METABOLISM OF MALTOSE AND SUCROSE BY MICROSPORES ISOLATED FROM BARLEY(HORDEUM-VULGARE L)

The aim of this work was to discover why barley (Hordeum vulgare L.) m icrospores die when cultured on media containing 40 mM sucrose but und ergo embryogenesis on 40 mM maltose. Freshly isolated microspores were cultured for 6-24 h on media containing either [U-C-14] maltose or [U -C-14] sucrose at 40 mM, and the detailed distribution of C-14 was det ermined. The amounts of glycolytic intermediates, ATP, ADP and AMP, in microspores were also measured. Cultures on sucrose differed from tho se on maltose in that the initial rate of metabolism was faster but de clined rapidly, less C-14 was recovered in polymers and more in alanin e, there was extensive leakage of assimilated carbon, significant accu mulation of ethanol and a lower adenylate energy charge. It is argued that microspores cultured on 40 mM sucrose die because they metabolize the sugar rapidly, become hypoxic and, as a result, accumulate large quantities of ethanol within the cells. Metabolism of maltose is slowe r and there is sufficient oxygen available to allow cells to survive i n culture. Consequently some of the cultured cells undergo embryogenes is.