Yr5-virulent races of Puccinia striiformis f.sp.tritici possess relative parasitic fitness higher than current main predominant races and potential risk

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is one of the most destructive fungal diseases of wheat,and seriously threatens safe production of the crop worldwide.In China,new races historically appeared and rapidly developed to be predominant races and have resulted in ineffectiveness and replacement of wheat resistance cultivars as well as massive reduction in yield.In the present study,the relative parasitic fitness of the two newlyemerged Yr5-virulent races(TSA-6 and TSA-9)were compared with those of four currently predominant Chinese races(CYR31,CYR32,CYR33,and CYR34)based on evaluation on 10 Chinese wheat cultivars.As a result,there were significant differences in the relative parasitic fitness parameters among overall tested races based on multiple comparison(LSD)analysis(P<0.05).The principal component analysis(PCA)of overall parasitic fitness parameters indicated that the sporulation ability,infection and spore survivability,expansion capacity,and potential pathogenicity were the most important parasitic fitness attributes of the tested races.Based on the establishment of extracted three principal components and a comprehensive factor score mathematical models,evaluations of the parasitic fitness attributes of tested races showed that the level of relative parasitic fitness of the tested six races was:CYR32(1.15)>TSA-9(0.95)>TSA-6(0.92)>CYR34(0.29)>CYR31(–1.54)>CYR33(–1.77).The results indicated that two Yr5-virulent races TSA-9 and TSA-6 possessed relative parasitic fitness higher than races CYR34,CYR31,and CYR33,but lower than race CYR32,and have potential risks in developing to be predominant races.Therefore,continual monitoring of both Yr5-virulent races,and their variants is needed.The use of wheat cultivars(lines)with Yr5 resistance gene singly in wheat breeding is essential for being avoided,and is suggested to combine with other effective stripe rust resistance genes.

Identification of eight Berberis species from the Yunnan-Guizhou plateau as aecial hosts for Puccinia striiformis f.sp.tritici,the wheat stripe rust pathogen

Puccinia striiformis Westend.f.sp.tritici Erikss.(Pst)infects wheat and causes stripe rust.The rust is heteroecious with wheat as the primary uredinial and telial host and barberry(Berberis spp.)as the alternate pycnial and aecial host.More than 40 Berberis species have been identified as alternate hosts for Pst,and most of these are Chinese Berberis species.However,little is known about Berberis species or their geographic distributions in the Yunnan-Guizhou plateau in southwestern China.The Yunnan-Guizhou plateau is considered to be an important and relatively independent region for the evolution of the wheat stripe rust pathogen in China because the entire disease cycle can be completed within the region.In this study,we conducted a survey of barberry plants in the Yunnan-Guizhou plateau and identified the eight Pst-susceptible Berberis species under controlled conditions,including B.julianae,B.tsienii,B.veitchii,B.wilsonae,B.wilsonae var.guhtzunica,B.franchetiana,B.lepidifolia and B.pruinosa.These species are reported here for the first time to serve as alternate hosts for the wheat stripe rust pathogen under controlled conditions.

Association Analysis of SP-SNPs and Avirulence Genes in Puccinia striiformis f. sp. tritici, the Wheat Stripe Rust Pathogen

Puccinia striiformis f. sp. tritici (Pst) is one of the pathogenic fungi on wheat, caused stripe rust that is a great threat for wheat production all over the world. Intensive efforts have been made to study genetics of wheat resistance to this disease, but few on avirulence of the pathogen due mainly to the nature of obligate biotrophism and the lack of systems for studying its genetics and molecular manipulations. To overcome these limitations, a natural Pst population comprising 352 isolates representative of a diverse virulence spectrum was genotyped using 97 secreted protein-single nucleotide polymorphism (SP-SNP) markers to identify candidate avirulence genes using association analysis. Among avirulence genes corresponding to 19 resistance genes, significantly associated SP-SNP markers were detected for avirulence genes AvYr1, AvYr2, AvYr6, AvYr7, AvYr8, AvYr44, AvYrExp2, AvYrSP, and AvYrTye. These results indicate that association analysis can be used to identify markers for avirulence genes. This study has laid the foundation for developing more SP-SNPs for mapping avirulence genes using segregating populations that can be generated through sexual reproduction on alternate hosts of the pathogen.

