Identification of Cucumber Mosaic Virus Subgroup I Isolates from Banana Plants Affected by Infectious Chlorosis Disease Using RT-PCR. Zora Singh, Western Australian State Agricultural Biotechnology Centre, School of Biological and Environmental Sciences, Murdoch University, Perth, Western Australia 6150 . R. A. C. Jones, Western Australian Department of Agriculture, BaronHay Court, South Perth, Western Australia 6151; and M. G. K. Jones, Western Australian State Agricultural Biotechnology Centre, School of Biological and Environmental Sciences, Murdoch University, Perth, Western Australia 6150. Plant Dis. 79:713-716. Accepted for publication 3 March 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0713.

Reverse transcriptionpolymerase chain reaction (RT-PCR) assays, restriction enzyme analysis, and comparison of nucleotide sequences were used to identify isolates of cucumber mosaic cucumovirus (CMV) that belong to subgroup I from infectious chlorosis-affected banana plants. Infected samples were from irrigated banana plantations at Carnarvon in the semiarid Gascoyne region of central Western Australia, and from Kununurra in the northern tropical Kimberley region. An RT-PCR assay with primers designed in a conserved region of the 3' end of the CMV coat protein gene amplified a 486- to 488-bp DNA fragment from infected banana samples. CMV was detected in leaf blades, midrib, and pseudostem of infected plants, but not in asymptomatic plants. Restriction enzyme analysis of PCR products using EcoRl and Mspl showed that the samples tested from diseased banana were infected with CMV subgroup I isolates. This result was confirmed by sequencing PCR-amplified products, which showed 98% homology to sequences of CMV subgroup I isolates but only 76% homology to sequences of CMV subgroup II isolates. The RT-PCR is a reliable assay to detect CMV in banana plants and, when combined with restriction enzyme digestion, provides a simple means of identifying the CMV subgroup present.

Keyword(s): heart rot, Musa, sheath rot