Rice OsACDR1 (Oryza sativa accelerated cell death and resistance 1) is a potential positive regulator of fungal disease resistance
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Rice Oryza sativa accelerated cell death and resistance 1 (OsACDR1) encodes a putative Raf-like mitogen-activated protein kinase kinase kinase (MAPKKK). We had previously reported upregulation of the OsACDR1 transcript by a range of environmental stimuli involved in eliciting defense-related pathways. Here we apply biochemical, gain and loss-of-function approaches to characterize OsACDR1 function in rice. The OsACDR1 protein showed autophosphorylation and possessed kinase activity. Rice plants overexpressing OsACDR1 exhibited spontaneous hypersensitive response (HR)-like lesions on leaves, upregulation of defense-related marker genes and accumulation of phenolic compounds and secondary metabolites (phytoalexins). These transgenic plants also acquired enhanced resistance to a fungal pathogen (Magnaporthe grisea) and showed inhibition of appressorial penetration on the leaf surface. In contrast, loss-offunction and RNA silenced OsACDR1 rice mutant plants showed downregulation of defense-related marker genes expressions and susceptibility to M. grisea. Furthermore, transient expression of an OsACDR1:GFP fusion protein in rice protoplast and onion epidermal cells revealed its localization to the nucleus. These results indicate that OsACDR1 plays an important role in the positive regulation of disease resistance in rice.
Keywordsdisease resistance lesion MAPKKK OsACDR1 pathogen rice
- Jung, Y.H., Agrawal, G.K., Rakwal, R., Kim, J.A., Lee, M.-O., Choi, P.G., Kim, Y.J., Kim, M.J., Shibato, J., Kim, S.-H., et al. (2006). Functional characterization of OsRacB GTPase-a potentially negative regulator of basal disease resistance in rice. Plant Physiol. Biochem. 44, 68–77.CrossRefPubMedGoogle Scholar
- Kim, J.A., Agrawal, G.K., Rakwal, R., Han, K.S., Kim, K.N., Yun, C.H., Heu, S., Park, S.Y., Lee, Y.H., Jwa, N.S., et al. (2003). Molecular cloning and mRNA expression analysis of a novel rice (Oryza sativa L.) MAPK kinase kinase, OsEDR1, an ortholog of Arabidopsis AtEDR1, reveal its role in defense/stress signaling pathways and development. Biochem. Biophys. Res. Commun. 300, 868–876.CrossRefPubMedGoogle Scholar
- Rakwal, R., Kimura, S., Shibato, J., Nojima, K., Kim, Y.-K., Nahm, B.H., Jwa, N.-S., Endo, S., Tanaka, K., and Iwahashi, H. (2008). Growth retardation and death of rice plants irradiated with carbon ion beams is preceded by very early dose- and timedependent gene expression changes. Mol. Cells 25, 272–278.PubMedGoogle Scholar