Project description:Broad-host root endophytes establish long-term interactions with a large variety of plants, thereby playing a significant role in natural and managed ecosystems and in evolution of land plants. To exploit plants as living substrates and to establish a compatible interaction with morphologically and biochemically extremely different hosts, endophytes must respond and adapt to different plant signals and host metabolic states. Here we identified host-adapted colonization strategies and host-specific effector candidates of the mutualistic root endophyte Piriformospora indica by a global investigation of fungal transcriptional responses to barley and Arabidopsis at different symbiotic stages. Additionally we examined the role played by nitrogen in these two diverse associations. Cytological studies and colonization analyses of a barley mutant and fungal RNAi strains show that distinct physiological and metabolic signals regulate host-specific lifestyle in P. indica. This is the foundation for exploring how distinct fungal and host symbiosis determinants modulate biotrophy in one host and saprotrophy in another host and, ultimately, gives hints into the mechanisms underlying host adaptation in root symbioses. Arabidopsis and barley roots were inoculated with Piriformospora indica and grown for 14 days. Additionally P. indica was grown on 1/10 PNM medium alone. Samples were taken 3 and 14 dpi (Arabidopsis), 14 dpi (barley) and 3dpi (1/10 PNM). Each experiment was performed in three independent biological repetitions. Piriformospora indica gene expression examined only.
Project description:Broad-host root endophytes establish long-term interactions with a large variety of plants, thereby playing a significant role in natural and managed ecosystems and in evolution of land plants. To exploit plants as living substrates and to establish a compatible interaction with morphologically and biochemically extremely different hosts, endophytes must respond and adapt to different plant signals and host metabolic states. Here we identified host-adapted colonization strategies and host-specific effector candidates of the mutualistic root endophyte Piriformospora indica by a global investigation of fungal transcriptional responses to barley and Arabidopsis at different symbiotic stages. Additionally we examined the role played by nitrogen in these two diverse associations. Cytological studies and colonization analyses of a barley mutant and fungal RNAi strains show that distinct physiological and metabolic signals regulate host-specific lifestyle in P. indica. This is the foundation for exploring how distinct fungal and host symbiosis determinants modulate biotrophy in one host and saprotrophy in another host and, ultimately, gives hints into the mechanisms underlying host adaptation in root symbioses.
Project description:The root-colonizing fungal endophyte Serendipita indica, formerly known as Piriformospora indica, is well known to promote plant biomass production and stress tolerance of its host plants. Previous studies highlighted an important role of calcium Ca2+ signaling in the establishment of the plant–fungus interaction. We here report the comparative analysis of the effect of a mock- and S. indica-infection on both wild-type Arabidopsis plants (Col-3) and cbl7 knockout mutants. Our data provide evidence for the involement of the Ca2+ sensor CBL7 in the control of potassium distribution in the plant and in adjusting plant defense responses to allow the establishment of the plant–fungus symbiosis. The impairment of CBL7 was shown to translate into increased induction of plant defense-related genes.
Project description:Numerous Trichoderma strains are beneficial for plants, promote their growth and confer stress tolerance. A recently described novel Trichoderma strain strongly promotes growth of Arabidopsis thaliana seedlings on media with 50 mM NaCl, while 150 mM NaCl strongly stimulated root colonization and induced salt-stress tolerance in the host without growth promotion. To understand the dynamics of plant-fungus interaction, we examined the secretome from both sides, and revealed a substantial change under different salt regimes, and during co-cultivation. Stress-related proteins, such as fungal Kp4-, WSC- and CFEM-domain-containing proteins, the plant calreticulin and cell-wall modifying enzymes, disappear when the two symbionts are co-cultured under high salt concentrations. More proteins involved in plant and fungal cell wall modifications and the battle of root colonization are found in the co-cultures under salt stress, while the number of plant antioxidant proteins decreased. We identified symbiosis- and salt concentration-specific proteins for both partners. The Arabidopsis PYK10 and a fungal prenylcysteine lyase are only found in the co-culture which promoted plant growth. The comparative analysis of the secretomes suggests that both partners profit from the interaction under salt stress but have to invest more in balancing the symbiosis. We discuss the role of the identified stage- and symbiosis-specific fungal and plant proteins for salt-stress and conditions promoting root colonization and plant growth.
