Leaf Sap Research Articles

Investigations of Leaf Sap Feeding by Three Species of Phytoseiid Mites by Labelling with Radioactive Phosphoric Acid (H3 32Po4)1

The phytoseiid mites, Amblyseius hibisci (Chant), A. stipulatus Athias-Henriot, and A. fructicolus Gonzales and Schuster, after confinement on citrus and avocado leaves labelled with radioactive phosphoric acid, were analyzed for radioactivity after 1 or 10 days. None of the predaceous mite species accumulated radioactivity from the lemon leaves but A. hibisci accumulated a significant amount from avocado leaves. The results indicated that A. hibisci extracts sap from avocado leaves, and that plant juices may provide an alternate source of food and/or moisture for this predaceous species.

Bacilliform particles associated with vein yellowing of Laburnum anagyroides

SUMMARYBacilliform particles characteristic of plant rhabdoviruses were found in negatively‐stained leaf sap and in thin sections of Laburnum anagyroides in England showing vein yellowing. The particles were detected principally in the perinuclear space of parenchyma cells. They were not transmitted by sap inoculation to twelve herbaceous species. The affected trees also showed mosaic symptoms but there was no evidence of an association between these and the bacilliform particles.

Título en español.

Un virus latente de Dioscorea floribunda y D. composita (DLV) se purificó mediante el uso de carbón activado pulverizado y bentonita tratada con magnesio para clarificar la savia extraída de las hojas de Dioscorea. El virus produjo una sola franja en los gradientes de densidad de la sacarosa. Los antisueros producidos en un conejo alcanzaron una concentración de 1:16,000. El DLV purificado no reaccionó con los antisueros a ninguno de los 25 virus cilíndricos. Myzus persicae (Sulzer), el áfido verde del melocotón, no transmitió el DLV de plantas de Dioscorea infectadas. El 74 por ciento de las partículas midieron de 395 a 445 nm. Las plantitas de D. floribunda inoculadas no revelaron síntomas, pero el virus se observó en preparaciones por inmersión del tejido sistémicamente infectado. El DLV apareció en combinación con otro virus que era transmisible por los áfidos y que provocaba síntomas del listado verde.

Some Properties of Inhibitors of Plant Virus Infection Occurring in the Leaves of Chenopodium album L.

Inhibitors of TMV infection contained in the sap of Chenopodium album were precipitated with 50% saturated ammonium sulfate and the precipitate was dissolved in neutral phosphate buffer. After centrifugation, the supernatant was obtained, and the inhibitors were again precipitated with 50% saturated ammonium sulfate. This precipitation procedure was repeated five times. The final supernatant (Sa) showed inhibitory effect to TMV infection fairly comparable to the original sap, indicating that the inhibitors were not so much affected during the course of the precedure. Sa fraction was adjusted at pH 4.5 and centrifuged. The precipitate was dissolved in neutral phosphate buffer, centrifuged, and the supernatant (Si) was obtained. The Si fraction showed a somewhat decreased inhibitory activity than Sa fraction. The Si fraction was separated into two fractions by ECTEOLA cellulose column chromatography. The both fractions showed inhibitory activity of about the same degree. Sephadex G50 or G100 gel filtration chromatography showed that the inhibitors consisted of particles of various sizes.The leaf sap retained the inhibitory activity after treatment with RNase, pronase, or chloroform. The activity of the inhibitors was destroyed by phenol treatment. An attempt to isolate polysaccharide having inhibitory activity was not successful.

温州ミカンの着果負担に関する研究 (第2報)

