Pbytochemi8try, 1973, Vol. l?. pp. 499 to 50% Rrsr;mon Pmu, Printed in England. TOTAL HEMICELLULOSES FROM WHEAT AT DIFFERENT STAGES OF GROWTH A. J. BUCHALA* and K. C. B. WILKIE Department of Chemistry, University of Aberdeen, Old Aberdeen, Scotland (Received 1 July 1912. Accepted 10 October 1972) Key Word Hindu-Triricum vu&are; zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA G ra m ine a e ; wheat; hemicelluloses; xylan; /?-&can; uroaic acids. Abe&net-The changes in total hemicellulose composition of leaf and stem tissues of field-grown wheat plants have been examined. In each plant tissue the percentage of xylose in the total hemicelluloee inaeascs with increasing plant maturity, that of galactose varies little and those of L-arabinose, ~-sluawe, and uroaic acid decrease. There is a markedly higher proportion of D-glucopyranuronosyl than of 4-O-methyl-~- glucopyranuronosyl residu*l in leaf and stem tissuea at all stages of maturity. The ratio of Ml+ 3) to Ml 34) linkages in the &&cans, and the DP of thest /l&cans decreax concommitantly with tissue maturity. INTRODUCTION THERE are variations in the proportion of sugar residues in total hemicelluloses’ from the non-endospermic tissues of oat plants at different stages of gr~wth.?~ These variations have been partially interpreted in terms of pure hemicellulosesl of known structure.5*6 No similar studies have been reported on other cereal plants. The stem and leaf tissues of the wheat plant have now been studied. Several D-xylans were earlier isolated from wheat straw, and others from wheat leaf’ and bran.“‘O All are heteroxylans and have the /I(1 --f 4) linked ~xylopyranosyl main chains typical of the xylans of higher land plants. I1 A branched homoxylan has been isolated from esparto grass, Stipa tenacissima, l 2~1 3 but no homoxylan has been isolated from any wheat tissue, nor from any other species of the Gramineae. Residues of L-arabino- furanose, D-glucopyranuronic acid and 4-O-methyl-D-glucopyranuronic acid are commonly present in hemicellulosic xylans. The L-arabinofuranosyl residues are terminal and linked a(1 + 3). 14*15 The earlier evidence’6-18 indicated that the uronosyl residues were linked l Present address : Institut de Biologic V&&ale et de Phytochemie, Universid de Fribourg, 1700 Fribourg Switzerland. * J. S. G. REID and K. C. B. WILKIE, Phykwhem. 8,204s (1969). 2 J. S. G. REIDand K. C. B. WILKIE, Phykxhem. 8,2059 (1969). 3 A. J. Buc~uu and K. C. B. WILKIE, J’hytochem. lo,2287 (1971). l A. J. BUCHALA and K. C. B. WIL~E, Phytochem. 12,655 (1973). ’ J. S. G. ROD and K. C. B. WILK~, P/tytoclrem. 8,2053 (1969). 6 G. 0. A~PIN~UL and K. C. B. WILKIE, J. Chem. Sot. 1072 (1956). ’ G. A. ADAMS,Can. J. Chem. 32,186 (1954). a G. A. ADAMS, Can. J. Chem. 33,56 (1955). ’ G. A. ADAMS and C. T. BISHOP. J. Am. Chem. Sot. 78,2842 (1956). lo J. SCHMORAK, C. T. BISHOP and G. A. ADAMS,Can. J. Chem. 35,108 (1957). I1 G. 0. A~PINALL. Adcam. Carbohyd. Chem. 14,424 (1959). I2 S. K. -ma, E. L. Hmsr, J. K. N. Jones and E. G. V. PeRclv~~, J. Chem. Sot. 1289 (1950). I3 I. EHRJNHAL. R. MONKH~~~Y and F. Sham. J. Am. Chem. &c. 76.5509 (1954). ‘* C. T. BISHOP and D. R. WHIT-, Chem. & ind. 37,827 (1959). Is C. T. BISHOP, J. Am. Chem. Sot. 78,284O (1956). I6 G. A. ADAMS, Can. J. Chem. 30,698 (1952). *’ C. T. BISHOP, Con. J. Chem. 31,134 (1953). I* G. 0. A~PINALL and R. S. Mluro~e~, J. Chem. Sk. 1731 (1954). 499 . ’ .