Presence and role of jasmonate in apple embryos

(-)Jasmonic acid (JA) was identified in extracts front embryos of apple (Mulus domestica) by combined gas chromatography-mass spectromelry. Quantification of JA in embryos isolated from seeds at different perexts of stratification by gas chromalography combined with mass spectrometry/selective ion monitoring indicated a sharp peak at day 30. At the same time the maximal ratio of conjugated to free JA was found by enzyme-linked imrnunosorbent assay (ELISA). Germination of embryo.s was stimulated by added JA and inhibited by salieylhydroxamic acid (SHAM, an inhibitor of lipoKygenase). Both stimulation and inhibition disappeared in embryos stratified for more than 30 days. Methyl jasmonate was more effective in stimulation of embryo germination than free JA. while JA-isoleucine inhibited germination. The possible mechanism responsible for changes in JA level as wel! as the role of JA and its conjugates in removal of dormancy in apple seeds are discussed.     

Occurrence of the plant growth regulator jasmonic acid in plants

The natural occurrence of jasmonic acid and its methyl ester in plants has been studied using different methods such as GC, GC-MS, HPLC, radioimmunoassay, and bioassay. Jasmonic acid was detected in several Leguminosae plants and a number of species belonging to nine other Angiospermae families. Highest amounts occurred in fruit parts, especially the immature pericarp, but it was found also in flowers and vegetative plant parts, e.g. leaves, stems, and germs. Young apple fruits contain both jasmonic acid and methyl jasmonate, and in Douglas fir, the only Gymnospermae species studied, only the methyl ester could be detected. Jasmonic acid is discussed as an endogenous plant growth regulator widely distributed in higher plants.     

Biological activity of gibberellin analogues

In order to determine the significance of the C-6 carboxyl group for the biological activity gibberellin A₃, 6-epigibberellin A₃, 7-norgibberellin A₃, 6-methyl-7-norgibberellin A₃, and 7-homogibberellin A₃ were studied using dwarf pea, dwarf maize, dwarf rice, dwarf barley and -amylase bioassays. All gibberellin A₃(GA₃)derivatives tested were considerably less active than GA₃. In all biossays, 6-epi-GA₃ showed a low activity of the same order, whereas 6-methyl-7-nor-GA₃ was inactive. Surprisingly, 7-nor-GA₃ had some activity in the dwarf rice (root application), dwarf barley, and -amylase bioassay, in contrary to its low potency in the dwarf pea, dwarf maize, and dwarf rice (micro drop) bioassay. 7-Homo-GA₃ was primarily active in the dwarf maize, dwarf barley and dwarf rice bioassay. It also caused antigibberellin effects in dwarf rice. The results demonstrate that the C-6 carboxyl group is not absolutely essential for biological activity of gibberellins. The different activities of 7-nor-GA₃ observed in the various test systems may indicate that the C-6 carboxyl group is a structural requirement more for uptake and/or transport processes than for receptor affinity.Abbreviation GA₃ gibberellic acid     

Anatomische Untersuchungen über die Reaktion vonSolanum demissum Lindl.,Solanum vernei Bitt. et Wittm. und vonSolanum-andigenum-Bastarden auf Befall durch den Kartoffelnematoden,Heterodera rostochiensis Woll.

Ohne ZusammenfassungMit 20 AbbildungenHerrn Dr. habil. H.Buhr, Mühlhausen/Thür., zum 60. Geburtstage gewidmet.9. Mitt. überHeterodera-Arten. — Teil der Dissertation vonG. Sembdner, Techn. Univ. Dresden, 1961. —8. Mitt.Sembdner, G., Nematologica9, i. Druck (1963).     

