The plant-specific receptor-like cytoplasmic kinases (RLCKs) form a large, poorly characterized family. Members of the RLCK VI_A class of dicots have a unique characteristic: their activity is regulated by Rho-of-plants (ROP) GTPases. The biological function of one of these kinases was investigated using a T-DNA insertion mutant and RNA interference. Loss of RLCK VI_A2 function resulted in restricted cell expansion and seedling growth. Although these phenotypes could be rescued by exogenous gibberellin, the mutant did not exhibit lower levels of active gibberellins nor decreased gibberellin sensitivity. Transcriptome analysis confirmed that gibberellin is not the direct target of the kinase; its absence rather affected the metabolism and signalling of other hormones such as auxin. It is hypothesized that gibberellins and the RLCK VI_A2 kinase act in parallel to regulate cell expansion and plant growth. Gene expression studies also indicated that the kinase might have an overlapping role with the transcription factor circuit (PIF4-BZR1-ARF6) controlling skotomorphogenesis-related hypocotyl/cotyledon elongation. Furthermore, the transcriptomic changes revealed that the loss of RLCK VI_A2 function alters cellular processes that are associated with cell membranes, take place at the cell periphery or in the apoplast, and are related to cellular transport and/or cell wall reorganisation.

• Keywords
• Arabidopsis thaliana, cell expansion, gibberellins, hypocotyl growth, plant hormones, plant size, receptor-like cytoplasmic kinase, skotomorphogenesis, transcriptomic analysis,
• MeSH
• Arabidopsis drug effects   enzymology   genetics   growth & development   MeSH
• DNA, Bacterial genetics   metabolism   MeSH
• DNA-Binding Proteins genetics   metabolism   MeSH
• Plants, Genetically Modified MeSH
• Gibberellins metabolism   pharmacology   MeSH
• Hypocotyl drug effects   enzymology   genetics   growth & development   MeSH
• Mutagenesis, Insertional MeSH
• Cotyledon drug effects   enzymology   genetics   growth & development   MeSH
• Indoleacetic Acids metabolism   pharmacology   MeSH
• Protein Serine-Threonine Kinases genetics   metabolism   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Plant * MeSH
• Plant Growth Regulators pharmacology   MeSH
• Seedlings drug effects   enzymology   genetics   growth & development   MeSH
• Gene Expression Profiling MeSH
• Basic Helix-Loop-Helix Transcription Factors genetics   metabolism   MeSH
• Transcription Factors genetics   metabolism   MeSH
• Transcriptome MeSH
• Gene Expression Regulation, Developmental MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• auxin response factor 6, Arabidopsis MeSH Browser
• BZR1 protein, Arabidopsis MeSH Browser
• DNA, Bacterial MeSH
• DNA-Binding Proteins MeSH
• Gibberellins MeSH
• Indoleacetic Acids MeSH
• PIF4 protein, Arabidopsis MeSH Browser
• Protein Serine-Threonine Kinases MeSH
• Arabidopsis Proteins MeSH
• Plant Growth Regulators MeSH
• T-DNA MeSH Browser
• Basic Helix-Loop-Helix Transcription Factors MeSH
• Transcription Factors MeSH