The Carbohydrate Nutrition of Tomato Roots

The Relation of Glucose Absorption to Respiration in Potato Slices

“…The low value for C1409 production during the first 20 minutes in figure 1 reflects the time required for CO2 production and absorption to come to a steady state in the relatively large erlenmever flasks. In the first experiment of table III, where the exter- Table IV The Prevalence and Specific Activity of Sugars in Aged Potato Slices Potato slices (3.0 g) were incubated in 20 uc of glucose-U-C'4 in a 10 ml total volume containing, in addition, KH2PO4' 10-2 M, pH 5 Although the emphatic indifference of glucose absorption and oxidation to uncoupling agents gainsays the active transport of glucose in the thermodynamic sense, and perhaps brings into question direct metabolic implementation of glucose absorption of any kind, the indications are nevertheless that glucose uptake is carrier-mediated. On the one hand the constant absorption with time from dilute solution as the external concentration is reduced some 80 % suggests a saturation phenomenon.…”

Studies on the Growth of Excised Roots

“…The' ether-insoluble' fraction of yeast extract was tested because Dormer & Street (1949) had earlier observed that yeast extract, particularly at high concentration (100 mg./L), inhibited the growth in length of excised tomato roots and caused symptoms which suggested that the inhibitory effect was at least partly due to its content of auxin (Delarge, 1941;Burstrom, 1942). The 'ether-insoluble' fraction was prepared as follows: 500 mg. of 'Difco' yeast extract was dissolved in 100 ml.…”

“…The general culture technique has been outlined in earlier papers (Dormer & Street, 1949;Boll & Street, 1951). The standard culture medium (S) was that of White (1943 a) modified by addition of 0-005 P-P-ni.…”

“…yeast extract. In view of the relatively high concentrations of glutamic and aspartic acids in yeast extract and the evidence that they occupy a key position in aminoacid metabolism (Street, 1949) it was decided to test these individually in case their growth-promoting activity had been obscured by the other constituents of amino-acid solution (i). Glutamic acid was tested at concentrations up to 24 mg./l.…”

Absorption of Sugars by Plant Tissues

“…For example, the preferential absorption of particular sugars by Scenedesmus (21,22), Peltigera (12), and tomato roots (8), and the effects of metabolic inhibitors on uptake (5,11,15) are well established. Moreover, accumulation against apparent concentration gradients has been shown for sugar cane tissue (4) and the ability of carrot tissues, rich in sugar, to take up all of the glucose from dilute glucose solutions is of interest (9).…”