Identification of the rice blast resistance gene Pib in the National Small Grains Collection

The Pib gene in rice confers resistance to a wide range of races of the rice blast pathogen, Magnaporthe oryzae, including race IE1k that overcomes Pita, another broad-spectrum resistance gene. In this study, the presence of Pib was determined in 164 rice germplasm accessions from a core subset of the National Small Grains Collection utilizing DNA markers and pathogenicity assays. The presence of Pib was evaluated with two simple sequence repeat (SSR) markers and a dominant marker (Pib-dom) derived from the Pib gene sequence. Pathogenicity assays using two avirulent races (IE1k and IB1) and a virulent race (IB54) were performed to verify the resistance responses of accessions. Of the 164 accessions evaluated, 109 contained the Pib gene as determined using both SSR markers and pathogenicity assays, albeit different haplotypes were detected. The remaining 52 germplasm accessions were different in their responses to the blast races IB54, IE1k, and IB1, thus indicating the presence of R gene(s) other than Pib. The accessions characterized in this study could be used for marker-assisted breeding to improve blast resistance in indica and japonica cultivars worldwide.     

Identification and fine-mapping of Xa33, a novel gene for resistance to Xanthomonas oryzae pv. oryzae

Broadening of the genetic base for identification and transfer of genes for resistance to insect pests and diseases from wild relatives of rice is an important strategy in resistance breeding programs across the world. An accession of Oryza nivara, International Rice Germplasm Collection (IRGC) accession number 105710, was identified to exhibit high level and broad-spectrum resistance to Xanthomonas oryzae pv. oryzae. In order to study the genetics of resistance and to tag and map the resistance gene or genes present in IRGC 105710, it was crossed with the bacterial blight (BB)-susceptible varieties 'TN1' and 'Samba Mahsuri' (SM) and then backcrossed to generate backcross mapping populations. Analysis of these populations and their progeny testing revealed that a single dominant gene controls resistance in IRGC 105710. The BC(1)F(2) population derived from the cross IRGC 105710/TN1//TN1 was screened with a set of 72 polymorphic simple-sequence repeat (SSR) markers distributed across the rice genome and the resistance gene was coarse mapped on chromosome 7 between the SSR markers RM5711 and RM6728 at a genetic distance of 17.0 and 19.3 centimorgans (cM), respectively. After analysis involving 49 SSR markers located between the genomic interval spanned by RM5711 and RM6728, and BC(2)F(2) population consisting of 2,011 individuals derived from the cross IRGC 105710/TN1//TN1, the gene was fine mapped between two SSR markers (RMWR7.1 and RMWR7.6) located at a genetic distance of 0.9 and 1.2 cM, respectively, from the gene and flanking it. The linkage distances were validated in a BC(1)F(2) mapping population derived from the cross IRGC 105710/SM//2 × SM. The BB resistance gene present in the O. nivara accession was identified to be novel based on its unique map location on chromosome 7 and wider spectrum of BB resistance; this gene has been named Xa33. The genomic region between the two closely flanking SSR markers was in silico analyzed for putatively expressed candidate genes. In total, eight genes were identified in the region and a putative gene encoding serinethreonine kinase appears to be a candidate for the Xa33 gene.     

甜玉米茎秆强度相关性状的数量性状基因座定位

为选育抗倒伏玉米品种,挖掘甜玉米茎秆强度相关性状的数量性状基因座（quantitative trait locus,QTL）,应用复合区间作图法以甜玉米组合T49×T56的F₂为作图群体,通过测定F_2：3家系的茎秆穿刺强度、茎秆抗压强度和茎秆弯折性能3个性状进行相关性状的QTL定位。结果表明,遗传连锁图谱包含153个SSR标记位点,覆盖玉米基因组1 199.1 cM,平均图距7.83 cM。3个性状共检测到10个QTL,其中与茎秆穿刺强度相关的2个QTL位于第3、7染色体上,解释11.81%和22.15%的表型变异,与茎秆抗压强度相关的4个QTL位于第1、3、7染色体上,单个QTL可解释3.68%~33.26%的表型变异,与茎秆弯折性能相关的4个QTL位于第3、6、8染色体上,单个QTL可解释3.55%~18.58%的表型变异。第7染色体检测到1个同时控制茎秆穿刺强度和茎秆抗压强度2个性状的QTL,位于umc1015~umc1987标记区间,分别可解释11.81%和33.26%的表型变异,第3染色体检测到1个同时控制茎秆穿刺强度、茎秆抗压强度、茎秆弯折性能3个性状的QTL,位于umc1400~dupssr23标记区间,分别可解释22.15%、13.27%和18.58%的表型变异。3个茎秆强度性状共同检测到的主效QTL,可在育种实践中用于分子标记辅助选择和抗倒伏玉米品种的选育。     

