Limited efficacy of a commercial microbial inoculant for improving growth and physiological performance of native plant species.

Soil microbial inoculants are increasingly being explored as means to improve soil conditions to facilitate ecological restoration. In southwestern Western Australia, highly biodiverse woodland plant communities are increasingly threatened by various factors including climate change, land development and mining. woodland restoration is necessary to conserve this plant community.

Plant interactions can lead to emergent relationships between plant community diversity, productivity and vulnerability to invasion.

Understanding what makes a community vulnerable to invasion is integral to the successful management of invasive species. Our understanding of how characteristics of resident plant interactions, such as the network architecture of interactions, can affect the invasibility of plant communities is limited. Using a simulation model, we tested how successfully a new plant invader established in communities with different network architectures of species interactions.

Cicer super-pangenome provides insights into species evolution and agronomic trait loci for crop improvement in chickpea.

Chickpea (Cicer arietinum L.)-an important legume crop cultivated in arid and semiarid regions-has limited genetic diversity. Efforts are being undertaken to broaden its diversity by utilizing its wild relatives, which remain largely unexplored.

Local adaptation to climate inferred from intraspecific variation in plant functional traits along a latitudinal gradient.

Ascertaining the traits important for acclimation and adaptation is a critical first step to predicting the fate of populations and species facing rapid environmental change. One of the primary challenges in trait-based ecology is understanding the patterns and processes underpinning functional trait variation in plants. Studying intraspecific variation of functional traits across latitudinal gradients offers an excellent approach to assess associations with environmental factors, which naturally covary along these spatial scales such as the local climate and soil profiles.

Interspecific facilitation of micronutrient uptake between cluster-root-bearing trees and non-cluster rooted-shrubs in a woodland.

Background And Aims: Belowground interspecific plant facilitation is supposed to play a key role in enabling species co-existence in hyperdiverse ecosystems in extremely nutrient-poor, semi-arid habitats, such as woodlands in southwestern-Australia. Manganese (Mn) is readily mobilised by cluster root activity in most soils and accumulates in mature leaves of native Australian plant species without significant remobilisation during leaf senescence. We hypothesised that neighbouring shrubs are facilitated in terms of Mn uptake depending on distance to surrounding cluster root-forming trees.

Dihydroxyacetone in the Floral Nectar of (Turcz.) Rye (Myrtaceae) and Endl. (Myrtaceae) Demonstrates That This Precursor to Bioactive Honey Is Not Restricted to the Genus (Myrtaceae).

Ma̅nuka honey is known for its strong bioactivity, which arises from the autocatalytic conversion of 1,3-dihydroxyacetone (dihydroxyacetone, DHA) in the floral nectar of (Myrtaceae) to the non-peroxide antibacterial compound methylglyoxal during honey maturation. DHA is also a minor constituent of the nectar of several other species. This study used high-performance liquid chromatography to test whether DHA was present in the floral nectar of five species in other genera of the family Myrtaceae: (Turcz.

Flow similarity, stochastic branching, and quarter-power scaling in plants.

The origin of allometric scaling patterns that are multiples of one-fourth has long fascinated biologists. While not universal, quarter-power scaling relationships are common and have been described in all major clades. Several models have been advanced to explain the origin of such patterns, but questions regarding the discordance between model predictions and empirical data have limited their widespread acceptance.

Sugar and dihydroxyacetone ratios in floral nectar suggest continuous exudation and reabsorption in Leptospermum polygalifolium Salisb.

Leptospermum polygalifolium Salisb. can accumulate high concentrations of dihydroxyacetone (DHA), precursor of the antimicrobial compound methylglyoxal found in honey obtained from floral nectar of Leptospermum spp. Floral nectar dynamics over flower lifespan depends on internal and external factors that invariably impact nectar quality.

Thermal imagery of woodland tree canopies provides new insights into drought-induced tree mortality.

Our understanding of how water dynamics determines the probability of tree mortality during drought is incomplete. Here we help address this shortcoming by coupling approaches from the disciplines of ecophysiology, geophysics and remote sensing in a woodland ecosystem undergoing protracted drying. Water uptake and use strategies varied between the dominant canopy species of the ecosystem.

Effect of Drought and Low P on Yield and Nutritional Content in Common Bean.

Common bean ( L.) production in the tropics typically occurs in rainfed systems on marginal lands where yields are low, primarily as a consequence of drought and low phosphorus (P) availability in soil. This study aimed to investigate the physiological and chemical responses of 12 bush bean genotypes for adaptation to individual and combined stress factors of drought and low P availability.

The barrier to radial oxygen loss impedes the apoplastic entry of iron into the roots of Urochloa humidicola.

Lack of O2 and high concentrations of iron (Fe) and manganese (Mn) commonly occur in waterlogged soils. The development of a barrier to impede radial O2 loss (ROL) is a key trait improving internal O2 transport and waterlogging tolerance in plants. We evaluated the ability of the barrier to ROL to impede the entry of excess Fe into the roots of the waterlogging-tolerant grass Urochloa humidicola.

