Year: 1940
Type: article
Abstract: CARBOHYDRATES are often stored in plants to be used in subsequent metabolic processes.Cell membranes are permeable to the low-molecular carbohydrates, and therefore the carbohydrates in storage organs are usually polymerized.Sometimes the polymerization goes so far that the carbohydrates become insoluble in water, e.g.starch, but in other instances the stored carbohydrates remain soluble although appreciably polymerized.The best-known soluble polysaccharide is probably inulin, which is built up exclusively of fructose molecules.Fructose seems to be a rather common unit in soluble polysaccharides.Johansson [1889] found several inulin-like carbohydrates in the Gramina.Parkin [1899] found what he called inulin (i.e.fructose-yielding polysaccharides) in the bulbs and tubers of several monocotyledons, sometimes together with starch.Monosaccharides other than fructose also build up soluble polysac- charides.Glucose, mannose and galactose are all found as constituents of poly- meric soluble carbohydrates (lichenin, "Konjak"-mannan, polygalactans and others).During an investigation of soluble high-molecular carbohydrates in plants [Svedberg & Gral6n, 1938] it was found that the sap from the bulbs of different species of the family Liliaceae gave distinct and characteristic sedimentation diagrams on ultracentrifugal examination.This fact led to a more exhaustive investigation of different species and genera of Liliaceae and the closely related plant families.& Prantl [1930] has been used as the reference to botanical systematics. MATERIAL AND ITS PREPARATION The monograph of EnglerThe work has been limited to the plant families Liliaceae, Amaryllidaceae and Iridaceae.These three families belong to the group Liliifloreae, which is divided into the subgroups Juncineae (rush plants), Liliineae (lily plants), and Iridineae (iris plants).In general the rush plants have only small dry rhizomes and, consequently, they were considered not to be suitable objects for this investigation.The Liliineae include the families Liliaceae and Amaryllidaceae together with some smaller families containing mostly tropical species.Iridaceae is the only family of Iridineae.About 75 different species, representing a selection from the three families mentioned, have been investigated.A large proportion of the material was obtained from the Botanical Garden of Uppsala.Most of the othet material was bought from Tubergen Ltd., Haarlem, Holland.From the biological point of view it is certainly of greatest interest to study the polysaccharides in as nearly as possible the native state.The preparation was made as follows.The bulb or the tuber for investigation was peeled and grated or ground in a meat-grinder in order to break up the cell structure.The grater has been used almost exclusively.There is less risk of cracking the starch grains, which might cause solution of the inner part of the grain, the amylose.The ( 234 )
Source: Biochemical Journal
DOI: 10.1042/bj0340234
Authors: Nils Gralén, The Svedberg
Institution: Uppsala University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W1832087486