Aphids andPseudomonas syringaeare a permanent challenge for agriculture, causing severe losses to the crop industry worldwide. Despite the obvious phylogenetic distance between them, both have become predominant colonizers of the plant kingdom. In this study, we reviewed three key steps of spread and colonization that aphids andP. syringaehave mastered to successfully colonize the phyllosphere. These steps involve (i) plant-to-plant movement for locating new nutritional sources, (ii) disruption and modification of the apoplast to facilitate nutrient acquisition, and (iii) suppression of host defenses through effector proteins. In addition, we will provide insights about the direct interaction between aphids andP. syringaeand how this yet underrated phenomenon could bring new ecological implications for both organisms beyond their pathogenicity.

Environmental fluctuations such as increased temperature, water availability, and air CO₂ concentration triggered by climate change influence plant disease dynamics by affecting hosts, pathogens, and their interactions. Here, we describe a newly discovered Pseudomonas syringae strain found in a natural population of Arabidopsis thaliana collected from the southwest of France. This strain, called Psy RAYR-BL, is highly virulent on natural Arabidopsis accessions, Arabidopsis model accession Columbia 0, and tobacco plants. Despite the severe disease phenotype caused by the Psy RAYR-BL strain, we identified a reduced repertoire of putative Type III virulence effectors by genomic sequencing compared to P. syringae pv tomato (Pst) DC3000. Furthermore, hopBJ1_Psy is found exclusively on the Psy RAYR-BL genome but not in the Pst DC3000 genome. The plant expression of HopBJ1_Psy induces ROS accumulation and cell death. In addition, HopBJ1_Psy participates as a virulence factor in this plant-pathogen interaction, likely explaining the severity of the disease symptoms. This research describes the characterization of a newly discovered plant pathogen strain and possible virulence mechanisms underlying the infection process shaped by natural and changing environmental conditions.

Carbon dots (CDs) are promising for agro-environmental applications; however, clear connections between synthesis, photophysical properties, size, and biosafety are often not well established. In this study, we map these relationships for glucose–arginine CDs (GA-CDs). By using microwave and hydrothermal routes at precursor ratios of 1:3, 1:9, and 1:15, we produced sub-10 nm nanoparticles (analyzed by dynamic light scattering and atomic force microscopy) that exhibit tunable absorption and emission properties, as well as surface properties (demonstrated through UV–Vis spectroscopy, 3D photoluminescence, and FTIR analysis). The hydrothermal 1:9 condition yielded the narrowest size distribution and red-shifted photoluminescence. Across biological models spanning plants, insects, plant-growth-promoting bacteria (PGPR), and human cells, GA-CDs were well tolerated, with no adverse changes detected in plant stress markers, aphid feeding behavior or fecundity, or PGPR growth. In A549 cells, viability remained stable up to a concentration of 0.125 mg mL⁻¹, while exposure to 0.5 mg mL⁻¹ reduced viability, establishing a practical operating range. These results provide a clearer picture of how the structure and properties of carbon dots derived from arginine and glucose are correlated to their safety. The GA-CDs are, therefore, useful, and traceable tools for agro-environmental research. The findings support their use as biocompatible nanomaterials for studying interactions among plants, insects, and microbes in agriculture.

Tristerix corymbosus and Tristerix Aphyllus are keystone mistletoes in southern South American ecosystems, providing critical nutritional resources to frugivores during winter, a period of severe food limitation. However, despite their ecological relevance, how iron is stored in Tristerix fruits and embryos, and the developmental mechanisms underlying this process, remain unknown. Here, we investigated iron accumulation, storage forms, and hormonal sensitivity in the fruits and embryos of two closely related epiphytic mistletoes, Tristerix corymbosus (hemiparasitic) and T. aphyllus (holoparasitic). Using histological analyses, immunodetection, and elemental quantification, we show that iron in both species predominantly accumulates as iron-FERRITIN complexes within the embryo, a storage form of iron associated with high bioavailability for animal consumers. Total iron concentrations in mature fruits indicate that both species represent a nutritionally relevant iron source in the trophic chain. Notably, embryos of both species remain green at maturity, suggesting altered regulation of late embryogenesis. We further demonstrate that T. corymbosus embryos are highly insensitive to abscisic acid (ABA) during germination, in contrast to Arabidopsis thaliana, despite exhibiting elevated endogenous ABA levels. This reduced ABA sensitivity correlates with chlorophyll retention, early xylem differentiation, and strong accumulation of FERRITIN proteins in the embryo, linking hormonal regulation to iron storage strategy. Our findings reveal a previously unrecognized connection between ABA sensitivity, embryo developmental state, and iron storage form in epiphytic mistletoes. These traits likely enhance seedling establishment and increase the nutritional value of fruits for frugivores, underscoring the central ecological role of T. corymbosus and T. aphyllus in winter food webs and nutrient flow in terrestrial ecosystems.

Changes in environmental temperatures and water availability can disrupt plant–pollinator interactions by altering floral attractive and rewarding traits. Here, we investigated the effects of warming and drought on floral scent and rewards in Vaccinum corymbosum (an entomophilous crop), and how these changes affect pollinator behavior. Plants were exposed to two temperatures (24 °C and 28 °C) and two watering treatments (optimal watering, W+, and water stress, W−). We measured floral volatiles, pollen and nectar quantity, as well as the nutritional composition of pollen (C, carbon, and N, nitrogen percentage) and nectar (hexose-to-amino acids ratio). Bioassays with honeybees were conducted to assess responses to the attractive and rewarding traits specific to each treatment. Floral volatiles significantly increased at 28° W+; nevertheless, they declined under the combination of both warming and drought. Pollen and nectar production were only negatively affected by warming. Pollen’s nutritional composition was negatively affected by the interaction of both stresses, with greater reductions in % C and N occurring when both stresses were combined. We observed that the synthetic floral scent representing the blend emitted by flowers under 28° W+ conditions, at low concentrations, attracted the highest percentage of honeybees. Additionally, honeybees tended to visit artificial diets of pollen with a more nutritious composition (50% carbon and 6% nitrogen), as found in 24° W+. We showed that changes in the composition of floral scent and pollen in varieties of V. corymbosum affected pollinator preferences in laboratory bioassays. This study contributes to our understanding of how climate change may impact trophic interactions by showing that changes in floral traits are associated with alterations in pollinator preferences.