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1. Spatial variation in phylogenetic diversity of communities of Atlantic Forest harvestmen (Opiliones, Arachnida)

   https://doi.org/10.1111/icad.12356  

   Nogueira, André do Amaral ; Bragagnolo, Cibele ; DaSilva, Márcio Bernardino ; Carvalho, Leonardo Sousa ; Benedetti, Alípio Rezende ; Pinto‐da‐Rocha, Ricardo ; Basset, ed., Yves ; Buddle, ed., Chris ( June 2019 , Insect Conservation and Diversity)

   The study of diversity has become increasingly sophisticated, including the use of measures of phylogenetic diversity.

   We calculate the spatial variation in species richness, taxonomic beta diversity, and alpha and beta phylogenetic diversity (PDαandPDβ, respectively) of Atlantic Forest harvestman communities using a data set containing 556 species from 68 sites, distributed in 12 Brazilian states.

   We compare the congruence of phylogenetic and taxonomic diversity patterns, and also comparePDαwith null model expectations, to check for phylogenetic clustering or overdispersion in communities.

   Species richness andPDαare correlated, peaking in southern and south‐eastern coastal sites and decreasing towards the interior and towards the north‐east.PDαin north‐eastern sites was higher than expected, while a clustered phylogenetic pattern characterised most other sites.

   Communities in the southern and south‐eastern regions were dominated by species from the large family Gonyleptidae, presenting a high richness and a lowPDα. As the dominance of Gonyleptidae decreased towards the north, where local communities have fewer species, but a higherPDα, they contain representatives of other families. The beta diversity was more sensitive to the compositional changes involving closely related Gonyleptidae species, whilePDβis more influenced by deeper phylogenetic compositional changes, between more distant lineages.

   Phylogenetic diversity may be of special importance to assess the conservation value of distantly related lineages. These species‐poor groups are less likely to influence taxonomic‐based diversity analyses, but their importance for conservation arises from their phylogenetic distinctiveness, captured byPDαandPDβmeasures.

    

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2. Diacylglycerol kinase and associated lipid mediators modulate rice root architecture

   https://doi.org/10.1111/nph.15801  

   Yuan, Shu ; Kim, Sang‐Chul ; Deng, Xianjun ; Hong, Yueyun ; Wang, Xuemin ( April 2019 , New Phytologist)

   Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DAG) to generate phosphatidic acid (PA), and bothDAGandPAare lipid mediators in the cell. Here we show thatDGK1 in rice (Oryza sativa) plays important roles in root growth and development.

   Two independentOsDGK1‐knockout (dgk1) lines exhibited a higher density of lateral roots (LRs) and thinner seminal roots (SRs), whereasOsDGK1‐overexpressing plants displayed a lowerLRdensity and thickerSRsthan wild‐type (WT) plants.

   Overexpression ofOsDGK1led to a decline in theDGKsubstrateDAGwhereas specificPAspecies decreased indgk1roots. Supplementation ofDAGtoOsDGK1‐overexpressing seedlings restored theLRdensity andSRthickness whereas application ofPAtodgk1seedlings restored theLRdensity andSRthickness to those of theWT. In addition, treatment of rice seedlings with theDGKinhibitor R59022 increased the level ofDAGand decreasedPA, which also restored the root phenotype ofOsDGK1‐overexpressing seedlings close to that of theWT.

   Together, these results indicate thatDGK1 and associated lipid mediators modulate rice root architecture;DAGpromotesLRformation and suppressesSRgrowth whereasPAsuppressesLRnumber and promotesSRthickness.

    

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3. Increased adaxial stomatal density is associated with greater mesophyll surface area exposed to intercellular air spaces and mesophyll conductance in diverse C 4 grasses

   https://doi.org/10.1111/nph.16106  

   Pathare, Varsha S. ; Koteyeva, Nuria ; Cousins, Asaph B. ( September 2019 , New Phytologist)

   Mesophyll conductance (g_m) is the diffusion ofCO₂from intercellular air spaces (IAS) to the first site of carboxylation in the mesophyll cells. In C₃species,g_mis influenced by diverse leaf structural and anatomical traits; however, little is known about traits affectingg_min C₄species.

   To address this knowledge gap, we used online oxygen isotope discrimination measurements to estimateg_mand microscopy techniques to measure leaf structural and anatomical traits potentially related tog_min 18 C₄grasses.

