Xa7
Contents
Annotated Information
Introduce
Xianhui 207, the male parent of widely-used hybrid rice Jinyou 207 (Jin 23A/Xianhui 207), was used as the recipient parent to cross with two resistance varieties, Huahui 20 carrying Xa7 and Xa21 genes and T1c-19 carrying cry1C* gene, as donor parents, to improve the bacterial blight (BB) and borer resistance of Xianhui 207. Two improved lines, designated as CY10038-1 and CY10039-1, carrying the genes of Xa7, Xa21 and cry1C*, were developed by hybridizing, backcrossing and multi-crossing with the method of molecular marker-assisted selection. Crossed with Jin 23A, two hybrids Jin 23A/CY10038-1 and Jin 23A/CY10039-1 were made. The resistances of bacterial blight, leaf folder and stem borer, the expression of CRY1C* protein and main agronomic traits including yield and grain quality were studied for the new improved lines and their derived hybrids. The results showed that two improved lines and their hybrids were resistant to seven Xoo strains, i.e., ZHE173, GD1358, PXO61, PXO99, FuJ, YN24 and HeN11. Though the CRY1C* expression in two hybrids was lower than that in the improved lines, the hybrids were highly resistant to leaf folder and stem borer in field conditions. The testing results of main agronomic traits and grain quality showed that two hybrids were similar to Jinyou 207 except for their higher yield than that of Jinyou 207. Thus, these new improved lines would have a good prospect in future hybrid rice breeding..
Function
Continuous planting of crops containing single disease resistance (R) genes imposes a strong selection for virulence in pathogen populations, often rendering the R gene ineffective. Increasing environmental temperatures may complicate R-gene-mediated disease control because high temperatures often promote disease development and reduceR gene effectiveness. Here, performance of one rice bacterial blight disease R gene was assessed in field and growth chamber studies to determine the influence of temperature on R gene effectiveness and durability. Disease severity and virulence of Xanthomonas oryzae pv. oryzae (Xoo) populations were monitored in field plots planted to rice with and without the bacterial blight R geneXa7 over 11 yr. The performance of Xa7 was determined in high- and low-temperature regimes in growth chambers. Rice with Xa7 exhibited less disease than lines without Xa7 over 11 yr, even though virulence of Xoo field populations increased. Xa7 restricted disease more effectively at high than at low temperatures. Other R genes were less effective at high temperatures.
Development and Mapping of Markers
Markers were generated that are linked to the rice bacterial blight resistance gene Xa7. Amplified restriction fragment length polymorphism (AFLP) analysis of a segregating, near-isogenic F3 population of IR24 x IRBB7 revealed one polymorphic fragment, M1, which was mapped to position 107.3 centimorgans (cM) on the Rice Genome Research Program (RGP) map. Sequence comparisons of resistant and susceptible lines near M1 were used to develop additional markers. A sequence tagged site (STS) named M2 wasmapped proximal to M1 and farther from Xa7, indicating that Xa7 lies distal to M1. On the distal side of M1, two simple sequence repeats (SSRs), M3 and M4, were mapped 0.5 and 1.8 cM, respectively, from Xa7. The pattern of recombinants was consistent with the order of M1–Xa7–M3–M4, and the map distances indicated that Xa7 is located in the region corresponding to the ends of the physically mapped Clemson University Genomics Institute (CUGI) bacterial artificial chromosome (BAC) contigs 96 and 143. A complex repeat was identified in the DNA sequence from rice (Oryza sativa L.) cultivars 93-11 and Nipponbare that matched the end of contig 96 and a previously mapped expressed sequence tag (EST) marker (C52865S). Amplification of the repeat and flanking sequences revealed the presence and absence of the repeat in IR24 and IRBB7, respectively. No recombinants were identified between Xa7 and the polymorphic repeat, which was named M5, in 277 F3 susceptible progeny of the IR24 x IRBB7 cross. Comparison of the physical and genetic maps of rice in this region indicates that Xa7 could lie within 40 kilobases (kb) of M5, a distance suitable for gene pyramiding effortsand Xa7 cloning strategies..
