Journal Article

The Compromised Recognition of Turnip Crinkle Virus1 Subfamily of Microrchidia ATPases Regulates Disease Resistance in Barley to Biotrophic and Necrotrophic Pathogens

Claar, Martina, Kogel, Karl-Heinz, Koch, Aline, Klessig, Daniel F., Langen, Gregor, von Einem, Sabrina, Manohar, Murli, Schmidt, Rebekka, Kang, Hong-Gu, Imani, Jafargholi, Ehlers, Katrin, Bordiya, Yogendra, Pai, Subhash B., Choi, Hyong Woo, Mang, Hyung-Gon

2014

Overview

MORC1 and MORC2, two of the seven members of the Arabidopsis (Arabidopsis thaliana) Compromised Recognition of Turnip Crinkle Virusl subfamily of microrchidia Gyrase, Heat Shock Protein90, Histidine Kinase, MutL (GHKL) ATPases, were previously shown to be required in multiple layers of plant immunity. Here, we show that the barley (Hordeum vulgare) MORCs also are involved in disease resistance. Genome-wide analyses identified five MORCs that are 37% to 48% identical on the protein level to AtMORCl. Unexpectedly, and in clear contrast to Arabidopsis, RNA interference-mediated knockdown of MORC in barley resulted in enhanced basal resistance and effector-triggered, powdery mildew resistance locus A12-mediated resistance against the biotrophic powdery mildew fungus (Blumeria graminis f. sp. hordei), while MORC overexpression decreased resistance. Moreover, barley knockdown mutants also showed higher resistance to Fusarium graminearum. Barley MORCs, like their Arabidopsis homologs, contain the highly conserved GHKL ATPase and S5 domains, which identify them as members of the MORC superfamily. Like AtMORCl, barley MORC1 (HvMORC1) binds DNA and has Mn ²⁺-dependent endonuclease activities, suggesting that the contrasting function of MORC1 homologs in barley versus Arabidopsis is not due to differences in their enzyme activities. In contrast to AtMORCs, which are involved in silencing of transposons that are largely restricted to pericentromeric regions, barley MORC mutants did not show a loss-of-transposon silencing regardless of their genomic location. Reciprocal overexpression of MORC1 homologs in barley and Arabidopsis snowed that AtMORC1 and HvMORC1 could not restore each other's function. Together, these results suggest that MORC proteins function as modulators of immunity, which can act negatively (barley) or positively (Arabidopsis) dependent on the species.

• Publisher: American Society of Plant Biologists
• Subject: Adenosine triphosphatases / Adenosine Triphosphatases - chemistry / Adenosine Triphosphatases - metabolism / Adenosine Triphosphatases - ultrastructure / adenosinetriphosphatase / Amino Acid Sequence / Arabidopsis - genetics / Arabidopsis - immunology / Arabidopsis - microbiology / Arabidopsis - ultrastructure / Ascomycota / Barley / Botrytis - physiology / Carmovirus - metabolism / Cell Nucleus - metabolism / Cell Nucleus - ultrastructure / disease resistance / Disease Resistance - immunology / DNA / DNA Transposable Elements - genetics / DNA, Plant - metabolism / Epidermal cells / Fungi / Fusarium - physiology / Gene Expression Regulation, Plant / Gene Silencing / Genes, Plant - genetics / Hordeum - enzymology / Hordeum - genetics / Hordeum - immunology / Hordeum - microbiology / immunity / Mildews / Molecular Sequence Data / pathogens / Phylogeny / Plant Diseases - immunology / Plant Diseases - microbiology / Plant Immunity - genetics / Plant Proteins - chemistry / Plant Proteins - genetics / Plant Proteins - metabolism / Plants / Plants, Genetically Modified / Plasmids / Protein Binding / Proteins / Pseudomonas syringae - physiology / Sequence Homology, Nucleic Acid / SIGNALING AND RESPONSE / Transposons