Insights into Citrus limon nonhost and host resistance against Xanthomonas spp.

ROESCHLIN R.A.; UVIEDO F.; MOLINA M.C.; MARANO M.R.; FAVARO M.A.; DANDREA R.; CHIESA M.A.; CAMPOS-BENEYTO L.; GADEA J.

Coimbra

Workshop; Annual Conference on ?Integrating science on Xanthomonadaceae for integrated plant disease management in Europe; 2017

EuroXanth

Citrus is an economically important fruit crop that is severely afflicted by Asiatic citrus canker, a disease caused by the bacterial Xanthomonas citri subsp. citri (X. citri). There is great need for new and sustainable strategies to manage citrus canker disease. Strong evidence in several pathosystems indicates that nonhost resistance is more durable and robust compared with host resistance. In order to identify novel resistance mechanisms and genes with a role in canker resistance, we have characterized at the histological and molecular level the main differences between the defence response in Citrus limon to the non-adapted pathogen X. campestris pv. campestris (Xcc) and to the host pathogen X. fuscans subsp. aurantifolii strain C (Xfa C). Xfa C develops necrotic hypersensitive response (HR) in C. limon. Our results indicate that Xcc induces type I nonhost resistance in C. limon without necrotic hypertensive response. Both nonhost and host defense responses against Xcc and Xfa C, respectively, interfere with biofilm development on C. limon leaves. However, differential patterns of reactive oxygen species, accumulation of phenolic secondary metabolites and genes related to SA-defense signalling pathway are observed between nonhost and host resistance. Furthermore, both defense responses protect C. limon plants from disease upon subsequent challenges by pathogenic X. citri. This knowledge will rationally exploit the plant immune system as a biotechnological approach to manage the disease.