Wasternack, C.; Hause, B. Jasmonsäure – ein universelles Pflanzenhormon: Blütenduft, Abwehr, Entwicklung Biologie in unserer Zeit 44, 164 - 171, (2014) DOI: 10.1002/biuz.201410535
Jasmonsäure (JA) und ihre Metaboliten kommen in allen niederen und höheren Pflanzen vor. Sie sind universell wirksame, aus Lipiden gebildete Signalstoffe bei der Abwehr von biotischem und abiotischem Stress sowie in der pflanzlichen Entwicklung. Rezeptor und Komponenten von JA–Signalketten wurden identifiziert. In der Entwicklung von Blüten, Früchten, Samen, Trichomen oder in der Abwehr von Insekten und Pathogenen treten ähnliche JA-vermittelte Signalproteine auf, die eine Feinregulation der Prozesse erlauben und eine Verbindung (cross-talk) zu anderenPflanzenhormonen aufweisen.
Ziegler, J.; Abel S. Analysis of amino acids by HPLC/electrospray negative ion tandem mass spectrometry using 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) derivatization Amino Acids 46, 2799-2808, (2014) DOI: 10.1007/s00726-014-1837-5
A new method for the determination of amino acids is presented. It combines established methods for the derivatization of primary and secondary amino groups with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) with the subsequent amino acid specific detection of the derivatives by LC–ESI–MS/MS using multiple reaction monitoring (MRM). The derivatization proceeds within 5 min, and the resulting amino acid derivatives can be rapidly purified from matrix by solid-phase extraction (SPE) on HR-X resin and separated by reversed-phase HPLC. The Fmoc derivatives yield several amino acid specific fragment ions which opened the possibility to select amino acid specific MRM transitions. The method was applied to all 20 proteinogenic amino acids, and the quantification was performedusing l-norvaline as standard. A limit of detection as low as 1 fmol/μl with a linear range of up to 125 pmol/μl could be obtained. Intraday and interday precisions were lower than10 % relative standard deviations for most of the amino acids. Quantification usingl-norvaline as internal standard gave very similar results compared to the quantificationusing deuterated amino acid as internal standards. Using this protocol, it was possible to record the amino acid profiles of only a single root from Arabidopsis thaliana seedlings and to compare it with the amino acid profiles of 20 dissected root meristems (200 μm).
Farmer, E. E.; Gasperini, D.; Acosta, I. F. The squeeze cell hypothesis for the activation of jasmonate synthesis in response to wounding New Phytol 204, 282-288, (2014) DOI: 10.1111/nph.12897
Jasmonates are lipid mediators that control
defence gene expression in response to wounding and other environmental
stresses. These small molecules can accumulate at distances up to
several cm from sites of damage and this is likely to involve
cell‐to‐cell jasmonate transport. Also, and independently of jasmonate
synthesis, transport and perception, different long‐distance wound
signals that stimulate distal jasmonate synthesis are propagated at
apparent speeds of several cm min–1 to tissues distal to wounds in a
mechanism that involves clade 3 GLUTAMATE RECEPTOR‐LIKE (GLR) genes. A
search for jasmonate synthesis enzymes that might decode these signals
revealed LOX6, a lipoxygenase that is necessary for much of the rapid
accumulation of jasmonic acid at sites distal to wounds. Intriguingly,
the LOX6 promoter is expressed in a distinct niche of cells that are
adjacent to mature xylem vessels, a location that would make these
contact cells sensitive to the release of xylem water column tension
upon wounding. We propose a model in which rapid axial changes in xylem
hydrostatic pressure caused by wounding travel through the vasculature
and lead to slower, radially dispersed pressure changes that act in a
clade 3 GLR‐dependent mechanism to promote distal jasmonate synthesis.
Antolín-Llovera, M.; Petutsching, E. K.; Ried, M. K.; Lipka, V.; Nürnberger, T.; Robatzek, S.; Parniske, M. Knowing your friends and foes - plant receptor-like kinases as initiators of symbiosis or defence New Phytol 204, 791-802, (2014) DOI: 10.1111/nph.13117
The decision between defence and symbiosis signalling in plants involves
alternative and modular plasma membrane‐localized receptor complexes. A
critical step in their activation is ligand‐induced homo‐ or
hetero‐oligomerization of leucine‐rich repeat (LRR)‐ and/or lysin motif
(LysM) receptor‐like kinases (RLKs). In defence signalling, receptor
complexes form upon binding of pathogen‐associated molecular patterns
(PAMPs), including the bacterial flagellin‐derived peptide flg22, or
chitin. Similar mechanisms are likely to operate during the perception
of microbial symbiont‐derived (lipo)‐chitooligosaccharides. The
structurally related chitin‐oligomer ligands chitooctaose and
chitotetraose trigger defence and symbiosis signalling, respectively,
and their discrimination involves closely related, if not identical,
LysM‐RLKs. This illustrates the demand for and the challenges imposed on
decision mechanisms that ensure appropriate signal initiation.
Appropriate signalling critically depends on abundance and localization
of RLKs at the cell surface. This is regulated by internalization, which
also provides a mechanism for the removal of activated signalling RLKs.
Abundance of the malectin‐like domain (MLD)‐LRR‐RLK Symbiosis
Receptor‐like Kinase (SYMRK) is additionally controlled by cleavage of
its modular ectodomain, which generates a truncated and rapidly degraded
RLK fragment. This review explores LRR‐ and LysM‐mediated signalling,
the involvement of MLD‐LRR‐RLKs in symbiosis and defence, and the role
of endocytosis in RLK function.