Genetics of resistance to race TTKSK of Puccinia graminis f. sp. tritici in Triticum monococcum

Race TTKSK (or Ug99) of Puccinia graminis f. sp. tritici possesses virulence to several stem rust resistance genes commonly present in wheat cultivars grown worldwide. New variants detected in the race TTKSK lineage further broadened the virulence spectrum. The identification of sources of genetic resistance to race TTKSK and its relatives is necessary to enable the development and deployment of resistant varieties. Accessions of Triticum monococcum, an A-genome diploid wild and cultivated wheat, have previously been characterized as resistant to stem rust. Three resistance genes were identified and introgressed into hexaploid wheat: Sr21, Sr22, and Sr35. The objective of this study was to determine the genetic control and allelic relationships of resistance to race TTKSK in T. monococcum accessions identified through evaluations at the seedling stage. Generation F(2) progeny of 8 crosses between resistant and susceptible accessions and 13 crosses between resistant accessions of T. monococcum were evaluated with race TTKSK and often with North American races, including races QFCSC, TTTTF, and MCCFC. For a selected population segregating for three genes conferring resistance to race TTKSK, F(2:3) progeny were evaluated with races TTKSK, QFCSC, and TTTTF. In that population, we detected two genes conferring resistance to race TTKSK that are different from Sr21, Sr22, and Sr35. One of the new genes was effective to all races tested. The identification of these genes will facilitate the development of varieties with new resistance to race TTKSK.     

云南省小麦品种(系)苗期抗秆锈性评价及3个重要抗病基因的分子检测

正小麦秆锈病是严重影响小麦产量的病害之一。小麦秆锈菌新小种Ug99及其变异菌株的出现~([1]),随后在肯尼亚和埃塞俄比亚引起的流行,引起了全球对小麦抗秆锈性的再次关注~([2,3])。云南省地处中国西南边境,历史上是中国小麦秆锈菌主要越冬区,为小麦秆锈病的流行提供初菌源。近几年我们对小麦秆锈病的调查研究发现,即使在全国各地几乎见不到该病的情况下,云南省每年均有小麦秆锈     

43个中国小麦品种(系)抗叶锈性研究

 选用12个墨西哥叶锈菌生理小种对43个中国小麦品种(系)所携带的抗叶锈病基因进行了推导,在25个品种(系)中推导出6个抗叶锈基因Lr1,Lr10,Lr13,Lr14a,Lr16和Lr26,9个品种(系)对本试验所使有的12个叶锈菌生理小种都表现感病反应,另有9个品种(系)携带未知的抗叶锈基因。在墨西哥2个地点进行的田间成株期抗叶锈性试验表明,12个品种(系)表现慢叶锈性,在将来的抗病育种中有一定的应用价值。     

江苏省重要小麦品种抗叶锈病和秆锈病基因初步分析

作者分别选用15个具不同毒性基因组合的叶锈菌系和10个具不同毒性基因组合的秆锈菌系推导分析了江苏省26个重要小麦品种(系)所携带的抗叶锈病和抗秆锈病基因。在供试的39个已知抗叶锈病基因(或基因组合)和44个已知抗秆锈病基因中,推导出了Lr1、Lr10、Lr13、Lr16、Lr26、Lt13 3Ka等6个抗叶锈病基因(或基因组合)和Sr5、Sr6、Sr7b、Sr8a、Sr9e、Sr10、Sr13、Sr14、Sr15、Sr17、Sr20、Sr23、Sr27、Sr28、Sr29、Sr31、SrTmp等17个抗秆锈病基因,以单基因或基因组合的形式分别分布在20和24个小麦品种(系)中,其中Lr16、Lr26和Sr5、Sr23、Sr31是供试材料的主要已知抗叶、秆锈病基因。初步发现一些品种(系)携带有Lr13和Sr31等已知持久抗锈基因(或基因组合)及不同于本研究所用的已知基因的未知基因。     

Temperature-sensitive wheat stem rust resistance gene Sr15 is effective against Puccinia graminis f. sp. tritici race TTKSK

