Cytopathology, Mode of Aphid Transmission and Search for the Casual Agent of Cotton Bunchy Top Disease

• Published in: Journal of phytopathology Vol. 155; no. 4; pp. 220 - 227
• Main Authors: Ali, A, Reddall, A, Roberts, J, Wilson, L.J, Rezaian, M.A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.04.2007; Blackwell Publishing Ltd; Blackwell
• Subjects: abnormal root; aphid transmission; Aphididae; Aphis; Aphis gossypii; Bacterial plant pathogens; Biological and medical sciences; epidemiology; Fundamental and applied biological sciences. Psychology; graft transmission; Luteovirus; Myzus persicae; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Prunus; scanning electron microscopy; transmission electron microscopy; Malvaceae; graft transmission; Aphis gossypii; Double stranded RNA; aphid transmission; Luteovirus; Insecta; Transmission; Fiber crop; Myzus persicae; Mollicutes; epidemiology; Pest; Homoptera; Dicotyledones; Viroid; Angiospermae; Aphididae; Bacteria; Luteoviridae; Nanoviridae; Nanovirus; transmission electron microscopy; Phytoplasma; scanning electron microscopy; Aphidoidea; Root; Enzyme; Transferases; abnormal root; Seedlings; Virus; Polymerase chain reaction; Nucleotidyltransferases; Arthropoda; Morphology; Cytopathology; Isolate; Spermatophyta; Gossypium hirsutum; Two dimensional electrophoresis; Invertebrata; ELISA assay; DNA-directed DNA polymerase
• ISSN: 0931-1785; 1439-0434
• DOI: 10.1111/j.1439-0434.2007.01220.x

The cytopathological effects of cotton bunchy top (CBT) disease and its mode of transmission by Aphis gossypii Glover (cotton aphid), were studied. CBT infection affected the leaf epidermal layer producing a loose, ruptured and rough surface morphology with many stomata closed and misshapen. Roots of CBT-infected plants showed reduced growth, small knots and a dark brown appearance. A single aphid per plant was capable of transmitting CBT at 5%, whereas three aphids per plant transmitted CBT to 50% of the cotton seedlings and 20 aphids per plant transmitted the disease agent to 80% of the cotton seedlings. Aphis gossypii acquired CBT after a minimum acquisition access period of 5 min and transmitted the agent after a minimum inoculation access period of 1 h. Both alate and apterous aphids and nymph instars 2, 3 and 4 of A. gossypii transmitted CBT. This preliminary data suggest that A. gossypii transmits CBT in a semi-persistent manner. Myzus persicae Sulz (green peach aphid) was unable to transmit CBT. A comprehensive attempt to isolate the CBT agent, using a range of virological techniques including double-stranded RNA extraction, two-dimensional gel electrophoresis for viroid, circular DNA test, nanovirus polymerase chain reaction (PCR), luteovirus PCR and enzyme-linked immunosorbent assay, phytoplasma test, nucleoprotein purification and electron microscopy, was unsuccessful, raising the possibility that CBT may be caused by a unique new pathogen.