Pathogenicity of bacteria isolated from 'Hua Moa' plantain with bunch abortion symptoms inoculated into other clones of plantain and banana

Abstract

Plantain production (Musa spp.) in Central and South America and the Caribbean is affected by bacterial diseases. In Puerto Rico, production of the plantain 'Hua Moa' is affected by a condition known as bunch abortion or 'choke neck'. This condition in some cases is accompanied by soft rot symptoms and therefore could be related to phytopathogenic bacteria. The purpose of this study was to identify the bacteria related to the soft rot tissues on plants affected with the bunch abortion symptoms and determine their virulence in other clones of plantain and banana. Bacterial colonies were isolated from pseudostems of Hua Moa at three locations in Puerto Rico, using semi-selective and nutritive agar media. The pathogenicity was determined by using potato and plantain pseudostem discs in humid chambers under in vitro conditions. Pathogenic bacteria were identified by using the BIOLOG® system. Under greenhouse conditions, the virulence of Burkholderia gladioli, Pseudomonas spinosa, Erwinia chrysanthemi and Pseudomonas aeruginosa was confirmed on plantain (Maricongo, FIAH-121, Enano Común, and Hua Moa) and banana (Grand Nain) using a scale from 1 to 9. All clones evaluated under greenhouse conditions were susceptible to E. chrysanthemi, potential causal agent of soft rot in Hua Moa plantain once the bunch abortion appears. Burkholderia gladioli is reported for the first time affecting plantain and banana.This bacterium was more virulent in Hua Moa and Grand Nain clones with severity of 7 and 5, respectively, than in Maricongo, severity 3. Pseudomonas spinosa and P. aeruginosa produced less damage with severity less than 4, than E. chrysanthemi and B. gladioli with severity greater than 4. This research was conducted under in vitro and greenhouse conditions and demonstrates that the most important bacteria causing soft rot in plants with the choke neck condition are E. chrysanthemi and B. gladioli. It is recommended to conduct field studies using plants up to the reproductive stage to determine whether these bacteria are also related as causal agents of the choke neck.