A Matter of Life and Death: Alternative Stable States in Trees, From Xylem to Ecosystems
William Hammond demonstrates that the xylem of trees has characteristics indicative of alternative stable states. Through empirical evidence, he identify a catastrophic shift during hydraulic failure which prevents trees from returning to pre-droughted physiological states after environmental stressors (e.g., drought, heat) are relieved. Thus, the legacy of climate-induced hydraulic failure likely contributes to reduced resilience of forests under future climate.
Frontiers in Forests and Global Change
Fruiting body form, not nutritional mode, is the major driver of diversification in mushroom-forming fungi
Sánchez-García et al. assembled a “megaphylogeny” with 8,400 species that represent ∼23% of the known diversity of Agaricomycetes and used it to investigate the relative impact of fruiting body forms and nutritional modes on diversification rates. Across all Agaricomycetes, a pileate-stipitate fruiting body is associated with increased diversification compared to other forms. No such relationship was found for nutritional modes, including mycorrhizal symbiosis.
A distinct ecotonal tree community exists at central African forest–savanna transitions
Cardoso et al. sampled 28 vegetation transects across forest–savanna ecotones in a central African forest–savanna mosaic. They collected data on the size and species of all established (basal diameter >3 cm) trees in each transect. Split moving window dissimilarity analysis detected the location of borders delineating savanna, ecotone and forest tree communities. They assessed whether the ecotonal tree community was likely to facilitate fire spreading into the forest by burning experimental fires and evaluating shade and grass biomass along the transects. To decide whether the ecotone was likely to facilitate woody encroachment of the savanna, they evaluated if ecotonal tree species were forest pioneers.
Journal of Ecology
The Arabidopsis leucine‐rich repeat receptor‐like kinase MIK2 is a crucial component of early immune responses to a fungal‐derived elicitor
Coleman et al. mapped the causal mutation in fere1 to the leucine‐rich repeat receptor‐like kinase MDIS1‐INTERACTING RECEPTOR‐LIKE KINASE 2 (MIK2) and confirmed a crucial role of MIK2 in fungal elicitor perception. MIK2‐dependent elicitor responses depend on known signaling components and transfer of AtMIK2 is sufficient to confer elicitor sensitivity to Nicotiana benthamiana.
Tissue-specific transcriptome profiling of the Arabidopsis inflorescence stem reveals local cellular signatures
Shi et al. provide gene expression profiles of the mature inflorescence stem of Arabidopsis thaliana covering a comprehensive set of distinct tissues. By combining fluorescence-activated nucleus sorting and laser-capture microdissection with next generation RNA sequencing, they characterized the transcriptomes of xylem vessels, fibers, the proximal and distal cambium, phloem, phloem cap, pith, starch sheath, and epidermis cells. Our analyses classified more than 15,000 genes as being differentially expressed among different stem tissues and revealed known and novel tissue-specific cellular signatures.
The Plant Cell
Enabling evolutionary studies at multiple scales in Apocynaceae through Hyb‐Seq
Target capture sequencing is a powerful approach for genome reduction that facilitates studies requiring data from the nuclear genome in non‐model taxa, such as Apocynaceae. From 853 candidate nuclear genes, 835 were consistently recovered in single copy and were variable enough for phylogenomics. The inferred gene trees were useful for coalescent‐based species tree analysis, which showed all subfamilies of Apocynaceae as monophyletic, while also resolving relationships among species within the genus Apocynum. Intraspecific comparison of Elytropus chilensis individuals revealed numerous single‐nucleotide polymorphisms with potential for use in population‐level studies.
Applications in Plant Sciences
Direct pathogen-induced assembly of an NLR immune receptor complex to form a holoenzyme
Ma et al. studied the Arabidopsis thaliana TIR-NLR RPP1 (recognition of Peronospora parasitica 1) and its response to effectors from an oomycete pathogen.
Structure of the activated ROQ1 resistosome directly recognizing the pathogen effector XopQ
Martin et al. studied the Nicotiana benthamiana TIR-NLR ROQ1 (recognition of XopQ 1) and its response to the Xanthomonas effector.
Interspecific anatomical differences result in similar highly flexible stems in Bignoniaceae lianas
Lianas are intriguing forest components in the tropics worldwide. They are characterized by thin and flexible stems, which have been related to a unique stem anatomy. Here, we hypothesized that the anatomical diversity of lianas, varying in shapes, proportions, and dimensions of tissues and cell types, would result in different stem bending stiffnesses across species. To test this hypothesis, we chose four abundant liana species of central Amazonia belonging to the monophyletic tribe Bignonieae (Bignoniaceae) and compared their basal stems for their anatomical architectures and bending properties.
American Journal of Botany
Plant carbohydrate depletion impairs water relations and spreads via ectomycorrhizal networks
Sapes et al. connected well‐watered Pinus ponderosa seedling pairs via ectomycorrhizal (EM) networks where one seedling was shaded (D) and the other kept illuminated (LD) and compared responses to seedling pairs in full light (L). They measured plant NSC, osmotic and water potential, and transfer of 13CO2 through EM to explore mechanisms linking stored NSC to plant water balance regulation and identify potential tradeoffs between plant water retention and EM fungi under carbon‐limiting conditions.