Biology subjects

Malisic, M.

Publications and source records attributed to Malisic, M..

4 recordsLinked to original sources

bioRxiv2025

A multigenic quantitative trait locus underlies natural variation in Arabidopsis thaliana root system architecture and transcriptional responses to microbiota-derived Pseudomonas

Plants interact with structured microbial communities called the microbiota, which can have a profound impact on plant growth and health. However, how plants perceive and respond to specific core microbiota members at a molecular level is still unclear. We identified natural variation in Arabidopsis thaliana root responses to bacterial strains of the genus Pseudomonas, a core genus of the plant microbiota. Some A. thaliana accessions such as Van-0 show strong root responses to Pseudomonas strains, including changes in root system architecture and transcriptional reprogramming. Through a forward genetic screen using Pseudomonas isolate R569, we found that the nuo NADH dehydrogenase complex, part of the bacterial electron transport chain, contributes to the bacterial activity on Van-0 roots. Using recombinant inbred lines, we further mapped a multigenic quantitative trait locus in the host that is associated with the root responses. In Van-0, the exocyst subunit EXO70E2 positively contributes to the response, while Col-0 haplotypes of malectin-like and leucine-rich-repeat domain-containing receptor-like kinases play an inhibitory role. The identification of these components in the bacteria and the host establishes a genetic framework for how root developmental plasticity is integrated with the microbe-rich soil environment and is subject to intraspecific natural variation.

plant biology↗

bioRxiv2025

Cooperation between a root fungal endophyte and host-derived coumarin scopoletin mediates Arabidopsis iron nutrition

O_LIIron acquisition is a critical challenge for plants, especially in iron-deficient soils. Recent research underscores the importance of root-exuded coumarins in modulating the root microbiome community structure and facilitating iron uptake. However, interactions between root-associated fungi and coumarins in plant iron nutrition remain unknown. We investigated the mechanism by which a fungal endophyte, Macrophomina phaseolina (F80), enhances Arabidopsis iron nutrition. C_LIO_LIFungal-coumarin interactions were assessed by profiling metabolites and measuring iron mobilisation in F80 cultures supplemented with specific coumarins, alongside quantifying growth performance and iron content in Arabidopsis coumarin-biosynthesis mutants inoculated with F80. C_LIO_LIOur findings reveal that an interaction between the coumarin scopoletin and F80 in the rhizosphere rescues plant growth under iron-limiting conditions by resolving the iron mobility bottleneck. F80 exhibits a capacity to modify scopoletin into iron-chelating catechol coumarin esculetin, thereby releasing available iron. C_LIO_LIWe conclude that Arabidopsis-produced scopoletin functions as a precursor for fungal conversion into iron-chelating coumarins. By extending the role of coumarins from bacterial to fungal members of the root microbiota, this study places coumarins at the centre of commensal-mediated enhancement of plant iron nutrition across microbial kingdoms. C_LI

plant biology↗

bioRxiv2022

Brassicaceae display diverse photorespiratory carbon recapturing mechanisms

Carbon concentrating mechanisms enhance the carboxylase efficiency of the central photosynthetic enzyme rubisco by providing supra-atmospheric concentrations of CO2 in its surrounding. In the C4 photosynthesis pathway, this is achieved by combinatory changes to leaf biochemistry and anatomy. Carbon concentration by the photorespiratory glycine shuttle requires fewer and less complex modifications. It could represent an early step during evolution from C3 to C4 photosynthesis and an inspiration for engineering approaches. Plants displaying CO2 compensation points between 10 to 40 ppm are therefore often termed C3-C4 intermediates. In the present study, we perform a physiological, biochemical and anatomical survey of a large number of Brassicaceae species to better understand the C3-C4 intermediate phenotype. Our phylogenetic analysis suggested that C3-C4 metabolism evolved up to five times independently in the Brassicaceae. The efficiency of the pathways showed considerable variation between the species but also within species. Centripetal accumulation of organelles in the bundle sheath was consistently observed in all C3-C4 classified accessions indicating a crucial role of anatomical features for CO2 concentrating pathways. Leaf metabolite patterns were strongly influenced by the individual plant accessions, but accumulation of photorespiratory shuttle metabolites glycine and serine was generally observed. Analysis of PEPC activities suggests that C4-like shuttles have not evolve in the investigated Brassicaceae. HighlightOur physiological, biochemical and anatomical survey of Brassicaceae revels multiple evolution of C3-C4 intermediacy connected to variation in photorespiratory carbon recapturing efficiency and a distinct C3-C4 bundle sheath anatomy.

plant biology↗

bioRxiv2021

Fungi hijack a plant apoplastic endoglucanase to release a ROS scavenging β-glucan decasaccharide to subvert immune responses

Plant pathogenic and beneficial fungi have evolved several strategies to evade immunity and cope with host-derived hydrolytic enzymes and oxidative stress in the apoplast, the extracellular space of plant tissues. Fungal hyphae are surrounded by an inner, insoluble cell wall (CW) layer and an outer, soluble extracellular polysaccharide (EPS) matrix. Here we show by proteomics and glycomics that these two layers have distinct protein and carbohydrate signatures, implicating different biological functions. The barley (Hordeum vulgare) {beta}-1,3-endoglucanase HvBGLUII, which belongs to the widely distributed apoplastic glycoside hydrolase 17 family (GH17), releases a conserved {beta}-1,3;1,6-glucan decasaccharide ({beta}-GD) from the EPS matrices of fungi with different lifestyles and taxonomic positions. This low molecular weight {beta}-GD does not activate plant immunity, is resilient to further enzymatic hydrolysis by {beta}-1,3-endoglucanases due to the presence of three {beta}-1,6-linked glucose branches and can scavenge reactive oxygen species. Additionally, exogenous application of {beta}-GD leads to enhanced fungal colonization in barley. Our data highlights the hitherto undescribed capacity of this often overseen fungal EPS layer to act as an outer protective barrier important for fungal accommodation within the hostile environment at the apoplastic plant-microbe interface. SignificanceHere we identify and characterize a conserved {beta}-1,3;1,6-glucan decasaccharide with antioxidant activity released from the fungal extracellular polysaccharide (EPS) matrix by the activity of a plant apoplastic endoglucanase. In addition, we provide a quantitative proteomic analysis of the fungal EPS and cell wall (CW) layers. HIGHLIGHTSO_LIThe fungal extracellular polysaccharide (EPS) matrix and the cell wall (CW) are specific layers with distinct protein and carbohydrate signatures C_LIO_LIA conserved {beta}-1,3;1,6-glucan decasaccharide ({beta}-GD) is released from the EPS matrices of different fungi by the activity of the barley {beta}-1,3-endoglucanase BGLUII, a member of the widely distributed apoplastic GH17 family C_LIO_LIThe {beta}-GD efficiently scavenges reactive oxygen species (ROS) and enhances fungal colonization C_LIO_LIThe immunomodulatory potential as microbe-associated molecular pattern (MAMP) as well as the biochemical activity as ROS scavenger of soluble low molecular weight {beta}-glucans are defined by the presence of {beta}-1,6-glucose branches C_LI

microbiology↗