title: Proteome analysis in Arabidopsis reveals shoot- and root-specific targets of cytokinin action and differential regulation of hormonal homeostasis.
abstract: The plant hormones cytokinins (CKs) regulate multiple developmental and physiological processes in Arabidopsis (Arabidopsis thaliana). Responses to CKs vary in different organs and tissues (e.g. the response to CKs has been shown to be opposite in shoot and root samples). However, the tissue-specific targets of CKs and the mechanisms underlying such specificity remain largely unclear. Here, we show that the Arabidopsis proteome responds with strong tissue and time specificity to the aromatic CK 6-benzylaminopurine (BAP) and that fast posttranscriptional and/or posttranslational regulation of protein abundance is involved in the contrasting shoot and root proteome responses to BAP. We demonstrate that BAP predominantly regulates proteins involved in carbohydrate and energy metabolism in the shoot as well as protein synthesis and destination in the root. Furthermore, we found that BAP treatment affects endogenous hormonal homeostasis, again with strong tissue specificity. In the shoot, BAP up-regulates the abundance of proteins involved in abscisic acid (ABA) biosynthesis and the ABA response, whereas in the root, BAP rapidly and strongly up-regulates the majority of proteins in the ethylene biosynthetic pathway. This was further corroborated by direct measurements of hormone metabolites, showing that BAP increases ABA levels in the shoot and 1-aminocyclopropane-1-carboxylic acid, the rate-limiting precursor of ethylene biosynthesis, in the root. In support of the physiological importance of these findings, we identified the role of proteins mediating BAP-induced ethylene production, METHIONINE SYNTHASE1 and ACC OXIDASE2, in the early root growth response to BAP.
authors.affiliation: Functional Genomics and Proteomics of Plants, Central European Institute of Technology, Masaryk University, CZ-625 00 Brno, Czech Republic.
authors.forename: Markéta
authors.initials: M
authors.lastname: Žd'árská
authors.forename: Pavlína
authors.initials: P
authors.lastname: Zatloukalová
authors.forename: Mariana
authors.initials: M
authors.lastname: Benítez
authors.forename: Ondrej
authors.initials: O
authors.lastname: Šedo
authors.forename: David
authors.initials: D
authors.lastname: Potěšil
authors.forename: Ondřej
authors.initials: O
authors.lastname: Novák
authors.forename: Jana
authors.initials: J
authors.lastname: Svačinová
authors.forename: Bedrich
authors.initials: B
authors.lastname: Pešek
authors.forename: Jiří
authors.initials: J
authors.lastname: Malbeck
authors.forename: Jana
authors.initials: J
authors.lastname: Vašíčková
authors.forename: Zbyněk
authors.initials: Z
authors.lastname: Zdráhal
authors.forename: Jan
authors.initials: J
authors.lastname: Hejátko
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001593:Benzyl Compounds; D003583:Cytokinins / Q000378:metabolism* / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D007701:Kinetin / Q000378:metabolism / Q000494:pharmacology; D008954:Models, Biological; D008957:Models, Genetic; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D011687:Purines; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D003583:Cytokinins; D010937:Plant Growth Regulators; D020543:Proteome; D011687:Purines; C480551:benzylaminopurine; D007701:Kinetin