Study Genetic Variation Using DNA Molecular Markers and Identification Physiological Races of Wheat Stripe （yellow） Rust Puccinia striiformis f.sp tritici during 2010-2014 in Some Regions of Syria

Yellow Rust （stripe） rust （Puccinia striiformis West. f. sp. tritici） is one of the most epidemic diseases infect wheat in cold and wet regions. In 1988, this disease caused a loss of seasonal production amounted 70% on wheat variety Mexipak in Syria, and recurrent infection in 2010, caused by a virulent race called Yr27, caused a considerable loss in the production of bread wheat cultivars （Cham 8, Cham 6 particularly） amounted 90%. Recently, 15 races of yellow rust had been addressed in Syria for seasons 2010-2014; 159E256, 166E254, 166E256, 255 E112, 0 E0, 64 E 6, 230 El50, 0 E 18, 198 El30, 166 El50, 102 El60, 128 E0, 126 El50, 214E150, and 6E16. The race 6E16 was the most frequent during the two seasons, while the race 255El12 was the most virulent, followed by the race 230E222 and the race 0E0 was the weakest one. This study revealed the presence of fourteen newly observed races in Syria. Molecular Variance Analysis of Molecular Variance （AMOVA） of 55 yellow rust Puccinia striiformis f.sp tritici isolates examined by Amplify Fragment Length Polymorphism （AFLP） revealed high genetic variation within population, and the dimensional scale analysis （MSD） and tree diagram showed that the Syrian yellow rust isolates were clustered in three groups： the first group contained isolates derived from durum wheat, the second one contained bread wheat isolates, but the third was made of isolates derived from both durum and bread wheat species.

Molecular mapping of stripe rust resistance gene YrH9017 in wheat-Psathyrostachys huashanica introgression line H9017-14-16-5-3

Several new stripe rust pathogen races emerged in the wheat growing regions of China in recent years.These races were virulent to most of the designated wheat seedling resistance genes.Thus,it is necessary and worthwhile to identify new valuable resistant materials for the sake of diversifying resistant sources,pyramiding different resistance genes and achieving durable resistance.Here,we identified the resistance gene,temporarily designated as YrH9017,in wheat-Psathyrostachys huashanica introgression line H9017-14-16-5-3.A total of 146 F2 plants and their derived F2:3 families in a cross of Mingxian 169 and H9017-14-16-5-3 were used to evaluate seedling stripe rust response and as a mapping population.Finally,we constructed a genetic map including eight simple sequence repeat(SSR) markers and expressed sequence tag(EST) markers.YrH9017 was located on the long arm of chromosome 2A and closely linked with two EST-sequence tagged site(EST-STS) markers BG604577 and BE471201 at 1.3 and 1.8 cM distance,respectively.The two closest markers could be used for marker-assisted selection of YrH9017 in breeding.

Effects of UV-B radiation intensity and timing on epidemiological components of wheat stripe rust

Stripe rust caused by Puccinia striiformis f. sp. tritici is an important wheat disease worldwide that is greatly influenced by environmental conditions. Ultraviolet B(UV-B) radiation is one important environmental factor affecting the occurrence and epidemiology of wheat stripe rust. Investigating UV-B radiation effects on the epidemiology of stripe rust may be conducive to monitoring and predicting this disease. In this study, wheat seedlings were exposed to UV-B radiation during different periods under laboratory conditions and radiation effects on epidemiological components of wheat stripe rust were investigated. Results showed that incubation period was shortened, and the infection efficiency, sporulation quantity and disease index increased when UV-B radiation was performed only pre-inoculation. When the UV-B radiation was performed only postinoculation or both pre-and post-inoculation, the incubation period was prolonged, and the infection efficiency, sporulation quantity and disease index were reduced. When healthy wheat seedlings were inoculated using urediospores collected from wheat leaves irradiated by UV-B only post-inoculation or both pre-and post-inoculation, infection efficiency, sporulation quantity and disease index were also reduced. However, in the latter, the disease incubation period did not differ under varying UV-B radiation intensities compared to that when wheat leaves were not treated with UV-B radiation. Overall, the effects of direct exposure of wheat plants to UV-B radiation with different intensities in different periods on epidemiological components of wheat stripe rust were systematically explored, and the results suggest that the effects of UV-B radiation increased gradually with the increase of UV-B radiation intensity. This information provides a basis for monitoring and predicting this disease as well as for conducting further studies on pathogen virulence variation.

