Leaf curl virus disease in the tomato (Lycopersicon esculentum Mill) crop plant is a serious disease in many countries (Yassin & Nour, 1965; Costa, 1976, Makkouk, 1978; Mazyad et al., 1979; Green, 1984 and Ioannou, 1985). Many workers found that some accessions of L. pimpinellifolium (Jusl) Mill are resistant to the disease (Pilowsky & Cohen, 1974; Hassan et al., 1982 and Yassin, 1985). Yassin (1987) reported that each of accessions LA 121 and LA 1582 of L. pimpinellifolium (Jusl) Mill (both kindly supplied by Professor C. M. Rick) carries a dominant gene for resistance against the virus disease, but it is not known whether the two genes are related or not. The work, reported here, was done to investigate this relationship.
The material consisted of the two accessions, their F1 and F2 generations. F3 families were not grown for reasons beyond control. 488 F2 seedlings, from two randomly selected F1 plants, as well as 27 seedlings from each from LA 121 and LA 1582, and 17 seedlings of their F1 generation were transplanted in the field in December 1987 at the Research Farm at Salalah (17 deg. 02'N, 54 deg. 06'E). Furthermore, 24 plants of each of three susceptible tomato cultivars were also grown to serve as controls. The material was evaluated for leaf curl virus disease infection by noting the visible symptoms of the disease, and symptomless plants were considered as resistant. No artificial infection was done, but also no protection against against insects or diseases were adopted.
All 488 F2 plants as well as the plants of the parent accessions and their F1 generation were resistant to the virus disease. On the other hand all the plants of the three tomato cultivars clearly showed the symptoms of the disease. These results suggest that accessions LA 121 and LA 1582 carry the same dominant gene or alternative alleles at the same locus for resistance against tomato leaf curl virus disease. Unfortunately this conclusion could not be confirmed by growing the F3 families.
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