Cytokinins can stimulate Arabidopsis hypocotyl elongation at decreased light intensity
| Authors | |
|---|---|
| Year of publication | 2009 |
| Type | Article in Proceedings |
| Conference | Auxin and Cytokinin in Plant Development |
| MU Faculty or unit | |
| Citation | |
| Field | Genetics and molecular biology |
| Keywords | hypocotyl; two-component pathway; cytokinins |
| Description | Cytokinins (CKs) were reported not to affect hypocotyl elongation in Arabidopsis seedlings grown in the light, and CK reportedly promoted hypocotyl elongation in the white light when ethylene action or auxin transport was blocked. Here we re-investigated the effects of CKs on hypocotyl elongation in Arabidopsis. While only a marginal effect of CKs on hypocotyl length was observed at a standard white light intensity (80 umol m-2 s-1), a pronounced stimulation of hypocotyl elongation by CKs was found when the seedlings were cultivated at a decreased white light intensity (20 umol m-2 s-1). The CK effect on hypocotyl length was due to cell elongation. The stimulation of hypocotyl elongation was observed for all four principal CKs (t-Z, iP, BA, TDZ) and was dose-dependent in the nanomolar range. The stimulatory effect of the CKs was antagonized by PI-55. Mutant and transgenic plant analysis indicated that the canonical two-component response pathway is necessary for this process with prevailing contribution of AHK2 and AHK3 receptors. This CK action was independent of ethylene signaling and partially inhibited by IAA. |
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