Proteome regulation in Arabidopsis reveals shoot- and root-specific effects of cytokinins on hormonal homeostasis and cytokinin-ethylene signaling crosstalk
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| Year of publication | 2012 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Cytokinins (CK) mediate a large spectrum of developmental and physiological regulations in plants. Shoot and root reveal specific and sometimes even contrary responses to CK. However, the molecular mechanisms underlying the shoot and root specificity of CK-mediated regulations remain mostly unclear. We show that differential CK-mediated proteome regulation underlies the shoot and root specificity of CK response at the hormonal metabolism and signaling levels. Overall, we identified 43/18 differentially regulated proteins in the shoot and 31/21 in the root in the early/delayed response, respectively. We demonstrate that CK predominantly regulate proteins involved in carbohydrate and energy metabolism in the shoot and in protein synthesis and destination in the root. In the root we identified 3 out of 4 enzymes of the ethylene biosynthetic pathway to be upregulated in an early CK response, suggesting that majority of the ethylene biosynthetic pathway is under strong control of CK in the root. On the other hand, in the shoot we identified several abscisic acid (ABA)-related proteins to be upregulated by CK.To substantiate potential crosstalk of BAP with metabolism of other hormones, we analyzed changes of the endogenous hormone levels after CK application. In a good accordance with our proteomic data, we found prompt upregulation of 1-aminocyclopropane-1-carboxylic acid, the rate-limiting precursor of ethylene biosynthesis in the root, while ABA was upregulated in the early response of the shoot. Furthermore, we show that CK-induced ethylene production contributes to CK response in the root and modulates multistep phosphorelay (MSP) output through the direct interaction of ethylene receptor ETR1 with AHP proteins, the members of the MSP signaling cascade. Finally, we demonstrate that MSP mediates ethylene response, thus integrating both CK and ethylene signaling. |
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