Proteoglycan that may contribute to the strengthening of cell walls. Expressed in vascular bundles of roots, leaves, sepals and stamen filaments, and pistils but not stigma. Down-regulated by wounding, abscisic acid (ABA) and jasmonic acid (JA). Hydroxylated on numerous prolines in the proline-rich region. O-glycosylated on numerous hydroxyprolines in the proline-rich region; noncontiguous hydroxylproline residues are glycosylated with arabinogalactan. Belongs to the non-classical AGP family.