The presence of typical plant-type N-glycans (eg, M3FX, Gn2M3FX, and Le a 2M3FX) in mosses, ferns, and other organisms was examined to determine which plant initially acquired glycosyltransferases to produce plant-type N-glycans during organic evolution. No M3FX-type N-glycan was detected in lichens (Cladonia humilis) or in any one of the three preland plants Enteromorpha prolifera, Ulva pertusa Kjellman, and Chara braunii Gmelin. In Bryophyta, M3FX-type Nglycan was detected at trace amounts in Anthocerotopsida (hornworts) and at certain amounts in Bryopsida (mosses), but not in Hepaticopsida (liverworts). Le a 2M3FX was detected in some Bryopsida of relatively high M3FX content. Most Tracheophyta (ferns and higher plants) contained the three typical M3FX-type glycans as the main N-glycans in different ratios. These results suggest that organisms acquired xylosyltransferase and fucosyltransferase during the development of mosses from liverworts, and that later all plants retained both enzymes. Bryopsida have also obtained galactosyltransferase and fucosyltransferase to synthesize the Le a antigen.Key words: N-glycan; fern; moss; M3FX Gn2M3FX and Le a M3FX; Le a antigenSince the structure of the oligosaccharide of pineapple stem bromelain was elucidated, 1) the determined fucoseand xylose-containing core structure has been found universally in plant glycoproteins. M3FX, consisting of three Man (M), two GlcNAc (Gn), and one each of Fuc (F) and Xyl (X) residues is the most common structure in plants. The oligosaccharides GnM3FX and Gn2M3FX, composed of one and two GlcNAc residues respectively attached to M3FX, are also found universally in plants. The oligosaccharide with the Lewis a antigen, Le a 2M3FX, in which galactose and fucose residues are attached to both GlcNAc residues of Gn2M3FX, is also a main N-glycan universally found in plants, [2][3][4][5] except for Brassicaceae plants such as Arabidopsis thaliana and Raphanus sativus (kaiware raddish). Accordingly, the processing of plant N-glycans in the Golgi apparatus as shown in Fig. 1 is assumed to be almost universal. 5,6) N-Glycan processing byglucosidases I and II in ER is important in plants, [7][8][9][10] whereas N-glycan processing in the Golgi apparatus has little effect on plant growth, as determined in the varous studies: Arabidopsis mutants that lack N-acetylglucosaminyltransferase I 11) or both fucosyltrasferase and xylosyltransferase activities 12) grow normally and produce normal seeds. Fucosyltransferase and xylosyltransferase knockout plants of Bryopsida (Physcomitrella patens) grow normally.13) In my study using glycosidase inhibitors on germination, the seedling and leaf growth of R. sativus showed that ER-glucosidase inhibition inhibited the growth of the plant, although the inhibition of N-glycan processing in Golgi by deoxymannojirimycin, swainsonine, and 1,2-dideoxy-2-acetamido-nojirimysin had no eminent effect except for a change in the N-glycan structure. 10,14) These results indicate that the final N-glycan structure is not directly as...