Variation in Telial Formation of <i>Puccinia striiformis</i>in the United States

Puccinia striiformis, the causal agent of stripe rust in wheat, barley, and various wild grasses, produces urediniospores and teliospores on these primary or auxiliary hosts. Telial formation, which stops producing infectious urediniospores, is affected by various host and environmental conditions. However, it is not clear if variation exists among different isolates in the United States. To determine the differences in the pathogen population, 1423 isolates collected in the United States from 2013 to 2016 were tested for telial formation in the seedling stage at a diurnal temperature profile of 4&deg;C - 20&deg;C. The percentages of telial formation varied greatly among the isolates. Of the 1423 isolates, 62.97% produced telia with the percentages of telial formation ranging from 1% to 95% under the test conditions. The formation of telia was significantly affected by the year and the month when the isolates were collected. The epidemiological regions or states, host plants (wheat, barley, and grasses), and races of the isolates did not significantly affect telial formation. However, significant effects on telial formation were observed by interactions between year and region, year and race, month and region and among year, month, and region, as well as between year and month. The results showed that telial formation is a complex trait under the genetic control of the pathogen isolates for adaptation to different environments. Further studies are needed to identify genes involved in the formation of telia and the relationship of telial formation to the survival, aggressiveness, fitness, and evolution of the pathogen.

Wheat Stripe Rust Virulence and Varietal Resistance in the Foot Hill Himalayas of Nepal

Stripe rust, caused by Puccinia striiformis f. sp. tritici （Pst） is an important disease of wheat （Triticum aestivum） in Nepal, which is a part of the Himalayas stretching over the North of Nepal, India, Pakistan, Bhutan and beyond. Wheat production plays a crucial role in food security of the marginal hill farmers of Nepal. Frequent epidemics of the rust have caused huge loss in farmer＇s field. Periodic monitoring during 1980-2008 showed that changes in virulence occurred during this period. The objective of this study was to evaluate Pst resistance and its effective genes in wheat genotypes. For this, trap nurseries, wheat stripe rust differentials, commercial cultivars and advanced breeding lines were tested under artificial epiphytotic and natural hot spots conditions during 2005 to 2010. Four genes （Yr5, Yr10, Yr15 and YrSp） consistently showed resistance to the prevailing races. The gene Yr9 and Yr27 in combinations with Yrl8 were found effective. Other lines with combination of minor genes were also found effective. The genotypes Amadina, Kukuna, Tukuru, Kakatsi and Buck Buck widely used in breeding program were resistant. The cultivation of varieties WK1204, Gautam, Gaura and Dhaulagiri have ensured genetic diversity for the rust resistance and slowed down frequent occurrence of epidemics. The findings of these studies could help in developing effective varietal resistance program in the sub-continent.