The wheat stem rust fungus, Puccinia graminis f. sp. tritici (Pgt), race TTKSK and related races pose a serious threat to world wheat production. Knowing the effectiveness of wheat stem rust resistance (Sr) genes against Pgt race TTKSK is fundamental in mitigating this threat through resistance breeding. Sr15 was previously identified as being ineffective against Pgt race TTKSK. Here, multirace disease phenotyping data, linkage analyses, allelism testing and haplotype analyses are presented to support the conclusion that Sr15 is effective against Pgt race TTKSK. Resistance to race TTKSK was mapped to Sr15 in a biparental population. Thirty-two accessions with Sr15 displayed seedling resistance phenotypes against race TTKSK. However, these accessions were susceptible as seedlings at high temperatures (22–25 °C), consistent with previous reports that the interaction between avirulent Pgt isolates and Sr15 is temperature-sensitive. Markers STS638, wri4 and KASP_IWB30995 were found to predict the presence of Sr15, suggesting the utility of these assays for marker-assisted selection in breeding programmes. The effectiveness of Sr15 to specific Pgt races and temperatures makes it a less-desirable TTKSK-effective gene. Wheat lines assayed as resistant to race TTKSK at the seedling stage may possess Sr15 and breeders should be aware of the limitations of Sr15 for conferring stem rust resistance.     

83份西农系小麦品种（系）抗性鉴定及抗病基因分子检测

为西北农林科技大学小麦新育成品种（系）在黄淮麦区的大面积推广,该研究对83份西农新育成的小麦品种（系）进行苗期抗条锈病和白粉病鉴定,成株期抗条锈病、白粉病、叶锈病和赤霉病鉴定,并在田间自然环境下对其抗性进行鉴定及对相关抗病基因进行分子检测。结果显示,在苗期人工接种鉴定中,有63、29和16份小麦品种（系）分别对条锈菌Puccinia striiformis f.sp.tritici生理小种CYR32、CYR33和CYR34表现出抗性,9份小麦品种（系）对3个条锈菌生理小种均表现出抗性;有10、3和0份小麦品种（系）分别对白粉菌Blumeria graminis f.sp.tritici生理小种E15、E09和A13表现出抗性。在成株期人工接种鉴定中,有23、15、28和62份小麦品种（系）分别对条锈病、白粉病、叶锈病和赤霉病表现出抗性。在83份小麦品种（系）中有6份在苗期和成株期均对小麦条锈病表现出抗性。在田间抗性鉴定中,有57、6、65和40份小麦品种（系）分别对条锈病、白粉病、赤霉病及叶锈病表现出抗性。在83份小麦品种（系）中,3份含有Yr5基因,22份含有Yr9基因,3份含有Yr17基因,2份含有Pm24基因,14份含有Lr1基因,所占比例分别为3.6%、26.5%、3.6%、2.4%和16.8%。     

我国25个小麦品种抗秆、叶锈基因初步分析

 本文采用基因推导法分析了我国25个重要小麦生产品种和抗源材料抗秆、叶锈菌的基因型。在供试的19个抗秆锈基因中,推导出了Sr5,Sr6、Sr7b、Sr8a、Sr9b、Sr31等6个基因,分布在20个小麦品种中;在14个抗叶锈基因中,推导出了Lr1、Lr2C、Lr10、Lr18、Lr26等5个基因,分布在11个小麦品种中。Sr5、Sr31、Lr2c和Lr26是供试品种的主要抗锈基因。     

