A crossing test was made among L. esculentum F-207 (breeding line developed by UPV breeding group) and 18 accessions of L. peruvianum collected by our working group in different areas of Peru (Cuartero et al., 1984). In all crosses, L. esculentum was used as pistillate parent.
One of these accessions (PE-23) shows an unusual capacity to cross with L. esculentum; cross-fertility was 0.3 hybrid seeds/fruit. Moreover, embryos of this cross degenerated in more advanced stages than the other crosses. PE-23 was collected at Culluchaca in the Ancash Dept. at 2300 m of altitude.
The hybrid seeds germinated well and their hybrid nature was verified in mature plants. They showed the typical characteristics of the hybrid L. esculentum x L. peruvianum mentioned by other authors (Nethancourth et al., 1974; Rick, 1983). The most important differences among F-207, PE-23 and their interspecific hybrid are given below:
Characteristics F-207 F1 PE-23 ____________________________________________________________ Length of inflorescence (cm) 6-8 10-14 20-25 Number of flowers/inflorescence 5-8 11-15 20-25 Diameter flower (cm) 2.5-3 2-2.5 2-2.5 Color ripe fruit red yellow-orange green Diameter fruit (cm) 8-10 1.8-2.3 1-1.5 ____________________________________________________________The F1 hybrid plants are strongly self-incompatible and cross-incompatible with L. esculentum as staminate parent. The F2 progeny was obtained by crosses among different hybrid plants. The capacity to obtained hybrid seed in the cross L. esculentum x L. peruvianum seems to increase in the BC1 to L. esculentum (3.1 BC1 seeds/fruit). In this cross, every fruit yields at least two or three viable seeds. It has also been noted that the embryos abort at a more advanced stage than the original cross. It is common to find a high number of apparently well developed seeds with early degenerated embryos.
Currently, we are verifying the crossability of segregating generations with L. esculentum.
Literature cited:
Nettancourt, D. de, M. Devreux, U. Laneri, M. Cresty, E. Pacini, and G. Sarfatti. 1974. Genetical and ultrastructural aspects of self and cross incompatibility in interspecific hybrids between self-compatible L. esculentum and self-incompatible L. peruvianum. Theoret. Appl. Genet. 44:278-238.
Rick, C. M. 1983. Crossability between L. esculentum and a new race of L. peruvianum. TGC Report 33:13.
Cuartero, J., F. Nuez and A. Diaz. 1984. Catalog of collections of Lycopersicon and L. pennellii from northwest of Peru. TGC Report 34:43.