Figure 3.—

Pollen tube growth on pistils of allotriploid S. lycopersicum × S. lycopersicoides hybrids pollinated by different species or genotypes. Pistils were fixed 24 hr after pollination and stained with aniline blue to visualize pollen tubes. (Note: the color of images was inverted, thus pollen tubes appear darkly stained). For the incompatible crosses, arrowheads indicate the zone of the style where growth of most tubes stopped, and arrows indicate the longest pollen tube. The bridging line genotypes contained one or both pollen compatibility factors (ui1.1, ui6.1) from S. pennellii introgressed into the background of S. lycopersicum.