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Publikationen - Molekulare Signalverarbeitung

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Publikation

Weichert, H.; Kohlmann, M.; Wasternack, C.; Feussner, I.; Metabolic profiling of oxylipins upon sorbitol treatment in barley leaves Biochem. Soc. Trans. 28, 861-862, (2001) DOI: 10.1042/bst0280861

In barley leaves 13-lipoxygenases (LOXs) are induced by salicylate and jasmonate. Here, we analyse by metabolic profiling the accumulation of oxylipins upon sorbitol treatment. Although 13-LOX-derived products are formed and specifically directed into the reductase branch of the LOX pathway, accumulation is much later than in the cases of salicylate and jasmonate treatment. In addition, under these conditions only the accumulation of jasmonates as additional products of the LOX pathway has been found.
Publikation

Ticconi, C. A.; Delatorre, C. A.; Abel, S.; Attenuation of Phosphate Starvation Responses by Phosphite in Arabidopsis Plant Physiol. 127, 963-972, (2001) DOI: 10.1104/pp.010396

When inorganic phosphate is limiting, Arabidopsis has the facultative ability to metabolize exogenous nucleic acid substrates, which we utilized previously to identify insensitive phosphate starvation response mutants in a conditional genetic screen. In this study, we examined the effect of the phosphate analog, phosphite (Phi), on molecular and morphological responses to phosphate starvation. Phi significantly inhibited plant growth on phosphate-sufficient (2 mm) and nucleic acid-containing (2 mmphosphorus) media at concentrations higher than 2.5 mm. However, with respect to suppressing typical responses to phosphate limitation, Phi effects were very similar to those of phosphate. Phosphate starvation responses, which we examined and found to be almost identically affected by both anions, included changes in: (a) the root-to-shoot ratio; (b) root hair formation; (c) anthocyanin accumulation; (d) the activities of phosphate starvation-inducible nucleolytic enzymes, including ribonuclease, phosphodiesterase, and acid phosphatase; and (e) steady-state mRNA levels of phosphate starvation-inducible genes. It is important that induction of primary auxin response genes by indole-3-acetic acid in the presence of growth-inhibitory Phi concentrations suggests that Phi selectively inhibits phosphate starvation responses. Thus, the use of Phi may allow further dissection of phosphate signaling by genetic selection for constitutive phosphate starvation response mutants on media containing organophosphates as the only source of phosphorus.
Publikation

Hilpert, B.; Bohlmann, H.; Den Camp, R. o.; Przybyla, D.; Miersch, O.; Buchala, A.; Apel, K.; Isolation and characterization of signal transduction mutants of Arabidopsis thaliana that constitutively activate the octadecanoid pathway and form necrotic microlesions Plant J. 26, 435-446, (2001) DOI: 10.1046/j.1365-313X.2001.2641036.x

Thionins are a group of antimicrobial polypeptides that form part of the plant's defense mechanism against pathogens. The Thi 2.1 thionin gene of Arabidopsis thaliana has been shown to be inducible by jasmonic acid (JA), an oxylipin‐like hormone derived from oxygenated linolenic acid and synthesized via the octadecanoid pathway. The JA‐dependent regulation of the Thi 2.1 gene has been exploited for setting up a genetic screen for the isolation of signal transduction mutants that constitutively express the Thi 2.1 gene. Ten cet‐mutants have been isolated which showed a c onstitutive e xpression of the t hionin gene. Allelism tests revealed that they represent at least five different loci. Some mutants are dominant, others recessive, but all cet mutations behaved as monogenic traits when backcrossed with Thi 2.1‐GUS plants. Some of the mutants overproduce JA and its bioactive precursor 12‐oxophytodienoic acid (OPDA) up to 40‐fold while others have the same low levels as the control wildtype plants. Two of the mutants showed a strong induction of both the salicylic acid (SA)‐ and the JA‐dependent signaling pathways, while the majority seems to be affected only in the octadecanoid pathway. The Thi 2.1 thionin gene and the Pdf 1.2 defensin gene are activated independently, though both are regulated by JA. The cet‐mutants, except for one, also show a spontaneous leaf cell necrosis, a reaction often associated with the systemic acquired resistance (SAR) pathway.
Publikation

Feussner, I.; Kühn, H.; Wasternack, C.; Lipoxygenase-dependent degradation of storage lipids Trends Plant Sci. 6, 268-273, (2001) DOI: 10.1016/S1360-1385(01)01950-1