Stems and leaves from satsuma mandarin trees bearing different crop loads were sampled during the year and analyzed for osmotic concentration, soluble solids and water content in the expressed sap. Seasonal fluctuation in the specific gravity and concentration of water extract of tissue powder in leaves and stems were also examined. The following results were observed.1) With respect to leaves, high positive simple and partial correlations were established between osmotic value and soluble solids content, while conversely, a negative but high simple correlation was found between osmotic value and water content. Hence, it seems that osmotic value of the sap is dominantly affected by the soluble solids content. Higher correlation ship was detected between these variables in alternate bearing trees than in annual bearers.2) With stems, positive simple and partial correlations were found between the osmotic concentration and soluble solids content in the expressed sap in the annual bearing trees but not in the biennial bearers. Their values were lower for stems than for leaves from the same trees. No correlation existed between the osmotic value of stem sap and the water content.3) Comparison between water and soluble solids contents of leaves revealed a negative simple correlation, whereas in stems, both negative simple and partial correlations existed. Thus, it is concluded that the soluble solids content of the sap in the stem is greatly influenced by the water content.4) Evaluation of environmental factors revealed that high negative correlations existed between osmotic value of leaf sap and both dry and wet-bulb temperatures (°C), the latter being higher than the former. This finding indicates that the osmotic value of the leaf is governed in part by the vapor pressure deficit or relative humidity of the atmosphere. Although no such distinct correlation was found in the stem samples, a negative one was recognized between the osmotic value and the amount of precipitation. Hence, it appears that humidity in the soil or atmosphere affects the osmotic values of the sap in the stem.5) Comparison of seasonal changes in specific gravity of tissue powder obtained from bearing and non-bearing shoots revealed that no difference existed between leaves from these shoots collected on the same dates, whereas the specific gravity of non-bearing stems was consistently higher than that of bearing ones especially in the summer and fall months.6) The seasonal trends in total carbohydrate and nitrogen contents in young satsuma mandarin shoots expressed as percentage dry weight were paralleled to those in specific gravity of the powdered tissue. Hence a high positive correlation was found to exist between these variables.7) In the leaves, a low positive simple correlation was found between the specific gravity of tissue powder and the solute ratio, but not in the stems.8) Slight differences of the concentrations of water extracts obtained from powdered leaves were observed between non-bearing and bearing shoots. However, the concentrations of stem extracts from non-bearing shoots were noticeably higher than those from bearing ones from summer to winter.

Use ofNicotiana debneyi to detect viruses S, X and Y in potato seed stocks and relative susceptibility of six common varieties to potato virus S

Nicotiana debneyi Domin. proved a reliable test plant for potato viruses S, X, and Y. Test plants with several leaves 6 cm long, were dusted with carborundum and rubbed with potato leaf sap, or with raw surfaces of cut tubers. The plants were then held at 20°C under approximately 250 ft cd light intensity on a 16–18 h photoperiod. Each of the 3 viruses, or X and Y combined, could be distinguished, but symptoms of S were obscured by those of X or Y. At two elite seed farms, virus S spread into virus-free stocks of the varietyNetted Gem. but little intoKatahdin. In greenhouse tests, 3 older varieties,Green Mountain, Irish Cobbler andNetted Gem, as a group, were more susceptible to PVS, when inoculated with infective sap, than the newer varieties,Katahdin, Kennebec andSebago.

Evaluation of systemic fungicides for use in the glasshouse industry

AbstractThe primary evaluation of ten fungicides for the control of cucumber powdery mildew (Sphaerotheca fuliginea), tomato leaf mould (Cladosporium fulvum) and tomato grey mould (Botrytis cinerea) indicated that nine of them were systemically active against one or more of the pathogens when applied as soil drenches. Benomyl, thiophanate, thiophanate‐methyl, thiabendazole and Cela W52A showed activity against all three diseases, but dimethirimol, triarimol and dodemorph were more specific and mainly active against cucumber powdery mildew. An in vitro bioassay generally indicated that fungitoxicity was not translocated from sprayed to unsprayed leaves, and though toxicity to B. cinerea, following soil drenches of benomyl, thiophanate and thiophanate‐methyl, was detected by bioassay in leaf sap and calyces it was not detected in fruit. Furthermore, extended evaluation of benomyl for the control of grey mould on cropping tomotoes showed that in the presence of abundant B. cinerea inoculum, benomyl soil drench treatment effectively controlled flower and leaf infection but not fruit ghost‐spotting.

Effects of Soil Moisture Stress on Two Varieties of Upland Cotton in Israel II. The Northern Negev Region

SUMMARYThe effects of moisture stress at various stages of development were studied on two varieties of cotton in the arid Negev region of Israel. Experiments over two years indicated that the stage at which moisture stress occurred determined its effect: when at the beginning of flowering, yield was considerably reduced; at the peak of flowering there was a less pronounced effect; and when stress occurred during boll development it had an effect in only one year, when reserves of moisture in the deep soil layers were low. Lint yield ranged from 380 kg./ha. without irrigation to 2150 kg./ha. with five irrigations. Effects on lint length and lint strength were also studied. Two physiological indices, stomatal aperture and refractive index of leaf sap, were used to determine the onset of moisture stress.

