ISHS Acta Horticulturae 190: Symposium on Tomato Production on Arid Land
GERMPLASM RESOURCES IN THE WILD TOMATO SPECIES |
| Author: | C. M. Rick |
| DOI: | 10.17660/ActaHortic.1986.190.2 |
| Abstract:
Wild germplasm has been utilized for tomato improvement, starting in the 1930's and accelerating to the present time. The cultivated Lycopersicon esculentum is represented in the wild by its var. cerasiforme; the remaining eight species are known only in the wild. With varying degrees of difficulty, all can be hybridized with horticultural tomatoes and desired genes bred into the latter. These facts, as well as the restricted genetic variation in modern cultivars, account for the remarkable extent of exploitation of wild resources. Amongst the various categories of improvement, disease resistance has been emphasized to the greatest extent. Starting with resistance to race 1 of Fusarium wilt, first reported in 1940, resistance to 28 serious diseases has been detected in exotics, and the majority of these resistances have been bred into horticultural cultivars. Resistances to many diseases have been combined in true breeding and F1 hybrid cultivars. From the same sources, breeders have discovered and utilized superior fruit quality characters. Progress has been made via this route in elevating soluble solids content, vitamin content, intensifying color, lowering pH, etc. Other useful traits thus exploited include jointless pedicel, and male sterility. Much research has been devoted recently to arthropod resistance and tolerance of various stresses. Significant resistance to serious insect and arachnid pests has been found (particularly in L. hirsutum), and the nature of certain resistances analyzed. Tolerance to such stresses as aridity, excessive moisture, high and low temperature extremes, and salinity has also been detected in wilt sources. Utilization of these tolerances is progressing, although the quantitative nature of inheritance and high environmental variance components render the projects difficult and slow. The Tomato Genetics Stock Center and other organizations maintain extensive collections of the wild species and derivatives. | |
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