Pollen tube behavior in yellow passion fruit following compatible and incompatible crosses

Pistil squashes were used to examine the growth of Passiflora edulis f. fla vicarpa Deg pollen tubes in self-compatible and self-incompatible crosses. Compatible tubes typically showed a uniform layer of callose deposition in the walls and in small plugs spaced at regular intervals within the tube. T wo sites of rejection were observed in incompatible crosses: the stigma and on some occasions the style, especially in anomalous crosses. In the style the inhibition of pollen-tube growth occurred in both the upper and middle parts of the transmitting tract. These findings are consistent with the hy pothesis that suggests the presence of a gametophytic gene which acts in as sociation with the sporophytic S-gene in P. edulis.