CHARACTERIZATION OF CELL-WALL COMPONENTS FROM THE ENDOSPERM OF SORGHUM VARIETIES VARYING IN HARDNESS

Cell walls, isolated from two varieties of sorghum endosperm varying i n hardness, were extracted with 1 M, 4 M and 8 M alkali and subsequent ly neutralised to give an insoluble 'A' and a soluble 'B' fraction. Th e soluble 'B' fractions had higher arabinose-to-xylose and pentose-to- hexose ratios compared with their respective 'A' fractions. The residu e after extraction with 8 M alkali in the soft variety contained 16% p entoses, whereas the residue from the hard variety had only traces of pentoses. On further fractionation of 1 M 'B' on Diethyl amino ethyl ( DEAE) cellulose, a glucose-rich unbound fraction, and a bound fraction containing a considerable amount of pentoses were obtained. Prolamins (sorghum storage proteins) were associated with isolated cell wall fr actions. Antibodies were raised against three of the cell wall polymer fractions and were capable of recognising specific and common epitope s. Our results indicate that the more loosely held polymers are rich i n glucose, while the tightly held polymers, probably attached to cellu lose, are made up of pentoses