Project description:Trichoderma harzianum T34 is a fungal strain able to promote the plant growth and to increase plant defense responses. Trichoderma harzianum transformants expressing the amdS gene, encoding an acetamidase, of Aspergillus nidulans produce a higher plant development than the wild type T34. We used microarrays to analyze the physiological and biochemical changes in tomato plants produced as consequence of interaction with Trichoderma harzianum T34 and amdS transformants
Project description:Plants are naturally associated with diverse microbial communities, which play significant roles in plant performance, such as growth promotion or fending off pathogens. The roots of Alkanna tinctoria L. are rich in naphthoquinones, particularly the medicinally used chiral compounds alkannin, shikonin and their derivatives. Former studies already have shown that microorganisms may modulate plant metabolism. To further investigate the potential interaction between A. tinctoria and associated microorganisms we performed a greenhouse experiment, in which A. tinctoria plants were grown in the presence of three distinct soil microbiomes. At four defined plant developmental stages we made an in-depth assessment of bacterial and fungal root-associated microbiomes as well as all primary and secondary metabolites. Our results showed that the plant developmental stage was the most important driver influencing the plant metabolite content, revealing peak contents of alkannin/shikonin at the fruiting stage. In contrast, the soil microbiome had the biggest impact on the plant root microbiome. Correlation analyses performed on the measured metabolite content and the abundance of individual bacterial and fungal taxa suggested a dynamic, at times positive or negative relationship between root-associated microorganisms and root metabolism. In particular, the bacterial Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group and the fungal species Penicillium jensenii were found to be positively correlated with higher content of alkannins.
Project description:To test the hypothesis that gene expression by the fungal partner in this beneficial interaction is modulated by the plant host, Trichoderma virens was co-cultured with maize or tomato in a hydroponic system allowing interaction with the roots. The transcriptomes for T. virens alone were compared with fungus-inoculated tomato or maize roots by hybridization on oligonucleotide microarrays Based on the relevant role of Trichoderma virens as a biological control agent this study provides a better knowledge of its crosstalk with plants in a host-specific manner.
Project description:Diversification of effector function, driven by a co-evolutionary arms race, enables pathogens to establish compatible interactions with their hosts. Structurally conserved plant pathogenesis-related PR-1 and PR-1-like (PR-1L) proteins are involved in plant defense and fungal virulence, respectively. It is unclear how fungal PR-1L counteracts plant defense. Here, we show that Ustilago maydis UmPR-1La and yeast ScPRY1 with conserved phenolic detoxification functions are Ser/Thr-rich region-mediated cell-surface localization proteins. However, UmPR-1La has gained additional specialized activity in eliciting hyphal-like formation, suggesting that U. maydis deploys UmPR-1La to sense phenolics and direct their growth in plants. U. maydis also hijacks plant cathepsin B-like 3 (CatB3) to release functional CAPE-like peptides after cleaving a conserved CNYD motif of UmPR-1La to subvert plant immunity for promoting fungal virulence. Surprisingly, CatB3 avoids cleavage of plant PR-1s, despite the presence of the same conserved CNYD motif. Our work highlights that UmPR-1La has acquired additional dual roles to suppress plant defense and sustain the infection process of fungal pathogens.
Project description:To test the hypothesis that gene expression by the fungal partner in this beneficial interaction is modulated by the plant host, Trichoderma virens was co-cultured with maize or tomato in a hydroponic system allowing interaction with the roots. The transcriptomes for T. virens alone were compared with fungus-inoculated tomato or maize roots by hybridization on oligonucleotide microarrays Based on the relevant role of Trichoderma virens as a biological control agent this study provides a better knowledge of its crosstalk with plants in a host-specific manner. Trichoderma virens was co-cultured for three days with maize or tomato in a hydroponic system allowing interaction with the roots. 3 experiments were performed for each treatment, and compared to 5 experiments with T. virens grown under the same conditions without plants.