RELEASE OF GRAMINE FROM THE SURFACE OF BARLEY LEAVES

Gramine, an indole protoalkaloid found in barley leaves, is toxic to mammals, insects and plants. A time course experiment, in which barley leaves were dipped into 0.1 M hydrogen chloride-ethanol (7: 3 v/v) for 1-60 sec, suggested that some gramine was on the leaf surface. The suitability of this and other solvents for surface gramine extraction is discussed. About 0.04-0.18% of total gramine was released from the leaf surface of several lines of Hordeum vulgare sub-species vulgare and spontaneum. Artificial rain experiments showed that gramine was eluted from leaves. No differences were found between amounts eluted by acid and normal rain. The implications that these findings may have for plant defence and allelopathy are discussed.