Cassava friable embryogenic calli infection with Xanthomonas axonopodis pv. manihotis (Xam)

Abstract

New technologies for genome edition, such as TALENs and CRISPR/Cas9 system, are a great opportunity to improve desirable features in different organisms. TALENs are the result from coupling nucleases and TALEs (Transcription Activator-Like Effectors), which are natural effectors with an important role in pathogenicity for the Xanthomonas species. Xanthomonas axonopodis pv. manihotis (Xam) is the cassava bacterial blight causal agent, and this pathogen is able to translocate its effectors to the plant cell during pathogenesis by using the type-three secretion system (TTSS). Currently, there are no standard protocols for genome edition in cassava. In this study, we explored the possibility to translocate effectors to friable embryogenic calli (FEC) through Xam inoculation, in order to establish the potential of this pathogen as a TALEN delivery system. Friable embryogenic calli derived from two different susceptible varieties (COL2215 and cv. 60444) were co-cultured with the strain Xam668 using different culture times. Subsequently, we evaluated the expression of makers corresponding to reported target genes for TALEs present in this bacterial strain. Although we were not able to demonstrate effector translocation, we established the conditions for co-culturing cassava calli and Xam and determined the effects derived from bacterial infection on embryo regeneration from FECs.