黑龙江省83份小麦品种抗秆锈病基因的分子检测

 为了明确黑龙江省小麦品种(系)对中国秆锈菌的抗性水平和了解抗秆锈病基因在该区域的分布情况,本研究选用中国小麦秆锈菌流行小种21C3CTHQM、34MKGQM和34C3RTGQM对从该区域征集到的83份主要小麦品种(系)进行了苗期抗秆锈病的评价,并利用与抗秆锈病基因Sr2、Sr24、Sr25、Sr26、Sr31和Sr38紧密连锁的分子标记分别进行了分子检测,结合苗期表型及系谱,推测这些品种(系)可能含有的抗病基因。结果表明,83份小麦品种(系)对供试秆锈菌小种均表现抗性,对21C3CTHQM、34MKGQM和34C3RTGQM表现免疫或近免疫的分别为57、53和60份,各占供试材料数量的68.68%、63.85%和72.29%,其他剩余材料对3个供试秆锈菌小种表现中抗或高抗。分子标记分析表明,83份主要小麦品种(系)中有12份可能含有Sr2;克旱3号可能含有Sr25;6份小麦品种可能含有Sr31;19份小麦品种可能含有Sr38;没有检测出含有Sr24和Sr26的品种。因此,黑龙江省小麦品种对中国小麦秆锈病抗性水平相对较高,含有抗秆锈病基因Sr2以及对我国小麦秆锈病表现良好抗性的基因Sr31和Sr38,可能含有其他未知抗秆锈病基因,这些优良抗源材料可作为未来小麦生产育种的种质资源。     

30个小麦新品系抗条锈病基因分析及成株期抗病性评价

 小麦条锈病是影响我国小麦生产的重要病害之一,利用抗病品种是控制小麦条锈病流行的最经济有效的措施。逐步澄清我国小麦品种抗病基因组成及特点是合理利用抗病品种的基础。     

Gene Action and Linkage of Avirulence Genes to DNA Markers in the Rust Fungus Puccinia graminis

ABSTRACT Two strains of the wheat stem rust fungus, Puccinia graminis f. sp. tritici, were crossed on barberry, and a single F(1) progeny strain was selfed. The parents, F(1), and 81 F(2) progeny were examined for virulence phenotypes on wheat differential cultivars carrying stem rust resistance (Sr) genes. For eight Sr differentials, phenotypic ratios are suggestive of single dominant avirulence genes AvrT6, AvrT8a, AvrT9a, AvrT10, AvrT21, AvrT28, AvrT30, and AvrTU. Avirulence on the Sr; (Sr 'fleck') differential showed phenotypic ratios of approximately 15:1, indicating epistatic interaction of two genes dominant for avirulence. Avirulence on Sr9d favored a 3:13 over a 1:3 ratio, possibly indicating two segregating genes-one dominant for avirulence and one dominant for avirulence inhibition. Linkage analysis of eight single dominant avirulence genes and 970 DNA markers identified DNA markers linked to each of these avirulence genes. The closest linkages between AvrT genes and DNA markers were between AvrT6 and the random amplified polymorphic DNA marker crl34-155 (6 centimorgans [cM]) AvrT8a and the amplified fragment length polymorphism marker eAC/mCT-197 (6 cM) and between AvrT9a and the amplified fragment length polymorphism marker eAC/mCT-184 (6 cM). AvrT10 and AvrTU are linked at distance of 9 cM.     

African wheat germplasm – a valuable resource for resistance to rust diseases

Known and unknown genes conferring seedling and adult plant resistance (APR) to leaf rust, stem rust and stripe rust were detected either singly or in combination in a set of 136 African wheat genotypes using multi-pathotype tests with characterized Australian Puccinia triticina (Pt), P. graminis f. sp. tritici (Pgt) and P. striiformis f. sp. tritici (Pst) pathotypes. Lines Beladi 132, IYN 68/9.44, Kenya Kifaru and Kenya Mbweha were postulated to carry resistance against multiple pathotypes of Pt, Pgt and Pst, whereas IAR/W/163-3, Grano Di Moggio Tipo 44 and Trigo 48 had resistance against all pathotypes tested in the current study. Field evaluation with the three rust pathogens detected low to high APR in more than 50% of lines, and while most tested positive with markers linked to known APR genes (csLV34, csLV46G22, TM10KASPAR, csGS, Cfb5006 and csSr2), many carried unidentified and useful resistance to all three rusts. Genetic analysis of F₃ mapping populations based on seven genotypes showed either monogenic or digenic inheritance of APR to leaf rust, stem rust and stripe rust. The lines postulated to carry effective uncharacterized seedling genes and APR genes are of great potential value in diversifying resistance to help achieve durable control of all three rust diseases of wheat.     

