- Results as:
- Print view
- Endnote (RIS)
- BibTeX
- Table: CSV | HTML
Publications
Publications
Research Mission and Profile
Molecular Signal Processing
Bioorganic Chemistry
Biochemistry of Plant Interactions
Cell and Metabolic Biology
Independent Junior Research Groups
Program Center MetaCom
Publications
Good Scientific Practice
Research Funding
Networks and Collaborative Projects
Symposia and Colloquia
Alumni Research Groups
Publications
The fatty acid hydroperoxide (HP) substrates required for the biosynthesis of jasmonic acid (JA) and green leaf volatiles (GLVs) are supplied by separate lipoxygenases (LOX). We silenced the expression of two genes downstream of the LOX: allene oxide synthase (AOS) and HP lyase (HPL) by antisense expression of endogenous genes (NaAOS , NaHPL ) in Nicotiana attenuata , in which the biosynthesis of JA is amplified by herbivore‐specific elicitors. We report that these elicitors also amplify wound‐induced GLV releases, but suppress the wound‐induced increase of NaHPL transcripts, suggesting that substrate flux controls GLV biosynthesis. As expected, silencing of NaHPL and NaAOS reduced GLV release and JA accumulation, respectively. Surprisingly, HPL‐ and AOS‐silenced plants had enhanced JA and GLV responses, suggesting substrate ‘crosstalk’ between these two oxylipin cascades. Plants with depleted GLVs (as‐hpl ) were less attractive than wild type (WT) or empty vector control plants in choice‐tests with native lepidopteran herbivores. In feeding trials, Manduca sexta larvae developed slower on as‐hpl plants. The reduced larval consumption and performance, which was not caused by increases in defense responses in as‐hpl plants, could be restored to WT levels by the addition of synthetic GLVs, demonstrating that GLVs function as feeding stimulants. Gene expression profiling by cDNA microarray analysis and characterization of several induced defenses in herbivore‐elicited as‐hpl and as‐aos plants revealed differential involvement of JA and GLVs in defense signaling. Elicitation of volatile terpenoids (an indirect defense) requires JA signaling, where as trypsin protease inhibitor elicitation (a direct defense) requires both functional JA and GLV cascades.
Publications
Coronalon, a synthetic 6‐ethyl indanoyl isoleucine conjugate, has been designed as a highly active mimic of octadecanoid phytohormones that are involved in insect and disease resistance. The spectrum of biological activities that is affected by coronalon was investigated in nine different plant systems specifically responding to jasmonates and/or 12‐oxo‐phytodienoic acid. In all bioassays analyzed, coronalon demonstrated a general strong activity at low micromolar concentrations. The results obtained showed the induction of (i) defense‐related secondary metabolite accumulation in both cell cultures and plant tissues, (ii) specific abiotic and biotic stress‐related gene expression, and (iii) root growth retardation. The general activity of coronalon in the induction of plant stress responses together with its simple and efficient synthesis suggests that this compound might serve as a valuable tool in the examination of various aspects in plant stress physiology. Moreover, coronalon might become employed in agriculture to elicit plant resistance against various aggressors.