Journal of
Plant Breeding and Crop Science

  • Abbreviation: J. Plant Breed. Crop Sci.
  • Language: English
  • ISSN: 2006-9758
  • DOI: 10.5897/JPBCS
  • Start Year: 2009
  • Published Articles: 318

Full Length Research Paper

Molecular diagnostics of groundnut rosette disease agents in Uganda: Implications on epidemiology and management of groundnut rosette disease

David Kalule Okello
  • David Kalule Okello
  • Department of Groundnut Improvement, National Semi-Arid Resources Research Institute, P. O. Box 56 Soroti, Uganda
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Michael Adrogu Ugen
  • Michael Adrogu Ugen
  • Department of Groundnut Improvement, National Semi-Arid Resources Research Institute, P. O. Box 56 Soroti, Uganda
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Phinehas Tukamuhabwa
  • Phinehas Tukamuhabwa
  • Department of Agricultural Production, School of Agricultural Sciences, Makerere University, P. O. Box 7062, Kampala, Uganda
  • Google Scholar
Mildred Ochwo-Ssemakula
  • Mildred Ochwo-Ssemakula
  • Department of Agricultural Production, School of Agricultural Sciences, Makerere University, P. O. Box 7062, Kampala, Uganda
  • Google Scholar
Thomas Lapaka Odong
  • Thomas Lapaka Odong
  • Department of Agricultural Production, School of Agricultural Sciences, Makerere University, P. O. Box 7062, Kampala, Uganda
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John Adriko
  • John Adriko
  • Biodiversity and Biotechnology Programme, National Agricultural Research Laboratories (NARL), Kawanda, P. O. Box 7065 Kampala, Uganda
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Faith Kiconco
  • Faith Kiconco
  • Center for International Tropical Agriculture (CIAT), P. O. Box 6247, Kampala, Uganda
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Allan Male
  • Allan Male
  • Center for International Tropical Agriculture (CIAT), P. O. Box 6247, Kampala, Uganda
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Carl Michael Deom
  • Carl Michael Deom
  • Department of Plant Pathology, University of Georgia, Athens GA, 30602, USA
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  •  Received: 07 December 2016
  •  Accepted: 20 January 2017
  •  Published: 31 May 2017

Abstract

The objective of this study was to use molecular diagnostic tools to detect the agents of groundnut rosette disease (GRD) to guide in varietal development and disease management. Samples were collected from both GRD infected and healthy plants and sites geo-referenced. RNA extraction, cDNA synthesis, polymerase chain reaction (PCR) amplification, electrophoresis, staining and visualization were performed according to standard procedures. Molecular diagnosis of the samples showed various combinations of the GRD agents, some in isolation and others a combination of two or three agents. This distribution is attributed to dependence on the aphid feeding behaviour and pathogenicity of GRD agents. Chlorotic and green rosette symptoms were observed throughout the sampling sites signifying the presence of satellite RNA (sat-RNA) variants. Some plants showing GRD symptoms tested negative for GRD, whereas some healthy-looking plants tested positive for the GRD complexes pointing to the ineffectiveness of phenotypic screening and the need for a molecular diagnostic tool that detects all three GRD agents both in absence or presence of disease symptoms. The absence of groundnut rosette assistor virus (GRAV) in some symptomatic samples signifies that they are epidemiologically dead end sources since GRV and sat-RNA must be packaged within the GRAV coat protein to be aphid transmissible. Oyado (Cassia obtusifolia) tested positive for all the GRD agents making it a potential alternative host. There is an urgent need for validation of the phenotypic screening with molecular tools in efficient diagnosis of the multi-pathogenic GRD in guiding both plant breeding and pathology work.

 

Key words: Arachis hypogaea L., groundnut rosette disease, molecular diagnostics, polymerase chain reaction (PCR).