Soilborne wheat mosaic virus movement protein and RNA and wheat spindle streak mosaic virus coat protein accumulate inside resting spores of their vector, Polymyxa graminis

To study virus-vector interactions between Soilborne wheat mosaic virus (SBWMV) or Wheat spindle streak mosaic virus (WSSMV) and Polymyxa graminis Ledingham, P. graminis was propagated in plants grown hydroponically. P. graminis accumulated to high levels in several barley cultivars tested. Multiple developmental stages of P. graminis could be identified in infected barley roots. Accumulation of SBWMV and WSSMV inside P. graminis sporosori in the roots of soil-grown winter wheat and hydroponically grown barley was compared to determine if data obtained from plants naturally infected plants and plants infected by manual inoculation were similar. WSSMV coat protein (CP), SBWMV RNAs, SBWMV movement protein but not SBWMV CP were detected in both soil-grown winter wheat and hydroponically grown barley roots. These data are the first direct evidence that SBWMV and WSSMV are internalized by P. graminis.     

抗条锈病小麦—中间偃麦草异附加系的生化与分子标记

对小麦-中间偃麦草部分双二倍体无芒中4、异附加系C076、宛7107和中国春进行了肽链内切酶（EP-1）等电聚焦电泳。结果表明,肽链内切酶在阳极处有一特异带。肽链内切酶已定位于小麦第7部分同源群,故附加的染色体为第7部分同源群的2条染色体,对中间偃麦草,无芒中4、C076和宛7107进行了RAPD分析。获得了可用于检测C076中外源染色体的3个RAPD标记,即OPI05-800、OPI10-600、OPK01-900。     

抗黄矮病小麦新品系YW443的分子细胞遗传学鉴定

以小麦－中间偃麦草二体附加系Ｌ１衍生抗病系ＰＰ９－１为抗源,与小麦推广品种陕７８５９．丰抗８号杂交并自交,在Ｆ６代中选到农艺性状优良的高抗黄矮病小麦新品系ＹＷ４４３。对ＹＷ４４３及其亲本进行抗病性鉴定。结果表明：ＹＷ４４３高抗大麦黄矮病毒ＧＰＶ、ＧＡＶ株系。利用基因组原位杂交,ＲＦＬＰ分析和ＲＡＰＤ分析,研究诉遗传构成及其抗病基因染色体归属。结果表明：ＹＷ４４３（２ｎ＝４３）的遗传构成了４０条（２     

Disomic Thinopyrum intermedium addition lines in wheat with barley yellow dwarf virus resistance and with rust resistances.

Zhong 5 is a partial amphiploid (2n = 56) between Triticum aestivum (2n = 42) and Thinopyrum intermedium (2n = 42) carrying all the chromosomes of wheat and seven pairs of chromosomes from Th. intermedium. Following further backcrossing to wheat, six independent stable 2n = 44 lines were obtained representing 4 disomic chromosome addition lines. One chromosome confers barley yellow dwarf virus (BYDV) resistance, whereas two other chromosomes carry leaf and stem rust resistance; one of the latter also confers stripe rust resistance. Using RFLP and isozyme markers we have shown that the extra chromosome in the Zhong 5-derived BYDV resistant disomic addition lines (Z1, Z2, or Z6) belongs to the homoeologous group 2. It therefore carries a different locus to the BYDV resistant group 7 addition, L1, described previously. The leaf, stem, and stripe rust resistant line (Z4) carries an added group 7 chromosome. The line Z3 has neither BYDV nor rust resistance, is not a group 2 or group 7 addition, and is probably a group 1 addition. The line Z5 is leaf and stem rust resistant, is not stripe rust resistant, and its homoeology remains unknown.     