水稻稻瘟病抗性QTL的定位分析

 稻瘟病是危害水稻最严重的病害之一。以抗稻瘟病的云南省地方品种魔王谷（MWG）和感稻瘟病的湖北省审定品种鄂晚8号（EW8）为亲本材料,构建双单倍体分离群体（DH）。利用22个菌株对亲本材料MWG/EW8进行致病性鉴定,从中筛选到5个毒性不同的鉴别菌株用于考察DH群体的稻瘟病抗性,构建包含120对SSR标记的分子遗传连锁图进行数量性状位点（QTL）的分析,鉴定出3个抗性QTL,均位于第6染色体长臂RM541附近, 3个QTL对抗病表型的贡献率介于7.7%~15.2 %之间,3个QTL的抗病等位基因均源自亲本MWG。     

Molecular Mapping of the rps1.a Recessive Gene for Resistance to Stripe Rust in BBA 2890 Barley

ABSTRACT Stripe rust, caused by Puccinia striiformis f. sp. hordei, is one of the most important diseases of barley in the south-central and western United States. Growing resistant cultivars is the best approach for controlling the disease. The barley genotype BBA 2890 has all-stage resistance against all races of P. striiformis f. sp. hordei (PSH) identified thus far in the United States. The resistance in BBA 2890 is controlled by a single recessive gene, rps1.a. The objectives of this study were to identify resistance gene analog polymorphism (RGAP) markers for the all-stage resistance gene rps1.a, to map the gene on a barley chromosome using chromosome-specific simple sequence repeat (SSR) markers, and to determine the presence or absence of the flanking RGAP markers for the gene in 24 barley genotypes. Seedlings of the parents and 200 F(8) recombinant inbred lines (RILs) were tested for resistance to pathogen races PSH-14, PSH-48, and PSH-54 in the greenhouse in 2005. Genomic DNA was extracted from the parents and 150 F(8) RILs. The RGAP technique was used to identify molecular markers for the rps1.a gene. Twelve primer pairs generating repeatable polymorphic bands were selected for genotyping the 150 F(8) RILs. A genetic linkage group was constructed for the resistance gene with 13 RGAP markers and four chromosome-specific SSR markers. The four SSR markers mapped the gene on the long arm of barley chromosome 3H. The closest RGAP marker for the resistant allele was within a genetic distance of 2.1 centimorgans (cM). The closest marker for the susceptible allele was 6.8 cM away from the locus. The two closest RGAP markers for the resistant allele detected polymorphisms in 67 and 71% of the 24 barley genotypes when used individually, and detected polymorphism in 88% of the genotypes when used in combination. This information should be useful in incorporating the resistance gene into barley cultivars and in pyramiding the gene with other resistance genes for superior stripe rust resistance.     

湘资3150 微效抗瘟性基因鉴定

 以湘资3150 和CO39 为亲本建立F10 重组自交系群体为材料, 在桃江病圃应用自然诱发接种法对群体的田间叶瘟抗性表现进行了分析。结果表明, 在LOD 2. 5 的域值上,共检测到14 个有效的微效基因QTL 位点(LOD 值均大于2. 5),分别位于水稻第3、8 和10 染色体上,其表型变异贡献值差异比较大,介于11. 78% ~ 40. 57% 之间;表明可能控制不同抗性表型的QTL 紧密连锁或者同一个QTL 对不同的抗性表型均具有抗性贡献。     

