Fig. 3. Wild-type pollen grains incubated for 24 hours in vitro in the presence of pollinated stigmas germinate and develop tubes (A). Pollen from cap1-1 and cap1-2 plants shows a visibly lower frequency of germination and reduced tube development (B). Analysis of larger numbers of pollen grains (C) shows that the germination rate of mutant pollen grains is less than half that of wild-type grains (n>800 for all genotypes). The mean length of pollen tubes after 24 hours (D) is similarly reduced (n>180). The growth speed of pollen tubes was compared at 5 hours after exposing the pollen grains to germination medium (E). The mean speed of mutant grains is reduced to nearly a third that of wild-type (n=32 for wild-type, n=17 for cap1).