Mechanism
AvrXa7 is a member of the avrBs3 avirulence gene family, which encodes proteins targeted to plant cells by a type III secretion apparatus. AvrXa7, the product of avrXa7, is also a virulence factor in strain PXO86 of Xanthomonas oryzae pv. oryzae. Avirulence and virulence specificities are associated with the central repeat domain, which, in avrXa7, consists of 25.5 direct repeat units. Mutations in three C-terminal nuclear localization signal motifs eliminated avirulence and virulence activities in rice and severely reduced nuclear localization in a yeast assay system. Both pathogenicity functions and nuclear localization were restored on the addition of the sequence for the nuclear localization signal motif from SV40 T-antigen. The loss of avirulence activity because of mutations in the acidic transcriptional activation domain was restored by addition of the activation domain from the herpes simplex viral protein VP16. The activation domain was also required for virulence activity. However, the VP16 domain could not substitute for the endogenous domain in virulence assays. In gel shift assays, AvrXa7 bound double-stranded DNA with a preference for dA/dT rich sequences. The results indicate that products of the avrBs3-related genes are virulence factors targeted to host cell nuclei and have the potential to interact with the host DNA and transcriptional machinery as part of their mode of action. The results also suggest that the host defensive recognition mechanisms are targeted to the virulence factor site of action.
Evolution
Please input evolution information here.
In rice genome, the putative membrane-anchored endo-b-1,4-D-glucanases were encoded by three genes: OsGLU1, OsGLU2, and OsGLU3.Recently,Libertiniet al.(2004) reported that 15 endoglucanase genes were present in rice genome.that these proteins could be classified into four main clusters. One cluster contained OsGLU4, OsGLU8, OsGLU12, OsGLU13,OsGLU14 and OsGLU15. Another cluster contained OsGLU1, OsGLU2, OsGLU3, KOR and CEL3. The third cluster contained OsGLU5,OsGLU6, OsGLU7, OsGLU9, OsGLU10 and OsGLU11.OsGLU1to OsGLU10 each gene had different numbers of introns and exons. All proteins of the OsGLU family contained the EGase domain. The OsGLU1, OsGLU2 and OsGLU3 contained a predicted highly hydrophobic transmembrane motif in the N-terminal and belonged to the type II integral membrane protein anchored in the membrane. The results demonstrated thatOsGLU1, OsGLU2,OsGLU3 and OsGLU10 showed constitutive expression patterns in all the organs tested, and the OsGLU4, OsGLU5, OsGLU6, OsGLU9were abundant in roots and developing flowers of plants. The other two genes OsGLU7 and OsGLU8 showed relatively higher expression in rachis and developing flowers. These different expression patterns indicated multiple functions of these genes in different processes of plant growth and development. Specific and combinational expression of these genes may be essential for the formation or function of a given organ（2）.
Identification and Discussion
Breeding for bacterial blight resistance in rice requires an understanding of the contemporary pathogen populations in the locations where resistance genes are to be deployed. We characterized 450 strains of Xanthomonas oryzae pv. oryzae collected from three states of India using polymerase chain reaction fingerprinting and virulence analysis. This pathogen collection was differentiated into 17 haplotypes (12 lineages at 80% similarity level). Significant differences in the distribution of haplotypes were observed among regions. Virulence analysis of the pathogen collection revealed nine pathotypes. Among the populations from three regions, the Orissa population was the most diverse, consisting of 11 out of 17 haplotypes and five out of nine pathotypes detected in the total collection. Representative pathotypes were used to evaluate seven near-isogenic lines carrying individual bacterial blight resistance genes (Xa3, Xa4, xa5, Xa7, Xa10, xa13, and Xa21) and gene pyramids. Pathogen strains compatible to individual genes were present in detectable frequencies, although no single strain could overcome all resistance genes. Gene combinations Xa4 + xa5, xa5 + Xa21, and Xa4 + xa5 + Xa21 conferred a broad spectrum of resistance to all the strains evaluated, supporting the strategy of pyramiding appropriate resistance genes. We propose that Xa7 restricts disease and Xoo population size more efficiently in high temperature cropping seasons compared with cool seasons creating fluctuating selection, thereby positively impacting durability of Xa7.