稻瘟菌无毒基因AVR-Pikm的定位

 无毒基因是病原物中决定寄主抗病性表达与否的功能基因,其功能的丧失导致毒性小种的产生。在先前的研究中,本研究小组从稻瘟病菌中分离了与无毒基因AVR-Pik^m连锁的2个SCAR标记SCO12₉₄₆和SCE12₁₄₀₆。在本研究中,作者首先通过TAC克隆末端核苷酸序列的测定及其与70-15全基因组序列的比较,将这2个标记定位到稻瘟菌第1号染色体上;然后,利用稻瘟菌70-15全基因组草图序列和SSR技术,又分离了与无毒基因AVR-Pik^m连锁的4个SSR标记:SSR47T34、SSR50CA24、SSR52TAGG18和SSR56A28。进一步分析表明:上述4个SSR标记位于与SCO12₉₄₆和SCE12₁₄₀₆相反的一侧,与AVR-Pik^m位点的遗传距离分别为4.90、7.01、19.12和21.94cM,无毒基因AVR-Pik^m位于SCE12₁₄₀₆和SSRA7T34之间。本研究获得的稻瘟菌无毒基因AVR-Pik^m的精细定位为通过染色体步移克隆该基因奠定了基础。     

New gene for bacterial blight resistance in rice located on chromosome 12 identified from minghui 63, an elite restorer line

ABSTRACT Bacterial blight, caused by Xanthomonas oryzae pv. oryzae, is a serious disease of rice worldwide. A new dominant gene for bacterial blight resistance in rice, Xa25(t), was identified from Minghui 63, a restorer line for a number of rice hybrids that are widely cultivated in China. This gene conferred resistance to Philippine race 9 (PXO339) of X. oryzae pv. oryzae in both seedling and adult stages. It was mapped to the centromeric region of chromosome 12, 2.5 cM from a disease resistance gene-homologous sequence, NBS109, and 7.3 cM from a restriction fragment length polymorphism marker, G1314. The genomic location of this gene is similar to the previously identified blast resistance genes, Pi-ta and Pi-ta2.     

普通小麦-华山新麦草易位系H9015-17抗条锈病基因的标记定位

 采用我国当前流行的小麦条锈菌小种和重要致病类型, 在常温条件下对普通小麦-华山新麦草易位系H9015-17进行苗期抗条锈性鉴定, 并用当前主要流行小种CYR32对H9015-17与铭贤169的杂交后代及其双亲进行抗条锈性遗传分析, 以揭示H9015-17抗条锈性遗传基础。结果显示, H9015-17对小麦条锈菌小种CYR31、CYR32、CYR33和致病类型Su11-4、Su11-7、V26、Su11-11均有良好的抗病性, 对当前主要流行小种CYR32的抗病性由1对显性基因控制, 暂命名为YrHua1。 采用分子标记定位技术,筛选到5个与抗病基因YrHua1连锁的RGAP标记(M1、M2、M3、M4和M5)和1个SSR标记(Xgwm292),这些标记与抗病基因YrHua1的遗传距离分别为17.3、15.7、13.1、3.3、2.9和11.2,并将基因YrHua1定位在小麦染色体5DL上。研究结果将为分子标记辅助选择改良小麦抗条锈性提供宝贵的种质材料,建议在抗病育种加以利用。     

小麦-滨麦易位系M8657-1抗条锈病基因遗传分析和分子标记

 M8657-1, one of the wheat translocation lines derived from Leymus mollis Trin. Hara, is possessed of effective resistance at all stages to Su-ll and other dominant races of Puccinia striiformis f. sp. tritici in China. Seedlings of the parents, F₁, and F₂ progeny derived from the cross of M8657-1 (resistant) Mingxian169 (susceptible) were inoculated with Su-ll in greenhouse to identify and map the probable new stripe rust resistance gene. The results suggested that the stripe rust resistance in M8657-1 was conferred by a pair of recessive genes. Simple sequence repeat (SSR) technique was used to detect molecular marker associated with the resistance gene:208 pairs of wheat SSR primers were used to screen the two parents, as well as resistant and susceptible bulks and then three SSR markers were selected for genotyping the F₂ population. The geue, temporarily designated as YrLml, was found to be located on the chromosome 7DL and flanked by three SSR markers GDM67, WMC150 and WMC671, with the genetic distance of 5.0, 9.7 and 11.8cM, respectively.     