Identification and characterization of a novel efficient resistance response to the furoviruses SBWMV and SBCMV in barley

The interaction between the furoviruses Soilborne cereal mosaic virus (SBCMV) and Soilborne wheat mosaic virus (SBWMV) and their main host wheat is well documented; however, to date, only a few reports have addressed the response of other cereal species to these viruses. Here, we show that, in contrast to wheat, barley germplasm is a rich source of resistance to furoviruses. Moreover, we demonstrate that barley genotypes respond differentially to SBCMV and SBWMV, thereby providing an additional biological basis for classification of these viruses as two separate species. Following natural (soil) inoculation, some barley genotypes permitted foliar infection by SBWMV, whereas all 22 genotypes tested were resistant to SBCMV. Resistance is unlikely to be directed toward the virus vector, because Polymyxa graminis DNA was detected in the roots of all tested genotypes. Resistance to SBCMV in some barley genotypes was overcome by artificial virus inoculation onto the leaves, suggesting a block on virus translocation from roots to shoots as in resistant wheat genotypes. However, other genotypes were fully resistant following both inoculation techniques. One barley genotype, 'Dayton,' exhibited extreme resistance to both furoviruses. Further molecular analyses suggested that this novel and highly efficient resistance to furoviruses in barley operates by limiting virus spread from the primary inoculated cells.     

小偃麦衍生品系CH7086抗白粉基因的遗传及SSR分析

CH7086是兼抗白粉病、条锈病的小麦新品系,衍牛于来自十倍体长穗偃麦草的八倍体小偃麦与普通小麦的杂种后代.温室接种鉴定结果显示,CH7086对白粉病菌系E09、E21、E26均表现为免疫,且其抗件来自长穗偃麦草.抗性遗传分析表明CH7086的白粉病抗性由1对显性基因控制,暂定名为MlCH86.应用分离群体分组法(BSA)对从CH5241×CH7086的F2中随机选取的95个单株进行微卫星标记检测,发现位于2BL、2DL上的SSR位点Xbarc159在双亲和抗、感池间有特异性,并与抗性基因MlCH86连锁,其遗传距离为10.8 cM.用中国春第2部分同源群的缺体-四体系和双端体系进行验证,进一步将MlCH86定位在2BL上.用白粉病菌系E21、E26接种鉴定表明,MlCH86的抗性反应明显不同于2BL上已命名的抗性基因Pm6、Pm33.根据抗性基因的来源、染色体位置及抗性反应,初步推断存在于CH7086的抗性基因来自长穗偃麦草,它不同于已有的抗白粉病基因,可能是一个新基因.     

用顺序GISH-FISH 技术鉴定小麦-中间偃麦草小片段易位系

利用顺序基因组-重复序列原位杂交技术对1个来自中3不育系和普通小麦恢75杂种后代稳定株系H96276-2的染色体组成进行了分析。以中间偃麦草（Agropyronintermedium）基因组DNA为探针的荧光原位杂交结果表明,H96276-2的体细胞中有42条染色体,包括20对小麦染色体和1对小麦-中间偃麦草易位染色体,中间偃麦草染色体的易位片段位于1对小麦染色体的端部。进而用重复序列探针pSc119进行第2次荧光原位杂交,证明H96276-2中的中间偃麦草染色体易位片段位于小麦2B染色体的短臂上。     

Characterization of a partial wheat-Thinopyrum intermedium amphiploid and its reaction to fungal diseases of wheat

