A XYLOGALACTURONAN WHOSE LEVEL IS DEPENDENT ON THE SIZE OF CELL CLUSTERS IS PRESENT IN THE PECTIN FROM CULTURED CARROT CELLS

A substantial level of xylose was detected in the pectic polysaccharid es that had been extracted from carrot (Daucus carota L.) calli and pu rified by gel-permeation and ion-exchange chromatography. The results of the removal of neutral sugar chains and beta-elimination indicated that the xylose was not included in the neutral sugar chains but was d irectly bound to a polygalacturonic-acid backbone. Methylation analysi s confirmed that the xylose was directly linked to galacturonic acid a t position 2 or 3, as a terminal residue. The amount of xylose was pos itively correlated with the size of cell clusters in several lines of cultured carrot cells.