小麦条锈病跨区域全周期绿色防控技术体系的构建与应用

小麦条锈病是我国小麦生产上一种跨区域流行的重大病害。1949年以来,我国小麦条锈病研究,治理能力明显提升,发病面积、流行程度、流行频率明显降低,但由于条锈菌Puccinia striiformis f.sp.tritici新毒性小种不断产生和气候异常变化等因素的影响,近年来其流行规律和成灾机制出现了新的变化,发生危害加重,严重威胁小麦生产和国家粮食安全。基于“十二五”以来我国在小麦条锈病菌毒性新小种产生、有性生殖、侵染循环和大区流行规律等方面的最新研究成果,作者在学习和实践以往病害治理经验的基础上,坚持长短结合、标本兼治、分区治理、综合防治的指导思想,制定了“以绿色防控为基础,以全周期管理为重点,以跨区域联防联控为保障”的防控策略,提出了精准监测预报、毒性小种变异监测、早期菌源控制、抗病品种合理布局和应急防控等关键技术,集成构建了全国小麦条锈病跨区域全周期绿色防控技术体系,制定了越夏易变区、冬季繁殖区(越冬区)和春季流行区分区防控技术体系。经在小麦条锈病主要流行区大面积试验示范,取得了防控效果85%以上,化学农药用量减少10%以上,小麦单产提高5%以上的成效。2022年-2023年在全国小麦主产区大范围组织推广应用,有效控制了小麦条锈病严重流行势头,全国病害发生面积出现了新低,有效减轻了灾害损失,保障了国家粮食安全。

Genomic analysis,trajectory tracking,and field surveys reveal sources and long-distance dispersal routes of wheat stripe rust pathogen in China

Identifying sources of phytopathogen inoculum and determining their contributions to disease outbreaks are essential for predicting disease development and establishing control strategies.Puccinia striiformis f.sp.tritici(Pst),the causal agent of wheat stripe rust,is an airborne fungal pathogen with rapid virulence variation that threatens wheat production through its long-distance migration.Because of wide variation in geographic features,climatic conditions,and wheat production systems,Pst sources and related dispersal routes in China are largely unclear.In the present study,we performed genomic analyses of 154 Pst isolates from all major wheat-growing regions in China to determine Pst population structure and diversity.Through trajectory tracking,historical migration studies,genetic introgression analyses,and field surveys,we investigated Pst sources and their contributions to wheat stripe rust epidemics.We identified Longnan,the Himalayan region,and the Guizhou Plateau,which contain the highest population genetic diversities,as the Pst sources in China.Pst from Longnan disseminates mainly to eastern Liupan Mountain,the Sichuan Basin,and eastern Qinghai;that from the Himalayan region spreads mainly to the Sichuan Basin and eastern Qinghai;and that from the Guizhou Plateau migrates mainly to the Sichuan Basin and the Central Plain.These findings improve our current understanding of wheat stripe rust epidemics in China and emphasize the need for managing stripe rust on a national scale.

1997～2001年我国小麦条锈菌生理小种变化动态

1997～ 2 0 0 1年采自我国 13个省和自治区的主要生产品种和重要抗源上的小麦条锈菌标样 4 0 0 8份 ,其鉴定结果基本反映了这期间我国小麦条锈菌生理小种的变化状况。 1997年发现了水源 11致病类型 13和 14 ,2 0 0 1年把原Hybrid 4 6致病类型 3(HY 3)命名为条中 32号。这期间共监测到 4 1个小种和致病类型 ,每年都能监测到的小种和致病类型有 32个 ,为条中 17、19、2 1、2 2、2 3、2 5、2 6、2 8号 ,洛 10 2 ,条中 2 9,洛 13 2、3,条中 30、31、32 ,Hybrid 4 6 4、5、6、7、8,水源 11 2、3、4、5、6、7、8、10、11、12、13和 14。条中2 9、30、31、32号为主要流行小种。 1997～ 2 0 0 0年间条中 31号位居第一 ,出现频率为 10 .8%～ 13.5 % ,其次为条中 32号 (4 .8%～11.7% ) ,由于条中 32号逐年持续上升 ,2 0 0 1年超过条中 31号而位居第一。其次是条中 2 9和 30号 ,两者出现频率基本相当 ,1997～ 1999年条中 2 9号略高位第 3(3.3%～ 4 .0 % ) ,条中 30号位第 4 (2 .6 %～ 3.3% ) ,2 0 0 0～ 2 0 0 1年 ,条中 30号略高位第 3(3.6 %～7.3% ) ,条中 2 9号位第 4 (2 .7%～ 3.1% )。出现频率较高的还有条中 2 3号、2 5号、2 6号、2 8号和Hybrid 4 6 4、5、7、8,水源 11 3、4、5、7、11、13和 14 ,其它为?

