically different plant species and species that employ different photosynthetic mechanisms (i.e., C3, C4 and CAM). To examine the effect of sucrose on stomata, we treated leaves with sucrose and then measured their stomatal apertures. Sucrose reduced stomatal aperture, as compared to an osmotic control, suggesting that regulation of stomata by sugars is a trait that evolved early in evolutionary history and has been conserved across different groups of plants