番茄黄萎病抗病基因Ve的AFLP和SSR分子标记

 本研究以番茄抗病品种05046与感病品种051355配制杂交组合,接种鉴定F1代及F2代分离群体的黄萎病发生情况,结果表明,番茄黄萎病属单基因显性遗传。用545对AFLP引物和101对SSR引物对两个亲本、抗感池及F2代分离群体进行AFLP和SSR分析,得到3个与番茄抗黄萎病基因Ve连锁的AFLP标记和1个SSR标记,分别是E66M84-A、E78M84-D、E66M40-A和SSR599,与抗病基因Ve的连锁遗传距离分别为10.3、14.2、30.5 和12.5 cM。     

Chromosomal location and genetic relationship of leaf rust resistance genes rph9 and rph12 in barley

ABSTRACT Barley lines Hor 2596 and Triumph are the sources of leaf rust resistance genes Rph9 and Rph12, respectively. An allelism test was performed with F(2) progeny of the cross Triumph/Hor 2596 inoculated with Puccinia hordei. No recombinants were found in a population of 3,858 progeny, indicating Rph9 and Rph12 are alleles. Molecular and morphological markers were used to identify the chromosomal location of these genes in the crosses Bowman/Hor 2596 and Triumph/I91-533-va. A linkage was detected between Rph9 and the flanking sequence-tagged site (STS) markers ABC155 and ABG3 on chromosome 7(5H) at a distance of 20.6 and 20.1 centimorgans (cM), respectively, and to the microsatellite marker dehydrin-9 (HVDHN9) at a distance of 10.2 cM in the Bowman/ Hor 2596 cross. Analysis of isozymes in bulks of the same population showed that Rph9 may be closely linked to the Est9 locus on chromosome 7(5H). The Rph12 locus was linked to the morphological trait locus va (controlling variegated leaf color) on chromosome 7(5H) at a distance of 22.6 cM in the Triumph/I91-533-va cross. Rph12 also was linked with STS marker ABC155 (24.4 cM) and RAPD marker OPA19 (1.5) (17.8 cM). These data indicate that Hor 2596 and Triumph carry a leaf rust resistance gene at the same locus on the long arm of chromosome 7(5H) of barley.     

小麦持久抗病品种N. Strampelli的抗条锈病基因分析和微卫星标记

 N. Strampelli是由意大利引入我国的小麦持久抗病性品种,对我国目前多数的条锈菌流行小种均有良好的抗性。为了明确其抗条锈病基因的遗传机制,利用小麦条锈病小种CYR30、CYR31、Su-4和Su-14对N. Strampelli与中国春杂交后代进行遗传分析,结果表明N. Strampelli对CYR30、CYR31的抗病性均由1对显性基因和1对隐性基因互补控制,对Su-14、Su-4的抗病性各由1对隐性基因控制,将其中控制Su-14抗病性的隐性基因暂时命名为YrNS-1。利用分离群体分析法(BSA)对接种Su-14的正交F₂代群体进行SSR分子标记,在1BL上找到4个与YrNS-1紧密连锁的微卫星标记Xwmc719、Xgwm124、Xwmc44和Xcfa2147,遗传距离分别为3.2、4.6、5.7和10.3cM。与已知位于1BL染色体上的抗条锈基因比较分析表明,YrNS-1可能是1个新的抗条锈病基因。     

Quantitative trait loci conferring blast resistance in hexaploid wheat at adult plant stage

Blast disease, caused by the Magnaporthe oryzae Triticum pathotype (MoT), is a major concern for wheat production in tropical and subtropical regions. The most destructive symptoms occur in wheat spikes. Infected spikes become bleached due to partial or total sterility, producing small and wrinkled grains. High disease pressure of the disease results in significant yield losses. This study aimed to identify wheat quantitative trait loci (QTLs) conferring resistance to blast disease at the heading stage. A doubled-haploid population was developed from the cross between BRS 209 (susceptible) and CBFusarium ENT014 (resistant, carrying the 2NS translocation). A linkage map was constructed containing 5,381 molecular markers and the inclusive composite interval mapping method was employed for QTL detection. Four QTLs were mapped in response to two MoT isolates. The major QTL identified on the 2AS chromosome explained an average of 84.0% of the phenotypic variation for spike bleaching at 9 days postinoculation and reinforces the potency of the 2NS translocation. Recombination between the distal region of chromosome 2AS and the 2NS marker was found. These results could explain why some lines carrying the VENTRIUP/LN2 marker have a variable reaction to the disease. QTLs on 5B and 7B chromosomes were also identified. Two mechanisms of resistance were hypothesized: the hypersensitive response and resistance to colonization of host tissues. The KASP markers thus developed and simple sequence repeats (SSRs) allocated in QTL regions can be used in the future for the development of wheat blast-resistant cultivars.     

