Comunicação na rizosfera e interações entre plantas, nemátodes e rizóbios – novas soluções para a proteção das culturas

The European Green Deal aims to significantly reduce application of synthetic pesticides and fertilizers to approach carbon neutrality in agriculture. Its application will undoubtedly result in climate change mitigation, and improved, ecologically-efficient agroecosystems, ultimately reflecting on human health and well-being. However, alternatives to chemical inputs for crop protection against plant pathogens are scarce; agroecosystems, often degraded by decades of conventional management, lack biodiversity, complexity and resilience. Root-knot nematodes (RKN) are the most damaging soilborne plant parasites in horticultural crops worldwide, causing serious yield losses, and conventionally controlled by the application of highly toxic nematicides. Climate change is likely to lead to unpredictable dynamics, increased incidence and severity of RKN attack. Alternative management practices that provide efficient, long-term control are currently unavailable, leaving horticulture vulnerable to RKN. Recently, a large body of research has built up on RKN ecology in agricultural and natural systems, accompanied by fine biochemical and molecular characterisations of rhizosphere interactions and communication, that can be translated into sustainable, novel solutions for crop protection against these nematodes. This proposal brings together a multi-disciplinary team integrating research backgrounds in agroecology, soil ecology, plant-nematode and plant-rhizobia interactions, microbiome effects on plant health, metabolic and molecular characterisation of rhizosphere communication and signalling. We will work in synergy to complement mechanistic knowledge on RKN control and develop applied research to address their sustainable management in horticulture. Our approach is novel in integrating multiple interactions and communication across soil community compartments, learning and optimising strategies from in vitro to field conditions. We propose to investigate the potential role of legumes as mediators of plant-soil interactions capable of mitigating damage caused by RKN to susceptible crops. Specifically, we will: i) assess the communication mechanisms responsible for the attraction and infection of nematode-plant-rhizobia (root exudates, rhizobial and nematode filtrates) with a direct or plant-mediated effect, advancing this research field; ii) ascertain the best combinations of legume cover crops and rhizobia to enhance their resistance to RKN, further establishing any theoretically-anticipated trade-off effects between nitrogen fixation and defence against RKN; iii) elucidate associational resistance and legacy effect potential of selected legume-rhizobia combinations to crops in a gradient of domestication, thereby also addressing the loss of biodiversity and communication capacity in modern cultivars; and iv) design and test a novel crop protection against RKN via intercropping with RKN resistance-inducing associations of legumes with rhizobia, in what will be a low-tech, widely applicable practice. To promote transferability and application of our research to cropping systems worldwide, manipulative experiments will be complemented by fine characterisation of compound mixtures and by the taxonomical, functional and metabolic analysis of soil communities. Our research will be published in international scientific journals, communicated to the general public, and knowledge gained will be transferred to actors in the sector.