SUPPRESION OF CALLOSE SYNTHASE GENE IN CITRUS PLANTS CAUSES INCREASED SUSCEPTIBILITY TO XANTHOMONAS

ENRIQUE, R.1; FAVARO, M.A.1; GERHARDT, N.1, SICILIANO, F.1, SENDIN, L.2; CASTAGNARO, A.; VOJNOV, A. AND MARANO, M.R.

Tucumán

Congreso; SAIB 2009; 2009

Citrus is an economically-important fruit crop which is severely afflicted by citrus canker, a disease caused by the bacterial phytopathogen, Xanthomonas axonopodis pv. citri. Identification of host genes with a role in resistance to canker would be an important step in development of new and sustainable strategies to manage the disease. However, the introduction of new genes for functional analysis through stable transgenesis continues to be a difficult process in citrus, because transformation efficiencies are generally low, and competence for regeneration is very low or null. In this context, we have developed a post-transcriptional gene silencing system for Citrus limon to allow functional analysis of candidate genes. Double-stranded RNA expression vectors, encoding hairpin RNAs for the citrus callose synthase gene were delivered to lemon leaves by transient infiltration with transformed Agrobacterium. Phenotypic, histo-anatomic and molecular analysis showed that this vector was functional not only in lemon plants, but also in other species of the Rutaceas family. With this approach we demonstrate that plant cell wall-associated defence is the principal initial barrier against Xanthomonas infection in citrus plants.