Three bridging genotypes have been developed, based on the L. peruvianum accessions LA 1708, which is crossable with L. esculentum (Rick, 1983), and PI 128648-6, a CMV resistant line obtained from Dr. H. Laterrot. These bridging lines (EPP-1 = Lucullus/PI 128648-6//LA 1708; EPP-2 = H2653/PI 128648-6//LA 1708; and PP-1 = PI 128648-6/LA 1708) are crossable with L. esculentum. When crossed with six L. peruvianum accessions EPP-1 set an average of 4.3 fruits with culturable embryos for each peruvianum line, EPP-2 set 1.5, and PP-1 set 1.0, while neither LA 1708 nor PI 128648-6 produced any culturable embryos. In 1988 the two bridging lines, EPP-1 and EPP-2, were crossed successfully, as pistillate parents, to 11 of 15 L. peruvianum accessions tested (Table 1). The hybrids between the bridging lines and L. peruvianum accessions can be crossed and backcrossed with L. esculentum to introgress desirable genes from L. peruvianum into the tomato gene pool. While concurring with Lindhout and Purimahua (1988) that LA 1708 per se is not an efficient bridging genotype, this research shows that it can be an important component in the development of effective bridging lines.
Table 1. Percentage of L. peruvianum crosses setting fruit with culturable embryos. From 10 to 120 flowers were pollinated per cross.
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EPP-1 EPP-2.
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LA 364 0 0
LA 366 0 2.5
LA 464 8.5 0
LA 1551 10.3 0
LA 1552 3.3 0
LA 1722 0 5.0
LA 1989 0 0
LA 2150 3.4 1.7
LA 2153 3.1 0
LA 2326 6.1 1.7
LA 2334 0 0
LA 2563 11.4 1.7
LA 2575 9.4 0
LA 2582 0 0
PE 23 0 2.5
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TOTAL 3.7 1.0
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Literature cited:Lindhout, P. and C. Purimahua. 1988. Use of L. peruvianum LA 1708 and LA 2172 as a bridge between L. esculentum and L. peruvianum. TGC Report 38: 29.
Rick, C.M. 1983. Crossability between L. esculentum and a new race of L. peruvianum. TGC Report 33: 13.