Genetic diversity and pathogenicity of cucurbit-associated Acidovorax

Abstract

Bacterial fruit blotch of cucurbits is a destructive disease caused by Acidovorax avenae subsp. citrulli, which is a typical seedborne pathogen. In seed health testing for this disease, we have detected many strains of Acidovorax with some differences from A. avenae subsp. citrulli. Their 16S rRNA sequences were divided into six types. The most common sequence was completely consistent with that of A. avenae subsp. avenae originally isolated from rice. The other sequences were over 99% similar but not identical to those of A. avenae subsp. avenae and A. avenae subsp. citrulli. Some commercialized antibodies against A. avenae subsp. citrulli reacted with several of these strains. Some of these strains incited yellow spots or brownish water-soaked lesions mainly on young true leaves of cucumber and squash after spray inoculation. Histological observations showed that these strains entered the leaf tissues of cucurbit plants through stomata and multiplied in the intercellular spaces of parenchymatous tissues as well as in the vascular tissues. The amount of bacterial multiplication and spread in the tissues differed among the strains, presumably reflecting their ability to induce symptoms. These isolated strains are therefore different from A. avenae subsp. citrulli, and their potential threat to the cultivation of cucurbits is lower than that of A. avenae subsp. citrulli.

Nicotiana species as surrogate host for studying the pathogenicity of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits

“…By 9 dpi, brown lesions were observed on petioles and stems of inoculated tobacco leaves, as a possible result of systemic infection of A. citrulli . The ability of A. citrulli to infect and spread via vascular tissue was previously reported in melon seedlings (Bahar et al , ) and squash leaves (Makizumi et al , ).…”

Origins and Recombination of the Bacterial-Sized Multichromosomal Mitochondrial Genome of Cucumber

“…The bacterial plasmid-like sequence appears to have been transferred from Acidovorax, a destructive seed-borne pathogen and the cause of bacterial fruit blotch in cucumber (Martin et al, 1999) and other cucurbit crops (Makizumi et al, 2011). The mitochondrial genome of Vitis (grapevine) also contains foreign pathogenic sequence, in this case acquired from a grapevine leafroll-associated virus (Goremykin et al, 2009).…”

Acidovorax citrulli: generating basic and applied knowledge to tackle a global threat to the cucurbit industry

“…Bahar, R. Kumar Shrestha and S. Burdman, unpublished data).These results suggest that, in contrast with the importance of T4P for vascular infection of seedlings, T4P and twitching motility may not play a crucial role in local, foliar infection of mature plants by A. citrulli. Nevertheless, it is important to mention that vascular infection of A. citrulli has been reported recently in leaves of squash plants (Makizumi et al, 2011).WhetherT4P contribute significantly to fruit infection by this pathogen must be investigated.…”