Enzymic glucosylation of gibberellins

Starting from the well-known conversion of exogenously applied free gibberellic acid (GA₃) to its 3(O)-glucoside by intact immature fruits of runner beans (Phaseolus coccineus L.), a protein fraction has been prepared from this plant material possessing glucosylating activity towards GAs. This glucosyltransferase is located in the pericarp only and utilizes preferably UDP-glucose as a sugar donor. The product formed enzymically from GA₃ and UDP-glucose could be identified by derivatization and comparison with the authentic compound to be GA₃-3(O)-glucoside. Among 15 native or chemically modified GAs, the enzyme glucosylates only GA₃ and to a lower extent GA₇ and GA₃₀, indicating a high enzyme specificity with regard to the A ring of gibberellins. The physiological significance of the enzymic GA₃-3(O)-glucoside formation inPhaseolus coccineus is not clear, since this glucoside is not known to be endogenous in this plant. The enzyme preparation did not glucosylate substances of phenolic structure, such as hydroquinone, aesculetin, and quercetin. Glucosylation of GA₃ was achieved also by enzyme preparations fromVigna sinensis and from cell suspension cultures ofDigitalis purpurea. A number of other plant materials showed no activity.Gibberellins 100. For part 99 see Liebisch et al. 1984a.     

In vitro glucosylation of gibberellins

In maturing fruits ofPhaseolus coccineus a soluble glucosyltransferase activity occurs which converts gibberellins into their O-glucosides. The enzyme glucosylates GA₃ and structurally closely related gibberellins (GA₇ and GA₃₀) to their 3-O-glucosides by transfer of glucose preferentially from UDP-glucose. From cell suspension cultures ofLycopersicon peruvianum cytosolic glucosyltransferases were isolated which in the presence of UDP-glucose converted GA₇ and GA₉ to the corresponding glucosyl esters. In both cases numerous other gibberellins failed to serve as substrates. Thus, the enzymes are UDP-glucose: gibberellin glucosyltransferases of considerable substrate specificity.     

Über die Biologische Wirksamkeit einiger Gibberellinsäure-Abbauprodukte

Zusammenfassung Die biologische Wirksamkeit von 4 Gibberellinsäure-Abbauprodukten (Abb. 1) wurde an mehreren Testpflanzen unter Verwendung von A₃ als Standard vergleichend untersucht. Die Substanzen wurden dünnschichtchromatographisch gereinigt und auf Einheitlichkeit geprüft. Gibberellensäure. Die Mais-Zwergmutanten d-1, d-3 und d-5 reagierten auf Mindestdosen von l g/Pflanze. Im Zwergerbsen-und Reissämlingstest zeigte sich geringere, im Lactuca-Hypokotyltest sehr schwache Wirksamkeit. Die Dunkelkeimung von Lactuca-Achänen wurde nicht stimuliert.Dicarbonsäure A (s. Material und Methodik). Bei Zea mays d-5 besaß die Verbindung etwa gleichstarke, bei d-1 und d-3 etwas geringere Aktivität als Gibberellensäure. Bei Erbsen und im Lactuca-Hypokotyltest wurde nur schwache, bei Reissämlingen praktisch keine Wirksamkeit festgestellt. Allogibberinsäure war bei Lactuca sativa (Hypokotylverlängerung und Dunkelkeimung) und Oryza sativa stärker wirksam als die übrigen Abbauprodukte. Die Maismutante d-5 reagierte ebenfalls relativ empfindlich; bei d-3 und d-1 zeigte sich geringere, bei Zwergerbsen nur sehr schwache Aktivität. Gibberinsäure besaß lediglich bei Zea mays d-5 in hohen Dosen (100 g/Pflanze) eine geringe Wirksamkeit.

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On the biological activity of some degradation products of gibberellic acid. Gibberellins. Part VIII

Summary The potency of four degradation products of gibberellic acid (Fig.1) was studied in several bioassays using gibberellin A₃ as a standard. The substances had been purified and checked for homogeneity by means of thin-layer chromatography. Gibberellenic acid. Dwarf maize mutants d-1, d-3 and d-5 showed positive reactions after application of minimal doses of 1 g per plant. In the case of dwarf peas and rice seedlings gibberellenic acid exhibited a lower potency, and with Lactuca seedlings (hypocotyl extension) very low biological activity was observed. Germination of Lactuca seeds in the dark was not stimulated.Dicarbonic acid A (see Material und Methodik) had the same potency as gibberellenic acid with Zea mays d-5 and slightly lower potency with d-1 and d-3. With dwarf peas as well as in the Lactuca hypocotyl test dicarbonic acid A exhibited only low activity and in the case of rice seedlings the activity was negligible. Allogibberic acid had a higher potency than the other degradation products in bioassays with Lactuca sativa (both hypocotyl extension and seed germination) and with Oryza sativa. Zea mays d-5 was also relatively sensitive towards this substance. With d-1 and d-3 allogibberic acid exhibited a lower potency and with Pisum sativum only a very low potency. Gibberic acid. Only Zea mays d-5 showed positive reactions after application of hig doses (100 g per plant).

