Tomato yellow leaf curl virus (TYLCV), identification, virus vector relationship, strains characterization and a suggestion for its control with plant extracts in Iraq

Abstract

Tomato yellow leaf curl begomovirus (TYLCV) was identified on the basis of symptoms on test plants, transmission by whiteflies Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) biotype B and its incubation period in the insect. Symptomatic tomato plants showing leaf curling, leaf blade reduction, distortion and general stunting, indicative of TYLCV in greenhouses, were transplanted into pots (20 × 20 cm) containing soil mix and were maintained in growth room for identification. The virus was found to be easily acquired and transmitted by B. tabacibiotype B when given an acquisition access period on tomato infected plants for 30 min with incubation period of 24 h. Leaf curl and distortion associated with severe stunting and yellowing were developed on inoculated Datura stramonium, Nicotiana tabacum cv. Samsun NN, Nicotiana glutinosa and Phaseolus vulgaris var. Battle and were found as susceptible to the virus without visible symptoms. The virus caused vein clearing on inoculated Solanum nigrum leaves. No infections were observed on Gomphrena globosa, N. tabacum cv. White burly, Physalis floridana, Solanum melongena, Cucumis sativus, Chenopodium amaranlicolor and Chenopodium murale inoculated by the virus. Two strains for TYLCV were characterized by symptoms on tomato and immunu-double diffusion test. A spur was formed between the polyclonal antibodies of TYLCV isolate and the extracts from infected tomato plants showing different symptoms. Extracts from Thuja, Tamarix and Henna plants exhibited inhibitory effects on TYLCV multiplication in tomato treated plants with protection periods of 10 to 12 days. Key words: Bemisia tabaci, control, plant extracts, strains, Tomato yellow leaf curl begomovirus.