水稻抗白叶枯病基因Xa-25的分子定位

Xa-25是从体细胞突变体HX-3中鉴定出的水稻抗白叶枯病基因。通过花药培养构建了02428(粳稻)和HX-3(籼稻)的双单倍体(DH)群体,该群体包含了129个稳定株系,以我国长江流域水稻白叶枯病的代表菌株浙173对DH群体进行抗病性鉴定,抗病株系数和感病株系数分别为62和67。共选用覆盖水稻12条染色体的300对SSR引物对02428和HX-3进行多态性分析,有74对引物在双亲之间表现差异。利用这些差异引物对DH群体进行连锁分析,从而将抗白叶枯病基因Xa-25定位到第4染色体长臂末端的两个SSR标记RM6748和RM1153之间,连锁距离分别为9．3cM和3．0cM。     

用AFLP标记快速构建遗传连锁图谱并定位一个新基因tms5

报导了一个分子标记连锁图的快速构建方法。通过对水稻(Oryza sativa L．)“安农S-1”和“南京11”的F2分离群体的AFLP分析找到了142个AFLP标记,用这142个AFLP标记以及已定位的25个SSR标记和5个RFIP标记构建了水稻12个染色体的分子标记连锁图,该图覆盖水稻基因组的1537．4cM,相邻标记间的平均间距为9．0cM,这是在国内建立的第一张AFLP标记连锁图。在建立连锁图谱的同时把一个新基因tms5(水稻温敏核不育基因)定位在第2染色体上。     

水稻抗病基因定位进展与云南地方稻种资源研究

综述了水稻抗稻瘟病基因、抗白叶枯病基因、抗纹枯病基因、抗黄矮病基因和抗稻曲病基因的定位研究进展,标出了部分连锁分子标记与目的基因间的距离,初步探讨了水稻抗病基因在染色体上的分布规律,为选育水稻抗病品种提供相关分子标记数据.最后就云南地方抗病稻种资源研究中存在的问题进行了讨论,并对抗病基因相关分子标记在云南稻种资源研究的应用前景进行了展望.     

水稻中大麦Mlo和玉米Hm1抗病基因同源序列的分析和定位

大麦抗病基因Mlo和玉米抗病基因Hm1编码的产物不具有绝大多数植物抗病基因产物所含有的保守结构域。这两个抗病基因的作用机理也不符合基因对基因学说。从水稻中分离克隆了Mlo基因的同源序列OsMlo-1和玉米Hm1基因的同源序列DFR－1。利用水稻分子标记遗传连锁图,将OsMlo-1定位于水稻第六染色体的两俱RZ667和RG424之间;Osmlo-1距离这两个分子标记分别为20．6和6．0cM(centi-Morgan)。将DFR－1定位于水稻第一染色体两个分子标记R2635和RG462之间;DFR－1距离这两个分子标记分别为11．3和23．9cM。参照已发表的水稻分子标记连锁图,发现OsMlo-1和DFR－1的染色体位点分别与两个报道的水稻抗稻瘟病数量性状位点（QTL）有较好的对应关系。结果提示,水稻中与大麦Mlo 和玉米Hml同源的基因可能也参于抗病反应的调控。     

利用重组自交系群体检测水稻条纹叶枯病抗性基因及QTL分析

利用81个株系组成的Kinmaze(japonica)／DV85(indica)重组自交系(recombinant inbred lines,RIL)群体,采用苗期强迫饲毒的鉴定方法,以病情指数作为条纹叶枯病的表型值,鉴定亲本及81个RILs对水稻抗条纹叶枯病毒(rice stripe virus,RSV)的抗性。利用QTL Cartographer软件,对水稻条纹叶枯病抗性基因进行检测分析。检测到3个QTL位点：qStv1、qStv7、qStv11分别位于第1、7、11染色体上,各QTL的LOD值为2．44～3．83,贡献率为19．8％～30．9％。根据抗性基因加性效应的方向,在qStv7、qStv11位点上,亲本DV85存在抗条纹叶枯病增效基因,Kinmaze具有抗条纹叶枯病减效基因,而qStv1位点抗性基因效应来源正好相反。     

用AFLP标记快速构建遗传连锁图谱并定位一个新基因tms5

报导了一个分子标记连锁图的快速构建方法.通过对水稻(Oryza sativa L.)"安农S-1"和"南京11"的F2分离群体的AFLP分析找到了142个AFLP标记,用这142个AFLP标记以及已定位的25个SSR标记和5个RFLP标记构建了水稻12个染色体的分子标记连锁图,该图覆盖水稻基因组的1 537.4 cM,相邻标记间的平均间距为9.0 cM,这是在国内建立的第一张AFLP标记连锁图.在建立连锁图谱的同时把一个新基因tms5 (水稻温敏核不育基因)定位在第2染色体上.     