普通小麦-柔软滨麦草易位系M97抗条锈基因的遗传分析和分子作图

为了明确M97抗条锈性遗传规律,在苗期用7个小麦条锈菌系对M97与感病品种铭贤169的杂交后代F1、F2、F3和BC1代进行抗条锈性遗传分析,并对M97抗Sun11-4的抗条锈基因进行SSR分子标记。M97对Sun11-4和Sun11-11的抗病性均由1对显性基因控制,对CY29、CY30、CY33的抗病性由1显1隐2对基因共同控制,对CY31的抗病性由2对显性基因独立或重叠作用控制。以接种Sun11-4的F2代分离群体构建作图群体,筛选到Xwmc222、Xwmc147、Xbarc229和Xwmc339等4个与抗病基因连锁的SSR标记,其遗传距离分别为3.4、4.8、7.6和12.1 cM。将该抗病基因定位于小麦1DS染色体,且该基因不同于已知的抗条锈基因,暂命名为YrM97。用YrM97两侧遗传距离最近的2个标记Xwmc222和Xwmc147对42个黄淮麦区主栽小麦品种进行分子检测,仅有9.5%的品种具有与YrM97相同的标记位点。     

源于华山新麦草抗条锈病基因 YrH122遗传分析和SSR标记

 H122是1个通过杂交和回交选育的普通小麦-华山新麦草易位系。为明确其抗条锈病基因及遗传特点,建立抗病基因SSR标记,利用我国小麦条锈菌流行小种CYR29、CYR31、CYR32、CYR33和致病类型Su11-4、Su11-11对H122进行苗期抗性鉴定,根据鉴定结果选用CYR32、CYR33和Su11-4对其与铭贤169杂交F1、F2及BC1代进行了遗传分析,同时应用258对SSR引物对将H122/铭贤169 F2代接种Su11-4的185个单株构建的作图群体进行了PCR扩增和电泳分析。结果表明,H122对供试小种均表现免疫或近免疫,对CYR32的抗病性由1对显性基因控制,对CYR33的抗病性由1对隐性基因控制,对Su11-4的抗病性亦由1对显性基因控制,将其暂命名为YrH122。筛选到3个与YrH122连锁的SSR标记Xbarc229、Xwmc339和Xwmc93,遗传距离分别为7.7、4.3和11.0 cM,并将该基因定位于小麦染色体1DL上。SSR标记回检显示,YrH122来源于华山新麦草。通过基因来源、分子检测及染色体位点比较,YrH122可能是1个不同于目前已知抗条锈病基因的新基因。     

普通小麦-柔软滨麦草易位系M852-1抗条锈基因的遗传分析和分子作图

 M852-1是经杂交和回交培育的普通小麦-柔软滨麦草易位系,苗期对我国小麦条锈菌流行小种均表现良好抗性。为明确其抗条锈性遗传规律,本研究选用条锈菌流行小种（类型）CYR29、CYR32、CYR33和Su11-7的单孢菌系对其与铭贤169杂交F₁、F₂、F₃及BC₁代群体进行遗传分析, 同时应用420对SSR引物对接种CYR32的M852-1/铭贤169 F₂代144个单株作图群体进行抗病基因定位。结果表明,M852-1对供试小种均表现免疫或近免疫,对CYR29的抗锈性由1对显性基因控制,对CYR32、CYR33和Su11-7的抗锈性均由1对隐性基因控制。筛选到3个与抗CYR32基因连锁的SSR标记Xbarc124、Xbarc200和Xgwm429,遗传距离分别为6.3、5.6 和 9.7 cM。根据SSR标记锚定性将该基因定位于小麦2BS染色体,暂命名为YrM852。基因来源、分子标记检测及染色体位点分析表明,YrM852很可能是1个不同于目前已知抗条锈病基因的新基因。     