远缘杂交衍生后代中筛选小麦抗条锈病新抗源

 针对小麦远缘杂交的一系列衍生系,在陕西杨凌人工条锈病圃(CYR32和CYR33混合小种)选择压力下,兼顾抗病性与农艺性状,经过连续6年系统选择,筛选了106份远缘杂交衍生后代选系。在此基础上,通过杨凌人工混合小种接种鉴定圃和甘肃天水自然诱发鉴定圃,对其进行成株期抗条锈病鉴定;利用当前流行小种CYR32、CYR33和G22-9进行苗期分小种鉴定;结合Yr26的分子标记检测评估抗源价值。建立基于成株期与苗期抗病性鉴定相结合,异地抗病表型鉴定与分子标记筛查的抗源筛选和评价体系。结果表明:106份远缘杂交后代衍生系中,筛选出54个能够抵抗包括G22-9在内的多个流行小种的选系;结合标记筛查结果,筛选到36份不含Yr26的抗病材料,其中4份为全生育期抗条锈病性类型(ASR),32份为成株期抗性(APR)类型。推测这些抗性选系可能具有抗条锈病新基因。     

Performance and Mapping of Leaf Rust Resistance Transferred to Wheat from Triticum timopheevii subsp. armeniacum

ABSTRACT Host plant resistance is an economical and environmentally sound method of control of leaf rust caused by the fungus Puccinia triticina, which is one of the most serious diseases of wheat (Triticum aestivum) worldwide. Wild relatives of wheat, including the tetraploid T. timopheevii subsp. armeniacum, represent an important source of genes for resistance to leaf rust. The objectives of this study were to (i) evaluate the performance of leaf rust resistance genes previously transferred to wheat from three accessions of T. timopheevii subsp. armeniacum, (ii) determine inheritance and allelic relationship of the new leaf rust resistance genes, and (iii) determine the genetic map location of one of the T. timopheevii subsp. armeniacum-derived genes using microsatellite markers. The leaf rust resistance gene transferred to hexaploid wheat from accession TA 28 of T. timopheevii subsp. armeniacum exhibited slightly different infection types (ITs) to diverse races of leaf rust in inoculated tests of seedlings compared with the gene transferred from TA 870 and TA 874. High ITs were exhibited when seedlings of all the germ plasm lines were inoculated with P. triticina races MBRL and PNMQ. However, low ITs were observed on adult plants of all lines having the T. timopheevii subsp. armeniacum-derived genes for resistance in the field at locations in Kansas and Texas. Analysis of crosses between resistant germ plasm lines showed that accessions TA 870 and TA 874 donated the same gene for resistance to leaf rust and TA 28 donated an independent resistance gene. The gene donated to germ plasm line KS96WGRC36 from TA 870 of T. timopheevii subsp. armeniacum was linked to microsatellite markers Xgwm382 (6.7 cM) and Xgdm87 (9.4 cM) on wheat chromosome arm 2B long. This new leaf rust resistance gene is designated Lr50. It is the first named gene for leaf rust resistance transferred from wild timopheevi wheat and is the only Lr gene located on the long arm of wheat homoeologous group 2 chromosomes.     

Virulence analysis of Puccinia graminis f.sp. tritici populations in Ethiopia with special consideration of Ug99

Wheat stem rust samples were collected in 2006 and 2007 in the Arsi, Bale, Shewa and northwest regions of Ethiopia to determine virulence diversity and race distribution in Puccinia graminis f.sp. tritici populations. Stem rust incidence was high in Arsi, Bale and east Shewa. In northwest Ethiopia, and north and west Shewa, stem rust was prevalent at low levels. A total of 152 isolates was analysed and 22 races were identified. Races TTKSR (Ug99), TTHSR and RRTTR were predominant, with frequencies of 26·6, 17·7 and 11·1%, respectively. These races were also detected in all regions. The highly virulent race designated Ug99 was present throughout the country and dominated in all regions except northwest Ethiopia. A variant of Ug99 virulent against the stem rust resistance gene Sr24 was not detected in this study. Four stem rust resistance genes ( Sr13, Sr30, Sr36 and SrTm p) were found to confer resistance to most of the races prevalent in Ethiopia. With the exception of Sr30 , which is not effective against Ug99, these genes could be used in breeding for resistance to stem rust in Ethiopia.     