Carbohydrates and nitrogenous compounds in the honeydew of the mustard aphid, Lipaphis erysimi

The chemical composition of the leaf sap of the radish, a host plant for the mustard aphid, Lipaphis erysimi, is compared with the composition of the honeydew that is excreted. The results indicate that the aphid utilizes sugars in a descending order of glucose, pentose sugars, fructose, and dextrins. Dextrin is utilized in very small amounts if at all and there is some evidence that the dextrin from honeydew has a larger molecule than the dextrin in the plant sap. Nitrogenous excretory products, when compared with the leaf sap materials, indicate the utilization of the essential amino acids and the elimination of nitrogen principally as arginine. Urea was detected and there were traces of ammonium salts. Amides and carbamyl compounds occur in significant concentrations high enough to indicate that the excretory mechanism of the aphid could be severely taxed to provide for their elimination.

Na and K Interactions in Increasing the Salt Tolerance of Atriplex halimus L.: I. Yield Characteristics and Osmotic Potential

AbstractGrowth of Atriplex halimus on four different saline media was studied. Growth was strongly stimulated by low levels of all saline media and reached a maximum at different external osmotic potentials for different salinity treatments. Plants grew much better on saline media containing equal parts of NaCl and KCl, and seemed to tolerate much lower external water potential than plants growing on NaCl, KCl, or on different concentrations of Hoagland solutions. In all the four different salinity treatments, osmotic potential of the expressed leaf sap remained nearly constant over all the external osmotic potentials. Although salinity did not change final size of the leaves, the fresh weight and dry weight of a given area of the leaves changed tremendously, depending upon the osmotic substrate. The effect of the kind of osmotically active salt present in the saline medium on the growth of A. halimus indicates that growth reduction under saline media is not solely a function of its osmotic potential. It appears that overall growth effects can best be described as a combination of stimulatory and inhibitory effects.

Degradation of RNA of partially uncoated tobacco mosaic virus during extraction from tobacco leaves.

Extracts of tobacco leaves, 3 to 22 hr after infection with 32P-labeled tobacco mosaic virus (TMV), were analysed by sucrose density-gradient centrifugation. As reported previously, a shoulder appeared on the lighter side of the main peak representing intact parent viruses. The shoulder was shown to contain partially uncoated virus particles with sedimentation constants of about 140–150 S, which withstood dialysis against a phosphate buffer. RNA from the uncoated particles was isolated on the sucrose density-gradient, and its sedimentation constant was estimated at 16–18 S. Intact TMV-RNA and RNA having 16–18 S were also obtained directly from homogenates of tobacco leaves infected with 32P-TMV. 32P-TMV was partially stripped by SDS and was added to tobacco leaf sap to test the RNase activity in tobacco leaves. A part of RNA which was exposed by SDS was digested and the 32P-radioactivity in the top zone of the centrifugation tube increased. This finding supported the idea that the partially uncoated virus particles in infected leaves lost a portion of their RNA during extraction by the action of the RNase contained in the homogenate.

Vesiculated Hairs: A Mechanism for Salt Tolerance in Atriplex halimus L

The concentration of salts in the vesiculated hairs of Atriplex halimus L. was measured and was remarkably higher than that of the leaf sap and xylem exudate. In spite of their unusually high salt content, these hairs when immersed seemed unable to absorb water, in apparent contradiction to the previously held hypothesis that vesiculated hairs make it possible for such plants to absorb water from the atmosphere. Although growing the plants under saline conditions increased the salt content of the hairs from 2.3 m Na+K to 11.6 m, salt content of the expressed leaf sap from young leaves did not change significantly. This observation indicates that in A. halimus the vesiculated hairs play a significant role in removing salt from the remainder of the leaf and preventing the accumulation of toxic salts in the parenchyma and vascular tissues. Thus, a nearly constant salt content is maintained in leaf cells other than the hairs.

Stabilization of purified potato virus X by dextran T-10 during lyophilization

Purification and preservation of potato virus X from leaf sap of tobacco plants before lyophilization was carried out by two methods: 1) precipitation by polyethylene glycol and ultracentifugation, and 2) precipitation by ammonium sulphate, chromatography on Sephadex G-50 and ultracentrifugation. The first method is preferable to the second because the final preparation contains more virus antigen. Both preparations were strongly infectious and maintained antigenic properties after lyophilization. To achieve a more gentle course of lyophilization of virus preparations, addition of urotropine and dextran T-10 to the virus suspension, purified by the precipitation by polyethylene glycol-6000, was examined. Addition of urotropine was proved unsatisfactory, because only antigenic properties were maintained after lyophilization while the infectivity disappeared. But we can recommend addition of dextran T-10 up to a concentration of 6% to the preparation of virus antigen before lyophilization. The course of lyophilization is much rapider, the lyophilized product can be very easily dissolved in water and is not hygroscopic. The product is strongly infectious and gives the serological precipitation reaction in a dilution four times that of X virus antigen lyophilized without addition of dextran T-10.

