Fig. 2

HTA5:GFP expression is more dominant in dividing cells of the sporophyte. Epifluorescence images of developing Arabidopsis plants (cartoon key to structures at top) expressing both HTA5 (a) and HTA3 (b) proteins fused to GFP. Expression was observed in the first true leaves (i), the floral meristem (ii), the adaxial leaf surface (iii), root tips (vi), and secondary root meristems (v). In reproductive structures supporting gametophyte development such as anthers (iv), and ovules (vii) both isoforms were expressed, though HTA3:GFP expression was concentrated in the central cell. In next generation seeds, HTA.3:GFP was present in the early developing endosperm and embryo (b (viii); HTA.5:GFP not recorded at this stage). By the heart stage of embryo development, HTA5:GFP expression in endosperm was not visible, but was strong in embryo and also present in the surrounding seed coat (HTA3:GFP not recorded at this stage) (a (viii)). Scale bars indicate 250 nm