ALBERT

Notes: Abstract. Short-term fumigation of Spinacia oleracea with 380 μg m−3 H2S (250 ppb) resulted in a rapid accumulation of water-soluble SH-compounds in the shoots. After 1 h exposure a substantial increase in the SH-content was already detectable and maximal accumulation, three- to four-fold that in control plants, was observed after 24 h of exposure. Irradiation during H2S exposure only slightly affected the rate and level of SH-accumulation. H2S fumigation did not affect the water-soluble SH-content of the roots. Glutathione was the sole water-soluble SH-compound accumulating upon exposure to H2S. It was calculated that during the first hour of exposure to 380 μg m−3 H2S 39% of the possible absorbed H2S was converted into glutathione. The SH-content of the water-soluble proteins of the shoots was not affected by H2S exposure. When fumigation was stopped, a rapid decrease in glutathione content was observed and after 48 h the content was comparable to that of the control plants. Contrary to H2S, SO2 fumigation did not result in a rapid accumulation of glutathione in spinach shoots. The possible role of glutathione accumulation during H2S fumigation is discussed.

Notes: Glycolipids, neutral lipids and chlorophyll of chloroplasts of pine needles (Pinus sylvestris L.) and apple bark tissue (Malus sylvestris Mill. cv Golden Delicious) were determined in a series of experiments in which growth temperature and daylength were changed. Trees were exposed to 0 and 20°C and to daylength conditions of 9 and 14 h. All 16 possible combinations were studied by transfer of the trees from the original condition to each of the other conditions. There was no direct relation between cold hardiness and glycolipid composition in apple bark and pine chloroplasts, when temperature and/or daylength were changed. Glycolipid and neutral lipid composition seemed to be strongly determined by the sequence of the imposed sets of daylength and temperature, and the effects of these factors on lipids strongly differed from that on cold hardiness. When the treatments were given in seasonal order, the corresponding changes in chloroplast glycolipids matched those reported in the literature for needles collected in the forest the year around. Glycolipid synthesis could well be under phytochrome control.

Notes: The effect of replacing 50% or 95% of the potassium by sodium on growth and on potassium and sodium levels in three genotypes of sugar beet (MONOHILL; ADA; FIA) has been studied in water culture over a period from 2 to 9 weeks.In all three genotypes there was a preferential uptake of potassium compared to sodium. Nevertheless, at high sodium supply most of the potassium was replaced by sodium, particularly in the leaves. At the same supply the accumulation of sodium in the leaves increased in the following order: ADA 〈 MONOHILL 〈 FIA. Even with high dominance of sodium in the medium, the youngest leaves of FIA held about 0.5 mmol potassium per g dry matter, and potassium was evidently translocated from old leaves to the new growth.Effects of sodium on growth became more important with time. After 9 weeks, 50% replacement of potassium by sodium increased growth of all plant organs of the three genotypes. Replacing 95% of potassium by sodium depressed growth of the storage root in MONOHILL and particularly in ADA, with simultaneous enhancement of leaf growth in the latter. In FIA, however, this treatment further stimulated both leaf and, particularly, storage root growth. Sodium in comparison with potassium increased the sucrose concentration in leaves and storage roots. The highest sucrose concentration in the storage roots of ADA and FIA was obtained in the treatment with 95% sodium.The results demonstrate pronounced genotypic differences in sugar beet with respect to the response to sodium. FIA has the most natrophilic behaviour and might be a promising genotype for breeding programmes for adaptation of sugar beet plants to soils high in sodium.

Notes: The effects of NaCl and replacement of K+ by Na+ on the lipid composition of the two sugar beet inbred lines FIA and ADA were studied (a) with increasing additions of NaCl to the basal medium, and (b) with increasing replacement of K+ by Na+ at the same total concentration as in the basal medium. Direct relations were noted between NaCl concentration of the nutrient solution and the phospholipid concentration in the roots of FIA, the genotype characterized by a low K+/Na+ ratio, as well as between NaCl in the medium and the phospholipid concentration in the shoots of ADA, the genotype with a high K +/Na + ratio. The sulfolipid level in the roots of FIA was maintained at higher NaCl concentrations, while it was decreased in ADA. The glycolipid concentration in the shoots of ADA and the degree of unsaturation of the fatty acids of the total lipid fraction were decreased by salinity, indicating reduced biosynthesis of chloroplast glycolipids and/or accelerated oxidation of these lipids in the presence of NaCl.In the Na+ for K+ replacement experiment a low content of K+ in the medium resulted in decreased levels of total lipids, phospholipids and sulfolipid in the roots of both genotypes, which did not relate to root growth. K+-leakage from the roots at low K+-level in the medium may be reduced by the increase in saturation of the lipids. In the shoots of ADA increased levels of total lipids, phospholipids and Sulfolipid were noted at a low K+-concentration of the nutrient solution.

Notes: A comparison was made between the lipid and fatty acid composition of the salt-sensitive bean (Phaseolus vulgaris L. cv. Saxa), the less salt-sensitive barley (Hordeum vulgaris L. cv. Wisa) and the salt-tolerant sugar beet (Beta vulgaris L. cv. Kawemono). Sugar beet roots showed a higher content of sterol components and sulfolipid as compared with bean and barley roots. The lipids of sugar beet roots contained more linoleic acid and less linolenic acid than those of bean and barley roots. For barley and sugar beet roots a higher amount of extra-long chain fatty acids was observed than for bean roots. It was concluded that differences in membrane structure are correlated with differences in membrane permeability to sodium and chloride and in salt-resistance of the studied species.