水稻条纹叶枯病抗性位点的检测和效应分析

利用111个家系组成的热研2号（Oryza sativa subsp．japonica‘Reyan2’）／Milyang23（Oryza sativa subsp．indica‘Milyang23’）重组自交系（recombinant inbred lines,RIL）群体（F7）,采用重病区田间自然接种方法,以病情指数作为条纹叶枯病的表型值,鉴定了2个亲本及111个RIL家系对条纹叶枯病的抗性。使用QTL Cartographer软件复合区间作图法,对水稻（Oryza sativa）条纹叶枯病抗性基因进行了QTL分析。结果检测到2个抗水稻条纹叶枯病的QTL,分别位于第2和第11染色体上,其中第11染色体上的QTL贡献率为19．58％,表明这是一个主效的QTL,该QTL及其附近的分子标记,可以用于水稻条纹叶枯病抗性分子标记辅助育种。     

水稻抗白叶枯病基因Xa12区间连锁图的构建

利用SSR标记对143株Java14/珍珠矮F₂随机群体进行分析,构建了水稻第4染色体上抗白叶枯病基因Xa12高饱和度的SSR标记区间连锁图。该分子图谱整合了SSR标记RM349、RM348、RM255、MRG4611,为进一步利用SSR标记在Java14/珍珠矮F₂群体中精细定位Xa12以及克隆该基因奠定了基础。     

水稻条纹叶枯病抗性位点的检测和效应分析

利用111个家系组成的热研2号(Oryza sativa subsp. japonica ‘Reyan2’)/ Mi lyang23(Oryza sativa subsp. indica ‘Mi lyang23’)重组自交系(recombinant inbred l ines, RIL)群体(F7), 采用重病区田间自然接种方法, 以病情指数作为条纹叶枯病的表型值, 鉴定了2个亲本及111个RIL家系对条纹叶枯病的抗性。使用QTL Cartographer 软件复合区间作图法, 对水稻(Oryza a sativa)条纹叶枯病抗性基因进行了QTL分析。结果检测到2个抗水稻条纹叶枯病的QTL, 分别位于第2和第11染色体上, 其中第11染色体上的QTL贡献率为19.58%, 表明这是一个主效的QTL, 该QTL及其附近的分子标记, 可以用于水稻条纹叶枯病抗性分子标记辅助育种。     

无选择标记和载体骨干序列的Xa21转基因水稻的获得

利用双右边界T-DNA载体通过根癌农杆菌介导法将水稻白叶枯病广谱抗性基因Xa21导入杂交稻重要恢复系C418中。T0代共获得27个独立转基因株系,通过田间抗性鉴定与PCR分析,有17个株系的Xa21基因分子鉴定为阳性,且对白叶枯病原菌P6生理小种具有抗性。通过对17个株系的后代植株进行田间抗性鉴定,分子标记辅助选择及Southern杂交分析,结果显示4个株系的T1代植株中能分离出无潮霉素标记基因的Xa21转基因植株。无选择标记Xa21转基因株系的获得率为15%。PCR检测还表明,这些无选择标记的Xa21转基因植株不带有载体骨架序列。通过对转基因后代进一步的抗性鉴定与PCR辅助选择,获得了无选择标记和载体骨架序列的转基因Xa21纯合的抗白叶枯病水稻。     

Molecular mapping and genetic analysis of a rice brown planthopper (Nilaparvata lugens Stål) resistance gene

The brown planthopper (BPH), Nilaparvata lugens St?l, is a serious insect pest of rice (Oryza saliva L.). We have determined the chromosomal location of a BPH resistance gene in rice using SSR and RFLP techniques. A rice line 'B14', derived from the wild rice Oryza latifolia, showed high resistance to BPH. For tagging the resistance gene in 'B14X', an F2 population and a recombinant inbred (RI) population from a cross between Taichung Native 1 and 'B14' were developed and evaluated for BPH resistance. The results showed that a single dominant gene controlled the resistance of 'B14' to BPH. Bulked segregant SSR analysis was employed for identification of DNA markers linked to the resistance gene. From the survey of 302 SSR primer pairs, three SSR (RM335, RM261, RM185) markers linked to the resistance gene were identified. The closest SSR marker RM261 was linked to the resistance gene at a distance of 1.8 cM. Regions surrounding the resistance gene and the SSR markers were examined with additional RFLP markers on chromosome 4 to define the location of the resistance gene. Linkage of RFLP markers C820, R288, C946 with the resistance gene further confirmed its location on the short arm of chromosome 4. Closely linked DNA markers will facilitate selection for resistant lines in breeding programs and provide the basis for map-based cloning of this resistance gene.     

