Figure 4.

Deletion of N-terminal domains abolishes effects of truncated variants of AtPIP5K5, NtPIP5K6-1, or AtPIP5K2 on pollen tube growth. The effects of overexpression of truncated variants of AtPIP5K5, NtPIP5K6-1, or AtPIP5K2 on pollen tube growth were analyzed (gray bars, as indicated). Phenotypes were categorized as normal, as secretion phenotypes (wavy growth, tip branching and protoplast trapping), or as tip swelling. Full-length enzymes (black bars) and catalytically inactive variants (white bars) were used as controls. (A) AtPIP5K5 and derived proteins; (B) NtPIP5K6-1 and derived proteins; (C) AtPIP5K2 and derived proteins. Data are means ± SD from four independent transformation experiments and represent ≥300 transgenic pollen tubes observed for each construct. n.d., Not detected. The asterisks indicate a significant difference from the full-length control within each category according to a Student’s t test (**p < 0.01).