African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5233

Full Length Research Paper

Distribution and pathotype identification of Xanthomonas citri subsp. citri recovered from south-western region of Saudi Arabia

Mohammed A. Al-Saleh
  • Mohammed A. Al-Saleh
  • Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Kingdom of Saudi Arabia.
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Arya Widyawan
  • Arya Widyawan
  • Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Kingdom of Saudi Arabia.
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Amgad A. Saleh
  • Amgad A. Saleh
  • Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Kingdom of Saudi Arabia.
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Yasser E. Ibrahim*
  • Yasser E. Ibrahim*
  • Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Kingdom of Saudi Arabia.
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  •  Received: 12 December 2013
  •  Accepted: 28 January 2014
  •  Published: 12 February 2014

Abstract

We investigated the distribution of Xanthomonas citri subsp. citri (Xcc) pathotypes in south-western region of Saudi Arabia. A total of 76 Xanthomonas like strains were isolated from different citrus species showing bacterial canker symptoms from citrus commercial farms, backyard orchards and nurseries. These strains were subjected to biochemical, molecular and pathogenicity tests on leaves of grapefruit (Citrus paradisi). Based on symptoms induced on leaves of grapefruit, these strains were divided into two groups. There were 21 strains that induced typical erumpent canker lesions with water-soaked margin, belonging to Xcc type A. On the other hand, strains that produced flat necrotic lesions with water-soaked margin on grapefruit leaves belonged to Xcc A* type (55 strains). The physiological and biochemical tests, ImmuneStrip ® assays and 16S rDNA analysis confirmed the identity of the two Xcc pathotypes: A and A*. Our results indicate that, the two pathogenic variants co-exist in south-western region of Saudi Arabia and this could further favour the generation of new genetic variants through recombination and horizontal genetic exchange. The generation of new aggressive pathotypes may threaten the citrus plantation in Saudi Arabia.

Key words: Disease diagnosis, pathogenicity, citrus bacterial canker.

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This article is published under the terms of the Creative Commons Attribution License 4.0

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