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VII. Mitt.: Sembdner u. Schreiber (1965b).     

Endogenous gibberellins and inhibitors in caryopses of rye

Gibberellins A₈, A₁₆, A₂₄, and abscisic acid were identified by GC-MS of derivatized extracts from immature fruits of Secale cereale. Mature caryopses contained ABA and trans-ABA in a ratio 1:1 as well as 4′-dihydrophaseic acid. During milk ripeness a neutral GA conjugate was detected. Free GA, afforded by enzymatic hydrolysis of the conjugate, was chromatographically identified as GA₁₆     

Occurrence and identification of jasmonic acid and its amino acid conjugates induced by osmotic stress in barley leaf tissue

The effect of osmotically active substances on the alteration of endogenous jasmonates was studied in barley (Hordeum vulgare L. cv. Salome) leaf tissue. Leaf segments were subjected to solutions of d-sorbitol, d-mannitol, polyethylene glycol 6000, sodium chloride, or water as a control. Alterations of endogenous jasmonates were monitored qualitatively and quantitatively using immunoassays. The structures of jasmonates isolated were determined on the basis of authentic substances by capillary gas chromatography-mass spectrometry. The stereochemistry of the conjugates was confirmed by high performance liquid chromatography with diastereoisomeric references. In barley leaves, jasmonic acid and its amino acid conjugates, for example, with valine, leucine, and isoleucine, are naturally occurring jasmonates. In untreated leaf segments, only low levels of these native jasmonates were found. After treatment of the leaf tissues with sorbitol, mannitol, as well as with polyethylene glycol, an increase of both jasmonic acid and its conjugates could be observed, depending on the stress conditions used. In contrast, salt stress was without any stimulating effect on the levels of endogenous jasmonates. From barley leaf segments exposed to sorbitol (1m) for 24 h, jasmonic acid was identified as the major accumulating compound. Jasmonic acid-amino acid conjugates increased likewise upon stress treatment.Abbreviations JM methyl jasmonate - JA jasmonic acid - JIP(s) jasmonate-induced protein(s) - PEG polyethylene glycol - RIA radioimmunoassay - ELISA enzyme-linked immunosorbent assay - HPLC high performance liquid chromatography - GC-MS gas chromatography-mass spectrometry - R _t retention time - IAA indole-3-acetic acid     

Degradation of ribulose-1,5-bisphosphate carboxylase and chlorophyll in senescing barley leaf segments triggered by jasmonic acid methylester, and counteraction by cytokinin

Barley ( Hordeum vulgare L. cv. Salome) primary leaf segments responded to the application of a putative plant growth regulator, ± jasmonic acid methylester (JA-Me). with accelerated senescence, as indicated by the loss of chlorophyll and the rapid decrease in activity and immunoreactive protein content of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBP carboxylase, EC 4.1.1.39). The senescence-promoting action of JA-Me differed in light and in darkness; e.g. the initial rates of chlorophyll and RuBP carboxylase breakdown were markedly higher in light than in darkness in the presence of 4.10⁻⁵ M JA-Me. Cytokinin (benzyladenine, 4.10⁻⁵ M ) stopped the loss of chlorophyll and RuBP carboxylase during senescence; however, the rapid drop induced by JA-Me in the early phase of leaf segment senescence could not be prevented by concomitant or previous addition of BA. On the other hand, BA added 24 h after JA-Me application resulted in a recovery of chlorophyll and RuBP carboxylase at the later stages, indicating a possible rapid inactivation of JA-Me in the tissues. The activities of a number of other chloroplastic and cytosolic enzymes were not significantly altered in JA-Me-treated leaf segments compared with controls floated on water. Time-dependent chlorophyll decrease in isolated chloroplasts did not change upon JA-Me addition to the isolated organelles. It is suggested that JA-Me acts on chloroplast senescence by promoting cytoplasic events which eventually bring about the degradation of chloroplast constituents.