Labs working on this gene
1.Submitted (14-MAR-2012) Internal Medicine, University of Michigan,5220 MSRBIII, 1150 West Medical Center Dr, Ann Arbor, MI 48105, USA. 2.Submitted (13-JAN-2010) Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, 2 North Green Lake Road,Kunming, Yunnan 650091, China 3.The State Key Laboratory of Plant Physiology and Biochemistry, College of Life Science, Zhejiang University,People’s Republic of China. 4.College of Science and Technology, Ningbo University, Ningbo, Zhejiang , China. 5.State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, People’s Republic of China. 6.Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou , People’s Republic of China. 7.Laboratoire de Biologie Cellulaire, Institut National de RechercheAgronomique 8.Universite´ de Rouen, CNRS UPRESA 6307, Faculte´ des Sciences 9.Centre de Physiologie Ve´ge´tale de l’Universite ´ Paul Sabatier, U.A.
References
1. YAN Cheng-ye, LIU Yan, MOU Tong-min. Pyramiding Xa7, Xa21 and cry1C* for the Improvement of Bacterial Blight and Borer Resistance of Hybrid Rice Jinyou 207 by Molecular Marker-Assisted Selection. Hybrid Rice, 2013, 28(5): 52-59. 2. K. M. Webb, I. Oñ, a, J. Bai, K. A. Garrett, T. Mew, C. M. Vera Cruz, J. E. Leach, et al. A benefit of high temperature: increased effectiveness of a rice bacterial blight disease resistance gene. New Phytologist, 2009, 185(2): 568-576. 3. B. W. Porter, J. M. Chittoor, M. Yano, T. Sasaki, and F. F. White, et al. Development and Mapping of Markers Linked to the Rice Bacterial Blight Resistance Gene Xa7. Crop Science, 2003, 43(0): 1484-1492. 4. Marella Lalitha Shanti; M. L. C. George; C. M. Vera Cruz; M. A. Bernardo; R. J. Nelson; H. Leung; J. N. Reddy and R. Sridhar. Identification of Resistance Genes Effective Against Rice Bacterial Blight Pathogen in Eastern India. Phytopathology, 2001, 85(5): 506-512. 5. Bing Yang, Weiguang Zhu, Lowell B. Johnson, and Frank F. White. The virulence factor AvrXa7 of Xanthomonas oryzae pv. oryzae is a type III secretion pathway-dependent nuclear-localized double-stranded DNA-binding protein. Proc Natl Acad Sci USA, 2000, 97(17): 9807-9812 .
Structured Information
| Gene Name |
Os08g0114200 |
|---|---|
| Description |
Similar to CEL5=CELLULASE 5 (Fragment) |
| Version |
NM_001067383.1 GI:115474502 GeneID:4344508 |
| Length |
926 bp |
| Definition |
Oryza sativa Japonica Group Os08g0114200, complete gene. |
| Source |
Oryza sativa Japonica Group ORGANISM Oryza sativa Japonica Group
Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
Spermatophyta; Magnoliophyta; Liliopsida; Poales; Poaceae; BEP
clade; Ehrhartoideae; Oryzeae; Oryza.
|
| Chromosome | |
| Location |
Chromosome 8:762215..764081 |
| Sequence Coding Region |
762288..762572,762658..763944 |
| Expression | |
| Genome Context |
