ISOLATION AND LECTIN-BINDING PROPERTIES OF BARLEY EPIDERMAL AND MESOPHYLL PROTOPLASTS

Protoplasts from primary leaves of barley (Hordeum vulgare L.) were ob tained by enzymatic digestion and fractionated by discontinuous densit y gradient centrifugation to yield highly enriched fractions of mesoph yll and epidermal protoplasts. A characterization of both protoplast t ypes resulted in a clear differentiation of the outer protoplast surfa ces. The protoplasts were examined for affinity to various lectins by agglutination tests and by labeling with lectin - fluorescein isothioc yanate conjugates. Both types of protoplasts agglutinated with soybean lectin. Fluorescein isothiocyanate-labeled soybean lectin was uniform ly distributed on the protoplast surface. Mesophyll protoplasts, but n ot protoplasts from the epidermis, were agglutinated by Concanavalin A . Both types of protoplasts exhibited fluorescence labeling with Conca navalin A - fluorescein isothiocyanate conjugate. This label often sho wed a patchy distribution on the protoplast surface. Tetragonolobus le ctin and beta-D-glucosyl Yariv artificial antigen agglutinated mesophy ll but not epidermal protoplasts. One of three tested monoclonal antib odies with specificity for arabinogalactans had affinity to the surfac e of mesophyll and epidermal protoplasts.