b'THE EVOLUTION OF GENETIC DIVERSITY IN TOMATO0.300.25 Wild ancestors gave rise to the vintage types through Genetic Diversity (H-index)domestication.Fruit size, colour, &0.20 flavour started to vary, further increasing the genetic diversity of modern varieties.0.15Resistances to diseases & 0.10 pests were introgressed, increasing genetic Inbreeding & selection led todiversity. 0.05 commercial varieties with a low genetic diversity. 0.00WILD VINTAGE 1960s 1980s 2000-PRESENTFIGURE 1: The evolution of genetic diversity in tomato. The upper left group represents the ancestors (S. lycopersicum var. lycopersicum, S. lycopersicum var. cerasiforme,S. pimpinellifolium and ), which gave rise to the vintage types including landraces through a process of domestication. Inbreeding and selection among these vintage tomatoes led to commercial varieties in the 1960s with a very low genetic and phenotypic diversity. From the 1970s onwards, resistances to diseases and pests were introgressed from distant species, including S. peruvianum, S. pennellii, S. chilense,S. habrochaites, andincreasing genetic diversity among commercial tomato varieties considerably. After the 1980s, fruit size, colour, and flavour started to vary substantially, further increasing the genetic diversity of modern varieties.was significant. However, a recovery of diversity was observed in the 1990s. For seven other major crops (barley, maize, oat, flax, soybean, pea, rice), a dip in diversity was also observed in the 1960s, but the recovery was earlier compared to wheat. Apparently, the trends which are described for tomato in the Schouten et al. paper are similar for other crops. However, the changes in genetic diversity have been far more pronounced and clearer for tomato, not showing an increase of a few percent, butPLANT BREEDING HAS LED a nine-fold increase since the 1960s. Therefore, one may conclude that the concern aboutTO AN EIGHT-FOLD INCREASE decreasing diversity among varieties, due to modern plant breeding, is not supported. In contrast, a tremendous increaseIN GENETIC DIVERSITY IN in diversity has been observed, both at the genotypic and phe- GREENHOUSE GROWN notypic level. This however does not take away the concern that crop diversity as well as architectural diversity is decreasedTOMATOES IN NW EUROPE although both for their own reasons. In crop diversity because the economics of farming put a heavy burden on farmers to growSINCE THE 1960S.those crops which will enable them to earn a living while archi-tectural diversity is abiding to those phenomena (erectness, size and type of fruits, size of plants, etc) which fit with the grow-ing and harvesting systems. Responsibility to ensure that other types of diversity are within acceptable ranges reside thus not only with breeders but also with government and society. 40IEUROPEAN SEEDIEUROPEAN-SEED.COM'