Plant, Cell & Environment最新文献

Plant pathogens cause crop loss. Genetic resistance, through natural genetic diversity or engineered resistance, can be highly effective in protecting plants from infection. Genetic resistance from wild relatives of crops has been successfully introduced into crops to control pathogen infection. Natural genetic diversity has also been used to dissect the molecular mechanisms of immunity. Pathogen recognition can be engineered due to advances in structural and computational biology, which have accelerated rational design approaches. We specifically focus on natural and engineered diversity in indirect recognition of pathogens, where the pathogen modifies a host protein and the modification is detected by a plant immune receptor, as these recognition systems are particularly common in bacterial pathogen resistance. We explore natural genetic diversity for indirect recognition at three scales (1) across species (2) within species and (3) within individuals. Finally, we extend these insights to approaches for rational engineering of plant-pathogen recognition.

Tropical forests account for approximately 60% of global terrestrial photosynthesis, yet their function into the future may be compromised by rising ground-level ozone (O₃) pollution. Although O₃ is known to impair plant productivity, the physiological mechanisms underlying interspecific variation in O₃ susceptibility-especially among tropical trees-remain poorly resolved. Here we exposed 11 tropical tree species to a gradient of O₃ concentrations using open-top chambers and quantified whole-plant biomass responses alongside key plant functional traits. Species varied markedly in O₃ susceptibility, with relative growth reductions best explained by differences in plant mass per unit leaf area (PMA). Contrary to expectations, antioxidant capacity and leaf mass per area were not predictive of O₃ susceptibility of tropical tree species. These findings indicate that fundamental structural traits may mediate tropical tree responses to O₃, and that species with higher PMA exhibit greater resilience-within the experimental framework employed here. Our results help inform trait-based risk assessments and support the need for improved representation of O₃ impacts in models of carbon cycling in tropical forests.

Accurate estimation of the photorespiratory CO₂ compensation point (Γ*) is essential for describing the balance between Rubisco carboxylation and oxygenation and for parameterising biochemical models of photosynthesis. Γ* and the rate of CO₂ release in the light (D_L) are commonly estimated using the Laisk method, based on measurements of net CO₂ assimilation rate (A_net) at low chloroplastic CO₂ concentrations (c_c), under several sub-saturating irradiance levels. However, many widely used temperature dependence relationships for Γ* (Γ*(T)) were derived using conventional linear implementations of the Laisk method, despite the intrinsically nonlinear behaviour of the A_net-c_c response predicted by the photosynthetic theory. Here, we revisited the temperature dependence of Γ* and D_L using the improved Laisk-FvCB framework that simultaneously constrains the nonlinear A_net-c_c response across multiple irradiance levels. Gas exchange of sunflower leaves was measured across a wide temperature range from 3.9°C to 42.0°C. The conventional linear implementation generated highly dispersed pairwise intersections and unstable estimates of both Γ* and D_L, including some physiologically unrealistic negative D_L values at low temperatures. In contrast, the mechanistically constrained Laisk-FvCB framework produced physiologically meaningful temperature responses and substantially reduced methodological artefacts associated with linear extrapolation. Using this framework, we derived a revised in vivo Γ*(T) relationship described by an Arrhenius-type function with Γ*(25) = 43.4 μmol mol^-1 and an apparent activation energy of 27.7 kJ mol^-1, such that Γ*(T) = 43.4 exp[11.176 ((T - 25)/(T + 273.15))], where T is leaf temperature in °C. Comparison with other widely used Γ*(T) formulations showed substantial divergence at temperature extremes, often exceeding the variability expected from realistic interspecific differences in Rubisco specificity among C₃ species.

Cuticular waxes undeniably form the primary barrier restricting uncontrolled water loss from leaves, yet the functional consequences of environmentally induced wax modifications for residual (cuticular) transpiration remain a matter of debate. This review summarises current knowledge on how major abiotic stimuli influence foliar cuticular wax amount and composition and critically re-evaluates their effect on transpirational properties of leaves. By focusing on a strictly curated set of studies integrating gas chromatography for chemical wax analysis and permeance-based residual (cuticular) transpiration measurements, we demonstrate that light quantity seems to represent the most dominant driver of wax deposition and that naturally increased wax amounts do not inherently translate into an enhanced water barrier, with the latter aspect challenging the recurrently postulated 'more cuticular wax must equal lower rates of residual (cuticular) transpiration' narrative. Instead, bridging modern research with long-standing transport models indicates that the qualitative composition and spatial arrangement of cuticular wax might constitute the more decisive factors orchestrating cuticular water barrier properties. While the available data are still insufficient to identify clear causal relationships between compound classes, chain length distributions and structural heterogeneity affecting water permeability, they might point to further complexities, such as unintended off-target effects as a consequence of genetic engineering.