三个小麦野生近缘种抗条锈性传递的初步研究

以当前小麦条锈病菌的优势小种条中２９ 号、３０ 号和３１ 号测定了小麦近缘植物长穗偃麦草、簇毛麦和华山新麦草及其各自与小麦的杂交后代的抗条锈性。试验结果表明，３ 个小麦近缘植物均含有宝贵的抗条锈基因，此类基因具有较强的传递性能，可在小麦遗传背景下高度表达，表现出良好的抗条锈性能。

小麦品种贵农22号抗条锈基因遗传分析

贵农22号是利用簇毛麦 Haynaldiavillosa 、硬粒小麦 Triticumdurum 及普通小麦 Triticum.aestuvum 杂交而育成的普通小麦品种,其抗中国目前流行和出现的条锈菌小种,已成为目前重要的抗小麦条锈病抗源.为了明确该品种抗锈遗传规律并进行应用前景评价,用一个流行的强毒性小种条中31号和一个突变弱毒性小种CY29-mut3,分别接种贵农22与国际已知抗锈基因品种Moro及感病品种辉县红双列杂交F2、F3代各株系幼苗,对贵农22号进行了抗锈性遗传分析,以便于在抗病育种中进一步应用.研究结果表明,贵农22号有三对独立遗传的抗条锈基因,暂定名为YrGui1、YrGui2和YrGui3,它们表达稳定,不受亲本正反交影响,而并不具有Yr10.Yr10基因载体品种Moro中有二或四对基因抗中国不同的条锈菌小种,不同小种及正反交对基因的表达有影响,为父本时其对CY29-mut3小种有两对完全显性基因、一对中度抗病基因及一对隐性抗病基因,而为母本时有一对完全显性基因和一对中度抗病基因起抗病作用;对条中31号,其为父本时有一对显性基因和一对隐性基因,为母本时可能存在两对累加作用基因或两对隐性抗病基因控制抗病作用.

80份国外春小麦种质资源抗条锈性评价

【目的】小麦条锈病是由小麦条锈菌(Puccinia striiformis f.sp.tritici,Pst)引起的世界范围内小麦重要病害之一,培育和种植抗病品种是控制该病害的最有效策略。评价80份国外春小麦种质资源对中国当前小麦条锈菌流行小种的抗条锈性,为中国小麦抗条锈病育种提供依据和抗源。【方法】应用中国流行小麦条锈菌生理小种CYR29、CYR31、CYR32、CYR33以及致病类型PST-HY8和PST-V26对80份国外小麦种质资源进行苗期温室抗病性鉴定,以铭贤169和Av S为感病对照品种;并于2013年和2014年分别在陕西省杨凌和甘肃省天水进行田间成株期抗病性鉴定。根据苗期和田间成株期的抗病性鉴定结果对其进行抗病类型分类和评价。【结果】80份小麦种质资源的抗病类型可分为3类。第1类为全生育期抗病类型,有8份。其中PI660067、PI660119和PI660122在苗期和田间成株期均表现较高水平的抗病性。其余5个品系PI660056、PI607839、PI591045、TA5602和PI660064在苗期则对个别小种表现感病,并且在不同年份和不同测试地点成株期也表现感病。第2类为成株抗病类型,有28份。其苗期对所有测试小种均表现感病,有23份在田间成株期均表现抗病。但PI660075、PI660083、PI660085、PI660097和PI660107在不同年份和不同测试地点成株期表现感病。第3类为兼具成株期和对部分中国小种失去抗性的全生育期抗病类型,有44份,其苗期至少对一个测试小种表现抗病。有37份在田间成株期均表现抗病。但PI660065、PI660076、PI660079、PI660080、PI660095、PI660096和PI610750在不同年份和不同测试地点成株期表现感病。【结论】80份国外小麦种质资源中大部分对中国小麦条锈菌流行小种表现优良的抗病性。这些种质资源可作为抗源在今后抗病育种中加以利用,将丰富中国小麦抗条锈病基因的多样性。可能由于不同年份田间流行小种不同,造成一些成株抗病品系在不同年份和不同测试地点表现感病,由此推测成株抗病性可能也具有小种专化性。

