A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases

June 6, 2003
Source: Plant Pathology, Vol. 52, June 2003 [edited]


Tomato leaf curl geminivirus in Australia: occurrence, detection, sequence diversity and host range
J Stonor, CSIRO Plant Industry, Adelaide Laboratory, PO Box 350, Glen Osmond, South Australia 5064; P Hart, CSIRO Entomology, Black Mountain Laboratory, PO Box 1700, Canberra, Australian Capital Territory 2601; M Gunther, Department of Primary Industries Queensland, PO Box 652, Cairns, Queensland 4870; P DeBarro (CSIRO Entomology, 120 Meiers Road, Indooroopilly, Queensland 4068, Australia; and M A Rezaian <ali.Rezaian@csiro.au> (as for Stonor).

The occurrence of whitefly-transmitted geminiviruses in Australia was studied using a mixed DNA probe capable of detecting a range of distinct geminiviruses. The only geminivirus species detected was Tomato leaf curl begomovirus (TLCV), which is spread across a vast geographical region of far-northern coastal Australia, an area inhabited by the Australasian-Oceania biotype of _Bemisia tabaci_.

The newly introduced silverleaf whitefly, _B. tabaci_ biotype B, forms high population densities in the eastern coastal region of Queensland and is currently located approximately 150 km from the nearest known TLCV-infected area.

The viral host range appeared to be narrow, and of 58 species of crop plants and weeds inoculated using the B biotype, only 11 became infected with the virus, including 5 that did not show foliar symptoms.

A DNA fragment of 694 nt, including the complete C4 open reading frame (ORF), the overlapping N-terminal part of the C1 ORF, and the viral iterons involved in replication, was amplified from 11 TLCV field isolates and sequenced. Sequence analysis revealed an overall sequence variation of up to 14 percent in this region, as well as the presence of distinct viral iterons (repeats).

Reference:

Stonor, J., Hart, P., Gunther, M., DeBarro, P. & Rezaian, M. A. Tomato leaf curl geminivirus in Australia: occurrence, detection, sequence diversity and host range. Plant Pathology 52 (3), 379-388.

[TLCV-Au was first reported in 1971 on tomato. As of 2001, it was known to occur in NT and WA, where it causes tomato leaf roll disease. It has been found in the Kimberly area of WA from Kununurra across coastal NT to Booroloola in the Gulf area of NT. It has also been detected in Kowanyama, Normanton, and Karumba in the southwestern Cape York Peninsula area of Queensland but not south of there. Infected plants are severely stunted, leaflets are smaller than normal, and fruits are drastically reduced in size and basically unmarketable. The virus is common in weedy hosts including apple of Peru (_Nicandra physalodes_) and Jimson weed (_Datura stramonium_)

Do any of our Australian colleagues have more information on the distribution of this virus in the country? Please let me know.

Additional reference: <http://www.avrdc.org.tw/LC/tomato/tylcv.html> - Mod.DH]