四川省100个小麦品种(系)抗条锈病基因的 分子检测

 为了解四川省近年小麦生产品种和后备品种对条锈菌致病类型G22-83和流行小种CYR32、CYR33的抗性水平,明确已知的主要抗条锈基因在该地区小麦品种中分布状况,利用小麦条锈菌G22-83、CYR32和CYR33对四川省100个小麦品种(系)进行苗期抗病性鉴定;采用已知基因Yr5、Yr9、Yr10、Yr15、Yr18 和Yr26的分子标记,对供试小麦材料进行抗性基因检测。结果表明,100个供试材料中,对CYR32 表现抗病的58份,占58%;对CYR33 表现抗病的63份,占63%;对G22表现抗病的43份,占43%;对CYR32、CYR33和G22均表现抗病性的品种(系)28个,占28%。供试小麦品种(系)中携带Yr9、Yr10、Yr15 和Yr26基因的材料分别有24份(24%)、9份(9%)、5份(5%)和26份(26%),所有供试品种(系)中未检测到Yr5和Yr18基因。     

Characterization of Puccinia graminis f. sp. tritici isolates derived from an unusual wheat stem rust outbreak in Germany in 2013

An unusual stem rust infestation occurred in German wheat fields in summer 2013. This study analysed 48 isolates derived from 17 Puccinia graminis f. sp. tritici (Pgt) samples and six races were identified: TKTTF, TKKTF, TKPTF, TKKTP, PKPTF and MMMTF. Infection type and genotypic data confirmed that none of these races belonged to the TTKS (Ug99) race group. German isolates of race TKTTF are phenotypically different to the ones responsible for the stem rust epidemic in Ethiopia in 2013–2014. Forty isolates were genotyped using a custom SNP array. Phylogenetic analysis showed that these 40 isolates represented two distinct lineages (clade IV and clade V). Thirty‐eight isolates clustered into clade IV, which previously was defined by Ethiopian isolates of race TKTTF. Race TKKTP is of special concern due to its combined virulence to stem rust resistance genes Sr24, SrTmp and Sr1RS^Amigo. The vulnerability to race TKKTP in US and international winter wheat was confirmed as 55% of North American and international cultivars and breeding lines resistant to race TTKSK (Ug99) became susceptible to TKKTP. Races identified in Germany in 2013 confirmed the presence of virulence to important resistance genes that are effective against race TTKSK. This information should be useful for breeders to select diverse and effective resistance genes in order to provide more durable stem rust resistance and reduce the use of fungicides.     

Genetics of resistance to wheat leaf rust, stem rust, and powdery mildew in Aegilops sharonensis

Aegilops sharonensis (Sharon goatgrass) is a wild relative of wheat and a rich source of genetic diversity for disease resistance. The objectives of this study were to determine the genetic basis of leaf rust, stem rust, and powdery mildew resistance in A. sharonensis and also the allelic relationships between genes controlling resistance to each disease. Progeny from crosses between resistant and susceptible accessions were evaluated for their disease reaction at the seedling and/or adult plant stage to determine the number and action of genes conferring resistance. Two different genes conferring resistance to leaf rust races THBJ and BBBB were identified in accessions 1644 and 603. For stem rust, the same single gene was found to confer resistance to race TTTT in accessions 1644 and 2229. Resistance to stem rust race TPMK was conferred by two genes in accessions 1644 and 603. A contingency test revealed no association between genes conferring resistance to leaf rust race THBJ and stem rust race TTTT or between genes conferring resistance to stem rust race TTTT and powdery mildew isolate UM06-01, indicating that the respective resistance genes are not linked. Three accessions (1644, 2229, and 1193) were found to carry a single gene for resistance to powdery mildew. Allelism tests revealed that the resistance gene in accession 1644 is different from the respective single genes present in either 2229 or 1193. The simple inheritance of leaf rust, stem rust, and powdery mildew resistance in A. sharonensis should simplify the transfer of resistance to wheat in wide crosses.     