豫鲁皖三省重要小麦品种抗条锈基因推导

根据对 2 6个不同毒性谱的小麦条锈菌菌系的反应 ,并结合品种系谱分析 ,研究了河南、山东和安徽 3省的 50个重要小麦生产品种所具有的抗条锈基因。结果表明 ,没有 1个品种可抵抗所有供试的 2 6个条锈菌菌系 ,在已知的抗条锈基因中 Yr9所占比例最大 ,至少存在于 17个品种中 ,Yr2和Yr 1次之 ,分别存在于 10个和 8个品种中 ,个别品种则具有 Yr A、Yr 3或 Yr Sel,还有些品种可能具有未知的抗条锈基因或基因组合。由于上述已知基因对目前的条锈菌优势小种基本上均不抵抗 ,培育和推广具有效抗条锈基因的新品种迫在眉睫。

2017年我国小麦条锈病流行特点及重发原因分析

2017年小麦条锈病在我国黄淮海麦区大范围流行,表现出汉水流域及黄淮南部见病时间早、扩散速度快、黄淮海麦区流行范围广等特点。本文在系统总结2017年全国小麦条锈病流行特点的基础上,分析认为极端暖冬气候、春季多雨适温气候条件和主产麦区缺乏抗性品种等因素是导致2017年我国小麦条锈病大流行的主要原因。

小麦品种抗条锈性分化的初步研究

以小麦条锈菌野生菌系（ＣＹＲ２９－１）及其７个毒性突变菌株测定小麦品种的抗锈性分化，发现水源１１、抗引６５５和无芒中四群体对某些菌系有抗病性分化，一些抗源品种和后备品种也出现比例不同的抗感植株和不同低反应型的植株，证实这些品种群体对不同菌系具有抗病异质性。讨论了品种抗锈性分化的原因及在抗病品种丧失抗锈性中的作用，对改进小种鉴定。

小偃6号抗条锈基因遗传分析及分子标记

用小麦条锈菌CY29-mut3、CY28、CY27和CY25分别接种小偃6号、铭贤169及其F2代各株系，在常温下（15～17℃）和高温下（20～22℃）进行了小偃6号抗条锈基因的遗传分析。结果发现，在常温下，小偃6号对4个条锈菌生理小种的抗病性均由1对显性核基因控制；在高温下，其抗病性由2对或3对基因控制，但其正反交的作用方式不同，抗锈性也可能与细胞质遗传有关；筛选到与抗条锈基因连锁的RAPD标记，分别命名为OPT17650、OPC111000。同时，具有长穗偃麦草血缘的小麦品种小偃22对OPC11进行了验证，明确了其在分子辅助育种中的价值。

四川省常规小麦品种抗条锈基因推导初报

根据对已知毒性基因的26个不同毒性谱小麦条锈菌的反应,结合系谱分析,研究了四川省32个常规小麦品种所具有的抗条锈基因。结果表明,在已知的抗条锈基因中,Yr2所占比例最大,至少存在于川麦29等7个品种中,Yr9次之,存在于绵农5号等4个品种中,个别品种则具有YrA、YrSel或Yr15,还有些品种可能具有未知的抗条锈基因或基因组合,但没有一个品种能够抵抗所有供试的26个条锈菌菌系,培育和推广具有有效抗条锈基因的新品种迫在眉睫。

2000～2006年新育成小麦品种(系)抗条锈性鉴定分析

为了明确2000-2006年新育成小麦品种（系）的抗条锈性,采用条锈菌优势小种对1212份小麦高代品系以及339份陕西省区试小麦品种分小种进行了抗条锈性鉴定。结果表明,供试品种（系）对条锈菌优势小种CY31、CY32及Su11-14的抗病性普遍较低,新育成小麦高代品系和陕西省区试品种对三个菌系抗病的频率分别为10.43%-55.30%和8.89%-44.82%。其中,远缘杂交后代品种（系）的抗锈性较好。另外,2001-2006年在自然诱发发病情况下,陕西省小麦区试岐山点和杨凌点共292份品种,抗病品种频率分别为5.88%-50.88%和0-50.88%。