Notes: Maximum ATPase activities in the cell wall fraction of English ryegrass (Lolium perenne L.) roots were stimulated by foru discrete millimole ratios of (Na++ K+); 40:0, 35:5, 5:35, and 0:40. The optimal pH for stimlation was found to be 6.5. Contrary to data in the literature, Mg2+ inhibited all stimulatory ratios of (Na++ K+) when plants were cultured on an adequate nutrient solution. When grown on a dilute solution, Mg2+ enhanced (Na++ K+)-stimulated ATPase activity in this membrane preparation. The single optimal combined concentration of (Na++ K+) for all stimulatory ratios was 40 MM. The ratios of (Na++ K+) which stimulated ATPase activity in the cell wall fraction varied with position along the root axis such that all rarely existed simultaneously nor did any exist in the terminal millimetre of the root. Both cell wall and microsomal fractions showed stimulation by (Na++ K+) at all the above ratios indicating the possible presence of plasma membrane fragments in both fractions. Only the 35:5 ratio was stimulations were found in the supernatant. Implications of ion-stimulated ATPase involvement in ion transport were drawn from the appearance of ATPase activity at a 40:0 ratio of (Na++ K+) and the disappearance of stimulations at 35:5, 5:35, and 0:40 ratios when plants were moved from a strong (35 mM total concentration) to a dilute (0.75 mM) nutrient solution.

Notes: Water uptake of root systems of Phaseolus vulgaris was measured in a Scholander pressure cylinder at a constant pressure. Water uptake rises gradually till a steady state is reached after 15 to 60 minutes. This time course can be described as a transport process with the property of a self-induction. The latter was not affected by temperature. It is concluded that the property of self-induction is located in the cytoplasm or at the interface between cytoplasm and plasmalemma of the endodermal cells. It is suggested that cytoplasmic streaming controls the time course of water transport.

Notes: The ATPase activity of the cell wall, mitochondrial and microsomal fractions of bean roots (Phaseolus vulgaris) shows non-linear curves when plotted logarithmically against temperature, producing high Q10-values in the low temperature range and low Q10-values in the high temperature range. The Q10-valuc of supernatant ATPase is constant and low as well as the Q10-value of soluble ATPase liberated from membranes. Cell wall ATPase from bean roots adapted to a low temperature has a much smaller temperature response. Such roots contain a larger quantity of membrane-bound ATPase and a smaller amount of soluble ATPase than roots adapted to a high temperature.Extraction of soluble ATPase with acetone reduces activity to practically zero, but activity could be partially restored by the addition of lipid. The temperature response of reconstituted phosphatidyl choline-ATPase is inconsiderable. That of reconstituted sulfolipid-ATPase is much larger.I am indebted to Bep Stuiver for skillful assistance with the experiments, to Ir. F. Kuiper and Mr. C. H. Vermeulen for help with the cultivation of the bean plants and to Prof. Dr. E. C. Wassink for reading the manuscript.Communication 292 of the Laboratory of Plant Physiological Research, Agricultural University, Wageningen, The Netherlands.

Notes: Field grown leaves of sugar beet contained 0.89% of their fresh weight as chloroform : methanol 1 :2 extractable material, whereas climate chamber grown material contained 0.34, 0.15, and 0.16% in leaves, stalks, and roots respectively. A striking feature was the high proportion of sulfolipid: 7% of the total extractable of the field grown leaves, 19.5, 28.0, and 37.0% of the total extractable of respectively leaves, stalks, and roots from the climate chamber grown material. Among the fatty acids, all chain lengths from C12 to C28 were found, except only C17 and C19—Exceptionally high contents of fatty acids with a chain length of C26 or C28 were noted in some cases.The 2500–20,000 g fraction of root homogenates contained 19% of the total root lipids. Almost all of the phosphatidyl choline and about half of the phosphatidyl ethanolamine, but only 5% of the sulfolipid followed the fraction. A fractionation of conjugate lipid types was evident, with a loss of 18/2 and 18/3 conjugates, and with an increase in the proportions of 16/0 and, possibly, of the long-chain (around C26) conjugates.The unspecific ATPase activity of the 2500–20,000 g fraction was rendered specific for (Na++ K+) stimulation by treatment with 0.1% deoxycholate for 1 hour. This induced a more than 2-fold swelling of the preparation. About half of its total lipids were lost. Again, this loss was a fractional one, so that the phosphatidyl choline lost its long-chain (about C26) fatty acid conjugate while the short to medium length chain conjugates remained; whereas the reverse was the case with the sulfolipid.The ATPase activity of the 2500–20,000 g fraction was destroyed by a 24 hour treatment with deoxycholate. As compared with the 1 hour treatment, the preparation lost about 20% both of its volume and of its chloroform : methanol extractable material. The quantitatively dominating loss was found in the (pigment + neutral fat) fraction. The monogalactosyl diglyceride, the phosphatidyl inositol, and a strongly acidic unknown fraction survived the deoxycholate treatments comparatively well. In the sulfolipid the fractionating effect of the prolonged deoxycholate treatment expressed itself as a loss mainly from the long-chain (about C26) fatty acid conjugate.The (Na++ K+) stimulation of the ATPase function of the particulate preparation is thus correlated with the balance between the long-chain (about C26) fatty acid conjugates of zwitterionic phosphatidyl choline and anionic sulfolipid. This is of theoretical interest, since it indicates that the specific lipid composition under appropriate conditions may influence the charge and conformation of a lipoprotein complex, thereby determining its functional capacities.