生命科学最新文献

Alterations in root exudates and their ecological significance across plant evolutionary divergence time remain elusive due to methodological challenges. Herein, we measured root exudate composition of 20 woody species and assessed its associations with root traits and rhizosphere microbiota to investigate the ecological functions of root exudates throughout plant evolution. The root exudates showed increased richness, polarity, unsaturation and aromaticity with divergence time. Furthermore, fungal richness markedly increased with divergence time, accompanied by the rhizosphere enrichment of copiotrophic bacteria (e.g., Bacteroidota and Actinobacteriota), ectomycorrhizal fungi and several functional microbes. Additionally, competitive root traits (e.g., specific root length and root nitrogen concentration) were positively correlated with exudate richness and chemical complexity in ectomycorrhizal (EcM) trees, whereas they were related to the exudation rates in the arbuscular mycorrhizal (AM) trees. Microbial richness and strategies were closely linked to exudate chemistry, and the exudate-microbe interactions were more tightly coupled in the rhizosphere of EcM trees than in that of the AM trees. Shifts in exudate composition and their associated microbial communities may reflect enhanced chemical defense and rhizosphere communication as plants evolve. These results provide evidence that root strategies extend beyond the root itself to include exudates and the rhizosphere, thereby advancing our understanding of root traits-exudate-microbiota associations across plant evolution.

Light acts as both the primary energy source for photosynthesis and a pivotal environmental signal that orchestrates plant growth and developmental transitions. The plant vascular system, comprising xylem, phloem, and cambium, dynamically adjusts its development in response to light intensity, quality, and photoperiod. This review synthesises current knowledge on how light signalling regulates cambial activity, xylem and phloem differentiation, and secondary cell wall formation. We elaborate on the molecular interplay between light signalling components and key vascular developmental regulators. Understanding these mechanisms is crucial for deciphering plant adaptation to variable light environments and holds significant potential for enhancing crop resilience and woody biomass yield in the context of global climate change.

Rising atmospheric CO₂ is expected to have limited direct effects on C₄ photosynthesis because the carbon-concentrating mechanism maintains near-saturating CO₂ at Rubisco. Consequently, growth responses of C₄ plants to elevated CO₂ (eCO₂) are generally attributed to indirect improvements in plant water relations. However, it remains unclear whether sustained exposure to eCO₂ also induces changes in photosynthetic capacity that contribute directly to carbon gain. We examined the interactive effects of CO₂ concentration and soil water availability on photosynthesis, biochemical capacity, and growth in three African C₄ grasses grown under ambient (400 ppm) and elevated (550 ppm) CO₂. Elevated CO₂ increased net photosynthesis across species, with stronger responses under drought. Intrinsic water-use efficiency increased primarily through enhanced assimilation, while stomatal responses were contingent on water availability rather than driven directly by elevated CO₂. Importantly, eCO₂ induced species- and context-dependent increases in apparent photosynthetic capacity after prolonged treatment exposure. Megathyrsus maximus showed strong V_cmax increases under both water treatments and J_max upregulation under well-watered conditions, Heteropogon contortus exhibited biochemical upregulation primarily under drought, and Themeda triandra showed little evidence of acclimation. Growth responses closely mirrored these physiological patterns, occurring only in species exhibiting coordinated biochemical adjustment. These results indicate that C₄ responses to eCO₂ cannot be explained solely by stomatal water saving and provide evidence that species-specific changes in apparent photosynthetic capacity may contribute to sustained carbon gain, particularly under water limitation.

Characterization of previously reported Arabidopsis mutants with increased aluminum (Al) resistance (alr) resulting from greater release of Al-chelating malate identified three unique amino acid substitutions that each impacts PHOSPHOENOLPYRUVATE CARBOXYLASE 1, a key anaplerotic carbon fixation enzyme. Expression of mutant versions of AtPPC1 in an Arabidopsis ppc1 loss-of-function mutant increased Al resistance in association with upwards of threefold higher release of Al-chelating malate from roots. Analyses of enzyme kinetics and protein structure of the variants revealed that each amino acid position is critical to proper interplay between the allosteric regulator malate and the active site. Since these affect amino acid positions generally conserved amongst plant PPCs, they were individually introduced into maize PPCs including ZmPPC1, the isozyme responsible for the first step of C4 photosynthesis, and ZmPEP7, a key PPC in resupply of the TCA cycle via anaplerosis. This resulted in similar or greater improvements in enzyme activity and reduced regulation in vitro for both ZmPPC1 and ZmPEP7 along with increased PPC-dependent output in planta for a ZmPEP7 transgenic. Therefore, engineering these amino acid changes into plants in general could be useful for increasing carbon fixation by PPCs to turn excess CO₂ into a resource for our growing population.

The greenhouse effect, primarily driven by CO₂ is changing the global climate and threatening ecosystem and human sustainability. Bamboo plays an integral role in mitigating climate change with its excellent photosynthetic carbon fixation capacity. The Golden2-like (GLK) transcription factor is a critical regulator of photosynthesis. In this study, we identified four GLK members in moso bamboo (Phyllostachys edulis), among which PeGLK1-1 functioned as a principal regulator of photosynthesis. Overexpressing PeGLK1-1 significantly enhanced the carbon fixation capacity of transgenic rice under elevated CO₂ (eCO₂) environment. Moreover, PeGLK1-1 was positively correlated with most photosynthesis-related genes, such as PeRbcS2 and PePRK1 in the Calvin cycle. PeGLK1-1 bound to 5'-AAAAA-3' in the promoters of PeRbcS2 and PePRK1, thereby activating their transcription. Furthermore, overexpressing PeRbcS2 and PePRK1 enhanced the photosynthetic capacity of transgenic rice under eCO₂ environment. In planta gene editing of PeRbcS2 and PePRK1 led to a decrease in photosynthetic capacity, whereas transient overexpression of them exhibited opposite trends. Collectively, eCO₂ environment could induce the expression of PeGLK1-1 to activate the Calvin cycle genes, ultimately enhancing the carbon fixation capacity. This study provides crucial evidence for GLK regulating the Calvin cycle, which will contribute to breeding new bamboo varieties with efficient carbon fixation capacity.