   In this study,g_mscaled positively with photosynthesis and intrinsic water‐use efficiency (TE_i), but not with stomatal conductance. Also,g_mwas not determined by a single trait but was positively correlated with adaxial stomatal densities (SD_ada), stomatal ratio (SR), mesophyll surface area exposed toIAS(S_mes) and leaf thickness. However,g_mwas not related to abaxial stomatal densities (SD_aba) and mesophyll cell wall thickness (T_CW).

   Our study suggests that greaterSD_adaandSRincreasedg_mby increasingS_mesand creating additional parallel pathways forCO₂diffusion inside mesophyll cells. Thus,SD_ada,SRandS_mesare important determinants of C₄‐g_mand could be the target traits selected or modified for achieving greaterg_mandTE_iin C₄species.

    

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4. Ectomycorrhizal fungi and soil enzymes exhibit contrasting patterns along elevation gradients in southern Patagonia

   https://doi.org/10.1111/nph.15714  

   Truong, Camille ; Gabbarini, Luciano A. ; Corrales, Adriana ; Mujic, Alija B. ; Escobar, Julio M. ; Moretto, Alicia ; Smith, Matthew E. ( March 2019 , New Phytologist)

   The biological and functional diversity of ectomycorrhizal (ECM) associations remain largely unknown in South America. In Patagonia, theECMtreeNothofagus pumilioforms monospecific forests along mountain slopes without confounding effects of vegetation on plant–fungi interactions.

   To determine how fungal diversity and function are linked to elevation, we characterized fungal communities, edaphic variables, and eight extracellular enzyme activities along six elevation transects in Tierra del Fuego (Argentina and Chile). We also tested whether pairingITS1rDNAIllumina sequences generated taxonomic biases related to sequence length.

   Fungal community shifts across elevations were mediated primarily by soilpHwith the most species‐rich fungal families occurring mostly within a narrowpHrange. By contrast, enzyme activities were minimally influenced by elevation but correlated with soil factors, especially total soil carbon. The activity of leucine aminopeptidase was positively correlated withECMfungal richness and abundance, and acid phosphatase was correlated with nonECM fungal abundance. Several fungal lineages were undetected when using exclusively paired or unpaired forwardITS1 sequences, and these taxonomic biases need reconsideration for future studies.

   Our results suggest that soil fungi inN. pumilioforests are functionally similar across elevations and that these diverse communities help to maintain nutrient mobilization across the elevation gradient.

    

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5. Assessing the factors influencing natural regeneration patterns in the diverse, multi‐cohort, and managed forests of Maine, USA

   https://doi.org/10.1111/jvs.12433  

   Bose, Arun_K ; Weiskittel, Aaron ; Wagner, Robert_G ; Kuehne, Christian ; Michalet, ed., Richard ( June 2016 , Journal of Vegetation Science)

   What are the primary biotic and abiotic factors driving composition and abundance of naturally regenerated tree seedlings across forest landscapes of Maine? Do seedling species richness (SR) and density (SD) decrease with improved growing conditions (climate and soil), but increase with increased diversity of overstorey composition and structure? Does partial harvesting disproportionately favour relative dominance of shade‐intolerant hardwoods (PIHD) over shade‐tolerant softwoods (PTSD)?

   Forest landscapes across the diverse eco‐regions and forest types of Maine,USA.

   This study usedUSDAForest Service Forest Inventory Analysis permanent plots (n = 10 842), measured every 5 yr since 1999. The best models for each response variable (SR,SD,PIHDandPTSD) were developed based onAICand biological interpretability, while considering 35 potential explanatory variables incorporating climate, soil, site productivity, overstorey structure and composition, and past harvesting.

   Mean annual temperature was the most important abiotic factor, whereas overstorey tree size diversity was the most important biotic factor forSRandSD. Both mean annual temperature and overstorey tree size diversity had a curvilinear relationship withSRandSD. Average overstorey shade tolerance and percentage tolerant softwood basal area in the overstorey were the top predictor variables ofPIHDandPTSD,respectively. Partial harvesting favouredPIHDbut notPTSD.

   This is one of the first studies to comprehensively evaluate a number of factors influencing naturally established tree seedlings at a broad landscape scale in the Northern Forest region of the easternUSAand Canada. Despite limitations associated with relatively small plot size, large seedling size class and lack of direct measurements of light, water and nutrients, this study documents the influence of these factors amid high variability associated with patterns of natural regeneration. The curvilinear relationship between mean annual temperature withSRandSDsupports the argument that species richness and abundance usually have unimodal relationships with productivity indicators, whereas the curvilinear relationship between overstorey tree size diversity andSRandSDsuggest that moderate overstorey diversity incorporates multiple species as well as higher seedling individuals.

    

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