Despite global turmoil, Gen Z researchers are not giving up

Four researchers born after 1997 describe how they stay motivated and cultivate resilience during difficult times.

nature.com

Europe’s record heatwave: does the continent have a new climate?

Nature asks researchers whether scorching summers are the new norm for London, Paris and Berlin.

nature.com

Un réseau de champignons long de dix millions d'années-lumière découvert sous nos pieds

Des chercheurs ont calculé, l'étendue et l'importance du vaste réseau de champignons qui se développe sous terre. Une véritable toile souterraine, longtemps méconnue, mais essentielle dans la régulati...

radiofrance.fr

Phytophthora root rot induces compositional and functional changes in avocado rhizosphere bacterial communities

Compositional and functional readjustments of the rhizobacterial community in avocado induced by Phytophthora root rot.

academic.oup.com

Bacillus populations restore amino acid metabolism in Mesorhizobium under saline–alkali stress to enhance nitrogen fixation efficiency

The root nodules formed by rhizobia and leguminous plants are specialized structures for nitrogen fixation. However, a large number of non-rhizobial endophytes also coexist within the nodules, and their contribution to nitrogen fixation under abiotic stress conditions remains unclear. Here, using the wild leguminous shrub Sophora davidii as model system, we identified an important NRE (Bacillus siamensis BT-9-1) by analyzing keystone taxa within the bacterial cooccurrence network of root nodules. This strain could improve the survival of Mesorhizobium metallidurans YC-39 under saline–alkali stress. A mechanistic investigation revealed that the expression of ilvA, ilvH, and ilvD was downregulated, and the contents of (2S)-isopropylmalate and succinic acid decreased in M. metallidurans YC-39 under saline–alkali conditions, whereas B. siamensis BT-9-1 presented increased accumulation of these metabolites. These findings indicate that B. siamensis BT-9-1 cross-feeds M. metallidurans YC-39 with these metabolites, rescuing the compromised branched-chain amino acid synthesis pathway and the tricarboxylic acid cycle in saline–alkali environments. Eventually, coinoculation with B. siamensis BT-9-1 and M. metallidurans YC-39, along with (2S)-isopropylmalate and succinic acid supplementation, increased nitrogenase activity of the symbionts. Our study reveals a novel mechanism by which non-rhizobial endophyte Bacillus species enhances the growth and nitrogen fixation efficiency of M. metallidurans under saline–alkali stress through the delivery of key metabolites.

sco.lt

Resource allocation to pea plant nodules impacted by nitrogen fixation potential of infecting rhizobia 

Legumes host nitrogen-fixing bacteria, called rhizobia, within specialised root structures called nodules, where carbon from the plant is exchanged for ammonia fixed from N2 by the bacteria. Legumes can host multiple bacterial strains at the same time, that vary in their fixation effectiveness, but legumes sanction nodules containing less effectively fixing strains by reducing the provision of nutrients. Understanding how sanctions are applied by plants and how bacteria may try to avoid them is important for understanding the stability of legume-rhizobial symbioses. Using near isogenic Rhizobium leguminosarum strains, on pea, we demonstrate that sanctions are sensitive to the proportion of nodules occupied by a less effective strain and by using split roots show that sanctions are applied based on a global comparison of nodules across the plant’s root system. By using several rhizobia with different levels of fixation, but all derived from the same parent, we show that pea plants can differentiate between bacteria with relatively small variations in fixation effectiveness. We demonstrate that peas integrate global signals to determine whether individual nodules are sanctioned. At the same time these results show that poorly fixing strains can avoid sanctions if they dominate nodulation.

sco.lt

Integrating microbial siderophores into concepts of plant iron nutrition

Iron is a crucial micronutrient for plants, but its availability in soil is often limited. Iron deficiency compromises plant growth, and low iron content in crops contributes substantially to the ‘hidden hunger’ that affects human health globally. The elucidation of Strategy I (reduction-based) and Strategy II (phytosiderophore-based) for iron acquisition was a milestone in plant biology and enabled the development of biofortification concepts. However, recent genetic evidence reveals that the boundary between the two strategies is blurred, with many plants possessing elements of both. Here we show that plant iron uptake mechanisms are more complex and diverse than the classical dichotomy suggests. We review evidence for this integrative view and highlight the critical role of microbial siderophores. We explain how plants access iron from microbial siderophores not only indirectly through Strategy I and II pathways but also via the direct uptake of iron–siderophore complexes, an overlooked mechanism that we introduce as Strategy III. We propose three potential routes for this direct uptake and conclude that harnessing Strategy III holds great potential for novel agricultural interventions to enhance iron biofortification and improve human health.

sco.lt

Ecological and genomic variation in ectomycorrhizal fungal exploration types

Ectomycorrhizal fungi (EMF) produce mycelia with variable extension and complexity, which can be classified according to soil ‘exploration types’ (ETs). ETs have received attention as one of the few.....

doi.org

Necromass chemistry drives the functional diversity of the necrobiome, resulting in microbe–organic matter feedbacks

Read the free Plain Language Summary for this article on the Journal blog.

besjournals.onlinelibrary.wiley.com

Developmental fates and N2-fixing efficiency of terminally-differentiated versus undifferentiated bacteroids from legume nodules

The higher symbiotic efficiency of pea bacteroids arises from their greater packing density and proteomic bias toward nitrogenase and dicarboxylate metabol

doi.org

The microbiota of avocado floral nectar inhibits pathogens and improves plant fitness

