TY - JOUR A1 - Witzel, Katja A1 - Strehmel, Nadine A1 - Baldermann, Susanne A1 - Neugart, Susanne A1 - Becker, Yvonne A1 - Becker, Matthias A1 - Berger, Beatrice A1 - Scheel, Dierk A1 - Grosch, Rita A1 - Schreiner, Monika A1 - Ruppel, Silke T1 - Arabidopsis thaliana root and root exudate metabolism is altered by the growth-promoting bacterium Kosakonia radicincitans DSM 16656(T) JF - Plant and soil N2 - Plant growth-promoting bacteria (PGPB) affect host physiological processes in various ways. This study aims at elucidating the dependence of bacterial-induced growth promotion on the plant genotype and characterizing plant metabolic adaptations to PGPB. Eighteen Arabidopsis thaliana accessions were inoculated with the PGPB strain Kosakonia radicincitans DSM 16656(T). Colonisation pattern was assessed by enhanced green fluorescent protein (eGFP)-tagged K. radicincitans in three A. thaliana accessions differing in their growth response. Metabolic impact of bacterial colonisation was determined for the best responding accession by profiling distinct classes of plant secondary metabolites and root exudates. Inoculation of 18 A. thaliana accessions resulted in a wide range of growth responses, from repression to enhancement. Testing the bacterial colonisation of three accessions did not reveal a differential pattern. Profiling of plant secondary metabolites showed a differential accumulation of glucosinolates, phenylpropanoids and carotenoids in roots. Analysis of root exudates demonstrated that primary and secondary metabolites were predominantly differentially depleted by bacterial inoculation. The plant genotype controls the bacterial growth promoting traits. Levels of lutein and beta-carotene were elevated in inoculated roots. Supplementing a bacterial suspension with beta-carotene increased bacterial growth, while this was not the case when lutein was applied, indicating that beta-carotene could be a positive regulator of plant growth promotion. KW - Arabidopsis KW - Carotenoids KW - Glucosinolates KW - Plant growth promoting bacteria KW - Phenylpropanoids KW - Root exudates Y1 - 2017 U6 - https://doi.org/10.1007/s11104-017-3371-1 SN - 0032-079X SN - 1573-5036 VL - 419 SP - 557 EP - 573 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Sakuraba, Yasuhito A1 - Balazadeh, Salma A1 - Tanaka, Ryouichi A1 - Müller-Röber, Bernd A1 - Tanaka, Ayumi T1 - Overproduction of Chl b retards senescence through transcriptional reprogramming in arabidopsis JF - Plant & cell physiology N2 - Leaf senescence is a developmentally and environmentally regulated process which includes global changes in gene expression. Using Arabidopsis as a model, we modified Chl arrangement in photosystems by overexpressing the catalytic domain (the C domain) of chlorophyllide a oxygenase (CAO) fused with the linker domain (the B domain) of CAO and green fluorescent protein (GFP). In these plants (referred to as the BCG plants for the B and C domains of CAO and GFP), the Chl a/b ratio was drastically decreased and Chl b was incorporated into core antenna complexes. The BCG plants exhibited a significant delay of both developmental and dark-induced leaf senescence. The photosynthetic apparatus, CO2 fixation enzymes and the chloroplast structure were lost in wild-type plants during senescence, while BCG plants retained them longer than the wild type. Large-scale quantitative real-time PCR analyses of 1,880 transcription factor (TF) genes showed that 241 TFs are differentially expressed between BCG plants and wild-type plants at senescence, similar to 40% of which are known senescence-associated genes (SAGs). Expression profiling also revealed the down-regulation of a large number of additional non-TF SAGs. In contrast, genes involved in photosynthesis were up-regulated, while those encoding Chl degradation enzymes were down-regulated in BCG plants. These results demonstrate that alteration of pigment composition in the photosynthetic apparatus retards senescence through transcriptional reprogramming. KW - Arabidopsis KW - Chloroplast KW - Chlorophyllide a oxygenase KW - Photosynthesis KW - Senescence Y1 - 2012 U6 - https://doi.org/10.1093/pcp/pcs006 SN - 0032-0781 VL - 53 IS - 3 SP - 505 EP - 517 PB - Oxford Univ. Press CY - Oxford ER -