Dem IPB wird erneut ein beispielhaftes Handeln im Sinne einer chancengleichheitsorientierten Personal- und Organisationspolitik bescheinigt. Das Institut erhält zum 6. Mal in Folge das TOTAL E-QUALITY…
Die Plant Science Student Conference (PSSC) wird seit 20 Jahren im jährlichen Wechsel von Studierenden der beiden Leibniz-Institute IPK und IPB organisiert. Im Interview erläutern Christina Wäsch…
Nguyen, T. H. V.; Nguyen, T. H. A.; Tran, V. S.; Franke, K.; Wessjohann, L.;Chemical study of Angelica sinensis's rootsVietnam J. Chem.43494-498(2005)
Autoregulatory mechanisms have been reported in the rhizobial and the mycorrhizal symbiosis. Autoregulation means that already existing nodules or an existing root colonization by an arbuscular mycorrhizal fungus systemically suppress subsequent nodule formation/root colonization in other parts of the root system. Mutants of some legumes lost their ability to autoregulate the nodule number and thus display a supernodulating phenotype. On studying the effect of pre-inoculation of one side of a split-root system with an arbuscular mycorrhizal fungus on subsequent mycorrhization in the second side of the split-root system of a wild-type soybean (Glycine max L.) cv. Bragg and its supernodulating mutant nts1007, we observed a clear suppressional effect in the wild-type, whereas further root colonization in the split-root system of the mutant nts1007 was not suppressed. These data strongly indicate that the mechanisms involved in supernodulation also affect mycorrhization and support the hypothesis that the autoregulation in the rhizobial and the mycorrhizal symbiosis is controlled in a similar manner. The accumulation patterns of the plant hormones IAA, ABA and Jasmonic acid (JA) in non-inoculated control plants and split-root systems of inoculated plants with one mycorrhizal side of the split-root system and one non-mycorrhizal side, indicate an involvement of IAA in the autoregulation of mycorrhization. Mycorrhizal colonization of soybeans also resulted in a strong induction of ABA and JA levels, but on the basis of our data the role of these two phytohormones in mycorrhizal autoregulation is questionable.
Publikation
Ludwig, A. A.; Saitoh, H.; Felix, G.; Freymark, G.; Miersch, O.; Wasternack, C.; Boller, T.; Jones, J. D. G.; Romeis, T.;Ethylene-mediated cross-talk between calcium-dependent protein kinase and MAPK signaling controls stress responses in plantsProc. Natl. Acad. Sci. U.S.A.10210736-10741(2005)DOI: 10.1073/pnas.0502954102
Plants are constantly exposed to environmental changes and need to integrate multiple external stress cues. Calcium-dependent protein kinases (CDPKs) are implicated as major primary Ca2+ sensors in plants. CDPK activation, like activation of mitogen-activated protein kinases (MAPKs), is triggered by biotic and abiotic stresses, although distinct stimulus-specific stress responses are induced. To investigate whether CDPKs are part of an underlying mechanism to guarantee response specificity, we identified CDPK-controlled signaling pathways. A truncated form of Nicotiana tabacum CDPK2 lacking its regulatory autoinhibitor and calcium-binding domains was ectopically expressed in Nicotiana benthamiana. Infiltrated leaves responded to an abiotic stress stimulus with the activation of biotic stress reactions. These responses included synthesis of reactive oxygen species, defense gene induction, and SGT1-dependent cell death. Furthermore, N-terminal CDPK2 signaling triggered enhanced levels of the phytohormones jasmonic acid, 12-oxo-phytodienoic acid, and ethylene but not salicylic acid. These responses, commonly only observed after challenge with a strong biotic stimulus, were prevented when the CDPK's intrinsic autoinhibitory peptide was coexpressed. Remarkably, elevated CDPK signaling compromised stress-induced MAPK activation, and this inhibition required ethylene synthesis and perception. These data indicate that CDPK and MAPK pathways do not function independently and that a concerted activation of both pathways controls response specificity to biotic and abiotic stress.