Two whitebacked planthopper resistance genes in rice share the same loci with those for brown planthopper resistance

The whitebacked planthopper (WBPH), Sogatella furcifera, and brown planthopper (BPH) Nilaparvata lugens St?l are important sucking insects of rice (Oryza sativa L.) crops throughout the world. Rice 'B5', which has derived its resistance genes from the wild rice O. officinalis Wall ex Watt, is a line that is highly resistant to both WBPH and BPH. Previously, two resistance genes against BPH, Qbp1, and Qbp2 in 'B5' had been mapped onto chromosome 3 and chromosome 4, respectively. In this study, we employed a mapping population composed of 187 recombinant inbred lines (RILs), produced from a cross between 'B5' and susceptible variety 'Minghui63', to locate the WBPH and BPH resistance genes. A RFLP survey of the bulked extremes from the RIL population identified two genomic regions, one on chromosome 3 and the other on chromosome 4, likely containing the resistance genes to planthoppers. QTL analysis of the RILs further confirmed that two WBPH resistance genes were mapped on the same loci as Qbp1 and Qbp2, using a linkage map with 242 molecular markers distributed on 12 rice chromosomes. Of the two WBPH resistance genes, one designated Wbph7(t) was located within a 1.1-cM region between R1925 and G1318 on chromosome 3, the other designated Wbph8(t) was within a 0.3-cM region flanked by R288 and S11182 on chromosome 4. A two-way analysis of variance showed that two loci acted independently with each other in determining WBPH resistance. The results have significant implications in studying the interactions between sucking insects and plants and in breeding programs of resistance to rice planthoppers.     

用PCR技术诊断水稻的白叶枯病抗性

植物育种中应用分子标记辅助选择要求分子标记与目的基因紧密连锁,而且分析手段经济简便、重复性好。Ｘａ２１是最近发现的一个具有广谱抗性的水稻白叶枯病抗性基因,利用一个含Ｘａ２１基因的品系ＩＲＢＢ２１分别与２个感病品种杂交获得２个Ｆ_２群体。用４对引物分别对３个亲本进行ＰＣＲ分析,其中一对引物（ＰＢ７８）的ＰＣＲ产物在抗、感病品种间可揭示多态性。对２个Ｆ_２群体进一步的遗传分析表明,ＰＣＲ标记和Ｘａ２１的白叶枯病抗性紧密连锁,其重组率仅为２．４８％。根据该标记选择基因型纯合的抗性植株,其准确率可达１００％。本文还就植物育种中分子标记的检测途径进行了评价。     

Genetic and physical mapping of a new gene for bacterial blight resistance in rice

The inheritance of resistance for bacterial blight, caused by Xanthomonas oryzae pv. oryzae ( Xoo), was studied in Minghui 63, an elite restorer line for a number of widely used rice hybrids in China. A new dominant gene against a Chinese Xoo strain JL691 in both the seedling and adult stages was identified in Minghui 63 and designated as Xa26( t). Using a total of 477 highly susceptible individuals from an F(2) population, the Xa26( t) locus was mapped to a region of about 1.68 cM. This locus co-segregated with marker R1506 and was 0.21 cM from marker RM224 on one side and 1.47 cM from marker Y6855RA on the other side, in rice chromosome 11. A contig map, composed of five non-redundant bacterial artificial chromosome (BAC) clones and spanning approximately 500 kb in length, was constructed. Analysis of recombination events in the Xa26( t) region with the highly susceptible F(2) individuals anchored the gene locus to a region covered by three overlapped BAC clones. Assay of the lines showing a double crossover in marker loci flanking Xa26( t), in a population of recombinant inbred lines carrying Xa26( t), further delineated the gene to a 20-kb fragment. The Xa26( t) locus is tightly linked to another bacterial blight resistance gene locus, Xa4.     