Partial amphiploids between wheat (Triticum aestivum L.) and Thinopyrum species play an important role in the transfer and use of traits from alien species. A wheat-Thinopyrum intermedium partial amphiploid, TAI8335, and its alien parent were characterized by a combination of genomic in situ hybridization (GISH) and cytological observations. Evidence from GISH indicated that the donor parent Th. intermedium possessed seven pairs of S, seven J(s) and 21 J chromosomes. Mitotic observation showed that the majority of TAI8335 plants had 56 chromosomes, but a few had 54 to 55, in some cases with two to three additional telochromosomes. The chromosomes in most pollen mother cells of plants with 2n = 56 formed 28 bivalents, averaging 27.12 in 223 cells, suggesting a basic cytological stability. Sequential GISH patterns using genomic Pseudoroegneria spicata and genomic Th. intermedium DNA as probes revealed that TAI8335 had fourteen chromosomes derived from Th. intermedium and its alien genome consisted of one pair of S-, three pairs of J(s) - and one pair of J-genome chromosomes as well as two translocated chromosome pairs, one being a Robertsonian translocation and another an intercalary translocation, both of which involved J and S genome. Two of the telochromosomes in the aneuploid plants originated from the J genome and one from wheat. Disease screening demonstrated this line was highly resistant to leaf rust, stem rust, stripe rust and powdery mildew. This study showed that the partial amphiploid TAI8335 appears to serve as a novel source for the transfer of resistance genes for multiple fungal pathogens to wheat.     

应用分子原位杂交技术解析小麦-天兰冰草部分双二倍体──远中2号的染色体构成

为分析普通小麦（Ｔｒｉｔｉｃｕｍａｅｓｔｉｖｕｍ）－天兰冰草（Ａｇｒｏｐｙｒｏｎｉｎｔｅｒｍｅｄｉｕｍ）部分双二倍体──远中２号（２ｎ＝５４）的染色体构成,用生物素（ｂｉｏｔｉｎ－１６－ｄＵＴＰ）标记天兰冰草染色体组ＤＮＡ作为探针,以普通小麦品种中国春染色体组ＤＮＡ为封闭ＤＮＡ（ｂｌｏｃｋｉｎｇＤＮＡ）,与远中２号的有丝分裂中期染色体ＤＮＡ进行了分子原位杂交。证明远中２号除具有普通小麦的２１对染色体外,附加了１对小麦－天兰冰草易位染色体（即天兰冰草染色体片段易位到小麦染色体的两臂端部）、５对天兰冰草染色体。说明小麦－天兰冰草部分双二倍体在形成过程中染色体行为是比较复杂的,不仅可能产生小麦－天兰冰草染色体间易位,而且小麦染色体也可能与天兰冰草染色体的３种染色休组染色体共同参与组建新的染色体组附加到小麦中去。     

54份CIMMYT小麦材料抗白粉病分析

选用来自我国不同地区的20个白粉病菌毒性菌株,对54个CIMMYT小麦品种(系)进行抗病性分析.结果表明:(1)34个品种(系)含有抗病基因,以Pm8基因出现频率最高,有15个品种(系)携带该基因;(2)参试主效基因中,Pm1、Pm3e、Pm5、Pm6和Pm7基因已丧失对我国白粉菌的抗性,Pm16和Pm20基因的抗性最强;(3)50个1B/1R易位系品种(系)中31个含有抗病基因,48%的抗病1B/1R易位系可检测到Pm8基因.根据田间成株期病程曲线下面积(AUDPC)聚类分析结果,可将54份材料分为高抗、中抗、中感和高感4类,7个品种(系)不含任何主效抗病基因而田间表现中到高的抗性,是典型慢病性品种.     

Cereal cyst nematode resistance conferred by the Cre7 gene from Aegilops triuncialis and its relationship with Cre genes from Australian wheat cultivars.

Cereal cyst nematode (CCN; Heterodera avenae Woll.) is a root pathogen of cereal crops that can cause severe yield losses in wheat (Triticum aestivum). Differential host-nematode interactions occur in wheat cultivars carrying different CCN resistance (Cre) genes. The objective of this study was to determine the CCN resistance conferred by the Cre7 gene from Aegilops triuncialis in a 42-chromosome introgression line and to assess the effects of the Cre1, Cre3, Cre4, and Cre8 genes present in Australian wheat lines on Spanish pathotype Ha71. Inhibition of nematode reproduction was rank-ordered as Cre1 >or = Cre4 > or = Cre7 > Cre8 > Cre3. Lines carrying Cre1, Cre4, or Cre7 exhibited a significantly higher level of resistance than those carrying Cre8 or Cre3. Allelism tests indicated that Cre7 segregated independently of Cre1 on chromosome 2BL and Cre4 on chromosome 2DL, and these genes could consistently be combined in the same genotype, inducing a more durable resistance. Tests to determine the chromosomal location of Cre7 using addition lines were inconclusive.     

