Overexpression of a human α3/4-fucosyltransferase alters pollen development in transgenic tobacco plants

Abstract

In plants, the function of α4-fucosylation remains largely unknown. To gain insight into the role of α4-fucosylation during plant development, we generated transgenic tobacco plants overexpressing the human α3/4-fucosyltransferase (hFuc-TIII). Overexpressors clearly contained high amounts of hFuc-TIII and revealed a strong increase in α(1,4)fucosyltransferase activity in plant sexual organs. As a consequence, a more significant staining of Lewisa motifs, the product of α(1,4)fucosyltransferase activity, was observed in transgenic pollen grains compared to those of controls. Here, we show that pollen grain development was altered in transgenic plants. The average size (polar and equatorial diameters) of mature pollen grains overexpressing hFuc-TIII was smaller than control pollen grains. Furthermore, whereas a reticulate cell wall surface was always observed on control pollen grains, a punctate and disorganized cell wall surface was observed on hFuc-TIII overexpressor pollen grains. In addition, transgenic pollen tube elongation was delayed compared to control pollen tube growth. This latter phenotype could at least explain the 35% reduction of seed production determined for the hFuc-TIII-overexpressing plants.