The floral nectar in avocado hosts microbes with anti-pathogenic activity and probiotic properties in a model plant species.

academic.oup.com

Nanodomain-localized formin gates symbiotic microbial entry in legume and solanaceous plants

Colonization of plant roots by symbionts requires substantial morphodynamic reorganization. Examples are actin-scaffolded microcompartments called infection pockets formed during root nodule symbiosis...

science.org

CRAGE-RB-PI-seq reveals transcriptional dynamics of plant-associated bacteria during root colonization

Plant roots release a wide array of metabolites into the rhizosphere, shaping microbial communities and their functions. While metagenomics has expanded our understanding of these communities, little is known about the physiology of their members in host environments. Transcriptome analysis via RNA sequencing is a common approach to learning more, but its use has been challenging because of low bacterial biomass and interference from plant RNA. To overcome this, we developed a randomly-barcoded promoter-library insertion sequencing (RB-PI-seq) combined with chassis-independent recombinase-assisted genome engineering (CRAGE). Using Pseudomonas simiae WCS417 as a model rhizobacterium, this method enabled targeted amplification of barcoded transcripts, bypassing plant RNA interference and allowing measurement of thousands of promoter activities during Arabidopsis root colonization. Our analysis revealed temporally resolved transcriptional regulation, including those associated with cell growth, chemotaxis, plant immune suppression, biofilm formation, and stress responses, reflecting the coordinated physiological adaptation to the root environment. Additionally, we discovered that transcriptional activation of xanthine dehydrogenase and a lysozyme inhibitor is crucial for evading plant immune systems. This framework is scalable to other bacterial species and provides new opportunities for understanding rhizobacterial gene regulation in native environments.

sco.lt

Poplar CLE peptides promoting ectomycorrhizal symbiosis identified through genome-wide analysis of responsive small secreted peptides

Trees use CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptides to promote ectomycorrhizal symbiosis, revealing an additional regulatory layer in tree–

academic.oup.com

Ecological constraints and evolutionary trade-offs shape nitrogen fixation across habitats

Abstract. From its earliest beginnings, life’s expansion into new habitats has been profoundly shaped by its reciprocal interactions with Earth’s changing

academic.oup.com

Symbiosome membrane-localized cationic amino acid transporters support symbiotic nitrogen fixation in Medicago truncatula

Legumes engage in nitrogen-fixing symbiosis with rhizobia, in which host legumes supply dicarboxylates as a carbon source to rhizobia, while rhizobia reciprocate by providing ammonium to the host plants. Beyond this classical model, accumulating evidence suggests that amino acid exchange is also essential for legume–rhizobium symbiosis. However, it remains unclear whether amino acid transporters are present on the symbiosome membrane (SM) to mediate amino acid exchange during symbiotic nitrogen fixation (SNF). In this study, we identified three amino acid transporters in Medicago truncatula—MtCAT1a, MtCAT1b, and MtCAT1c—which belong to a clade of the plant Cationic Amino acid Transporter (CAT) family known to transport a wide range of amino acids. Notably, MtCAT1b and MtCAT1c are predominantly expressed in infected nodule cells and localize to the SM. Genetic analyses further demonstrate that both MtCAT1b and MtCAT1c are required for amino acid exchange at the SM, with additional evidence indicating that bacteroid metabolism is disturbed in the mutants. Transport assays show that both MtCAT1b and MtCAT1c exhibit broad substrate specificity. Collectively, these findings identify MtCAT1b and MtCAT1c as key mediators of cross-kingdom amino acid exchange, which is essential for maintaining efficient SNF in root nodules.

sco.lt

Dihydroxyhexanoic acid biosynthesis controls turgor in pathogenic fungi

Many plant pathogenic fungi penetrate host surfaces mechanically, using turgor pressure generated by specialized infection cells called appressoria. These appressoria develop semipermeable cell walls ...

science.org

Transcriptomic and metabolomic analyses reveal the role of flavonoids in ectomycorrhizal symbiosis

Flavonoids are major plant secondary metabolites that mediate diverse plant–microbe interactions, including ectomycorrhizal (ECM) symbioses. However, their regulatory roles during ECM development remain poorly understood. Here, we investigated whether inoculation with Suillus bovinus alters flavonoid biosynthesis in Pinus yunnanensis roots and assessed how these flavonoids on fungal growth and gene expression. We applied exogenous flavonoids to S. bovinus mycelia to investigate fungal transcriptional and metabolic responses. Following inoculation, differentially expressed genes in P. yunnanensis roots were significantly enriched in the flavonoid biosynthesis pathway. Key enzyme-coding genes, including PAL, CHS, CHI, F3H, and FLS, were upregulated, and this was associated with increased flavonoid accumulation and enhanced antioxidant capacity. In S. bovinus, exogenous flavonoids promoted mycelial growth and induced metabolic adjustments related to carbohydrate and amino acid utilization. Several small secreted protein-related genes showed transcriptional responses to flavonoid exposure, indicating potential transcriptional modulation, although their specific roles in symbiosis remain unclear. These findings indicate that flavonoids may contribute to reciprocal interactions between host roots and ECM fungi and provide a molecular basis for further investigation.

sco.lt

Genomic and physiological signatures of adaptation in pathogenic fungi - Nature Communications

Emerging fungal pathogens have detrimental impacts on crops, animals, and humans, however little is known about their transition to a pathogenic lifestyle. This study demonstrates that the transition ...

nature.com