Insights to plant–microbe interactions provide opportunities to improve resistance breeding against root diseases in grain legumes

Abstract

Root and foot diseases severely impede grain legume cultivation worldwide. Breeding lines with resistance against individual pathogens exist, but these resistances are often overcome by the interaction of multiple pathogens in field situations. Novel tools allow to decipher plant-microbiome interactions in unprecedented detail and provide insights into resistance mechanisms that consider both simultaneous attacks of various pathogens and the interplay with beneficial microbes. Although it has become clear that plant-associated microbes play a key role in plant health, a systematic picture of how and to what extent plants can shape their own detrimental or beneficial microbiome remains to be drawn. There is increasing evidence for the existence of genetic variation in the regulation of plant-microbe interactions that can be exploited by plant breeders. We propose to consider the entire plant holobiont in resistance breeding strategies in order to unravel hidden parts of complex defence mechanisms. This review summarizes (a) the current knowledge of resistance against soil-borne pathogens in grain legumes, (b) evidence for genetic variation for rhizosphere-related traits, (c) the role of root exudation in microbe-mediated disease resistance and elaborates (d) how these traits can be incorporated in resistance breeding programmes.

Comparative Analysis of Rhizosphere Microbiomes of Southern Highbush Blueberry (Vaccinium corymbosum L.), Darrow’s Blueberry (V. darrowii Camp), and Rabbiteye Blueberry (V. virgatum Aiton)

“…There is a growing consensus that the traditional plant breeding should be expanded to include plant genotype × environment × microbiome interactions (Wei and Jousset, 2017). Such microbiome-supported breeding should be performed in the absence of excessive fertilizers and pesticides and complemented by the microbial community profiling and screening for metabolites that mediate interactions with key pathogenic or beneficial species (Wille et al, 2018). We reason that similar experimental approaches can be employed in blueberries to harness microbial communities that improve the disease resistance, tolerance to heat and drought, and vigor to thrive in soils with low organic matter content.…”

Legumes—The art and science of environmentally sustainable agriculture

“…The review by Wille, Messmer, Studer, and Hohmann () summarizes our current knowledge of resistance mechanisms against soil‐borne pathogens in grain legumes, providing evidence for genetic variation for rhizo‐sphere‐related traits. The role of root exudation in microbe‐mediated disease resistance and elaborates is considered together with how such traits can be incorporated in resistance breeding programmes.…”

“…Faba bean was more tolerant than chickpea to growth in an oxygen-deficient root zone, highlighting the importance of choosing which grain legume species to grow in flood-prone fields. The review by Wille, Messmer, Studer, and Hohmann (2018)…”

Effects of Soil Microbes on Functional Traits of Loblolly Pine (Pinus taeda) Seedling Families From Contrasting Climates

“…Different soil microbes are responsible for converting organic N into forms that are accessible to plants: either ammonium (NH 4 + ) or nitrate (NO 3 -) (Hayatsu et al, 2008;Ohyama, 2010;Jacoby et al, 2017). Therefore, within-species populations and families can use root exudates to recruit and repel different soil microbes (Haney et al, 2015;Wille et al, 2019) that cause the plant populations and families to use different forms of N (i.e., NH 4 + , NO 3 -). The form of N used by the plant is reflected in leaf N isotope ratios (d 15 N) (Kahmen et al, 2008;Temperton et al, 2012).…”