小麦—中间偃麦草抗条锈衍生系的分子细胞遗传学研究

应用缺体回交法,以部分阿勃缺体为母本,中4为父本,培育出1个对目前条锈病优势小种和新小种高抗至免疫的小麦－－中间偃麦草衍生系N9025－3－3－2－1－1。研究表明,该选系在形态学和细胞学上已经基本稳定,染色体构型为2n=42=21“,抗病性来自中间偃麦草（Thinopyron intermedium）。以中间偃麦草DNA为探针,对N9025－3－3－2－1－1进行基因组原位杂交分析结果证明,它为小麦－中间偃麦草异代换－易位系。     

Structural organization of an alien Thinopyrum intermedium group 7 chromosome in U.S. soft red winter wheat (Triticum aestivum L.).

Barley yellow dwarf virus (BYDV) resistance in soft red winter wheat (SRWW) cultivars has been achieved by substituting a group 7 chromosome from Thinopyrum intermedium for chromosome 7D. To localize BYDV resistance, a detailed molecular genetic analysis was done on the alien group 7 Th. intermedium chromosome to determine its structural organization. Triticeae group 7 RFLP markers and rye specific repetitive sequences used in the analysis showed that the alien chromosome in the P29 substitution line has distinguishing features. The 350-480 bp rye telomeric sequence family was present on the long arm as determined by Southern and fluorescence in situ hybridization. However, further analysis using a rye dispersed repetitive sequence indicated that this alien chromosome does not contain introgressed segments from the rye genome. The alien chromosome is homoeologous to wheat chromosomes 7A and 7D as determined by RFLP analysis. Presence of the waxy gene on chromosomes 7A, 7B, and 7D but its absence on the alien chromosome in P29 suggests some internal structural differences on the short arm between Th. intermedium and wheat group 7 chromosomes. The identification of rye telomeric sequences on the alien Thinopyrum chromosome and the homoeology to wheat chromosomes 7A and 7D provide the necessary information and tools to analyze smaller segments of the Thinopyrum chromosome and to localize BYDV resistance in SRWW cultivars.     

小偃麦附加系Z1和Z2中外源染色体2Ai-2的结构组成

小偃麦附加系Z1和Z2中外源染色体2Ai-2的结构组成@张增燕$中国农业科学院作物育种栽培研究所!北京100081@辛志勇$中国农业科学院作物育种栽培研究所!北京100081@陈孝$中国农业科学院作物育种栽培研究所!北京100081小偃麦;;附加系;;染色体     

禾谷多粘菌对小麦梭条斑花叶病毒的传播及其土壤侵染潜力的测定

从大田侵染小麦梭条斑花叶病毒的小麦病根中挑取禾谷多粘菌休眠孢子堆,接种受侵染小麦品种扬麦４号,经砂培养纯化,获得５个禾谷多粘菌分离物,但都为无毒。无毒多粘菌休眠孢子堆接种表现ＷＳＳＭＶ症状的小麦,经培养可饲获病毒,并可经接咱后将病毒传播给无病小麦,供试的４个大小麦禾谷多粘菌分离物都可对大小进行交叉侵染,产生同样数量的游动孢子产量。供试５个病土和２个无病土样品,都具有强大持多粘菌侵染潜力,即使稀释放     

Molecular Cytogenetic Identification of a Wheat-Thinopyron intermedium (Host) Barkworth & DR Dewey Partial Amphiploid Resistant to Powdery Mildew