Plants produce broad spectra of metabolites comprising primary metabolites involved in core physiological processes and specialized metabolites mediating responses to biotic and abiotic stress. Understanding how these various components of the metabolome respond to different environmental pressures can help us to understand drivers of phytochemical diversity and its role in plant ecology and evolution. We investigated how climatic stress, soil resources, and herbivory influence various measures of phytochemical diversity in four willow species along an elevational gradient (950-2250 m a.s.l.), focusing on flavonoids, salicinoids, and primary metabolites. Harsher climates increased metabolite concentrations, particularly salicinoids, but reduced flavonoid richness and overall structural α-diversity. Similar responses in primary metabolites suggest that these shifts extend beyond defence chemistry. Chemical properties showed the strongest shifts in flavonoids and salicinoids and weaker changes in primary metabolites. β-diversity generally increased with elevation and was most strongly associated with climate, while soil nutrients contributed to shifts in β-diversity of salicinoids and primary metabolites. Willow species showed weak genetic differentiation across elevation, suggesting limited population divergence. Together, these results indicate that elevational shifts in willow chemistry involve broad but uneven reorganization across the metabolome, with different metabolite groups and measures of diversity plastically responding to different drivers.

Berry cracking is a severe physiological disorder that compromises quality and causes economic losses in grapes. Despite recent research progress, current knowledge offers limited insight into the molecular pathways. This study shows that gibberellin (GA₃) effectively mitigates berry cracking in the susceptible cultivar 'White Munake' by modulating cell wall remodeling processes. Multi-omics analysis revealed that GA₃ treatment significantly alters key pectin-modifying enzymes and cell wall related pathways. Results showed that VviPME39, which encodes a pectin methylesterase, facilitates the maintenance of cell wall structure. Functional validation through heterologous overexpression in tomato confirmed that VviPME39 enhances fruit cracking susceptibility and reduces firmness. Furthermore, we identified VviWRKY50 as a transcriptional repressor that directly binds to the VviPME39 promoter and inhibits its expression, proposing a potential novel GA₃-VviWRKY50-VviPME39 regulatory module. This pathway operates independently of ethylene-mediated softening mechanisms reported in other species, revealing a unique hormonal regulatory strategy in grape. Our study showed fundamental insights into the molecular mechanism of berry cracking and identified possible targets for breeding crack-resistant grape varieties through manipulation of the VviWRKY50-VviPME39 regulatory mechanism.

Aluminium (Al) toxicity severely limits crop productivity in acidic soils by inhibiting root growth and nutrient uptake, yet the hormonal mechanisms coordinating Al defence in tobacco remain unclear. Here, we show that Al stress rapidly induces gibberellin (GA) biosynthesis in tobacco roots, and that GA signalling mitigates Al toxicity by promoting root growth and reducing Al accumulation. Using exogenous GA application, CRISPR/Cas9-mediated NtGA3-ox1 mutants, GA biosynthesis inhibitors, transcriptomic profiling, and biochemical analyses, we demonstrate that GA enhances Al exclusion through two complementary mechanisms: remodelling root cell wall composition, particularly by increasing hemicellulose content to sequester Al, and reinforcing the endodermal Casparian strip (CS) through the upregulation of CS-associated genes. Pharmacological manipulation of lignin biosynthesis confirms that early CS formation was critical for restricting Al entry. These findings reveal GA as a dynamic regulator of Al stress adaptation, coordinating structural and biochemical defences to maintain root growth, and highlight GA signalling as a potential target for improving crop tolerance to Al-toxic acidic soils.

Cuticular waxes, together with cutin, form a hydrophobic barrier that protects the plants against various biotic and abiotic stresses. The past decade has seen remarkable progress in deciphering the wax biosynthesis and transport, however, the continuous discovery of wax-defective mutants and the development of diverse technologies are progressively refining our current understanding of wax biosynthetic pathways. Here, we provide a comprehensive summary of the biosynthetic pathway and transport mechanisms of plant cuticular waxes, with a particular emphasis on recent breakthroughs, including the carbon reallocation mechanism between the alkane-forming and alcohol-forming pathways, as well as the emerging branched-chain wax biosynthesis pathway. We also review how wax synthesis responds to diverse abiotic stresses, including salt, extreme water conditions and temperature, light, and outline critical knowledge gaps that remain to be addressed, including the wax biosynthesis in non-model plants, the physiological function of branched wax and their underlying molecular mechanisms.

Temperate ring-porous tree species are more vulnerable to freezing-induced embolism than their diffuse-porous counterparts due to their large earlywood vessels. Although ring-porous species can restore hydraulic function by forming earlywood vessels in early spring, they may face high risk of embolism during spring frosts. Here, we tested the hypothesis that ring-porous temperate trees employ a strategy of enhanced freezing avoidance to protect their vulnerable earlywood vessels from the risk of freezing-induced embolism. We quantified the degree of embolism in overwintering stems, ice nucleation temperature (INT_xylem), water content (WC_xylem), and non-structural carbohydrate (NSC) concentrations in stem xylems of 20 temperate tree species (nine diffuse-porous and 11 ring-porous) grown in a common garden. Consistent with our hypothesis, ring-porous species suffered severe embolism over the winter and exhibited stronger freezing avoidance during spring. While diffuse-porous species rely on smaller vessels to resist freezing-induced embolism, ring-porous species showed stronger ability of freezing avoidance by lowering INT_xylem via reduced WC_xylem and higher NSC concentrations. This strategy likely protects their vulnerable, newly developed earlywood vessels from freezing-induced hydraulic dysfunction. These findings reveal distinct strategies between temperate diffuse-porous and ring-porous species for coping with spring frost stress, providing insights into forest responses to climate change.