A neoglycoprotein (a heptasaccharide of (1-->5)-alpha-L-linked-arabinosyl residues linked to bovine serum albumin) has been used to generate a rat monoclonal antibody specific to a linear chain of (1-->5)-alpha-L-arabinan which is a structural feature of the side chains of pectins. The antibody, designated LM6, detected 100 ng of debranched sugar beet arabinan in an immunodot binding assay and 1 microgram of commercial citrus pectin in a similar assay. Hapten inhibition studies indicated that the antibody recognized 5-6 Ara residues and 50% inhibition of antibody binding in a competitive inhibition ELISA was achieved with ca. 2ng (21 nM) of (1-->5)-alpha-L-Arabinohexaose. The antibody will be useful for the localization of arabinans in plant tissue and will have uses in the analyses of pectin structure. We report here on the localization of the arabinan epitope in lemon fruits using tissue printing.