Summary. A previously reported accumulation of proline in wilted turnip leaves has been observed in 6 additional species representing 5 different families. The results of experiments on the conditions affecting the behavior of proline in wilted leaves were interpreted to mean that the supply and metabolism of available carbohydrate was essential for proline accumulation.The role of sugar in proline accumulation was determined by incubating wilted leaves with different levels of carbohydrate (produced either by variations in conditions of preillumination or by infiltration with sucrose). The results showed that proline accumulation was greater and most prolonged in wilted leaves with higher sugar and starch contents. No proline accumulation was observed in unwilted leaves. Also some inhibitors of glycolysis and of the tricarboxylic acid cycle prevented proline accumulation in wilted leaves.Based on these results, the interpretation of the role of sugar in proline accumulation is that the oxidation of sugars furnishes a-ketoglutarate and NAD(P)H for proline synthesis in wilted leaves.In the previous paper ( 18) an accumulation (i.e., net synthesis) of proline in wilted, excised turnip leaves was reported. This accumulation was not observed in unwilted leaves. Following the period of proline accumulation, which lasted for 1 to 2 days, there was a net loss of proline corresponding in time to the diminution of metabolizable sugars. An accumulation of proline in wilted, excised perennial ryegrass plants was also observed by Kemble and Macpherson (8). In their experiment, no loss of proline was observed, the levels remaining high throughout the course of the experiment (8 days). wilted compared to non-wilted leaves have been reported in leaves of Bermuda grass (1), citrus (3), and wheat (10) but in the latter 2 cases it is not possible to tell from the data whether the increase in free proline exceeds a decrease in the proline content of proteins. Before this manuscript was revised, Routley (11) reported that wilted Ladino clover leaves were higher in uncombined proline than normal leaves. Routley suggested that there was an effect of carbohydrates on proline level but definitive data were not presented.The relationship between carbohydrate metabolism and proline accumtulation was studied following the suggestions in the previous paper (18 cised fibrous roots from corn seedlings. These observations tend to indicate further that the phenomenon is restricted to green tissue.The decrease in proline between 24 and 48 hours (fig 1) coincides with the decrease in soluble suigars. Since a similar correlation had been obtained previously (18), the behavior of sugar and starch in wilted and unwilted leaves during incubation was examined.The results (fig 2) demonstrate that, compared to tinwilted leaves, wilted leaves have an accelerated starch disappearance. When the initial starch content is high, this effect is accompanied by an increase in sugar. This effect has been observed by other investigators (7,15 fig 1). The absenc...

Simum ary. Excise(d leaves xwere inculbate(1 at various water contenits to dletermince the effect of water statuis on amino acid compositioni. Conisiderable proteoly sis took place dutiring incllbation Nx-ith a resultant increase iI each amino acid in the non-pr-oteill fractioni. However, serine, proline, y-aminobutyric acid and methylcysteine suilfoxide were the only amino aci(ls in which there was an accuimulationl (i.e., net synthesis). Serine showeed a small but conisistenit accutmullationi lastilng for 6 days. Proline showed a greater acculmuilatioln lut this ceased after 2 days.To learn more alout the conitrol of the proliine acctniillation (Iiring xvilting, tuirgid andl wiltedI leaves Nwere inculbated under aerobic and anaerobic conditiolns. The amino aci(I analyses showed that tuirgid leaves did niot accumnutilate proline and( that proline and methylcysteinie sillfoxide acculmuilation wx'as abolished )y naerobliosis. \Vith other amino acids, relative concentrationi changes between wilted and noni-xNilted leaves were less striking than the difference betweeni -aerobic and anaerobic coII-(litiomus.Und ( (diurnal). \Water insuifficieincy in a growing plant resuilts in wilting xxhich has profouind effects (9, 10, 38) on1 photosynthesis (4/7 ), respiration (23) iiucleic acids (8,29 ) and oIn nlitrogen metabolism (2,3,13,26,40,49). In order to iin(lerstanch and possibly control the effects of xvater deficiency on a plant, more nee(ls to be knoNx-n about the effects of dehydration at the cellullar anid suibcelluilar- le-vel THOMPSON ET AL.-AMINO ACIDS DURING WILTING AND ANAEROBIOSIS Materials and MethodsLeaves from greenhouse-grown turnips (Brassica rapa L. var. Shogoin) were used for most experiments. The leaves were excised and the midribs removed. One-half of each of 6 leaves were killed immediately after cutting to serve as controls. The other halves of these 6 leaves were incubated in the various treatments. Half leaf samples obtained in this way were similar in composition when compared on a fresh weight basis. The total amino nitrogen valuies were equivalent (on a fr wt basis) between paired half leaf samples to an average of 3.0 % (6 pairs), whereas the total uncombined amino nitrogen valutes agreed to an average of 2.5 %. The total amount of individual amino acids in comparable samples were equal to within ±5 %. The levels of individual uncombined amino acids in one half leaf sample were within ±10 % of the level in the other half leaf sample, except for valine and tyrosine which were equal to ±+15 % and asparagine to within ±30 %. Although these differences are relatively small, consideration of the effects of treatment has been restricted to changes of at least 20 % for total amino acids and of 100 % for uncombined amino acids.In the first experiment, leaves were dried in light (200 ft-c) at 200 until they had lost 50 % of their fresh weight (1-2 hrs). The leaf samples (6 half leaves) were then rolled loosely and placed in 100 ml bottles which were closed to prevent further water loss. The bottles ...

An unusual amino acid has been isolated from turnip roots using ion-exchange methods. This compound has been shown to be ( + )S-methyl-L-cysteine sulfoxide by comparison with synthetic material. It has been shown that this compound did not arise as an artifact during the isolation procedure. Quantitative data on the amount of S-methylcysteine sulfoxide in turnips and related plants are presented.

This is a rapid method with sufficient precision to give reliable results on large numbers of research and control samples of condensed phosphates and phosphate detergents. The modified solvents and use of the densitometer each contribute to the saving of considerable time over previously published methods. One operator can evaluate 20 samples per day with time during running, drying, etc., for other work.If it is desired to use an elution tech-nique for evaluation (1, 4~7), use of the modified solvents will decrease the time needed for separation and eliminate the necessity for a two-solvent, two-dimensional separation.

potassium was found in the basic amino acid fraction and no detectable amount with the other amino acids. In obtaining the amine fraction, the monovalent cations are removed from the resin with 0.5V hydrochloric acid, but the diand trivalent cations are only partially eluted. The remaining polyvalent cations which are eluted with 6Ar hydrochloric acid usually do not interfere with the chromatography of amines.The acid form of Dowex 50 does not retain strongly acidic amino acids such as cysteic acid and taurine (3) and these are not purified. Such strongly acidic amino acids have not been reported in plants (20). It would be possible to retain these acids and other anions on the salt form of a strongly basic resin while nonionic substances would pass through. Such variations would provide a basis for a more extensive fractionation scheme whereby separate fractions with nonionic materials, anions, neutral amino acids, acidic amino acids, basic amino acids, cations, and some amines could be obtained (10, 17).