TOMATO BREEDING .2. CHARACTERIZATION OF F1 AND F2 HYBRID PROGENIES OFLYCOPERSICON-ESCULENTUM X LYCOPERSICON-PERUVIANUM AND SCREENING FOR VIRUS AND INSECT RESISTANCE

Tomato spotted wilt virus (TSWV) is one of the major limiting factors of tomato production in Brazil and other tropical areas during summer months. A good source of resistance to this virus and to insect pests has been identified among some Lycopersicon peruvianum individuals. Du e to incompatibility and early embryo abortion, it has not been possib le by conventional methods to obtain hybrids between these peruvianum sources and the commercial tomato (L esculentum). In a previous report , the recovery of several interspecific hybrid plants with embryo resc ue techniques has been described (Segeren et al., 1993). In this paper , the characterization of the hybrid nature of such plants and their p rogenies, as well as the screening tests for TSWV and leaf miner, Scro bipalpuloides absoluta (Meyr.) (Lepidoptera: Gelechiidae), resistance is reported. Seeds of F1 plants were variable in size and color; small green seeds had to be recultured again and were then able to develop directly into plants, without a callus phase. Large brown seeds were s own directly in soil. The large seeds gave rise to plants with more L esculentum characteristics, whereas plants from small seeds resembled the peruvianum phenotype. F2 and F3 plants varied in relation to leaf hairs, leaf shape and size, and fruit color and size. Hybrid fruits va ried in color from green with stripes to yellow or orange at maturity, with a slightly larger size than those of L peruvianum. All F1 plants were self-incompatible. A few F2 and F3 plants obtained by sib crosse s were self-compatible. Allelic segregation for the acid phosphatase ( Aps 1) locus was detected among F2 and F3 individuals. Isozyme analysi s of APS 1 demonstrated the presence of three phenotypes corresponding to genotypes 1/1, +/1 and +/+. Screening tests among F2 and F3 hybrid populations were performed under controlled conditions and showed seg regation for resistance to TSWV and to tomato leaf miner. The recovery of interspecific hybrids through embryo culture was demonstrated to b e an effective technique for overcoming crossing barriers within the g enus Lycopersicon.