Fig. 3

HTA3:GFP expression is more dominant in gamete cells during gametophytic development. Confocal images of male and female gametophyte expression of HTA5 and HTA3 proteins fused to GFP. In the male gametophyte, both HTA3:GFP and HTA5:GFP are present in the microspore prior to mitosis. After Pollen Mitosis I (PMI) HTA3 was expressed in the generative and vegetative nucleus of bicellular pollen, and following Pollen Mitosis II (PMII), in both sperm cells and the vegetative nucleus of mature, tricellular pollen (a). HTA5:GFP expression was also present in both the generative and vegetative nucleus following PMI, but was lost in the vegetative nucleus following PMII, in tricellular pollen (b). In the female gametophyte, egg cell expression was visible for both HTA3:GFP and HTA5:GFP, but was weak. Conversely, HTA3:GFP expression was very striking in the central cell, where it persisted following fertilization in the first cell divisions of the developing endosperm (c and e). HTA5:GFP expression was also observed in the central cell, but expression in the surrounding ovule tissue was more prominent for this isoform (d)