Maldonado-Bonilla, L. D.; Eschen-Lippold, L.; Gago-Zachert, S.; Tabassum, N.; Bauer, N.; Scheel, D.; Lee, J.; The Arabidopsis Tandem Zinc Finger 9 Protein Binds RNA and Mediates Pathogen-Associated Molecular Pattern-Triggered Immune Responses Plant Cell Physiol. 55, 412-425, (2014) DOI: 10.1093/pcp/pct175
Recognition of pathogen-associated molecular patterns (PAMPs) induces multiple defense mechanisms to limit pathogen growth. Here, we show that the Arabidopsis thaliana tandem zinc finger protein 9 (TZF9) is phosphorylated by PAMP-responsive mitogen-activated protein kinases (MAPKs) and is required to trigger a full PAMP-triggered immune response. Analysis of a tzf9 mutant revealed attenuation in specific PAMP-triggered reactions such as reactive oxygen species accumulation, MAPK activation and, partially, the expression of several PAMP-responsive genes. In accordance with these weaker PAMP-triggered responses, tzf9 mutant plants exhibit enhanced susceptibility to virulent Pseudomonas syringae pv. tomato DC3000. Visualization of TZF9 localization by fusion to green fluorescent protein revealed cytoplasmic foci that co-localize with marker proteins of processing bodies (P-bodies). This localization pattern is affected by inhibitor treatments that limit mRNA availability (such as cycloheximide or actinomycin D) or block nuclear export (leptomycin B). Coupled with its ability to bind the ribohomopolymers poly(rU) and poly(rG), these results suggest involvement of TZF9 in post-transcriptional regulation, such as mRNA processing or storage pathways, to regulate plant innate immunity.
Vandenborre, G.; Miersch, O.; Hause, B.; Smagghe, G.; Wasternack, C.; Van Damme, E. J.; Spodoptera littoralis-Induced Lectin Expression in Tobacco Plant Cell Physiol. 50, 1142-1155, (2009) DOI: 10.1093/pcp/pcp065
The induced defense response in plants towards herbivores is mainly regulated by jasmonates and leads to the accumulation of so-called jasmonate-induced proteins. Recently, a jasmonate (JA) inducible lectin called Nicotiana tabacum agglutinin or NICTABA was discovered in tobacco (N. tabacum cv Samsun) leaves. Tobacco plants also accumulate the lectin after insect attack by caterpillars. To study the functional role of NICTABA, the accumulation of the JA precursor 12-oxophytodienoic acid (OPDA), JA as well as different JA metabolites were analyzed in tobacco leaves after herbivory by larvae of the cotton leafworm (Spodoptera littoralis) and correlated with NICTABA accumulation. It was shown that OPDA, JA as well as its methyl ester can trigger NICTABA accumulation. However, hydroxylation of JA and its subsequent sulfation and glucosylation results in inactive compounds that have lost the capacity to induce NICTABA gene expression. The expression profile of NICTABA after caterpillar feeding was recorded in local as well as in systemic leaves, and compared to the expression of several genes encoding defense proteins, and genes encoding a tobacco systemin and the allene oxide cyclase, an enzyme in JA biosynthesis. Furthermore, the accumulation of NICTABA was quanti-fied after S. littoralis herbivory and immunofluorescence microscopy was used to study the localization of NICTABA in the tobacco leaf.
Lannoo, N.; Vandenborre, G.; Miersch, O.; Smagghe, G.; Wasternack, C.; Peumans, W. J.; Van Damme, E. J. M.; The Jasmonate-Induced Expression of the Nicotiana tabacum Leaf Lectin Plant Cell Physiol. 48, 1207-1218, (2007) DOI: 10.1093/pcp/pcm090
Previous experiments with tobacco (Nicotiana tabacum L. cv Samsun NN) plants revealed that jasmonic acid methyl ester (JAME) induces the expression of a cytoplasmic/nuclear lectin in leaf cells and provided the first evidence that jasmonates affect the expression of carbohydrate-binding proteins in plant cells. To corroborate the induced accumulation of relatively large amounts of a cytoplasmic/nuclear lectin, a detailed study was performed on the induction of the lectin in both intact tobacco plants and excised leaves. Experiments with different stress factors demonstrated that the lectin is exclusively induced by exogeneously applied jasmonic acid and JAME, and to a lesser extent by insect herbivory. The lectin concentration depends on leaf age and the position of the tissue in the leaf. JAME acts systemically in intact plants but very locally in excised leaves. Kinetic analyses indicated that the lectin is synthesized within 12 h exposure time to JAME, reaching a maximum after 60 h. After removal of JAME, the lectin progressively disappears from the leaf tissue. The JAME-induced accumulation of an abundant nuclear/cytoplasmic lectin is discussed in view of the possible role of this lectin in the plant.
