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Published on: August 4, 2018
Mutation of the rice XA21 predicted nuclear localization sequence does not affect resistance to Xanthomonas oryzae
Tong Wei1,2,3, Tsung-Chi Chen1, Yuen Ting Ho1
1Department of Plant Pathology and the Genome Center, University of California, Davis, CA, United States.
Background:
The rice receptor kinase XA21 confers robust resistance to the bacterial pathogen Xanthomonas 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 immunity in 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, higher Xoobacterial populations after inoculation and lower levels of reactive oxygen species production compared with the Ubi-XA21-GFP control plants. However, the Ubi-XA21nls-GFP plants express lower levels of protein than that observed in Ubi-XA21-GFP.
Discussion:
These results demonstrate that the predicted NLS is not required for XA21-mediated immunity.
