Sources of resistance to whitefly (Bemisia spp.) in wild populations of Solanum lycopersicum var. Cerasiforme (Dunal) spooner GJ Anderson et RK Jansen in Northwestern Mexico

Abstract

Genetic variability of wild populations, closely related to domesticated species, constitute important genetic resources for plant breeding programs. In this paper, we analysed the variation of eight wild populations of Solanum lycopersicum var. cerasiforme in a common garden experiment for levels of plant infestation by whitefly, leaf trichome density as a defensive character preventing infestation by whitefly, and the effect of whitefly incidence into vegetative and reproductive plant characters. Number of adults of whitefly was recorded in the eight wild populations of S. lycopersicum var. cerasiforme, one population of the wild species S. habrochaites (C-360), and one of a cultivated variety of S. lycopersicum ( Rio Grande). There were significant differences among the wild populations of S. lycopersicum var. cerasiforme in the average level of whitefly incidence and trichome density. Cultivated tomatoes had the higher incidence of whiteflies ((x) over bar = 7.50 +/- 0.14) followed by plants of S. lycopersicum var. cerasiforme ((x) over bar = 2.02 +/- 0.92) and plants of S. habrochaites with the lowest incidence ((x) over bar = 0.36 +/- 0.35). Whitefly incidence was negatively correlated with trichome density (r = - 0.38, p < 0.0001), suggesting that trichomes deter or limit the establishment of whiteflies. Additionally, a significant negative effect of whitefly incidence along the growing season upon plant growth rate ( number of branches and height) and fruit production was detected.