Changes in Polyphenoloxidase Activity in the Cucumber Mosaic Virus Infected Tobacco Leaves and Its Non-Responsibility for the Changes in Virus Concentration in vivo

The purpose of this study is to find the changes in polyphenoloxidase (PPO) activity in cucumber mosaic virus (CMV) infected tobacco leaves at various periods after inoculation, and to find the effect of this enzyme on the changes in symptoms and virus concentration in vivo, which have been described in previous reports.Lower two leaves of tobacco seedlings (Nicotiana tabacunm L. cultivar Bright Yellow) were inoculated with ordinary strain of CMV (CMV-O), in an air-conditioned glasshouse at 25°C. PPO activity in the systemically infected upper three leaves was measured by the rapid method described by Shiroya, at weekly interval for 4 weeks after inoculation. Chlorogenic aid was used as the substrate of PPO reaction. PPO activity in the leaves increased from the 8th day to the 21st day after inoculation, and on the 14th and the 21st day the activities were significantly higher than those in healthy control leaves. On the 21st day, the difference of activities between infected and healthy leaves was highest, and reached 2.5 times on the basis of tissue dry weight. On the 28th day the enzyme activity decreased to the same level as on the 8th day (Fig. 2). These changes in enzyme activity were inversely proportional to the changes in symptoms and virus concentration in vivo.PPO activity in leaf extracts of tobacco plant grown in copper-deficient culture solution is known to decrease to about 1/10-1/25 of control non-deficient leaves, even when the sign of deficiency is not apparent. Tobacco plants were grown in Cu-deficient cuture solution prepared principally by the method of Staut and Arnon and inoculated with CMV-O. About two weeks after inoculation, greyish brown spots appeared on the lower leaves, as a sign of deficiency. During 4 weeks after inoculation, top leaves were harvested at weekly intervals, and homogenized with phosphate buffer (0.1M, pH 7.0) containing 1/30M Na-diethyldithiocarbamate. Infectivity in Cu-deficient and non-deficient leaves was compared by inoculation onto opposite primary leaves of cowpea. Changes in infectivity of Cu-dificient leaves were similar to those of non-deficient leaves (Fig. 5). Very low infectivity and masking of symptoms in newly developed leaves were obtained on the 21st day, even in Cu-deficient plants. The results were confirmed by using standard inoculum of vacuum-freeze dried infected leaf tissues and by serological assay.When Cu-deficient leaves were homogenized with purified yellow strain of CMV, the infectivity was 2.5-5 times higher than that of control inoculum with non-deficient leaves. In homogenate of Cu-deficient leaves, browning of sap was hardly detectable, whereas the non-deficient leaf sap showed strong browning. These results seem to indicate that deficient leaves has very low PPO activity, in agreement with Shiroya's previous finding.It appears that PPO is not directly responsible for the changes in symptoms and CMV concentration in vivo.

Estimation of the Osmotic Potential of Citrus Seedling Leaf Sap at Different Soil-Moisture Levels by Means of Refractometry and Conductimetry1

The refractive index and electrical conductivity of the leaf sap of two citrus species, sour orange and sweet lime, were measured at different soil-moisture levels. Their osmotic potentials contributed by electrolytes and soluble metabolites were estimated. The sum of these two estimates agreed fairly well with the total osmotic potential of the leaf sap as measured by cryoscopy. The results indicate that the refractometry-conductimetry method is adequate for studying the changes of osmotic potential of citrus seedlings during the course of irrigation cycles.

The problem of isolation of the X virus inhibitor from potato leaf sap

Using moving boundary electrophoresis in a veronal buffer, pH 8·5, of 0·05 ionic strength and at 4·3 mA, we succeeded in separating the inhibitor, which was obtained by fractionation on a Sephadex G-50 column, into four components. The two most substantial components represent 25% and 65% respectively from the separated proteins as a whole. The heterogeneity of the inhibitor was proved by analytical ultracentrifugation, too. The ionex chromatography was applied for the quantitative separation of the inhibitor. We used ionex chromatography on DEAE Cellulose the concentration gradient being 0–1m NaCl in a 0·01m phosphate buffer, pH 7·3, and on DEAE Sephadex A-50 using the same concentration gradient in a phosphate buffer, of 0·1 ionic strength and pH 7·3. In both cases four components were obtained. The most substantial component, representing 65% of the whole analysed material, was eluted at the concentration 0·15–0·3m NaCl, and was electrophoretically homogenous and showed the most effective inhibitory ability.

