Existence of salt glands on leaves of kallar grass (Leptochloa fusca L. Kunth.)

Light microscopic studies have established the existence of salt glands on “Kallar grass”; leaf blades. The salt glands resembled the two‐cell type structure described for some halophytic genera within the Gramineae. The secreted salts crystallized and formed whiskers when the plants were grown under continuously high saline conditions. The salt secretion appears to be selective. The secretion of Na exceeded that of K and considerable quantities of Cl were also extruded, preferentially in concomitance with Na. The significance of growth hormones and Ca in regulating the salt secretion process is discussed.     

Nematicidal potential of aqueous and ethanol extracts gained from Datura stramonium,D. innoxia and D. tatula on Meloidogyne incognita

Journal of Plant Diseases and Protection - The nematicidal effect of aqueous and ethanol extracts from leaves, roots and mixed plant parts...     

Sink strength and photosynthetic capacity influence tuber development in sweet potato

Summary

Tuber growth of sweet potato clones is shown to depend on the sink strength of the developing tuber, the potential of leaves to export photoassimilates, but also on the photosynthetic capacity of leaves. Evidence from experiments with the short-lived radioisotope ¹¹C and from growth experiments in the glasshouse is presented in favour of the hypothesis that tuber formation promoted photoassimilate export from fully expanded leaves and also leaf photosynthesis. In the sweet potato clone ‘AB94078.1’, a low photosynthetic capacity could be explained by a limitation of Calvin cycle activity, notably of Rubisco activity. The light reactions of photosynthesis did not limit net photosynthesis in the investigated clones under the non-saturating light conditions during the experiment.     

Effect of methionine sulphoximine on13 N-ammonium fluxes in the roots of barley and squash seedlings

¹³ N-Iabelled experiments were carried out with barley and squash seedlings to analyse the effect of methionine sulphoximine (MSO), as an inhibitor of the ammonium assimilation, on NH₄⁺ fluxes in the roots at the level (150 μM NH₄⁺) of the high affinity uptake system (HATS). MSO pretreatment in the root medium significantly accelerated NH₄⁺ influx and efflux in NH₄⁺ -fed plants of both species. Concomitantly, the level of NH₄⁺ extracted from the root and shoot tissues was strongly elevated whereas the translocation of¹³ N-Iabelled organic substances (presumably amino products) into the shoots was markedly reduced. The onset of the increased NH₄⁺ influx did not occur immediately but was indicated about 1 h after the application of MSO to the nutrient solution. Also, MSO did not directly affect the uptake of¹³ NO₃^?. The reason why MSO treatment leads to an acceleration of the NH₄⁺ influx against an increasing level in the cell tissue remains obscure. In squash, an intermediate of NO₃^? metabolism is thought to suppress NH₄⁺ uptake since NH₄⁺ influx was high in N-free- and NH₄⁺ -grown seedlings but was reduced about threefold in NO₃^? -fed squash plants; the suppression was not eliminated by MSO treatment.     

Untersuchungen zur Assimilatakkumulation im Weizenblatt nach Schwarzrostinfektion

Accumulation of assimilates in stem-rust-infected wheat leaves
Using wheat plants (cv. 'Prelude'), the effects of stem-rust infection on photosynthesis and assimilate partitioning were studied with the aid of the short-lived carbon isotope ¹¹C. Photosynthesis of strongly infected leaf parts declined by about 30 % within 1 day. This rapid inhibition was caused by the formation of appressoria and the growth of infection tubes into the stomata, leading to a reduction in gas exchange. Further decline of photosynthesis to 5–10 % was accompanied by the degradation of chlorophyll. Nevertheless, during sporulation, the dry weight of the infected leaf area increased by about 50 %. With the use of ¹¹C, the reduced export of photosynthate from the infected leaf part and the capture of labelled compounds from the apical leaf section were quantified. The enhanced storage of assimilates in stem-rust-infected leaves can be attributed to the increase in invertase activity.     

