PT  - JOURNAL ARTICLE
AU  - Nicholas Thomas
AU  - Nir Oksenberg
AU  - Furong Liu
AU  - Daniel Caddell
AU  - Alina Nalyvayko
AU  - Yen Nguyen
AU  - Benjamin Schwessinger
AU  - Pamela Ronald
TI  - The Rice XA21 Ectodomain Fused to the Arabidopsis EFR Cytoplasmic Domain Confers Resistance to <em>Xanthomonas oryzae</em> pv. <em>oryzae</em>
AID  - 10.1101/119925
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 119925
4099  - http://biorxiv.org/content/early/2017/03/23/119925.short
4100  - http://biorxiv.org/content/early/2017/03/23/119925.full
AB  - Rice (Oryza sativa) plants expressing the XA21 cell surface receptor kinase are resistant to Xanthomonas oryzae pv.oryzae (Xoo) infection. We previously demonstrated that expressing a chimeric protein containing the EFR (ELONGATION FACTOR Tu RECEPTOR) ectodomain and the XA21 endodomain (EFR:XA21) in rice does not confer robust resistance to Xoo.To test if the XA21 ectodomain is required for Xoo resistance, we produced transgenic rice lines expressing a chimeric protein consisting of the XA21 ectodomain and EFR endodomain (XA21:EFR) and inoculated these lines with Xoo. We also tested if the XA21:EFR rice plants respond to a synthetic sulfated 21 amino acid derivative (RaxX21-sY) derived from the activator of XA21-mediated immunity, RaxX.We found that five independently transformed XA21:EFR rice lines displayed resistance to Xoo as measured by lesion length analysis, and showed that five lines express markers of the XA21 defense response (generation of reactive oxygen species and defense response gene expression) after treatment with RaxX21-sY.Our results indicate that expression of the XA21:EFR chimeric receptor in rice confers resistance to Xoo. These results suggest that the endodomain of the EFR and XA21 immune receptors are interchangeable and the XA21 ectodomain is the key determinant conferring robust resistance to Xoo.