High resolution genetic mapping and candidate gene identification at the xa5 locus for bacterial blight resistance in rice (Oryza sativa L.)
High resolution genetic mapping and candidate gene identification at the xa5 locus for bacterial blight resistance in rice (Oryza sativa L.)
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DOI：
10.1007/s00122-003-1231-2
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发表时间：
2003-06-01
影响因子：
5.4
通讯作者：
McCouch, SR
中科院分区：
文献类型：
--
作者：
Blair, MW;Garris, AJ;McCouch, SR
水稻xa5抗性基因对稻黄单胞菌（Xanthomonas oryzae pv oryzae）引起的水稻细菌性枯萎病具有隐性、种族特异性的抗性。通过在水稻5号染色体远端放置44个DNA标记，建立了xa5染色体周围区域的高分辨率遗传图谱。定位的基础是基于pcr筛选1016个来自近等基因系（NIL）与其相应的复发亲本杂交的F-2个体，以确定该区域的重组。重组F-2个体用菲律宾菌株PXO 61接种F-3家族进行子代检测。xa5基因被定位到标记RS7和RM611之间的0.5 cm区间，该区间约为70 kb，共包含11个开放阅读框。该位点的序列数据来自覆盖部分区域的籼稻（IR24等值线，IRBB21） BAC，并与其他重叠的籼稻（cv 93-11）和粳稻（cv Nipponbare）序列进行比较。候选基因分析显示，基础转录因子（TFIIa）、ABC转运体、tRNA合成酶、MAP激酶和半胱氨酸蛋白酶以及四种未知的、假设的或假定的蛋白质在该位点编码，可能是抗性基因产物的潜在候选基因。这些基因提供隐性、种族特异性抗性的机制将通过基于图谱的xa5基因克隆来阐明。
The xa5 resistance gene from rice provides recessive, race-specific resistance to bacterial blight of rice caused by the pathogen Xanthomonas oryzae pv oryzae. A high-resolution genetic map of the chromosomal region surrounding xa5 was developed by placing 44 DNA markers on the distal end of rice chromosome 5. The basis for mapping was a PCR-based screening of 1,016 F-2 individuals derived from a cross between a near-isogenic line (NIL) and its corresponding recurrent parent to identify recombinants in the region. Recombinant F-2 individuals were progeny tested using F-3 families inoculated with the Philippine strain PXO 61 of bacterial blight pathogen. The xa5 gene was mapped to a 0.5-cM interval between the markers RS7 and RM611, which spanned an interval of approximately 70 kb and contained a total of 11 open reading frames. Sequence data for the locus was generated from an Indica (the IR24 isoline, IRBB21) BAC covering part of the region and compared to other overlapping Indica (cv 93-11) and Japonica (cv Nipponbare) sequences. Candidate-gene analysis revealed that a basal transcription factor (TFIIa), an ABC transporter, a tRNA synthase, a MAP kinase and a cysteine protease, as well as four unknown, hypothetical or putative proteins, are encoded at the locus and could be potential candidates for the resistance gene product. The mechanism by which these genes could provide recessive, race-specific resistance will be elucidated by map-based cloning of the xa5 gene.