Neighbouring plants are known to vary from having similar to dissimilar arbuscular mycorrhizal fungal (AMF) communities. One possibility is that closely related plants have more similar AMF communities than more distantly related plants, an indication of phylogenetic host specificity. However, in a new study published in AoB PLANTS, Reinhart and Anacker observed that mycorrhizal communities were more divergent among closely related plant species than among distantly related plant species. This was counter to the observation that plant mutualists (e.g. pollinators, seed dispersers) are often shared among closely related host plant species. Since mycorrhizae may affect nutrient competition among neighbouring plants, closely related plant neighbours that associate with unique mycorrhizae may have greater functional complementarity and a greater capacity to coexist.
During winter dormancy, temperate trees are capable of only a restricted response to wounding. Depending on the ambient temperature during winter dormancy, wounded trees may start compartmentalization, e.g. by producing inhibitory compounds, but it is thought that processes involving cell proliferation, such as the formation of callus and wound xylem, are delayed until the next growing season. In a recent study published in AoB PLANTS, Copini et al. investigated the effect of wounding on Acer palmatum trees during winter-bud dormancy and found that in the cold (4 °C) treatment, wound reactions were virtually absent. In the warm (15 °C) treatment, however, trees reacted actively to wounding within a three-week period by, e.g., forming callus and local wound xylem. They conclude that temperature is an important factor in wound reactions during winter dormancy and may even induce the formation of callus and wound xylem within a three-week period.
Invasive species represent examples of rapid evolutionary change in a relatively short time period. Lantana camara, a well known invasive plant in the tropics and sub-tropics that has expanded its range and successfully established almost throughout India, is a suitable model system to study the mechanisms underlying its rapid spread and evolution. In a new study in AoB PLANTS, Ray and Ray employed population genetics tools and found differential spread of two genetic varieties across the Indian landscape. Varieties also differ in terms of their climatic adaptation and gene flow, indicating possible local adaptation. Together, this may suggest that these varieties are divergent ecotypes at very early stages of differentiation.
Invasive plants alter plant communities and transform landscapes aboveground, but also have strong belowground effects that are potentially even more important to ecosystem outcomes. In a new study published in AoB PLANTS using management treatments of the widespread invasive tree, Lodgepole Pine, Dickie et al. found that pines and pine removal transform belowground ecosystems, increasing ectomycorrhizal inoculum and driving a change from slow-cycling fungal-dominated soils to fast-cycling bacterial-dominated soils with increased nutrient availability. This results in increased growth of graminoids, particularly exotic grasses, and facilitation of Douglas-fir establishment, hindering ecosystem restoration. The results highlight the importance of considering multiple species interactions in invasion, particularly in terms of belowground legacies.
If you add CO2 or nitrogen to a single plant it will likely grow more, but the amount by which each resource stimulates growth differs widely across species. When you add either resource to a whole ecosystem, total plant growth will likely also increase, but there will be winners and losers, causing a change in the relative abundance of plant species, and therefore altering the way the whole ecosystem responds to the added resource, a “community feedback”. Recent studies have shown that (1) shifts in plant community structure cannot be reliably predicted from short-term plant physiological response to global change and (2) the ecosystem response to multi-factored change is commonly less than the sum of its parts. In a new review published in AoB PLANTS, Langley and Hungate survey the results from long-term field manipulation to examine the role community shifts may play in explaining these common findings. They use a simple model to examine the potential importance of community shifts in governing ecosystem response and show that community dynamics can have a large impact on ecosystem response to any single factor. Understanding tradeoffs in the ability of plants to respond positively to, or to tolerate, different global change drivers may help identify generalizable patterns of covariance in responses to different drivers of change across plant taxa.
In several genera evolutionary chromosome change involves variation in DNA amount in diploids and genome downsizing in polyploids. In a new study in AoB PLANTS, Poggio et al. analysed the genome size and karyotypical parameters of Hippeastrum species with different ploidy levels.The constancy of bimodal karyotypes, even with changes in ploidy level, and DNA content per basic genome indicate that the distribution of DNA within the complement is not random and suggest the presence of mechanisms selecting for constancy, or against change, in the karyotype morphology.
White-tailed deer browsing has been implicated in the loss of species diversity from forests throughout eastern North America. In a new study published in AoB PLANTS, Begley-Miller et al. build on this previous research by examining how browsing also affects phylogenetic community structure in order to better understand the role of deer browsing in the community assembly process. In browsed plots, they found that reductions in phylogenetic diversity were much greater than reductions in species richness or diversity. Species persisting in browsed communities were also closely related. Their findings indicate that deer browsing acts as a biotic filter during the community assembly process. Their study also highlights the importance of utilizing new tools in assessing the influence of deer herbivory on plant communities, and should encourage future advances in our understanding of coexistence in communities.
For many species of conservation significance, multiple factors limit reproduction. In a new study published in AoB PLANTS, Walsh et al. examined the contribution of plant height, number of flowers, number of stems, as well as the joint impacts of mutualists and antagonists on the pollination biology and seed production of the imperiled, deceptive orchid, Cypripedium candidum. They found flowering stem height to be the only morphological feature significant in reproduction, with taller flowering stems simultaneously receiving increased pollination and decreased seed predation. Furthermore they found decreased seed mass in individuals subjected to hand-self pollination treatments. Their results may help explain the factors limiting seed production in other Cypripedium and further emphasize the importance of management in orchid conservation.
Invasive species cause ecological, economic and social impacts and are key drivers of global change. This is the case for the genus Prosopis (mesquite; Fabaceae) where several taxa are among the world’s most damaging invasive species. Prosopis taxa are currently naturalised or invasive in 103 countries and are bioclimatically suitable for many more. There are numerous management practices available to control Prosopis invasions, each with their benefits and costs, however, in most areas management has had only limited success. In a new article published in AoB PLANTS, Shackleton et al. present a global review of Prosopis, focusing on its distribution, impacts, benefits and approaches to management. Key gaps in knowledge and promising options for management are highlighted.
Genome doubling and changes in genome size are fundamental evolutionary processes, with polyploidy being one of the most important forces influencing plant diversification. However, little is currently known about the extent of genome size variation within taxa and the evolutionary forces acting on this variation. Arabidopsis kamchatica has been reported to contain both diploid and tetraploid individuals (2 or 4 copies of every chromosome). In a new study in AoB PLANTS, Wolf et al. found genome size differences among populations, and among populations genome size varied by 7%. However, all sampled A. kamchatica plants from a wide geographic range were tetraploids. This level of intraspecific genome size variation in A. kamchatica is lower than in other Arabidopsis taxa. Due to its close relationship to A. thaliana, A. kamchatica has the potential to be very useful in the study of polyploidy and genome evolution.