Portal de Periódicos da CAPES

GLYCINE IN THE NUTRITION OF EXCISED TOMATO ROOTS

1939; Oxford University Press; Volume: 14; Issue: 3 Linguagem: Inglês

10.1104/pp.14.3.527

1532-2548

Philip R. White,

Plant Physiology and Cultivation Studies

Five years ago it was unequivocally demonstrated for the first time that an isolated plant organ, the root, could be grown in culture for potentially unlimited periods of time (8). An environmental complex capable of supporting normal growth for such periods was outlined which included only one factor recognized as being of unknown constitution. That factor was an extract of dried brewers' yeast representing 1/10,000 of the total mass of the nutrient. Since this one unknown made interpretations of any experiments utilizing the complex of uncertain validity, much effort has been expended since then aiming at the elimination of this factor. Analysis showed the effective material to be soluble in 85 per cent, alcohol, insoluble in ether, and separable by extraction with 100 per cent, alcohol into two fractions both of which were essential for normal growth (10). The fraction insoluble in 100 per cent, alcohol was shown to be replaceable by a mixture of 9 amino acids (11). This demonstration was obtained before the nature of the 100 per cent, alcohol soluble material, now known to be thiamin or its precursors, was known (1, 4,12). A nutrient containing thiamin and amino acids was still inferior to the original yeast extract medium. It was shown to be improved by addition of a complex mixture of accessory salts. Analysis of the accessory salt mixture showed most of the ingredients to be either inert or detrimental, and by elimination of all but four (iodine, manganese, zinc, and boron), the nutrient was improved to the point where growth equal to that in a yeast extract medium could be obtained (13). A completely known nutrient for the maintenance of normal growth of excised tomato roots was thus made available.