The adaptation of tomato mosaic virus to resistant tomato plants

SUMMARYTomato mosaic virus derived from susceptible tomato plants (the standard virus) was cultured in resistant plants. Sap from non‐inoculated leaves of resistant tomato plants infected with virus from the resistant host was more infective and contained more virus particles than leaf sap of resistant plants infected with the standard virus. Leaves of resistant tomatoes infected with virus from the resistant host also showed more obvious symptoms. Susceptible plants infected with virus from resistant plants not only showed fewer symptoms than when infected with standard virus, but samples were less infective and contained less virus up to 26 weeks, when values for infectivity were similar.This modification in activity was not reversible and was obtained with two lines of tomato having different types of resistance. Passage of virus from resistant plants through susceptible plants did not impair its ability to infect resistant plants.

Changes in the Water Balance and Photosynthesis of Onion, Bean and Cotton Plants under Saline Conditions

AbstractThe osmotic concentration (osmotic potential) of onion leaf sap did not adjust to chloride salinity, and consequently water potential, turgor, stomatal aperture and transpiration were reduced. Although osmotic concentration of bean and cotton leaf sap did adjust to a saline root medium and turgor was no less in the salinized plants than in the controls, stomata of the salinized plants remained only partly open and transpiration was reduced.Net photosynthesis of onion plants was reduced by salinity (this effect being much enhanced in a hot dry atmosphere) but it could be rapidly raised to the level of the controls by inducing elevated leaf turgor.Stomatal closure was initially responsible for most of the ∼30 % reduction in photosynthesis of salinized beans. This was due to interference with CO2 diffusion and could be overcome by raising the CO2 concentration in the air. At a later stage of growth, salinity affected the light reaction of bean photosynthesis, and elevation of the air CO2 had little effect.Closure of stomata of salinized cotton plants had only a relatively small effect on net photosynthesis. Light intensity and CO2 concentration experiments showed that salinity was reducing the photosynthesis of cotton leaves mainly by affecting the light reaction of photosynthesis.It is concluded that chloride salinity does affect the water balance and rate of photosynthesis of plants and that the nature and degree of the effects will depend upon climatic conditions and may be very different between plant species and in the same species at different periods of growth.

Serological determination of the amount of the X virus inhibitor in potato leaf sap

Antiserum against the X virus inhibitor was prepared by immunizing rabbits with the inhibitor antigen obtained in two ways: (1) ultracentrifugation of potato leaf sap in a Spinco L for 1 h at 40000 r.p.m., (2) ultracentrifugation and fractionation of the sap on a Sephadex G-50 column.The antiserum is specific against the inhibitor protein and does not react with other proteins of the plant or with the X virus. Direct serological analysis makes it possible to determine in the potato leaf sap either the presence or the absence of the X virus inhibitor, to follow the degree of inactivation of the inhibitor due to various factors and finally to determine the relative amount of inhibitor in various cultivars and hybrids of the potato plant.A detailed description of the method for determining the amount of the X virus inhibitor in the leaf sap from various potato cultivars and hybrids is given. The amount of sap required for analysis is very small (1–2 ml) which makes it possible to carry out analyses on individual plants. The duration of analysis is about 1 h.The determination of the inhibitor amount in the potato leaf sap agrees with that of the inhibitory potency of the cell sap in 87·7% cases.

Investigation of the X virus inhibitor from potato leaf sap

The inhibitor of the X virus (Jermoljev, Albrechtová 1965) can be separated from other proteins by 60 min centrifugation at 40000 r.p.m. in the Spinco L centrifuge and by subsequent gel filtration of the supernatant on a Sephadex G-50 column. For the elution it is best to use Tris-maleate buffers and 0·2M Tris-HCl of pH 7·2. The inhibitor is present in the first fractions containing proteins, between 30 and 45 ml. It is most suitable to concentrate the inhibitor by salting out with ammonium sulphate to 30–50% saturation. The inhibitor can be preserved by adding ammonium sulphate to the sap. At 3°C it can be kept in this manner for 2 months. If the pH of the sap drops below 5·5, the inhibitor is inactivated. Complete inactivation of the inhibitor takes place after a 10 min heating at 67·5°C. No substantial difference in the amount of inhibitor in the sap from apical leaves and leaves from middle levels has been found. Keeping the plants in the dark has no effect on the inhibitor level.