Yeasts as new powerful bio-tools for sustainable agriculture: Biocontrol of plant fungal diseases and ecological implications

Crop diseases caused by fungi or oomycetes are responsible for significant losses in food production worldwide, and are increasingly recognized as a global threat to food security. This crisis derives from concurring factors, which include agricultural practices, global trade and climate change, all of which synergistically impact plants’ fitness, critical to the maintenance of function and services of agro-ecosystems. Yeasts are part of the plant holobiont, in the phytosphere, rhizosphere and adjacent soil, where they play mostly unknown roles, which do not include damage or disease to plants. In other respects, yeasts have beneficial potential for the biological control of fungal diseases and as promoters of plant health and growth. Their roles as endophytes, mutualists and as part of roots and soils microbiome are presented and discussed in this chapter, as are the ways by which yeasts kill fungi. These include the secretion of Killer toxins, hydrolytic enzymes, small peptides, siderophores and/or VOCs. Some species also act as necrotrophic mycoparasites. Yeasts’ resilience in face of environmental stress, specificity of action and amenability towards plants and humans, together with their fast proliferation, make them significant candidates for utilization in sustainable agriculture practices, both as BCAs and PGPs, urging research in this regard.

We thank Sofia Costa, a senior researcher at our research centre, for her critical reading and suggestions. This work was supported (i) by the “Contrato-Programa” UIDB/04050/2020 funded by national funds through the FCT I.P.; (ii) by the Fundação para a Ciência e Tecnologia (FCT), under the project LA/P/0069/2020 granted to the Associate Laboratory ARNET; and (iii) by the FCT, CCDR-NCCDR-N (Norte Portugal Regional Coordination and Development Commission) and European Funds (FEDER/POCI/COMPETE2020) through the project AgriFoodXXI (NORTE 01-0145-FEDER-000041).