<gbrowseImage1> name=NC_008401:762215..764081 source=RiceChromosome08 preset=GeneLocation </gbrowseImage1> |
| Gene Structure |
<gbrowseImage2> name=NC_008401:762215..764081 source=RiceChromosome08 preset=GeneLocation </gbrowseImage2> |
| Coding Sequence |
<cdnaseq>GCAAGTGCGGCGTGCTTACACATGCAAGTCGAACGATGAACCAGCCTTCGGGTGGGGATTAGTGGCGAAC GGGTGAGTAACACGTGGGCAATCTGCCCTGCACTCTGGGACAAGCCCTGGAAACGGGGTCTAATACCGGA TACTGACCTGCCGAGGCATCTCGGCGGGTCGAAAGCTCCGGCGGTGCAGGATGAGCCCGCGGCCTATCAG CTTGTTGGTGAGGTAATGGCTCACCAAGGCGACGACGGGTAGCCGGCCTGAGAGGGCGACCGGCCACACT GGGACTGAGACACGGCCCAGACTCCTACGGGAGGCAGCAGTGGGGAATATTGCACAATGGGCGCAAGCCT GATGCAGCGACGCCGCGTGAGGGATGACGGCCTTCGGGTTGTAAACCTCTTTCAGCAGGGAAGAAGCGAG AGTGACGGTACCTGCAGAAGAAGCGCCGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGGCGCAA GCGTTGTCCGGAATTATTGGGCGTAAAGAGCTCGTAGGCGGCTTGTCGCGTCGGTTGTGAAAGCCCGGGG CTTAACCCCGGGTCTGCAGTCGATACGGGCAGGCTAGAGTTCGGTAGGGGAGATCGGAATTCCTGGTGTA GCGGTGAAATGCGCAGATATCAGGAGGAACACCGGTGGCGAAGGCGGATCTCTGGGCCGATACTGACGCT GAGGAGCGAAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGGTGGGCACT AGGTGTGGGCAACATTCCACGTTGTCCGTGCCGCAGCTAACGCATTAAGTGCCCCGCCTGGGGAGTACGG CCGCAAGGCTAAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGCGGAGCATGTGGCTTAATTCGAC GCAACGCGAAGAAACT</cdnaseq> |
| Protein Sequence |
<aaseq>MCSWSLSSHTLTSPVRQAAMEPKSSSCGGAGIRLRLLVVLHLLL LVPSSAMAFNYADALAKSIIFFEGQRSGKLPPGNRMPWRADSGLTDGAQYNVDLVGGY YDAGDNVKFGLPMAFSTTMLAWSVLDFGKFMGAELPNARAAVRWGADYLLKAATATPG ALYVQVADPNQDHRCWERPEDMDTPRSVYRVTADKPGSDVAGETAAALAASSMVFRRA DPAYSARLLHAATQVFDFADRHRGSYSDSLASSVCPFYCSYSGYHDELLWGASWLHRA SRNASFMSYVEANGMQLGAGDDDYSFSWDDKRVGTKVLLAKGFLRNRLHGLELYKAHS DSYICSLVPGTASFQSRYTPGGLLYREGSSNMQYVTTATFLMLAYAKYLRSSGATASC GDGGGGARGEVSAAELVAVAKRQVDYILGKNPAGMSYMVGFGCRYPRRAHHRGASMPS VRAHPGRISCDAGFGYLHSGEPNPNVLVGAVVGGPDSRDAFADDRGNFAQSEPATYIN APLVGALAYFAGTTK</aaseq> |
| Gene Sequence |
<dnaseqindica>74..358#444..1730#GCAAGTGCGGCGTGCTTACACATGCAAGTCGAACGATGAACCAGCCTTCGGGTGGGGATTAGTGGCGAAC GGGTGAGTAACACGTGGGCAATCTGCCCTGCACTCTGGGACAAGCCCTGGAAACGGGGTCTAATACCGGA TACTGACCTGCCGAGGCATCTCGGCGGGTCGAAAGCTCCGGCGGTGCAGGATGAGCCCGCGGCCTATCAG CTTGTTGGTGAGGTAATGGCTCACCAAGGCGACGACGGGTAGCCGGCCTGAGAGGGCGACCGGCCACACT GGGACTGAGACACGGCCCAGACTCCTACGGGAGGCAGCAGTGGGGAATATTGCACAATGGGCGCAAGCCT GATGCAGCGACGCCGCGTGAGGGATGACGGCCTTCGGGTTGTAAACCTCTTTCAGCAGGGAAGAAGCGAG AGTGACGGTACCTGCAGAAGAAGCGCCGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGGGCGCAA GCGTTGTCCGGAATTATTGGGCGTAAAGAGCTCGTAGGCGGCTTGTCGCGTCGGTTGTGAAAGCCCGGGG CTTAACCCCGGGTCTGCAGTCGATACGGGCAGGCTAGAGTTCGGTAGGGGAGATCGGAATTCCTGGTGTA GCGGTGAAATGCGCAGATATCAGGAGGAACACCGGTGGCGAAGGCGGATCTCTGGGCCGATACTGACGCT GAGGAGCGAAAGCGTGGGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGGTGGGCACT AGGTGTGGGCAACATTCCACGTTGTCCGTGCCGCAGCTAACGCATTAAGTGCCCCGCCTGGGGAGTACGG CCGCAAGGCTAAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGCGGAGCATGTGGCTTAATTCGAC GCAACGCGAAGAAACT</dnaseqindica> |
| External Link(s) |