云南野生稻中的抗白叶枯病基因Xa21的鉴定

水稻白叶枯病是水稻生产上的主要细菌病害之一。从野生稻中发掘优异的水稻白叶枯病抗性材料,可以拓宽栽培稻抗白叶枯病遗传基础。经过温室接菌鉴定和PCR标记分析,对云南野生稻进行Xa21基因的检测鉴定。温室接菌鉴定表明,云南野生稻对广谱致病小种PX099及云南强致病菌Y8具有较好的抗性能力,特别是疣粒野生稻对致病菌株达到免疫程度;PCR标记分析表明,云南野生稻不含有Xa21基因,但含有与Xa21基因某些区域同源的片段。本研究结果为寻找新的抗源材料及快速发掘利用云南野生稻中的抗白叶枯病基因提供理论依据。     

水稻抗白叶枯病基因Xa4位点跨叠BAC克隆群的构建

水稻白叶枯病抗性基因Xa4已被定位于第11染色体长臂末端的分子标记VG181和L1044之间,并与抗性基因同源序列片段RS13共分离。利用这3个标记筛选IRBB56的BAC文库,共得到128个阳性BAC克隆,其中RS13获得18个阳性克隆,这18个克隆中有4个和6个我隆分别同时为G181和L1044的阳性克隆,选其中的12克隆进行分析,构建了一个从G181到L1044区间的BAC跨叠克隆,全长420kb,并且56M22、106P13和104B153个BAC克隆可覆盖整个跨叠克隆群。这一研究结果为进一步分离Xa4基因打下基础。     

Identification of a 47-kb DNA fragment containing <Emphasis Type="Italic">Xa4</Emphasis>, a locus for bacterial blight resistance in rice

Bacterial blight caused by Xanthomonas oryzae pv oryzae is a devastating disease in rice worldwide. The resistance gene Xa4 has been widely used in breeding programs and played an important role in protecting rice from this disease. Using 642 highly susceptible individuals and a random sample of 255 individuals from an F(2) population developed from a cross between IRBB4 and IR24, the Xa4 gene was genetically mapped to a region less than 1 cM. A contig map was constructed for the Xa4 region consisting of six non-redundant bacterial artificial chromosome (BAC) clones and spanning approximately 500 kb in length. Analysis of recombination events in the Xa4 region located the gene locus to one BAC, 3H8. Assay of the recombinants using the subclones of 3H8 in combination with sequence analysis further narrowed the Xa4 locus down to a 47-kb fragment.     

Xa26, a gene conferring resistance to Xanthomonas oryzae pv. oryzae in rice, encodes an LRR receptor kinase-like protein

Rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious rice diseases worldwide. A rice gene, Xa26, conferring resistance against Xoo at both seedling and adult stages was isolated by map-based cloning strategies from the rice cultivar Minghui 63. Xa26 belongs to a multigene family consisting of four members. It encodes a leucine-rich repeat (LRR) receptor kinase-like protein and is constitutively expressed. Sequence analysis revealed that IRBB3 and Zhachanglong lines that are resistant to a broad range of Xoo strains, also carry Xa26. However, significant difference in lesion length was observed among these lines after inoculation with a set of Xoo strains. Moreover, transgenic plants carrying Xa26 showed enhanced resistance compared with the donor line of the gene in both seedling and adult stages. These results suggest that the resistance conferred by Xa26 is influenced by the genetic background.     

The molecular basis of disease resistance in rice

The rice gene Xa21 conferring resistance to Xanthomonas oryzae pv. oryzae (Xoo), was isolated using a map-based cloning strategy. Compared with previously cloned genes, the structure of Xa21 represents a novel class of plant disease R genes encoding a putative receptor kinase (RK). This article proposes a model for the mode of action of Xa21 and summarizes our current knowledge of the modular basis of resistance in rice to bacterial leaf blight and blast.     

云南野生稻中Xa21基因外显子II的分离及序列分析

Xa21是已经分离克隆的一个具有广谱抗性的水稻白叶枯病抗性基因,根据已克隆的白叶枯病抗性基因Xa21外显子II序列设计特异性引物对云南三种野生稻及其它稻种进行PCR扩增。结果表明只有普通野生稻（景洪普通野生稻和元江普通野生稻）及长雄野生稻中扩增到了长400 bp的目的片段,而疣粒野生稻和药用野生稻及栽培稻中均没有扩增到目的片段。通过序列比较发现所克隆的序列同长雄野生稻的氨基酸序列变化是随机的。