Root positioning and trait shifts in Hibbertia racemosa as dependent on its neighbour's nutrient-acquisition strategy.

Nutrient-poor ecosystems globally exhibit high plant diversity. One mechanism enabling the co-existence of species in such ecosystems is facilitation among plants with contrasting nutrient-acquisition strategies. The ecophysiological processes underlying these interactions remain poorly understood.

Root length is proxy for high-throughput screening of waterlogging tolerance in Urochloa spp. grasses.

C4 perennial Urochloa spp. grasses are widely planted in extensive areas in the tropics. These areas are continuously facing waterlogging events, which limits plant growth and production.

The potential for phosphorus benefits through root placement in the rhizosphere of phosphorus-mobilising neighbours.

Plants that produce specialised cluster roots, which mobilise large quantities of poorly available nutrients such as phosphorus (P), can provide a benefit to neighbouring plants that produce roots in the cluster rhizosphere, as demonstrated previously in pot studies. To be effective, such roots must be present within the short time of peak cluster activity. We tested if this requirement is met, and quantified potential P benefits, in a hyperdiverse Mediterranean woodland of southwest Australia where cluster-rooted species are prominent.

Field drought conditions impact yield but not nutritional quality of the seed in common bean (Phaseolus vulgaris L.).

Drought substantially limits seed yield of common bean (Phaseolus vulgaris L.) in the tropics. Understanding the interaction of drought on yield and the nutrient concentration of the seed is vital in order to supply nutrition to the millions of consumers who rely on common bean as a staple crop.

Root-zone hypoxia reduces growth of the tropical forage grass Urochloa humidicola in high-nutrient but not low-nutrient conditions.

Background And Aims: The perennial C4 grass Urochloa humidicola is widely planted on infertile acidic and waterlogging-prone soils of tropical America. Waterlogging results in soil anoxia, and O2 deficiency can reduce nutrient uptake by roots. Interestingly, both nutrient deficiencies and soil waterlogging can enhance root cortical cell senescence, and the increased gas-filled porosity facilitates internal aeration of roots.

Two sides to every leaf: water and CO transport in hypostomatous and amphistomatous leaves.

Leaves with stomata on both upper and lower surfaces, termed amphistomatous, are relatively rare compared with hypostomatous leaves with stomata only on the lower surface. Amphistomaty occurs predominantly in fast-growing herbaceous annuals and in slow-growing perennial shrubs and trees. In this paper, we present the current understanding and hypotheses on the costs and benefits of amphistomaty related to water and CO transport in contrasting leaf morphologies.

Tree host-pathogen interactions as influenced by drought timing: linking physiological performance, biochemical defence and disease severity.

There is increasing concern about tree mortality around the world due to climatic extremes and associated shifts in pest and pathogen dynamics. Yet, empirical studies addressing the interactive effect of biotic and abiotic stress on plants are very rare. Therefore, in this study, we examined the interaction between drought stress and a canker pathogen, Quambalaria coyrecup, on the eucalypt - Corymbia calophylla (marri), which is experiencing increasing drought stress.

Hydraulic redistribution: limitations for plants in saline soils.

Hydraulic redistribution (HR), the movement of water from wet to dry patches in the soil via roots, occurs in different ecosystems and plant species. By extension of the principle that HR is driven by gradients in soil water potential, HR has been proposed to occur for plants in saline soils. Despite the inherent spatial patchiness and salinity gradients in these soils, the lack of direct evidence of HR in response to osmotic gradients prompted us to ask the question: are there physical or physiological constraints to HR for plants in saline environments? We propose that build-up of ions in the root xylem sap and in the leaf apoplast, with the latter resulting in a large predawn disequilibrium of water potential in shoots compared with roots and soil, would both impede HR.

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats.

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (d) is equal to the distance from these veins to the epidermis (d), expressed as d:d ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce d:d below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density.

Salinity tolerances of three succulent halophytes (Tecticornia spp.) differentially distributed along a salinity gradient.

We evaluated tolerances to salinity (10-2000mM NaCl) in three halophytic succulent Tecticornia species that are differentially distributed along a salinity gradient at an ephemeral salt lake. The three species showed similar relative shoot and root growth rates at 10-1200mM NaCl; at 2000mM NaCl, T. indica subsp.

Optimal allocation of leaf epidermal area for gas exchange.

A long-standing research focus in phytology has been to understand how plants allocate leaf epidermal space to stomata in order to achieve an economic balance between the plant's carbon needs and water use. Here, we present a quantitative theoretical framework to predict allometric relationships between morphological stomatal traits in relation to leaf gas exchange and the required allocation of epidermal area to stomata. Our theoretical framework was derived from first principles of diffusion and geometry based on the hypothesis that selection for higher anatomical maximum stomatal conductance (gsmax ) involves a trade-off to minimize the fraction of the epidermis that is allocated to stomata.