Wirkung einer Abscisinsäure-Applikation auf die Cl−Translokation in Sojabohnen bei niedriger und hoher Besalzung des Nährmediums

Effect of abscisic acid in the root medium on Cl^? translocation in soybeans under low and high salt conditions With soybeans of the varieties ?Lee”? and ?Jackson”? the effect of abscisic acid (ABA) applied to the root medium in different concentrations (10^?4, 10^?5 and 10^?6M) on Cl^? translocation was investigated. Under low salt conditions (0,5 mM NaCl) ABA, depending on its concentration, strongly decreased Cl^? translocation to the shoot. At the highest ABA concentration, within 24 h the Cl^? content of the shoots was reduced to about 40 % of the control, the Cl^? accumulation within the roots was reduced about 25 %. However, the 10^?5 and the 10^?6M ABA treatment increased Cl^? accumulation in the roots but decreased Cl^? translocation to the shoot. Under high salt conditions (75 mM NaCI) ABA had no measureable effect on CI- translocation to the shoot. It was found that the genetic mechanism responsible for high CI- accumulation within the roots of ?Lee”? and high CI- translocation to the shoot of ?Jackson”? was not affected by ABA. ABA strongly inhibited transpiration. High ABA concentration in combination with low salt treatment decreased the transpiration rate up to 50 % of the control. ABA also inhibited transpiration under high salt conditions. This result is discussed considering the fact, that ABA added to the highly saline nutrient solution did not decrease the CI- translocation to the shoot. An investigation using ¹⁴C-ABA showed, the radioactive substance was taken up by the roots and translocated to the shoot independently from the salt treatment. The metabolism of the radioactive substance was different for roots and leaves. However, no difference could be observed by comparing the two soybeans varieties with or without salt treatment.     

Aktivitätsverteilung polysaccharid- und proteinabbauender Enzyme bei Kartoffelfäule-Erregern der GattungFusarium

Zusammenfassung Es wurde versucht, die unterschiedlichen Ausbreitungsmechanismen der beiden Lagerf?uleerregerFusarium coeruleum undFusarium sulphureum physiologisch-biochemisch teilweise aufzukl?ren Alle Isolate vonF. coeruleum undF. sulphureum vermochten Pectinmethylesterasen (PME). Polygalacturonasen (PG), Cellulasen und Proteasen zu bilden. Die Synthese der PME erfolgte bei beiden Pilzen konstitutiv und wurde durch Substratzusatz erheblich gesteigert.F. coeruleum bildete auch PG konstitutiv, nicht jedochF. sulphureum. Die Cellulase-Synthese erfolgte bei beiden Pilzen konstitutiv, die der Protease bevorzugt konstitutiv. Die Kulturdauer beeinflusste die Syntheserate der Enzyme unterschiedlich. PME und PG vonF. coeruleum zeigten im Gegensatz zuF. sulphureum keinen Aktivit?tsabfall innerhalb von 39 Tagen. Die Cellulase-Synthese des ersteren Pilzes stieg bis zum 18. Tag an, um dann langsam abzufallen, die des letzteren fiel nach starker Aktivit?t bei 3 Tagen nach 6 Tagen stark ab, um dann aber wieder über den gesamten Zeitraum stetig anzusteigen. Anders verhielt sich die Protease-Synthese, die beiF. coeruleum mit ca. 21 Tagen ihr Optimum erreichte.

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Summary In vivo,Fusarium coeruleum grows intercellularly andF. sulphureum intracellularly. The possible relationship between this and the activity of various enzymes has been investigated. All isolates ofF. coeruleum andF. sulphureum were able to produce pectinmethylesterases (PME), polygalacturonases (PG), cellulases and proteases. Both fungi synthesized PME constitutively, more being produced if substrate was added. PG was formed constitutively only byF. coeruleum. Cellulase synthesis was constitutive in both fungi and protease synthesis mainly constitutive (Fig. 2). The PME activity ofF. coeruleum was influenced by the N-source. inorganic N-compounds being more effective than organic in this respect. Peptone from casein was found suitable for PG activity. In contrast to the proteases, cellulase activity. In contrast to the proteases, cellulase activity was not greatly influenced by the N-source. The PME and PG ofF. coeruleum showed no loss of activity up to 39 days. The cellulase activity of this fungus increased up to 18 days and then declined. The cellulase activity ofF. sulphureum rose to a high level on the 3rd day. decreased after 6 days but increased again between the 9th and 39th day. Protease activity inF. coeruleum reached a maximum in 33 days and inF. sulphureum in 21 days (Table 2).

