Final Report Summary - SYMUNITY (Function of SymRK, a key protein for microbial accommodation in plants roots)
The second half of the last century has witnessed the green revolution that resulted in improved crop yield mainly fuelled by extensive use of mineral fertilizers and pesticides. Beside the tremendous benefits brought by this strategy to sustain food security of an increasing human population we can now foresee some limits of this model. Pesticides threat environment and human health while fertilizers can also impact the costs of production. These concerns have been raised, notably by the European Union and restrictions in use of pesticides have stimulated research and development of alternative strategies to promote plant growth and protection against pests. Maintaining or improving agricultural yield to feed a growing human population in an environmental friendly fashion is one of the key challenges we are facing in this early 21st century. This milestone can be reached if we control and take benefit from interactions of plants with their biological environment, to fend off pathogens while retaining beneficial symbiotic interactions. The SYMUNITY proposal deals with this goal.
How beneficial associations occur without activating plant immunity is still largely unknown. Also, genetic engineering of plant resistance to microbial diseases may affect beneficial interactions.
To enable appropriate engineering of crops for microbial interactions, the SYMUNITY project aimed at deciphering the function of the SymRK cellular receptor in the regulation of symbiotic and immune plant processes. This protein facilitates beneficial interaction with endomycorrhizal fungi by perceiving their symbiotic signals. In the meantime, preliminary research demonstrated that SymRK also controls immune responses to a Phythophthora species, pathogens causing important losses all around the world. Whether SymRK is targeted by the pathogen and their signals to fulfill invasion still has to be addressed.
To reach this objective, an array of microscopic, molecular biology and biochemistry approaches were planned to understand how SymRK modulate colonisation by microbes, act in the perception of their associated molecular signatures and regulate additional signaling components. Three aims corresponding to these objectives were defined
1. Analysis of a SymRK contribution in the interaction with P. palmivora and endomycorrhizal fungi at the scale of the plant
2. Comparisons of SymRK dependent responses to endomycorrhizal fungi, P. palmivora and their molecular signatures at the scale of the genome-wide changes in gene expression
3. SymRK function upon beneficial and detrimental colonization at the cellular scale
The project assessed the effect of SymRK mutation (absence of the receptor) or overexpression (enhanced accumulation in plant cells) during the infection by P. palmivora. This analysis is part of a larger genetic survey which can be accessed here (DOI: 10.1111/nph.13233). Both, microscopical observations and detection of markers probing host responses to the colonisation and the pathogen lifestyle were analyzed. Because SymRK acts in microbial signal detection, extracts of chemicals released by spores of the pathogen have been prepared and were shown to induce host immune responses. Future prospect will lead us to dissect the role of SymRK in this genome-wide reprogramming. Studies of cellular responses identified the localisation of a SymRK coreceptor protein at haustoria, the interface formed by the pathogen mycelium within single host cells. Finally, the scientific literature has been scrutinized to identify additional genes potentially acting in immune and symbiotic pathways, which can be accessed here (DOI: 10.1016/j.pbi.2014.05.014).
The SYMUNITY project positioned SymRK as a central connector between symbiosis and immunity processes. This receptor seems to receive signaling input from both immune and symbiotic pathways and ensures appropriate signaling output. By thoroughly assessing the role of SymRK in the responses to symbiotic endomycorrhizal fungi and the oomycete Phytophthora palmivora as well as their cognate signaling compounds, the SYMUNITY project constitutes a milestone in our understanding of plant adaptation to their microbial environment.
How beneficial associations occur without activating plant immunity is still largely unknown. Also, genetic engineering of plant resistance to microbial diseases may affect beneficial interactions.
To enable appropriate engineering of crops for microbial interactions, the SYMUNITY project aimed at deciphering the function of the SymRK cellular receptor in the regulation of symbiotic and immune plant processes. This protein facilitates beneficial interaction with endomycorrhizal fungi by perceiving their symbiotic signals. In the meantime, preliminary research demonstrated that SymRK also controls immune responses to a Phythophthora species, pathogens causing important losses all around the world. Whether SymRK is targeted by the pathogen and their signals to fulfill invasion still has to be addressed.
To reach this objective, an array of microscopic, molecular biology and biochemistry approaches were planned to understand how SymRK modulate colonisation by microbes, act in the perception of their associated molecular signatures and regulate additional signaling components. Three aims corresponding to these objectives were defined
1. Analysis of a SymRK contribution in the interaction with P. palmivora and endomycorrhizal fungi at the scale of the plant
2. Comparisons of SymRK dependent responses to endomycorrhizal fungi, P. palmivora and their molecular signatures at the scale of the genome-wide changes in gene expression
3. SymRK function upon beneficial and detrimental colonization at the cellular scale
The project assessed the effect of SymRK mutation (absence of the receptor) or overexpression (enhanced accumulation in plant cells) during the infection by P. palmivora. This analysis is part of a larger genetic survey which can be accessed here (DOI: 10.1111/nph.13233). Both, microscopical observations and detection of markers probing host responses to the colonisation and the pathogen lifestyle were analyzed. Because SymRK acts in microbial signal detection, extracts of chemicals released by spores of the pathogen have been prepared and were shown to induce host immune responses. Future prospect will lead us to dissect the role of SymRK in this genome-wide reprogramming. Studies of cellular responses identified the localisation of a SymRK coreceptor protein at haustoria, the interface formed by the pathogen mycelium within single host cells. Finally, the scientific literature has been scrutinized to identify additional genes potentially acting in immune and symbiotic pathways, which can be accessed here (DOI: 10.1016/j.pbi.2014.05.014).
The SYMUNITY project positioned SymRK as a central connector between symbiosis and immunity processes. This receptor seems to receive signaling input from both immune and symbiotic pathways and ensures appropriate signaling output. By thoroughly assessing the role of SymRK in the responses to symbiotic endomycorrhizal fungi and the oomycete Phytophthora palmivora as well as their cognate signaling compounds, the SYMUNITY project constitutes a milestone in our understanding of plant adaptation to their microbial environment.