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Microbial Uptakes for Sustainable management of major bananA pests and diseases

Periodic Reporting for period 2 - MUSA (Microbial Uptakes for Sustainable management of major bananA pests and diseases)

Période du rapport: 2018-12-01 au 2020-05-31

Problem/issue addressed
Plant parasitic nematodes (PPN), Panama disease (PD, Fusarium oxysporum f. sp. cubense) and weevils (BW, Cosmopolites sordidus) are main threats to banana (Musa spp.) and enset (Ensete ventricosum) in Canary Islands, Caribbean and Africa. In sub Saharan Africa (SSA) many pesticides already withdrawn or restricted in the EU continue to be (mis)used, with threats to farmers, environment and consumers. In Ethiopia, enset is a crucial staple crop for million people, exposed to PPN and BW. A new emerging and severe race of PD, F. oxysporum TR4, can attack Cavendish bananas and is spreading from Asia and Middle East to other areas.
Social importance
Banana is a high income export crop and a basic diet component in the EU and the world. In SSA and Caribbean regions million farmers rely on cooking bananas as key staple food and for income. In tropical and sub-tropical farms the Cavendish variety replaced Gros Michel for export, as the latter is susceptible to PD. Hundred local varieties are used in the tropics for domestic consumption. In tropical and sub-tropical systems, pests and diseases cause billion € losses, affecting the food security of million small growers, and income of both small holders and commercial growers. TR4 is a severe threat to the lives and food security of million people in SSA and Caribbean.
Overall objectives
MUSA aims at developing new Integrated Pest Management (IPM) methods based on microbial consortia and banana or enset germplasm, including new hybrids, studying phenotypic and molecular reactions of plants to various biotic stresses. Main goal is to achieve a sustainable intensification of crops, improving their resilience through locally adapted IPM strategies based on beneficial microorganisms and tested germplasm. Partners will collect and characterize suitable beneficial microorganisms, evaluating in the field their interactions with selected banana lines, and identify the genes involved in resistant/tolerant or succumbent/susceptible responses. Beneficial microbes include endophytes and biocontrol agents (EBCAs). Field trials for efficacy will be conducted in subsistence small-scale farming systems (low income, small holders, SSA) and intensive export-oriented crops (Canary Islands, Caribbean). Dissemination, communication and exploitation actions will ensure persistence of the Project impact after completion.
The Consortium developed activities including EBCAs collection, identification and study, for management of banana and enset threats. Prospecting campaigns were carried out for collection of EBCAs from soil or roots, in the three world regions of the Action. Studies also concerned screening for EBCAs role in resistance/tolerance shown by plants in the field. Eight national/regional microbial collections were set up, available at participating institutions and SMEs, with a total of 1072 isolates of fungi and bacteria and five lines of entomopathogenic nematodes (EPN, Heterorhabditis). Beneficial organisms include promising strains selected through laboratory and greenhouse assays. Procedures have been set up for large scale cultivation of EBCAs and EPN, bioformulation and storage. Data on the response of banana lines to some EBCAs have also been produced, testing their efficacy vs the threats considered, for exploitation in IPM or bio-management. Assays on the EBCAs isolated and/or made available by the beneficiaries included fungi such as Trichoderma spp. as plant growth promoters, also active against the nematode Radopholus similis; Pochonia chlamydosporia, a plant growth promoter also antagonistic of PPN and PD, and bacteria (Bacillus, Pasteuria, Streptomyces, Pseudomonas fluorescens and other species) tested against PD or PPN. Endophytism of P. chlamydosporia in banana roots was demonstrated in vitro and in controlled conditions. EPN and fungi have been also tested against BW. In vitro and laboratory assays have been carried out on the biology and diversity of these isolates, including sequencing of DNA for taxonomic identifications. A number of isolates and procedures have been shared with stakeholders for mass production and exploitation in bio-management. Sampling studies on banana corm and rhizosphere microbial biodiversity have been carried out in Tenerife (Spain) farms and in the germplasm conservation fields of IITA, in Uganda. In particular, an effective Beauveria bassiana isolate obtained from weevils in Uganda (C. Nankinga, NARO), was recovered and is now in use. A non-pathogenic F. oxysporum endophyte (V5W2) previously isolated by IITA effectively controlled nematodes, with a growth stimulus to plantlets. Further studies, still in progress, aim at identifying the links of plant health with soil and corm microbial communities, to identify bio-ecological factors sustaining management, in conjunction to climate and environmental field factors. Genes suitable for exploitation in breeding has been identified for banana and enset lines. Studies are in progress on banana root gene expression during parasitism by Pratylenchus goodeyi and PD, including the most damaging TR4. Data on gene expression of banana roots have been produced in tri-trophic interactions with P. chlamydosporia, and a microbial community including Trichoderma and Streptomyces spp. to identify growth promotion or elicitors of plant defense. Antagonistic effects on PPN have been discovered for some natural products and compounds (i.e. xanthines such as caffeine). Chitosan, a natural bioactive compound elicitor of plant defense, does not affect banana growth at doses inhibitory for other crops. Dissemination and Communication events were carried out. Eight Practice Abstracts were produced, on issues afforded and crops phytosanitary status. Two Project meetings have been organized, by IITA at Kampala (Uganda) and by EARTH (Costa Rica). All meetings were followed by a Workshop with stakeholders on applied aspects of biological pest/disease management in banana productions.
MUSA will yield new strategies for protection of banana crops and adaptation to future climatic threats, using EBCAs and plant germplasm. Data mining of Musa spp., enset, P. chlamydosporia, F. oxysporum, P. fluorescens PICF7 and PPN genomes will underpin new IPM concepts, integrating -omics data to improve plant response and reduce damages. MUSA will generate: i) novel eco-friendly compounds disrupting pest communication pathways or inducing plant defence, ii) new resistant plant resources, iii) new resilience model parameters, iv) GPS-based IPM systems; v) new bioformulations for biocontrol and IPM.
Substituting pesticides with safe IPM methods is a key MUSA approach. Sustainable approaches (e.g. resistance, EBCAs) have often been used separately, neglecting the complex communications of plants with microbes. Our work relies on the biology of EBCAs and their metabolites, to interfere with pest/disease communication in roots, or priming plant defence system. New plant lines and genomic traits will be used, conferring resistance/tolerance. A practical aspect is the distribution of safe plantlets to farmers, through regional organizations. Linking EBCAs with the distribution of healthy plantlets provides a feasible strategy to achieve our goals. A key factor is the collaboration in research, integrating communication and dissemination with field farming schools to keep impact after project completion.