Optimization of a genetic transformation method for Acidovorax avenae, the causal agent of red stripe disease of sugarcane

ROMINIA PRISCILLA BERTANI; NATALIA MIELNICHUK; MARIA FRANCISCA PERERA; VICTORIA GONZÁLEZ; ADRIAN A. VOJNOV; MARIA INES CUENYA; ATILIO P CASTAGNARO

Tucumán

Congreso; XXX ISSCT Congress; 2019

Acidovorax avenae is the causal agent of red stripe, one of the main bacterial diseases that affect the sugarcane crop in Tucumán, Argentina. Because information on sugarcane colonization and movement of A. avenae during infections is limited, the aim of this study was to develop tools to monitor the bacteria during the disease cycle. Three A. avenae transformation methods were tested: chemical, electroporation and conjugation using plasmids containing different fluorescent proteins and antibiotic selective genes. Mutant A. avenae strains were evaluated for antibiotic resistance and expression of fluorescence signals. In addition, their identity was confirmed by PCR. Only transformation by conjugation presented stable fluorescent expression in the bacterium. Aa::pHC60-gfp showed the highest expression of the gfp gene. In vitro assays showed that the growth of the Aa::pHC60-gfp mutant in liquid media did not differ from that of the wild type. In addition, plants inoculated either with the GFP carrying strain or the wild type presented comparable incidence and severity 15 days after inoculation. This is the first report of an A. avenae mutant strain expressing a heterologous gene and represents a valuable tool to study the biology of the bacterium and its colonization in sugarcane.