Oilseed germination is characterized by the mobilization of storage lipids as a carbon source for the germinating seedling. In spite of the importance of lipid mobilization, its mechanism is only partially understood. Recent data suggest that a novel degradation mechanism is initiated by a 13-lipoxygenase during germination, using esterified fatty acids specifically as substrates. This 13-lipoxygenase reaction leads to a transient accumulation of ester lipid hydroperoxides in the storage lipids, and the corresponding oxygenated fatty acid moieties are preferentially removed by specific lipases. The free hydroperoxy fatty acids are subsequently reduced to their hydroxy derivatives, which might in turn undergo β-oxidation.
Publikation

BERGER, S.; Weichert, H.; Porzel, A.; Wasternack, C.; Kühn, H.; Feussner, I.; Enzymatic and non-enzymatic lipid peroxidation in leaf development BBA-Mol. Cell Biol. Lipids 1533, 266-276, (2001) DOI: 10.1016/S1388-1981(01)00161-5

Enzymatic and non-enzymatic lipid peroxidation has been implicated in programmed cell death, which is a major process of leaf senescence. To test this hypothesis we developed a high-performance liquid chromatography (HPLC) method for a simultaneous analysis of the major hydro(pero)xy polyenoic fatty acids. Quantities of lipid peroxidation products in leaves of different stages of development including natural senescence indicated a strong increase in the level of oxygenated polyenoic fatty acids (PUFAs) during the late stages of leaf senescence. Comprehensive structural elucidation of the oxygenation products by means of HPLC, gas chromatography/mass spectrometry and 1H nuclear magnetic resonance suggested a non-enzymatic origin. However, in some cases a small share of specifically oxidized PUFAs was identified suggesting involvement of lipid peroxidizing enzymes. To inspect the possible role of enzymatic lipid peroxidation in leaf senescence, we analyzed the abundance of lipoxygenases (LOXs) in rosette leaves of Arabidopsis. LOXs and their product (9Z,11E,13S,15Z)-13-hydroperoxy-9,11,15-octadecatrienoic acid were exclusively detected in young green leaves. In contrast, in senescing leaves the specific LOX products were overlaid by large amounts of stereo-random lipid peroxidation products originating from non-enzymatic oxidation. These data indicate a limited contribution of LOXs to total lipid peroxidation, and a dominant role of non-enzymatic lipid peroxidation in late stages of leaf development.
Publikation

Li, G.; Riaz, A.; Goyal, S.; Abel, S.; Quiros, C. F.; Inheritance of Three Major Genes Involved in the Synthesis of Aliphatic Glucosinolates in Brassica oleracea J. Am. Soc. Hortic. Sci. 126, 427-431, (2001) DOI: 10.21273/JASHS.126.4.427

Inheritance of three major genes involved in synthesis of aliphatic glucosinolates (GSL) was followed in segregating populations of Brassica oleracea L. generated from three crosses: broccoli × cauliflower, collard × broccoli, and collard × cauliflower. Two of these genes, GSL-PRO and GSL-ELONG, regulate sidechain length. The action of the former results in three-carbon GSL, whereas action of the latter produces four-carbon GSL. We determined that these two genes act and segregate independently from each other in B. oleracea. The double recessive genotype produces only trace amounts of aliphatic GSL. The third gene, GSL-ALK controls sidechain desaturation and, as it has been observed in Arabidopsis thaliana (L.) Heynh., we found that this gene cosegregates with a fourth gene, GSL-OH, that is responsible for sidechain hydroxylation. Elucidation of the inheritance of major genes controlling biosynthesis of GSL will allow for manipulation of these genes and facilitate development of lines with specific GSL profiles. This capability will be important for improvement of Brassica breeding lines with high content of desirable GSL, like glucoraphanin, a demonstrated precursor of anticarcinogenic compounds. Additionally, this work is the first step towards cloning the major genes of the aliphatic GSL pathway, and to use these clones in transformation strategies for further crop enhancement.
Bücher und Buchkapitel

Abel, S.; Köck, M.; Secretory Acid Ribonucleases from Tomato, Lycopersicon esculentum Mill. Methods Enzymol. 341, 351-368, (2001) DOI: 10.1016/S0076-6879(01)41163-3

