Aim
Description Of The Challenge (Main Aim)
The main aims of ROOT-BENEFIT are: i) to structure the European research community on beneficial root-associated microorganism interactions in order to favour networking, strengthen the European research capacity, and facilitate knowledge transfer to socio-economic actors; and ii) to evaluate the potential of various levers (described below) and propose strategies for the integration and improvement of the services provided by the beneficial root-associated microorganisms to agriculture.Several barriers currently hamper the implementation of beneficial root-associated microorganisms in more sustainable agricultural practices.
Challenges
Challenge 1. The European research community is fragmented:
The European research community working on this topic is mainly organized by i) the type of beneficial root-associated microorganism studied and ii) the level of study (molecular, cellular, eco-physiological, field, cropping system, …), while exploiting the potential of beneficial root-associated microorganisms in agriculture requires multi-scale and multidisciplinary research approaches. This is reflected in theEuropean/international academic societies and scientific conferences that follow the same pattern (e.g.ICOM, iMMM, ENFC, Biostimulants …conferences).
Challenge 2. Research on beneficial root-associated microorganisms for agriculture is under- represented in European calls:
Despite their potential for application in agriculture and to fulfil the general aims of the European GreenDeal (reducing net greenhouse gas emissions by at least 55% by 2030) and notably those of the Farm to Fork strategy (reducing fertilizer use by at least 20% by 2030 or increasing organic farming to 25% of total farmland by 2030), beneficial root-associated microorganisms are relatively under-represented among the topics of recent European calls for grant applications. In the last years, strong emphasis has been put on studies related to soil microbiota and biocontrol agents. Although beneficial root-associated microorganisms fall into these microorganism categories, the specificities of beneficial root-associated microorganisms make them generally not being characterized in global functional studies of microbiota and/or not considered for their dual role in nutrition and protection against pests and diseases. This has largely prevented both the scientific community and stakeholders from fully deciphering and benefiting from the potential of these beneficial plant-microorganism interactions.
Challenge 3. Limited tools and methodologies for the characterisation of microbial communities:
One of the current challenges for ecological studies of beneficial root-associated microorganisms is to understand how variations in the quantity and composition of the soil and of root communities influence the benefits they provide to crops. Nowadays, the description of the microbial community composition is mainly achieved by meta barcoding and microorganism isolation and characterization. These approaches have proved to be very effective in describing multiple samples in a timely fashion. Yet, they suffer from a lack of resolution in dissecting intra genus and species diversity among microorganisms. These data may be critical when considering microbial functions that deliver ecological services to the agro ecosystems.
Challenge 4. Limited knowledge about complex interaction outcomes:
Despite extensive knowledge on the molecular mechanisms of the interactions between plants and individual beneficial root-associated microorganism in controlled conditions, multipartite interactions(e.g. combined rhizobia + AM fungi + other PGP microorganisms or biocontrol agents) and the impact of the environment (e.g. mineral nutrient availability, temperature, atmospheric CO2 concentration) on these interactions have barely been analysed. This limits the translational exploitation of the current knowledge into agriculture, as well as predictions about the impact of climate changes on the root colonization by these microorganisms and on the efficacy of ecological services they provide.
Challenge 5. The potential of beneficial root-associated microorganism for climate change mitigation and for plant resilience needs to be better integrated:
Global warming and other climate changes associated with human activities lead to a combination of various threats affecting plant growth and agriculture yields. The role of beneficial root-associated microorganisms in these fast evolving and complex environmental conditions needs to be evaluated inmore depth through integrated approaches at different scales. Noteworthy, endosymbiotic interactionsare predicted to benefit more from the increased atmospheric CO2 availability whereas AM fungi may promote an increased water acquisition due to their ability to explore large soil volumes and to transport water. However, climate changes also directly bring some drawbacks on endosymbiotic interactions such as in relation to drought. In addition, root and rhizosphere microorganisms can contribute to stabilization of soil organic matter. Better understanding and managing the potential of root-associated microorganisms on soil carbon and nutrient storage is particularly relevant in organic matter-poor cropland soils as found in many regions in Europe.
Challenge 6. The potential for plant breeding to improve beneficial microbial interactions has not been exploited:
The genetic variation existing in cultivated plants can greatly impact both the capacity of beneficial root-associated microorganisms to colonize roots and the capacity of plants to benefit from these interactions. This represents an attractive avenue to enhance relationships between plants and beneficial root-associated microorganisms in agriculture. However, conventional breeding strategies have not explicitly considered the interactions with beneficial root-associated microorganisms. To achieve this, first appropriate agricultural practices and secondly specific tools to evaluate the plant responsiveness to these beneficial root-associated microorganisms, are required.
Challenge 7. Scientific results and recommendations often do not reach end-users:
It is well known that several conventional agricultural practices, such as tillage or high levels of chemical fertilization, reduce both the diversity in the root microbiota and interactions with AM fungi and N-fixing root nodule bacteria9. Beneficial root-associated microorganisms are thus likely to express their full potential in low-input and low soil-disturbance cropping systems. The combination of both low-input and low soil-disturbance practices remains however marginally used in Europe.
Challenge 8. The commercialized beneficial root-associated microorganisms do not always meet the expectations for long-term soil management:
Beneficial root-associated microorganisms are sold in Europe either as biostimulants or as biocontrol agents. Field inoculation with rhizobia has been used since a long time as it is indispensable for the establishment of the N-fixing symbiosis in legumes when the compatible rhizobia are absent in soils(e.g. for growing soybean in Europe). Inoculation with AM fungi and PGP bacteria and fungi is more recent, but represents a fast-growing market. However, there is a strong variability in the quality of the inoculants on the market, both in terms of quantity of living microorganisms and of their efficacy under field conditions. This leads to a risk of increasing scepticism of farmers for using beneficial root-associated microorganism inoculants. Beside the quality of inoculants, there is a current lack of ecological consideration relating to microorganism selection, such as the evaluation of their persistence, competitiveness and relative efficiency in different soils, leading to a risk of soil pollution by highly persistent, highly competitive, and lowly efficient strains.
Specific Objectives
To achieve the main objective described in this MoU, the following specific objectives shall be accomplished:
Research Coordination
- Compile and disseminate current knowledge on plant interactions with beneficial root-associated microorganisms, identify gaps in knowledge and define future research priorities.
- Facilitate the visibility and access to existing European beneficial root- associated microorganism resources and to coordinate development of resources useful for studies on beneficial root-associated microorganisms.
- Analyse the limitation of current methods and propose their improvement to better describe beneficial root-associated microorganism interactions and to better evaluate the services they provide to crops under field conditions.
- Evaluate the potential of various levers for improving plant interactions with beneficial root-associated microorganisms under various soil and climate conditions and propose strategies for future research and development on these levers.
- Make recommendations about beneficial root-associated microorganism inoculant selection, application, and quality control for producers and policy-makers.
Capacity Building
- Establish a large multidisciplinary network involving microbiologists experts in plant-microorganisminteractions, plant physiologists and geneticists, ecologists and agronomists, from both public and privatesectors, to promote the exchange of expertise and know-how on beneficial root-associatedmicroorganisms. Facilitate contacts with international companies/SMEs, policy-makers and end-users.
- Train students, Young Researchers and Innovators and stakeholders. Promote the emergence of newresearch capacities and facilitate the transfer of knowledge in relation to the use of beneficial root- associated microorganism interactions.
- Raise awareness of the economic sector, policy-makers, end-users as well as the general public, notablyof the younger generation, about the relevance of using beneficial root-associated microorganisminteractions to reach a more sustainable agriculture.