TY  - JOUR
A1  - Karimi, Sohail M.
A1  - Freund, Matthias
A1  - Wager, Brittney M.
A1  - Knoblauch, Michael
A1  - Fromm, Jörg
A1  - M. Mueller, Heike
A1  - Ache, Peter
A1  - Krischke, Markus
A1  - Mueller, Martin J.
A1  - Müller, Tobias
A1  - Dittrich, Marcus
A1  - Geilfus, Christoph-Martin
A1  - Alfaran, Ahmed H.
A1  - Hedrich, Rainer
A1  - Deeken, Rosalia
T1  - Under salt stress guard cells rewire ion transport and abscisic acid signaling
JF  - New Phytologist
N2  - Soil salinity is an increasingly global problem which hampers plant growth and crop yield. Plant productivity depends on optimal water-use efficiency and photosynthetic capacity balanced by stomatal conductance. Whether and how stomatal behavior contributes to salt sensitivity or tolerance is currently unknown. This work identifies guard cell-specific signaling networks exerted by a salt-sensitive and salt-tolerant plant under ionic and osmotic stress conditions accompanied by increasing NaCl loads.
We challenged soil-grown Arabidopsis thaliana and Thellungiella salsuginea plants with short- and long-term salinity stress and monitored genome-wide gene expression and signals of guard cells that determine their function.
Arabidopsis plants suffered from both salt regimes and showed reduced stomatal conductance while Thellungiella displayed no obvious stress symptoms. The salt-dependent gene expression changes of guard cells supported the ability of the halophyte to maintain high potassium to sodium ratios and to attenuate the abscisic acid (ABA) signaling pathway which the glycophyte kept activated despite fading ABA concentrations.
Our study shows that salinity stress and even the different tolerances are manifested on a single cell level. Halophytic guard cells are less sensitive than glycophytic guard cells, providing opportunities to manipulate stomatal behavior and improve plant productivity.
KW  - soil
KW  - stomata
KW  - abscisic acid (ABA)
KW  - glycophyte Arabidopsis
KW  - guard cell
KW  - halophyte Thellungiella/Eutrema
KW  - ion transport
KW  - salt stress
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259635
VL  - 231
IS  - 3
ER  - 
TY  - JOUR
A1  - Deeken, Rosalia
A1  - Gohlke, Jochen
A1  - Scholz, Claus-Juergen
A1  - Kneitz, Susanne
A1  - Weber, Dana
A1  - Fuchs, Joerg
A1  - Hedrich, Rainer
T1  - DNA Methylation Mediated Control of Gene Expression Is Critical for Development of Crown Gall Tumors
JF  - PLoS Genetics
N2  - Crown gall tumors develop after integration of the T-DNA of virulent Agrobacterium tumefaciens strains into the plant genome. Expression of the T-DNA–encoded oncogenes triggers proliferation and differentiation of transformed plant cells. Crown gall development is known to be accompanied by global changes in transcription, metabolite levels, and physiological processes. High levels of abscisic acid (ABA) in crown galls regulate expression of drought stress responsive genes and mediate drought stress acclimation, which is essential for wild-type-like tumor growth. An impact of epigenetic processes such as DNA methylation on crown gall development has been suggested; however, it has not yet been investigated comprehensively. In this study, the methylation pattern of Arabidopsis thaliana crown galls was analyzed on a genome-wide scale as well as at the single gene level. Bisulfite sequencing analysis revealed that the oncogenes Ipt, IaaH, and IaaM were unmethylated in crown galls. Nevertheless, the oncogenes were susceptible to siRNA–mediated methylation, which inhibited their expression and subsequently crown gall growth. Genome arrays, hybridized with methylated DNA obtained by immunoprecipitation, revealed a globally hypermethylated crown gall genome, while promoters were rather hypomethylated. Mutants with reduced non-CG methylation developed larger tumors than the wild-type controls, indicating that hypermethylation inhibits plant tumor growth. The differential methylation pattern of crown galls and the stem tissue from which they originate correlated with transcriptional changes. Genes known to be transcriptionally inhibited by ABA and methylated in crown galls became promoter methylated upon treatment of A. thaliana with ABA. This suggests that the high ABA levels in crown galls may mediate DNA methylation and regulate expression of genes involved in drought stress protection. In summary, our studies provide evidence that epigenetic processes regulate gene expression, physiological processes, and the development of crown gall tumors.
KW  - DNA methylation
KW  - DNA transcription
KW  - gene expression
KW  - oncogenes
KW  - plant genomics
KW  - sequence motif analysis
KW  - arabidopsis thaliana
KW  - agrobacterium tumefaciens
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96318
ER  -