Wide cross and molecular cytogenetic methods were used to transfer the powdery mildew resistance gene from Thinopyron intermedium (Host) Barkworth & DR Dewey to wheat. Among the progeny of crossing common wheat (Triticum aestivum L.) Yannong 15 with Th. intermedium, a partial amphiploid E990256, with resistance to powdery mildew, was developed. It had 56 chromosomes and could form 28bivalents in pollen mother cells at metaphase I of meiosis. Resistance verification by race 15 at the seedling stage and by mixed strains of Erysiphales gramnis DC. f. sp. tritici Em. Marchal at the adult stage showed it was immune to powdery mildew at both stages. Gene postulation via 21 isolates of E. gramnis f. sp. tritici and 29 differential hosts showed it was nearly immune to all the isolates used, and its resistance pattem was different from all the mildew resistance genes used, which indicated it probably contained a new resistance gene to powdery mildew. Biochemical verification showed it might convey different Th. intermedium chromosomes from those of the wheat-Th. intermedium partial amphiploids Zhong 1-5. Genomic in situ hybridization analysis by using St genomic DNA as the probe showed E990256 contained a recombination genome of St and E.     

兼抗白粉、条锈病小偃麦渗入系CH7124抗性遗传及细胞学鉴定

CH7124是通过八倍体小偃麦TAI8335与感病小麦杂交、回交育成的兼抗白粉病、条锈病的小偃麦种质系。利用抗性接种鉴定、细胞学和基因组原位杂交(GISH)技术相结合的方法,对CH7124的抗性来源、遗传方式及细胞学特征进行了分析和鉴定。结果表明,CH7124在苗期和成株期对条锈菌系CYR29、CYR31、CYR32、CYR33和白粉菌系E09、E20、E21、E26表现为免疫或近免疫,其抗性来自中间偃麦草,受1对显性核基因控制;CH7124的根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期I(PMC MI)绝大多数细胞内可观察到21个二价体,平均配对构型为2n=0.30 I+20.79 II+0.04 III;与普通小麦中国春、绵阳11的杂种F1中,有80%以上的花粉母细胞可观察到2n=21Ⅱ的染色体构型,其平均配对构型均为2n=21II。说明CH7124具有与普通小麦相似的染色体结构和规则的配对构型。由于利用以中间偃麦草总DNA为标记探针的原位杂交未观察到可见的外源DNA杂交信号,进一步证明CH7124是一个小麦-中间偃麦草的隐形异源渗入系。     

Genome-wide association analysis identified SNPs closely linked to a gene resistant to Soil-borne wheat mosaic virus

Key message

Using association and linkage mapping, two SNP markers closely linked to the SBWMV resistance gene on chromosome 5D were identified and can be used to select the gene in breeding.

Abstract

Soil-borne wheat mosaic virus (SBWMV) disease is a serious viral disease of winter wheat growing areas worldwide. SBWMV infection can significantly reduce grain yield up to 80 %. Developing resistant wheat cultivars is the only feasible strategy to reduce the losses. In this study, wheat Infinium iSelect Beadchips with 9 K wheat SNPs were used to genotype an association mapping population of 205 wheat accessions. Six new SNPs from two genes were identified to be significantly associated with the gene for SBWMV resistance on chromosome 5D. The SNPs and Xgwm469, an SSR marker that has been reported to be associated with the gene, were mapped close to the gene using F₆-derived recombinant inbred lines from the cross between a resistant parent ‘Heyne’ and a susceptible parent ‘Trego’. Two representative SNPs, wsnp_CAP11_c209_198467 and wsnp_JD_c4438_5568170, from the two linked genes in wheat were converted into KBioscience Competitive Allele-Specific Polymerase assays and can be easily used in marker-assisted selection to improve wheat resistance to SBWMV in breeding.     

