Os03g0821300

Xb15 encodes a PP2C that negatively regulates the XA21-mediated innate immune response.

Annotated Information

Function

• The rice XA21 protein is representative of the large class of non-RD RKs predicted to be involved in plant innate immunity. XB15 encoded by Xb15 Is an XA21 Binding Protein.

Mutation

• To explore the role of Xb15 in resistance, the researchers examined whether constitutive overexpression of Xb15 would affect resistance to Xoo. The resulting transgenic plants (NTAP-XB15, pollen donor) were crossed with another Kitaake line possessing an N-terminal Myc-epitope-tagged XA21, under control of its native promoter (Myc-XA21, pollen recipient). The presence

of the Myc-Xa21 and/or Ntap-Xb15 gene in the resulting F1 was confirmed by the PCR analysis (unpublished data). Next, they tested the expression of NTAP-XB15 and Myc-XA21 in the cross (XA21/XB15 17A-21 and 19A-72) using an anti-Myc antibody and peroxidase-anti-peroxidase (PAP, for detecting the TAP tag) (Figure 3A). Six-week-old progeny from self-pollinated XA21/XB15 17A-18, 17A-21, 19A-64, and 19A-72 were then inoculated with Xoo PR6 strain PXO99 expressing AvrXA21 and examined for cosegregation of genotype with phenotype by PCR analysis and measurement of the length of Xoo-induced lesions. All Myc-Xa21 plants overexpressing Ntap-Xb15 (Myc-Xa21/Ntap- Xb15, þ/þ) by PCR analysis showed accumulation of NTAPXB15 by protein gel blot analysis and displayed enhanced susceptibility to Xoo PR6 compared to transgenic plants carrying Myc-Xa21 alone (þ/�) (Figure 3B). Figure 3C shows a picture of two typical leaves from each of the following inoculated rice plants: F2 segregants of XA21/ XB15 17A and 19A, and transgenic plants overexpressing NTAP only (NTAP) 16 d after Xoo PR6 inoculation.

Expression

Please input expression information here.

Evolution

• The researchers next compared the PP2C domain of XB15 with other evolutionary related proteins from the reference plant species rice and Arabidopsis, such as Arabidopsis POL and POL-like proteins (PLLs) (Figure 2).

Figure 2. Phylogenetic Relationships among POL and PLL Genes from Rice and Arabidopsis .

Labs working on this gene

Please input related labs here.