Plant Biology最新文献

This study explores how bioactive compounds in green coffee beans (Coffea arabica L.) vary across different geographic regions, addressing the key question of how environmental factors shape coffee biochemistry and adaptation mechanisms to diverse conditions. Identifying these variations provides insight into how environmental and processing factors influence coffee's sensory quality. Samples from six major coffee-producing regions were analysed for key bioactive compounds, including biogenic amines, caffeine, trigonelline, sucrose, free amino acids, and phenolics. Total polyphenol content and polyamine concentrations were measured, and PCA was used to differentiate samples based on chemical composition. A correlation analysis was specifically conducted for Brazilian samples, using meteorological and environmental data. Total polyphenol content ranged from 44.8 to 70.7 mg GAeq g^-1 FW, with Brazilian samples having the highest levels. Putrescine, the most abundant polyamine, varied significantly (0.02-1.9 μg g^-1 FW). PCA highlighted Ethiopian samples with high sucrose and low caffeine. Brazilian samples showed distinct separation based on key compounds, including putrescine, trigonelline, and amino acids. Environmental factors in Brazil correlated with polyamine and amino acid composition, suggesting associations with heat and drought tolerance. Environmental factors, particularly heat and drought, influence the biochemical profile of coffee beans. Polyamine levels correlate with stress tolerance, while amino acid composition reflects adaptations for osmotic protection. These findings enhance our understanding of coffee's biochemical adaptation to diverse climates and offer valuable insights for optimizing cultivation strategies in the face of climate change.

The continuous fragmentation of tropical forests is a major threat to biodiversity and ecosystem functioning. This process creates extensive forest edges, alters microclimates, and promotes shifts in species composition. Functional traits are key to understanding how species respond to these disturbances and to predicting future vegetation dynamics. This study investigates the ecological strategies of species located at the edges and interiors of forest fragments in the Eastern Amazon. We sampled abundant tree species in seven forest fragments distributed across three municipalities in Pará, Brazil. We analysed 16 morphological and anatomical traits related to leaf economics and xylem function. Comparisons were made between edge and interior environments, and traits were correlated with edaphic variables. Species at forest edges had traits associated with hydraulic efficiency, including higher hydraulic conductivity and a greater fiber fraction. In contrast, interior species displayed a range of strategies, from resource-acquisitive to conservative. We found evidence of a decoupling between leaf and wood trait axes, with wood traits varying independently from leaf traits. Soil conditions influenced trait patterns only at fragment edges. Our study enhances understanding of the mechanisms regulating species survival, as evidenced by the different strategies adopted by plants in the interior and at the edges of forest fragments, reflecting contrasting responses to resource availability. These findings also provide support for conservation and forest management strategies and contribute to policy development aimed at mitigating the impacts of fragmentation on Amazonian biodiversity.

Caves present unique ecological conditions that influence the distribution and adaptation of species, yet studies on cave-associated vegetation remain limited. This study investigated how cave conditions affect the functional traits of Miconia sellowiana Naudin (Melastomataceae), comparing individuals from the cave interior with those from the adjacent understory. Our objective was to understand how these environments influence the species' morpho-functional characteristics and ecological relevance, aiming to identify physiological responses to the constraints of each habitat. Based on this, we hypothesize that caves act as distinct environmental filters compared to the understory, selecting for unique morphological and physiological variations. Leaf morpho-functional traits were evaluated, including macroscopic dimensions (length, width, and leaf area) and microscopic characteristics, such as the anatomy of the central vein, mesophyll, and epidermis. Samples were fixed, processed for histological sections, and analysed by optical and electron microscopy. Statistical analysis included PCA to identify morpho-functional patterns and Student's t-tests/Wilcoxon tests to compare variables between habitats. Cave individuals had thinner leaves, with fewer layers of photosynthetic parenchyma, smaller relative phloem area in the central vein, lower stomatal density, and reduced leaf area and length compared to understory individuals. Low light availability, high humidity, shallow soils, and nutrient scarcity in caves likely limit the development of thicker leaves and affect stomatal density, vascular tissue, and leaf size. These results suggest that cave environments drive morpho-functional and physiological variations in surrounding plants. This study fills gaps in the literature and highlights ecological mechanisms that sustain life in subterranean ecosystems.

Grasses and Epichloë endophytes often form mutualistic symbiotic defence systems. Studies have shown Epichloë endophytes improve resistance of host plants to airborne diseases. However, whether endophytes affect soil-borne disease resistance of host or neighbouring non-host plants remains unclear. We used endophyte-infected (EI) and endophyte-free (EF) Achnatherum sibiricum as host grass, Leymus chinensis as non-host grass, and Rhizoctonia solani as pathogen to explore the effects of endophyte infection on disease resistance of host and neighbouring non-host grasses. To clarify the contribution of root exudates to disease resistance of the non-host grass, three different root separation methods were employed between host and non-host plants: plastic barrier (PB), nylon mesh barrier (NL, allowing root exudates to pass through), or no barrier (NB). Epichloë endophytes decreased the disease index (DI) of the host A. sibiricum and reduced pathogen abundance in both host roots and soil. The DI of L. chinensis was affected by the interaction between root separation and endophyte infection. Under NL and NB treatments, the DI of L. chinensis with an EI neighbour was significantly lower than that with an EF neighbour, indicating that endophytic fungi can alleviate disease in non-host plants by influencing root exudates. Additionally, endophytic fungi increased the content of total phenolic compounds and salicylic acid in L. chinensis through activation of host root exudates, which could be one reason for the reduced DI of L. chinensis. Upon analysing root exudate components of the host, we found 2,4-di-tert-butylphenol (DTBP) and dibutyl phthalate (DBP) were the main antifungal compounds mediated by endophyte infection. Epichloë endophytes improved soil-borne disease resistance of the host and enhanced resistance of the neighbouring non-host grass through host root exudates; overall, host and non-host plants showed "associational resistance" to soil-borne diseases. This study highlights that Epichloë endophytes could potentially serve as efficient biological control agents against R. solani-associated diseases in grassland communities.