African Journal of
Plant Science

  • Abbreviation: Afr. J. Plant Sci.
  • Language: English
  • ISSN: 1996-0824
  • DOI: 10.5897/AJPS
  • Start Year: 2007
  • Published Articles: 628

Full Length Research Paper

Characterization of the common bean host and Pseudocercospora griseola, the causative agent of angular leaf spot disease in Tanzania

Luseko Amos Chilagane
  • Luseko Amos Chilagane
  • Department of Crop Science and Horticulture, Sokoine University of Agriculture, P. O. Box 3005, Chuo Kikuu Morogoro, Tanzania.
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Susan Nchimbi-Msolla
  • Susan Nchimbi-Msolla
  • Department of Crop Science and Horticulture, Sokoine University of Agriculture, P. O. Box 3005, Chuo Kikuu Morogoro, Tanzania.
  • Google Scholar
Paul Mbogo Kusolwa
  • Paul Mbogo Kusolwa
  • Department of Crop Science and Horticulture, Sokoine University of Agriculture, P. O. Box 3005, Chuo Kikuu Morogoro, Tanzania.
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Timothy Gabriel Porch
  • Timothy Gabriel Porch
  • USDA, ARS Tropical Agriculture Research Station, 2200 P. A. Campos Ave, Suite 201 Mayaguez, 00680-5470, Puerto Rico
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Luz Miryam Serrato Diaz
  • Luz Miryam Serrato Diaz
  • Department of Biology, University of Puerto Rico, Rio Piedras Campus, P. O. Box 23360, San Juan, 00931-3360, Puerto Rico.
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George Muhamba Tryphone
  • George Muhamba Tryphone
  • Department of Crop Science and Horticulture, Sokoine University of Agriculture, P. O. Box 3005, Chuo Kikuu Morogoro, Tanzania.
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  •  Received: 11 May 2016
  •  Accepted: 04 October 2016
  •  Published: 30 November 2016

Abstract

Angular leafspot (ALS), caused by the fungus, Pseudocercospora griseola, is one of the most important disease of common bean in Tanzania. Breeding for resistance to this disease is complicated by the variable nature of the pathogen. In Tanzania, a thorough analysis of the variability of this pathogen is lacking which limits breeding for durable resistance. This work aimed at characterizing P. griseola in relation to its host in Tanzania. A sample collection of both P. griseola and common bean was conducted in the 2013 and 2014 growing seasons from nine regions. Single spore isolation was performed for P. griseola isolates and DNA was extracted from both P. griseola mycelium and bean leaves from which the pathogen was collected. For characterization of the gene pool origin of the host, Phaseolin DNA marker was evaluated and for the pathogen, the Internal Transcribed Spacer region (ITS) and the Actin gene sequences were evaluated. Phylogenetic analysis showed the presence of 69.7% Andean and 30.3% Mesoamerican strains of P. griseola in Tanzania. The common bean host genotypes showed a similar distribution with 84.2% Andean and 15.8% Mesoamerican. In both cases, Andean strains of the pathogen and Andean bean genotypes outnumbered Mesoamerican. In relation to the common bean genotypes, Andean genotypes were more susceptible to ALS as compared to Mesoamerican genotypes. There were few strains that were of Andean origin but were pathogenic on Mesoamerican common bean genotypes, a group that has previously been termed Afro-Andean. Geographically, most of the regions of Tanzania had only Andean strains except for Kagera where 60% were Mesoamerican strains, and in Arusha and Tanga, where 50 and 33% were Mesoamerican, respectively. Only three regions, Kagera, Mbeya and Rukwa, were found to grow Mesoamerican beans. The findings of this study are important in setting basic objectives for breeding for angular leaf spot disease in Tanzania.

Key words: Actin gene, angular leaf spot (ALS), Internal Transcribed Spacer region (ITS), Phaseolin protein, Phaseolus vulgaris.