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Résumé II a été essayé d'éclaircir en partie par la voice de procédés physiologico-biochimiques le mécanisme différent de la propagation durant la conservation des deux agents de pourritureFusarium coeruleum etFusarium sulphureum. Touslesisolats deF.coeruleum etF. sulphureum ont été capables de développer des pectines-méthylestérases (PME), polygalacturonases (PG), cellulases et protéases. Pour les deux champignons, la synthèse de PME a été réalisée de manière constitutive et sensiblement activée par l'adjonction de substrats.F. coeruleum élabore aussi le PG de manière constitutive, contrairement à F. sulphureum. La synthèse de la cellulase fut constitutive pour les deux champignons, celle de la protéase fut de préférence constitutive (fig. 2). Le taux de la synthèse des enzymes varie pendant la duréc de la culture. Contrairement àF. sulphureum, les PME et PG deF. coeruleum n'ont pas diminué leur activité durant 39 jours. La synthèse de la cellulase deF. coeruleum s'est accrue jusqu'au 18e jour pour régresser ensuite lentement, celle deF. sulphureum, après une intense activité durant les 3 premiers jours, a fortement diminué pendant 6 jours puis a augmenté de fa?on continue jusqu'à la fin de la période. La synthèse de la protéase a évolué différemment; pourF. coeruleum, elle a atteint son optimum après 21 jours environ (tableau 2).

     

One-solvent extraction of astaxanthin from lactic acid fermented shrimp wastes

Free astaxanthin one-solvent extractions with ethanol, acetone, and liquid 1,1,1,2-tetrafluoroethane from raw and lactic acid fermented (ensilaged) shrimp residues were investigated. The total carotenoid recovery from ensilaged shrimp wastes was higher than that from non-ensilaged ones as assessed by HPLC analyses. Acetone gave the highest extraction yields of free astaxanthin with up to 115 microg/g of material. Moreover, liquid tetrafluoroethane is reported for the first time in a successful one-solvent extraction of carotenoids from shrimp.     

Auswirkungen hoher NaCl-Konzentration im Nährmedium auf die Transpiration,den Abscisinsäure-, Cytokinin- und Prolingehalt zweier Sojabohnensorten

Effect of high NaCl concentration in the nutrient medium on transpiration, abscisic acid, cytokinin and proline content of two soybean varieties With the differentially salt-sensitive soybean varieties ?Lee”? and ?Jackson”? the effect of salinization on transpiration, Cl^? and Na⁺ accumulation, and on abscisic acid (ABA), cytokinin and proline content was investigated. Salinization with 75 mM NaCl in the nutrient medium drastically inhibited the transpiration (about 40%) of both varieties but more so with the variety ?Jackson”?. Nevertheless this variety translocated substantially more Cl^? into the shoot than ?Lee”?. However, ?Lee”? accumulated more Cl^? into the roots and thus was able to effectively protect the shoot against a toxic Cl^? concentration. The Na⁺ distribution in the roots and shoots was nearly the same in both varieties. The ABA content of the leaves of both varieties increased 5-fold to 1200 ng × g^? dry weight after 48 h of salt stress. About the same time transpiration of the salt-stressed plants reached a minimum. Between 48 and 168 h the ABA content of ?Lee”? dropped to about half. The ABA level in ?Jackson”? remained higher which indicated that the shoot was stressed more intensely and/or longer. The results do not imply a causal relationship between the ABA concentration in the leaves and the exclusion of C1^? from the shoot of ?Lee”?. The cytokinin concentration of the two soybean varieties was not significantly affected by salinization. The proline content in the leaves increased markedly with salt stress in both varieties but much more so in ?Jackson”?. Proline content in the leaves increased from about 1.8 μmoles × g^?1 dr. w. before salt stress to 24.7 μmoles × g^?1 dr. w. after 168 h of stress. However, the proline concentration dropped to nearly the initial level within 48 h after a 120 h salt stress treatment was discontinued and the plants were returned to a control solution. In ?Lee”? salinization only doubled the amount of proline found initially. The highest value was observed after 120 h of salinization.