Ubiquity of a borate rhamnogalacturonan II complex in the cell walls of higher plants

The presence of a borate-rhamnogalacturonan II (RG-II) complex [Kobayashi et al. (1996) Plant Physiol. 110: 1017] was examined in cell walls of 24 species from higher plants. We studied two species in Brassicaceae, three in Cucurbitaceae, four in Leguminosae, two in Apiaceae, two in Chenopodiaceae, two in Solanaceae, two in Asteraceae, one in Liliaceae, one in Araeae, two in Amaryllidaceae and three in Gramineae. In all the species examined, cell-wall boron was judged to be associated with RG-II. Moreover, in 15 species it seemed likely that RG-II might be the exclusive carrier of boron in the cell wall.