The Arabidopsis ROP-activated receptor-like cytoplasmic kinase RLCK VI_A3 is involved in control of basal resistance to powdery mildew and trichome branching
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TheArabidopsisreceptor-like cytoplasmic kinase AtRLCK VI_A3 is activated by AtROPs and is involved in trichome branching and pathogen interaction.
Receptor-like cytoplasmic kinases (RLCKs) belong to the large superfamily of receptor-like kinases, which are involved in a variety of cellular processes like plant growth, development and immune responses. Recent studies suggest that RLCKs of the VI_A subfamily are possible downstream effectors of the small monomeric G proteins of the plant-specific Rho family, called ‘Rho of plants’ (RAC/ROPs). Here, we describe Arabidopsisthaliana AtRLCK VI_A3 as a molecular interactor of AtROPs. In Arabidopsis epidermal cells, transient co-expression of plasma membrane located constitutively activated (CA) AtROP4 or CA AtROP6 resulting in the recruitment of green fluorescent protein-tagged AtRLCK VI_A3 to the cell periphery. Intrinsic kinase activity of AtRLCK VI_A3 was enhanced in the presence of CA AtROP6 in vitro and further suggested a functional interaction between the proteins. In the interaction of the biotrophic powdery mildew fungus Erysiphe cruciferarum (E. cruciferarum) and its host plant Arabidopsis, Atrlck VI_A3 mutant lines supported enhanced fungal reproduction. Furthermore Atrlck VI_A3 mutant lines showed slightly reduced size and an increase in trichome branch number compared to wild-type plants. In summary, our data suggest a role of the AtROP-regulated AtRLCK VI_A3 in basal resistance to E. cruciferarum as well as in plant growth and cellular differentiation during trichome morphogenesis. Results are discussed in the context of literature suggesting a function of RAC/ROPs in both resistance and susceptibility to pathogen infection.
KeywordsReceptor-like cytoplasmic kinase (RLCK) RAC/ROP GTPase Arabidopsis thaliana Erysiphe cruciferarum Trichome
This work was supported by grants from the German Research Foundation (HU886/3 and SFB924 to R.H.) and the Hungarian Scientific Research Fund (OTKA K101112). The authors gratefully acknowledge the support by the Faculty Graduate Center Weihenstephan of TUM Graduate School at Technische Universität München, Germany.
Conflict of interest
The authors declare no conflict of interest.
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