Disease Note

Molecular Characterization of Tomato Yellow Leaf Curl Virus from Egypt. M. K. Nakhla, University of Wisconsin, Madison 53706. M. R. Rojas, W. McLaughlin, J. Wyman, D. P. Maxwell, and H. M. Mazyad. University of Wisconsin, Madison 53706, and Agricultural Research Center, Giza, Egypt. Plant Dis. 76:538. Accepted for publication 2 January 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0538E.

Tomato yellow leaf curl virus (TYLCV) causes major yield losses of tomatoes in Egypt. A TYLCV isolate (EGI) collected from the Fayoum governorate in 1984 was transmitted experimentally to tomato (Lycopersicon esculentum Mill.) by Bemisia tabaci (Gennadius) and to Nicotiana benthamiana L. by grafting. Geminivirus particles were observed in preparations from TYLCV -infected tomato. A 1.3-kb fragment of TYLCV-EGI from infected N. benthamiana was amplified in a polymerase chain reaction using general gemini viral primers (unpublished) that anneal to either ALI or ARI (1). The partial sequence of the clone (pTYREG1) is:
GATTACGTTG   TACCACGCAT   CAGTACTGTA
TAAATAATTA   TTGCCTGTTC   GTCTCCATGG
CACCTTTGGG   AGTGGGCCTA   TGCTATCACC
CCGCGCAGCA   CTTAGGTCTAC   GAGACCTGGCC
CTCAATGACA   GAAGACACGAC   GATGTCCACAC
CCACATTGTT   ATACTTATGGC   CGTTCTCGGCC
GACCCACTCTC   TCAAGTTCAT   CTGGAACTTGC
ATTAAAAGAAC   GAAGAAAGAA   ATGGAGA.
Nucleotide sequence comparisons of ALI with the same region of TYLCV from Israel (1), African cassava mosaic geminivirus, tomato golden mosaic gemini virus, and bean golden mosaic geminivirus-GA showed identities of 96, 81, 65, and 65%, respectively. On the basis of nucleotide sequence comparison for part of the Common Region, TYLCV -EG I was not closely related <50% identity) to TYLCV from Thailand (2). TYLCV-infected and healthy tomatoes from Egypt could be differentiated by means of radiolabeled pTY AEG I in nucleic acid squash hybridization tests under high stringency conditions. This is the first report that TYLCV from Egypt is a geminivirus and that it is nearly identical to TYLCV from Israel (1).

References: (1) N. Navot et aI. Virology 185:151, 1991. (2) D. Rochester et al. Virology 178:520, 1990.