小麦条锈菌鉴别寄主Heines peko抗性遗传分析及SSR标记

 用中国条锈菌生理小种对欧洲鉴别寄主Heines peko进行抗条锈性遗传机制研究,将为挖掘新的抗条锈基因、培育优良抗条锈性品种奠定基础。用Heinespeko与小麦感病品种铭贤169杂交、自交获F₁、F₂和F₃代群体。对亲本及其后代分别在苗期接种条中30号、条中31号、条中32号和水-4,进行遗传分析。结果表明,Heines peko对条中30号小种的抗性由1对隐性基因控制。对条中31号、水-4的抗性均由1显1隐2对基因互补或抑制作用控制,Heines peko对2个小种的抗性可能由相同基因控制。对条中32号的抗性是由2对隐性基因相互抑制控制。利用分组分析法(BAS)对抗条中30号小种的遗传群体进行分子作图,筛选到1个位于2AS与抗条中30号小种基因连锁的SSR标记Barc212,用Barc212对170个F₂代单株分析表明,该基因与Barc212引物扩增位点的遗传距离为10.6cM。Barc212可作为抗条中30号基因的SSR标记。     

黑龙江省稻瘟病菌生理小种鉴定

2005-2007年,从采自黑龙江省各主要水稻产区的稻瘟病标样中分离获得268个单孢菌株,采用全国统一的7个鉴别寄主共鉴定出7群31个中国小种。其中ZA、ZD、ZB为黑龙江省稻区的主要优势小种群,出现频率分别为33.58%、24.63%和18.28%。ZD1是优势小种,其出现频率为16.04%,其次是ZA49（13.43%）、ZE1（10.44%）、ZA17（8.96%）小种。不同地区小种的类型及其组成不同。     

Molecular mapping of rsp1, rsp2, and rsp3 genes conferring resistance to septoria speckled leaf blotch in barley

ABSTRACT Septoria speckled leaf blotch (SSLB) caused by Septoria passerinii is a common disease in barley. SSLB resistance genes Rsp1, Rsp2, and Rsp3 have previously been identified in the United States Department of Agriculture National Small Grains collection accessions CIho 14300, CIho 4780, and CIho 10644, respectively. Populations of 100 to 120 F(2) individuals were evaluated for SSLB resistance in the greenhouse. Inheritance was evaluated in F(2:3)-derived families in the field. Partial molecular maps for three Rsp genes were constructed on F(2) and F(2:3) families derived from crosses between Robust and the resistant accessions CIho 14300, CIho 4780, and CIho 10644. The resistant locus Rsp1 was mapped to the short arm of chromosome 3H with two flanking diversity arrays technology (DArT) markers, bPb-6978 (8.9 cM) and bPb-9945 (16.3 cM), and two random amplified polymorphic DNA (RAPD) markers, OPC2(441R) (3.0 cM) and UBC285(158R) (4.3 cM). The genes Rsp2 and Rsp3 were positioned on the short arm of barley chromosome 1H with two restriction fragment length polymorphism (RFLP), six DArT, and three RAPD markers. An RFLP marker, MWG938, and an RAPD marker, OPAH5(545C), were tightly associated with Rsp2 at a distance of 0 cM. Five DArT markers spanning the short arm of 1H surrounded Rsp3 at a distance of 2.3 and 5.8 cM, while two RAPD markers-OPBA12(314C) (2.4 cM) in coupling and OPB17(451R) (3.5 cM) in repulsion-flanked Rsp3. Molecular marker data associated with Rsp2 and Rsp3 indicated that the two genes are closely linked on chromosome 1HS. A total of 17 of 154 simple sequence repeats (SSRs) tested were associated with Rsp genes on chromosome 1H and 3H, and they were also integrated into genetic linkage maps of the three F(2) Robust populations. Knowledge about the map position of Rsp genes on barley chromosomes will be useful for breeding for SSLB resistance in barley and eventual gene cloning.