Os05g0112000
Os05g0107700, named as xb3, is a recessive gene associated with resistance to rice bacterial leaf blight.
Contents
Annotated Information
Function
The receptor kinase XA21 confers resistance to bacterial blight disease of rice (Oryza sativa) caused by Xanthomonas oryzae pv. oryzae (Xoo).The XA21 binding protein 3 (XB3) is capable of inducing cell death when overexpressed in Nicotiana benthamiana. XB3 is a RING finger-containing E3 ubiquitin ligase that has been positively implicated in XA21-mediated resistance. Mutation abolishing the XB3 E3 activity also eliminates its ability to induce cell death. Phylogenetic analysis of XB3-related sequences suggests a family of proteins (XB3 family) with members from diverse plant species. Members of the XB3 family from rice, Arabidopsis and citrus all trigger a similar cell death response in Nicotiana benthamiana, suggesting an evolutionarily conserved role for these proteins in regulating programmed cell death in the plant kingdom[1].
Expression
XB3 is a member of a highly conserved E3 ubiquitin ligase family. Overexpression of XB3 or other members of this E3 family from rice, Arabidopsis, and citrus induces a cell death response in N. benthamiana[2].
Evolution
A total of 58 proteins were identified from diverse plant species ranging from rice and Arabidopsis (annual) to woody citrus (perennial). All of the identified sequences share similar ankyrin-RING structures. Phylogenetic analysis revealed that 34 out of the 58 identified proteins, including XB3, form a large group with two major subclades that differentiate sequences from dicotyledonous and monocotyledonous plants (Figure 1). This group of proteins was apparently more related to XB3, and therefore named the XB3 family[3]. The copy number of the XB3 family members varies among plant species. For instance, rice contains three members, XB3, XBOS31 and XBOS37, whereas Arabidopsis carries only one, XBAT31. In the newly sequenced citrus genome, there are two XB3 family members, XBCT31 and XBCT32. The XB3 family is phylogenetically distinct from XBAT32, an ankyrin-RING protein that has been implicated in lateral root development[4].
Knowledge Extension
The demonstration of the XA21–XB3 interaction in vivo may be generally important for understanding RLK complexes in rice and in other plants. In a large-scale yeast two-hybrid analysis, nine of 50 randomly chosen rice RLKs interact with four putative E3 ubiquitin ligases[5]. In Brassica napus, the PUB-ARM protein ARC1 interacts with the kinase domain of the S receptor kinase in the yeast two-hybrid system and in vitro. ARC1 is positively involved in the self-incompatibility system . It has been proposed that ARC1 promotes the ubiquitination and proteasomal degradation of compatibility factors in the pistil. In tobacco (Nicotiana tabacum), the Nt PUB4 protein is also a member of the PUB-ARM family. Yeast two-hybrid analysis has linked Nt PUB4 to the kinase domain of the chitinase-related RLK CHRK1 that may be involved in development and cytokinin homeostasis. Thus, many plant RLKs may interact with E3 ubiquitin ligases[6]. When Xb3 is reduced, resistance to Xoo PR6 is compromised in the Xa21 lines. The compromised resistance can be attributed to a decrease in the level of the XA21 protein. The dosage effects have been suggested by several previous studies. Additionally, the heterozygous Xa21 plants generated by a cross between 4021-3 and TP309 are slightly less resistant than the homozygous plant 4021-3. Alternatively, but not mutually exclusive, the reduction of Xb3 may directly contribute to the compromised resistance as well. In this case, the XB3 level is a rate-limiting step for Xa21-mediated resistance[7].
Labs working on this gene
- Department of Plant Pathology, University of Florida, Gainesville, Florida
- Department of Agronomy, Louisiana State University, Baton Rouge, Louisiana
- Department of Plant Pathology, University of California, Davis, California
- Department of Crop Science, North Carolina State University, Raleigh, North Carolina
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
References
- ↑ Sasaki A, Ashikari M, Ueguchi-Tanaka M, Itoh H, Nishimura A, et al. (2002) Green revolution: a mutant gibberellin-synthesis gene in rice. Nature 416: 701-702.
- ↑ Spielmeyer W, Ellis MH, Chandler PM (2002) Semidwarf (sd-1), "green revolution" rice, contains a defective gibberellin 20-oxidase gene. Proc Natl Acad Sci U S A 99: 9043-9048.
- ↑ Monna L, Kitazawa N, Yoshino R, Suzuki J, Masuda H, et al. (2002) Positional cloning of rice semidwarfing gene, sd-1: rice "green revolution gene" encodes a mutant enzyme involved in gibberellin synthesis. DNA Res 9: 11-17.
- ↑ Hedden P. (2003) The genes of the Green Revolution. Trends Genet 19: 5-9.
- ↑ Peng J, Richards DE, Hartley NM, Murphy GP, Devos KM, et al. (1999) 'Green revolution' genes encode mutant gibberellin response modulators. Nature 400: 256-261.
- ↑ Asano K, Hirano K, Ueguchi-Tanaka M, Angeles-Shim RB, Komura T, et al. (2009) Isolation and characterization of dominant dwarf mutants, Slr1-d, in rice. Mol Genet Genomics 281: 223-231.
- ↑ Reagon M, Thurber CS, Olsen KM, Jia Y, Caicedo AL (2011) The long and the short of it: SD1 polymorphism and the evolution of growth trait divergence in U.S. weedy rice. Mol Ecol 20: 3743-3756.
