title: Mutation of the rice XA21 predicted nuclear localization sequence does not affect resistance toXanthomonas oryzaepv.oryzae.
abstract: BACKGROUND
  The rice receptor kinase XA21 confers robust resistance to the bacterial pathogenXanthomonas oryzaepv.oryzae(Xoo). We previously reported that XA21 is cleaved in transgenic plants overexpressing XA21 with a GFP tag (Ubi-XA21-GFP) and that the released C-terminal domain is localized to the nucleus. XA21 carries a predicted nuclear localization sequence (NLS) that directs the C-terminal domain to the nucleus in transient assays, whereas alanine substitutions in the NLS disrupt the nuclear localization.
  
  
  METHODS
  To determine if the predicted NLS is required for XA21-mediated immunityin planta, we generated transgenic plants overexpressing an XA21 variant carrying the NLS with the same alanine substitutions (Ubi-XA21nls-GFP).
  
  
  RESULTS
  Ubi-XA21nls-GFP plants displayed slightly longer lesion lengths, higherXoobacterial populations after inoculation and lower levels of reactive oxygen species production compared with theUbi-XA21-GFP control plants. However, theUbi-XA21nls-GFP plants express lower levels of protein than that observed inUbi-XA21-GFP.
  
  
  CONCLUSIONS
  These results demonstrate that the predicted NLS is not required for XA21-mediated immunity.
authors.affiliation: Department of Plant Pathology and the Genome Center, University of California, Davis, CA, United States.|Feedstocks Division, Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.|Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
authors.forename: Tong
authors.initials: T
authors.lastname: Wei
authors.affiliation: Department of Plant Pathology and the Genome Center, University of California, Davis, CA, United States.
authors.forename: Tsung-Chi
authors.initials: TC
authors.lastname: Chen
authors.affiliation: Department of Plant Pathology and the Genome Center, University of California, Davis, CA, United States.
authors.forename: Yuen Ting
authors.initials: YT
authors.lastname: Ho
authors.affiliation: Department of Plant Pathology and the Genome Center, University of California, Davis, CA, United States.|Feedstocks Division, Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.|Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
authors.forename: Pamela C
authors.initials: PC
authors.lastname: Ronald
keywords: Bacterial blight disease; Nuclear localization; XA21-mediated immunity; Xanthomonas oryzae pv. oryzae