小麦持久抗条锈病品种Champlein的抗性遗传分析

小麦条锈病是小麦生产中最重要的病害,培育抗病品种是防治条锈病最经济、有效、安全的措施。‘Cham-plein’引自法国,对条锈菌生理小种表现良好持久抗性。为了明确其抗性遗传特点,以感病品种‘铭贤169’与其杂交、自交和回交获得了F1、F2、F3和BC1代,人工接种小麦条锈菌生理小种CY32,在温室和田间对‘Champlein’进行遗传分析。结果表明:苗期‘Champlein’对CY32的抗病性由1对显性基因控制;成株期‘Champlein’对CY32的抗病性由2对显性和1对隐性抗条锈病基因以互补方式控制;系谱分析表明基因可能来源于‘Vilmorin27’。     

小麦秆锈菌新小种Ug99及其对我国的影响分析

Ug99(TTKS)是1999年在乌干达首次发现的对最重要小麦抗秆锈病基因Sr31有强毒力的秆锈菌新小种。大量证据显示:该小种不仅具有极其特殊的毒力组合而且传播十分迅速,除在中非乌干达、东非肯尼亚、埃塞俄比亚、苏丹流行外,Ug99现已越过红海、传到了阿拉伯国家也门,以及巴基斯坦的沿海地区,越来越逼近我国。Ug99堪称我国的超毒小种,我国最典型的秆锈菌小种只能分别克服或Sr5或Sr9 e或Sr11单基因抗性,而Ug99不仅具有Sr5、Sr9 e、Sr11的联合毒力,而且还具有Sr21、Sr31、Sr38的联合毒力,而我国从未有小种能克服后者的抗性。1B/1L(含Sr31)易位系曾是我国使用的重要秆锈抗源,必对Ug99高度脆弱,我国118份小麦品种在KARI的测定结果表明,高感品种频率98.3%。一旦Ug99入侵我国,其他流行条件也完全具备。因此,充分作好防范Ug99流行的准备十分必要。     

A unique race of the wheat stem rust pathogen with virulence on Sr31 identified in Spain and reaction of wheat and durum cultivars to this race

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a re-emerging disease, posing a threat to wheat production. In Spain, stem rust has been rarely detected since the 1970s, but infection was observed in wheat fields in 2018. We analysed six stem rust samples collected in Rota, Cádiz province and one from Monteagudo del Castillo, Teruel province. All the samples from Rota were typed as race TKTTF, whereas the sample from Monteagudo del Castillo, collected in a wheat field adjacent to barberry bushes, was typed as race TKHBK. This race has a unique and significant virulence combination that includes virulence to Sr31, Sr33, Sr53 and Sr59, and is avirulent to Rusty, a durum line developed for universal susceptibility to the wheat stem rust pathogen. TKHBK is the first race outside the Ug99 race group with virulence to Sr31 and the first known race with virulence to Sr59. Genotyping studies indicate that race TKHBK does not belong to the Ug99 or TKTTF race groups and constitutes a previously unknown lineage. Two hundred bread and durum wheat cultivars and breeding lines from Spain were evaluated against TKHBK, TKTTF, and six additional races. Resistance was observed to all the races evaluated. Molecular markers confirmed the presence of Sr7a, Sr24, Sr31, Sr38 and Sr57 in bread wheat, and Sr13 in durum wheat. The re-emergence of wheat stem rust in Spain and the occurrence of unique virulences underscore the need to continue surveying and monitoring this disease.