Angular leaf spot of cucurbits is associated with genetically diverse pseudomonas syringae strains

E. A. Newberry, T. M. Jardini, I. Rubio, P. D. Roberts, B. Babu, S. T. Koike, H. Bouzar, E. M. Goss, J. B. Jones, C. T. Bull, M. L. Paret

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Abstract

Angular leaf spot of cucurbits is generally considered to be caused by Pseudomonas syringae pv. lachrymans. It has a worldwide distribution and has been observed to emerge sporadically under humid and wet conditions. Reports of multiple P. syringae pathovars associated with the disease and lack of molecular analysis has left the true diversity of populations in the United States unclear. In this study, we collected 27 P. syringae strains causing foliar lesions and blighting on watermelon, cantaloupe, and squash in Florida, Georgia, and California over several years. Strains were fluorescent on King’s medium B agar and displayed the typical phenotypic and biochemical characteristics of P. syringae. P. syringae pv. lachrymans is a member of genomospecies 2. However, the genetic profiles obtained through both MLSA (gyrB, rpoD, gapA, and gltA) and BOX-PCR (BOXA1R) identified 26 of the P. syringae strains to be distributed among three clades within genomospecies 1, and phylogenetically distinct from genomospecies 2 member P. syringae pv. lachrymans. A novel MLSA haplotype of the pathogen common to all states and cucurbit hosts was identified. Considerable genetic diversity among P. syringae strains infecting cucurbits is associated with the same disease, and reflects the larger ecological diversity of P. syringae populations from genomospecies 1.

Original languageEnglish (US)
Pages (from-to)1397-1404
Number of pages8
JournalPlant disease
Volume100
Issue number7
DOIs
StatePublished - Jul 2016

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All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Plant Science

Cite this

Newberry, E. A., Jardini, T. M., Rubio, I., Roberts, P. D., Babu, B., Koike, S. T., Bouzar, H., Goss, E. M., Jones, J. B., Bull, C. T., & Paret, M. L. (2016). Angular leaf spot of cucurbits is associated with genetically diverse pseudomonas syringae strains. Plant disease, 100(7), 1397-1404. https://doi.org/10.1094/PDIS-11-15-1332-RE