Effect of Azospirillum-mediated plant growth promotion on the development of bacterial diseases on fresh-market and cherry tomato.
OBJECTIVE
Plant growth-promoting (PGP) activity of two Azospirillum strains and their effects on foliar and vascular bacterial diseases were evaluated on fresh market and cherry tomato.


RESULTS
Tomato seeds were inoculated with A. brasilense Sp7 or Azospirillum sp. BNM-65. Four-week-old plants were challenge-inoculated with Clavibacter michiganensis subsp. michiganensis (bacterial canker) or with Xanthomonas campestris pv. vesicatoria (bacterial spot). Azospirillum-induced PGP was greater on cherry than on fresh-market tomato. Cherry tomato was more resistant to bacterial canker but more susceptible to bacterial spot than the fresh-market tomato. Canker severity was not affected by Azospirillum seed treatments. However, leaf- and plant-death were delayed on Azospirillum-treated plants compared with nontreated controls. Azospirillum increased the bacterial spot severity on cherry but not on fresh-market tomato.


CONCLUSIONS
PGP was observed on both tomato genotypes, although growth effects were larger on cherry tomato. Also, Azospirillum treatments may alter tomato susceptibility to bacterial diseases.


CONCLUSIONS
The interaction between PGP rhizobacteria like Azospirillum spp., not known to induce systemic resistance, with plant pathogens distantly located is frequently overlooked. This work demonstrates the importance of this kind of evaluation.
Romero
A M
AM
Cátedra de Fitopatología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina. romeroa@agro.uba.ar
Correa
O S
OS
Moccia
S
S
Rivas
J G
JG
D000192:Actinomycetales; D000193:Actinomycetales Infections / Q000382:microbiology; D015806:Azospirillum brasilense / Q000378:metabolism*; D001424:Bacterial Infections / Q000382:microbiology*; D018533:Biomass; D005516:Food Microbiology; D005838:Genotype; D018551:Solanum lycopersicum / Q000254:growth & development* / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology*; D012639:Seeds / Q000254:growth & development* / Q000382:microbiology; D016959:Xanthomonas campestris