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Publikation

Hause, B.; Kogel, K.-H.; Parthier, B.; Wasternack, C.; In barley leaf cells, jasmonates do not act as a signal during compatible or incompatible interactions with the powdery mildew fungus (Erysiphe graminis f. sp. hordei) J. Plant Physiol. 150, 127-132, (1997) DOI: 10.1016/S0176-1617(97)80191-5

We have studied a possible function of jasmonates as mediators in the host-pathogen interaction of barley (Hordeum vulgare L.) with the powdery mildew fungus Egh (Erysiphe graminis f. sp. hordei). Previous findings from whole-leaf extracts demonstrated that (i) extracts from infected barley leaves did not contain enhanced levels of jasmonates, (ii) transcripts of jasmonate-inducible genes were not expressed upon infection, and (iii) exogenous application of jasmonates did not induce resistance to Egh (Kogel et al., 1995). Nevertheless, the question arises whether or not jasmonates are involved in the interaction of barley with the powdery mildew fungus at the local site of infection. Using an immunocytological approach the analysis of leaf cross-sections from a susceptible barley cultivar and its near-isogenic mlo5-resistant line revealed no accumulation of JIP-23, the most abundant jasmonate inducible protein, neither in epidermal cells attacked by the pathogen nor in adjacent mesophyll cells. As a positive control, cross-sections from methyl jasmonate-treated leaf segments showed a strong signal for JIP-23 accumulation. Because the presence of the jasmonate-inducible protein is highly indicative for an already low threshold level of endogenous jasmonate (Lehmann et al., 1995), the lack of JIP-23 accumulation at the sites of attempted fungal infection clearly demonstrates the absence of enhanced levels of jasmonates. This excludes even a local rise of jasmonate confined to those single cells penetrated (Mlo genotype) or attacked (mlo5 genotype) by the fungus.
Publikation

Görschen, E.; Dunaeva, M.; Reeh, I.; Wasternack, C.; Overexpression of the jasmonate-inducible 23 kDa protein (JIP 23) from barley in transgenic tobacco leads to the repression of leaf proteins FEBS Lett. 419, 58-62, (1997) DOI: 10.1016/S0014-5793(97)01433-6

We investigated transgenic tobacco lines which express different amounts of the barley JIP 23. In these plants the amount of several proteins decreased proportionally to increasing amounts of JIP 23 whereas the transcript levels were constant as determined for the small and the large subunit of RuBPCase. However, the translation initiation of the rbcS transcript was found to be less efficient than in the wild type. In contrast, the jip 23 transcript was efficiently initiated, indicating that no unspecific impairment of initiation occurred. The data suggest that the barley JIP 23 leads to discrimination among certain tobacco transcripts during translation initiation.
Publikation

Görschen, E.; Dunaeva, M.; Hause, B.; Reeh, I.; Wasternack, C.; Parthier, B.; Expression of the ribosome-inactivating protein JIP60 from barley in transgenic tobacco leads to an abnormal phenotype and alterations on the level of translation Planta 202, 470-478, (1997) DOI: 10.1007/s004250050151

In this paper we report the in-planta activity of the ribosome-inactivating protein JIP60, a 60-kDa jasmonate-induced protein from barley (Hordeum vulgare L.), in transgenic tobacco (Nicotiana tabacum L.) plants. All plants expressing the complete JIP60 cDNA under the control of the cauliflower mosaic virus (CaMV) 35S promoter exhibited conspicuous and similar phenotypic alterations, such as slower growth, shorter internodes, lanceolate leaves, reduced root development, and premature senescence of leaves. Microscopic inspection of developing leaves showed a loss of residual meristems and higher degree of vacuolation of mesophyll cells as compared to the wild type. When probed with an antiserum which was immunoreactive against both the N- and the C-terminal half of JIP60, a polypeptide with a molecular mass of about 30 kDa, most probably a processed JIP60 product, could be detected. Phenotypic alterations could be correlated with the differences in the detectable amount of the JIP60 mRNA and processed JIP60 protein. The protein biosynthesis of the transformants was characterized by an increased polysome/monosome ratio but a decreased in-vivo translation activity. These findings suggest that JIP60 perturbs the translation machinery in planta. An immunohistological analysis using the JIP60 antiserum indicated that the immunoreactive polypeptide(s) are located mainly in the nucleus of transgenic tobacco leaf cells and to a minor extent in the cytoplasm.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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