Fortes, A. M.; Miersch, O.; Lange, P. R.; Malhó, R.; Testillano, P. S.; Risueño, M. d. C.; Wasternack, C.; Pais, M. S.; Expression of Allene Oxide Cyclase and Accumulation of Jasmonates during Organogenic Nodule Formation from Hop (Humulus lupulus var. Nugget) Internodes Plant Cell Physiol. 46, 1713-1723, (2005) DOI: 10.1093/pcp/pci187
A crucial step in the biosynthesis of jasmonic acid (JA) is the formation of its stereoisomeric precursor, cis-(+)-12-oxophytodienoic acid (OPDA), which is catalyzed by allene oxide cyclase (AOC, EC 18.104.22.168). A cDNA of AOC was isolated from Humulus lupulus var. Nugget. The ORF of 765 bp encodes a 255 amino acid protein, which carries a putative chloroplast targeting sequence. The recombinant protein without its putative chloroplast target sequence showed significant AOC activity. Previously we demonstrated that wounding induces organogenic nodule formation in hop. Here we show that the AOC transcript level increases in response to wounding of internodes, peaking between 2 and 4 h after wounding. In addition, Western blot analysis showed elevated levels of AOC peaking 24 h after internode inoculation. The AOC increase was accompanied by increased JA levels 24 h after wounding, whereas OPDA had already reached its highest level after 12 h. AOC is mostly present in the vascular bundles of inoculated internodes. During prenodule and nodule formation, AOC levels were still high. JA and OPDA levels decreased down to 10 and 118 pmol (g FW)–1, respectively, during nodule formation, but increased during plantlet regeneration. Double immunolocalization analysis of AOC and Rubisco in connection with lugol staining showed that AOC is present in amyloplasts of prenodular cells and in the chloroplasts of vacuolated nodular cells, whereas meristematic cells accumulated little AOC. These data suggest a role of AOC and jasmonates in organogenic nodule formation and plantlet regeneration from these nodules.
Hause, B.; Hause, G.; Kutter, C.; Miersch, O.; Wasternack, C.; Enzymes of Jasmonate Biosynthesis Occur in Tomato Sieve Elements Plant Cell Physiol. 44, 643-648, (2003) DOI: 10.1093/pcp/pcg072
The allene oxide cyclase (AOC) is a plastid-located enzyme in the biosynthesis of the signaling compound jasmonic acid (JA). In tomato, AOC occurs specifically in ovules and vascular bundles [Hause et al. (2000)PlantJ. 24; 113]. Immunocytological analysis of longitudinal sections of petioles and flower stalks revealed the occurrence of AOC in companion cells (CC) and sieve elements (SE). Electron microscopic analysis led to the conclusion that the AOC-containing structures of SE are plastids. AOC was not detected in SE of 35S::AOCantisense plants. The enzymes preceding AOC in JA biosynthesis, the allene oxide synthase (AOS) and the lipoxygenase, were also detected in SE. In situ hybridization showed that the SE are free of AOC-mRNA suggesting AOC protein traffic from CC to SE via plasmodesmata. A control by in situ hybridization of AOS mRNA coding for a protein with a size above the exclusion limit of plasmodesmata indicated mRNA in CC and SE. The data suggest that SE carry the capacity to form 12-oxo-phytodienoic acid, the unique precursor of JA. Together with preferential generation of JA in vascular bundles [Stenzel et al. (2003)Plant J. 33: 577], the data support a role of JA in systemic wound signaling.
Hause, B.; Demus, U.; Teichmann, C.; Parthier, B.; Wasternack, C.; Developmental and Tissue-Specific Expression of JIP-23, a Jasmonate-Inducible Protein of Barley Plant Cell Physiol. 37, 641-649, (1996) DOI: 10.1093/oxfordjournals.pcp.a028993
Developmental expression of a 23 kDa jasmonate-induced protein (JIP-23) of barley leaves (Hordeum vulgare cv. Salome) was studied by measuring the time-dependent accumulation of transcript and protein during germination. Tissue-specific expression of JIP-23 was analyzed immunocytochemically and by in situ hybridizations, respectively. During seed germination JIP-23 mRNA was found to accumulate transiently with a maximum at 32 h, whereas the protein was steadily detectable after the onset of expression. The occurrence of new isoforms of JIP-23 during germination in comparison to jasmonate-treated leaves suggests, that the JIP-23 gene family of barley is able to express different subsets of isoforms dependent on the developmental stage.JIP-23 and its transcript were found mainly in the scutellum, the scutellar nodule and in lower parts of the primary leaf of 6 days old seedlings. All these tissues exhibited high levels of endogenous jasmonates. In situ hybridization revealed specific accumulation of JIP-23 mRNA in companion cells of the phloem in the nodule plate of the scutellum. In accordance with that, JIP-23 was detected immunocytochemically in phloem cells of the root as well as of the scutellar nodule and in parenchymatic cells of the scutellum. The cell type-specific occurrence of JIP-23 was restricted to cells, which are known to be highly stressed osmotically by active solute transport. This observation suggests, that the expression of this protein might be a response to osmotic stress during development.