Cashew-nut tree exudate gum: Identification of an arabinogalactan-protein as a constituent of the gum and use on the stimulation of somatic embryogenesis

Abstract

Arabinogalactan-proteins (AGPs) are a class of plant proteoglycans. In this work, we show that gel permeation chromatography of the cashew-nut tree exudate gum (CNTG), previously characterized as an acidic arabinogalactan (type II), yielded a fraction named fraction III. SDS-PAGE analysis of CNTG has an AGP-like smear, weakly stained by the β-glucosyl Yariv reagent. CNTG and fraction III reacted strongly with the JIM13 anti-AGP monoclonal antibody and presented a protein content of 1.0 and 0.2% (w/w), respectively. CNTG and fraction III showed a high Hyp content (∼50%), and Ser, Pro, Thr and Leu as the most abundant amino acids. Analysis of the carbohydrate structure, its extracellular locat..