Research progress in BYDV resistance genes derived from wheat and its wild relatives

Barley yellow dwarf virus （BYDV） may cause a serious disease affecting wheat worldwide. True resistance to BYDV is not naturally found in wheat. BYDV resistance genes are found in more than 10 wild relative species belonging to the genera of Thinopyrum, Agropyron, Elymus, Leymus, Roegneria, and Psathyrostachy. Through wide crosses combining with cell culture, use ofph mutants, or irradiation, 3 BYDV resistance genes in Th. intermedium, including Bdv2, Bdv3 and Bdv4, were introgressed into common wheat background. Various wheat-Th, intermedium addition and substitution, translocation lines with BYDV-resistance were developed and characterized, such as 7D-TAi#1 （bearing Bdv2）, 7B-7Ai#1, 7D-7E （beating Bdv3）, and 2D-2Ai-2 （bearing Bdv4） translocations. Three wheat varieties with BYDV resistance from Th. intermedium were developed and released in Australia and China, respectively. In addition, wheat-Agropyron cristatum translocation lines, wheat-Ag, pulcherrimum addition and substitution lines, and a wheat-Leymus multicaulis addition line （line24） with different resistance genes were developed. Cytological analysis, morphological markers, biochemical markers, and molecular markers associated with the alien chromatin carrying BYDV resistance genes were identified and applied to determine the presence of alien, chromosomes or segments, size of alien chromosome segments, and compositions of the alien chromosomes. Furthermore, some resistance-related genes, such as RGA, P450, HSP70, protein kinases, centrin, and transducin, were identified, which expressed specifically in the resistance translocation lines with Bdv2. These studies lay the foundations for developing resistant wheat cultivars and unraveling the resistance mechanism against BYDV.     

Molecular characterization of the genome composition of partial amphiploids derived from Triticum aestivum×Thinopyrum ponticum and T. aestivum×Th. intermedium as sources of resistance to wheat streak mosaic virus and its vector, Aceria tosichella

 Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (WCM), is one of the most important viral diseases of wheat (Triticum aestivum) in the world. Genetic resistance to WSMV and the WCM does not exist in wheat. Resistance to WSMV and the WCM was evaluated in five different partial amphiploids namely Agrotana, OK7211542, ORRPX, Zhong 5 and TAF 46, which were derived from hybrids of wheat with decaploid Thinopyrum ponticum or with hexaploid Th. intermedium. Agrotana was shown to be immune to WSMV and the WCM; the other four partial amphiploids were susceptible to the WCM. Genomic in situ hybridization (GISH) using genomic DNA probes from Th. elongatum (EE, 2n=14), Th. bessarabicum (JJ, 2n=14), Pseudoroegneria strigosa (SS, 2n=14) and T. aestivum (AABBDD, 2n=42) demonstrated that three of the partial amphiploids, Agrotana, OK7211542 and ORRPX, have almost identical alien genome constitutions: all have 16 alien chromosomes, with 8 chromosomes being closely related to the J^s genome and 8 chromosomes belonging to the E or J genomes and no evidence of any S-genome chromosomes. GISH confirmed that the alien genomes of Agrotana and OK7211542, like ORRPX, were all derived from Th. ponticum, and not from Th. intermedium. However, in contrast to Agrotana, ORRPX and OK7211542 were susceptible to the WCM and WSMV. The partial amphiploid Zhong 5 had a reconstituted alien genome composed of 4 S-and 4 J^s-genome chromosomes of Th. intermedium with 6 translocated chromosomes between the S and J^s genomes. This line was highly resistant to WSMV, but was susceptible to the WCM. TAF 46, which contained a synthetic genome consisting of 3 pairs of S-genome chromosomes and 4 pairs of E- or J-genome chromosomes in addition to the 21 pairs of wheat chromosomes, was susceptible to the WCM, but moderately resistant to WSMV. Agrotana offers great potential for transferring WSMV and WCM resistance into wheat. Received: 27 January 1998 / Accepted: 10 February 1998