Identificação de begomovirus em tomateiro na serra da Ibiapaba, CE e caracterização de um isolado obtido de Macroptilium lathyroides

Abstract

Tomato (Lycopersicon esculentum) is an important vegetable crop in Brazil and the Ibiapaba Moutain is the main producing area of fresh-market fruits in the State ofCeará, Brazil. The geminivirus transmitted by whitefly has been known as a pathogen that causes severe damage on tomato fields in Ceará since 1999. The objective of this work was to identify the virus and to evaluate its presence and distribuition in tomato fields in the Region and in tomatoes cultivated inside screenhouse. Inspections conducted from 1999 to 2001 in tomato fields in Ibiapaba counties, revealed the presence of plants showing leaf curling, leaf rolling, reduction in leaf size and stunting. Leaf samples collected from tomato plants expressing these virus symptoms were tested by indirect enzyme-linked immunosorbent assay (ELISA) against an antiserum prepared to Macroptilium golden mosaic virus (MaGMV), indicating the presence of a virus species of the genus Begomovirus, family Geminiviridae. The PCR products with primers PAL l v 1978 and PARc 496, for DNA A component, corresponded to a fragment of approximately 1,2 Kb, and with primers PBL 1v 2040 and PCR cl, for DNA B component, corresponded to a fragment of approximately 0,5 Kb. confirmed the presence of a virus species of the Begomovirus genus, family Geminiviridae. In the screenhouse, the percentage of tomato plants infected with begomovirus was 7,3% against 53,65% in the field, showing that growing tomatoes in screenhouse could be a good way to reduce begomovirus infection. Studies were also carried out with a virus of the same family found in Macroptilium lathyroides plants, with the objective to identify, characterize and evaluate its host range trough whitefly and grafting inoculations in screenhouse. Serological, PCR and nucleic acid hibridi7ntion studies indicated that the virus infecting M. lathyroides found in Ceará also belongs to Begomovirus genus, family Geminiviridae. This begomovirus was naturally transmitted by whitefly and grafting in screenhouse to M. lathyroides plants. The host range studies revealed that the begomovirus infected Canavalia ensiformis, Cassia tora, Macropitilium atropurpureum, M lathyroides, Phaseolus lunatus, .and P vulgaris.