Project description:Perennial ryegrass (Lolium perenne L.) is the most cultivated cool-season grass worldwide with crucial roles in carbon fixation and fodder for livestock. Protection of these grasses from biotic and abiotic factors are dictated through a mutually-beneficial relationship with endophytes that confer bioprotective properties. Common endophytes of the genus Epichloë promote the health and survival of cool-season forages greases and protect the plants from fluctuating environmental conditions. Climate change, and specifically, a steady increase in atmospheric CO2 levels, presents a dramatic and imminent threat faced by our ecosystem, which poses substantial pressures on plant health and survival. Defining the relationships between endophytes and the host plant may uncover mechanisms of bioprotection, which can be exploited to promote adaptable plant systems in rising CO2 conditions. In this study, we quantify changes in biomass and seed production of L. perenne L. at 400 and 800 ppm CO2 and identify endophyte-specific changes in metabolite production. Additionally, we discover protein-level changes from both the endophyte and plant perspectives, which underscore the compatible relationship between a common, natural endophyte and L. perenne L., compared to an incompatible and detrimental relationship the epichloid strain, AR1. Taken together, our data set provides new understanding into the intricacy of compatibility between endophyte and host from multiple molecular levels and suggests opportunity to promote plant robustness and survivability in rising CO2 environmental conditions through application of bioprotective epichloid strains.
Project description:Studying the endophyte strains of poplar that help the plant solubilize phosphate, we observed direct evidence of endophyte-promoted phosphorous fixation. Using synchrotron x-ray fluorescence (SR-XRF) microscopy combined with x-ray absorption near-edge structure (XANES), we visualized the nutrient phosphorous inside poplar roots inoculated by the selected endophytes and found that the phosphorus is fixated in the form of organic phosphate inside the root. Proteomics characterization on poplar roots revealed novel proteins and metabolic pathways involved in endophyte enriched phosphorus uptake.
Project description:Beneficial root-associated microbes can enhance plant resilience by complementing aspects of host immunity. The fungal root endophyte Serendipita indica (Si) is known to promote plant growth and confer broad stress tolerance. To assess how natural host genetic variation influences Si-mediated protection, we screened 47 Arabidopsis thaliana accessions for susceptibility to the fungal pathogen Bipolaris sorokiniana (Bs) with and without Si colonization. All accessions benefited from Si, indicating that endophyte-mediated disease mitigation occurs broadly across diverse host genotypes. A focused comparison of two genetically and geographically proximate Swedish accessions, T510 and T530, which displayed the most divergent protection scores, revealed substantial differences in Bs susceptibility. Transcriptome profiling under bi- and tripartite colonization showed conserved defense responses in both accessions. Bs infection downregulated growth- and development-related genes, consistent with a growth–immunity trade-off, with T530 exhibiting higher Bs colonization and a stronger transcriptional response than T510. Co-colonization with Si effectively suppressed pathogen growth and disease symptoms in both accessions. Comparative genomic and transcriptomic analyses identified four immune receptor genes, including the TIR-NLR ISI, present in T510 but absent in T530. An isi T-DNA insertion mutant phenocopied the heightened Bs susceptibility of T530, confirming that ISI contributes to root immunity, while Si-mediated protection remained intact despite increased pathogen susceptibility. Together, these findings demonstrate that fungal endophytes can mitigate the functional consequences of natural immune variation and enhance the resilience of genetically diverse plant populations.
Project description:The endophytic fungi of certain grasses and herbaceous plants provide anti-herbivore defense compounds, thus living in mutualistic interaction with their hosts. Still, there is little information on such cooperation for tree-associated endophytes. We investigate the influence of the endophytic fungus Cladosporium cladosporioides on the chemical defenses of black poplar Populus nigra trees and the consequences on feeding preference, fitness of herbivorous insects, and insect community assembly. Strikingly, endophyte colonization increases both constitutive- and induced poplar defenses. Generalist Lymantria dispar larvae prefer and perform better on uninfected poplars due to the higher concentrations of salicinoids and fungal alkaloid stachydrine in endophyte-infected leaves. Under field conditions, the endophytic fungus shapes insect community assembly in young black poplar trees. Our results show that endophytic fungi can play a significant role in defending trees against herbivorous insects and structuring insect communities.