中国小麦条锈菌转主寄主小檗的鉴定

用萌发的小麦条锈菌冬孢子接种采自陕西省境内的陕西小檗、少齿小檗和长穗小檗,3种小檗均产生了性孢子器和锈孢子器。用人工接种小麦条锈菌冬孢子在陕西小檗上产生的锈孢子器接种小麦铭贤169产生了典型的条锈菌夏孢子堆症状。特异性PCR和DNA序列分析表明,人工接种产生于小檗上的锈孢子、接种锈孢子于小麦上产生的夏孢子堆与小麦条锈菌DNA的ITS区序列完全一致。更为重要的是,用采自田间受锈菌侵染的小檗叶片产生的锈孢子接种小麦铭贤169,经培养在小麦铭贤169叶片上产生了典型的条锈病症状。从而证实,在自然条件下,在中国,小檗不仅可作为小麦条锈菌的转主寄主,而且小麦条锈菌可在小檗上完成其有性繁殖过程。这一发现对进一步揭示我国小麦条锈菌高度的群体遗传多样性与毒性变异机理、完善小麦条锈病的防治策略具有十分重要的理论和实际意义。     

陇南越夏区自生麦苗条形柄锈菌毒性表型及分子基因型分析

为了解陇南地区越夏自生麦苗上条形柄锈菌的毒性组成及群体遗传结构,将采自天水、陇南及定西的自生麦苗上的39个单孢子堆菌系采用中、美鉴别寄主毒性分析法和TP-M13-SSR荧光标记技术,进行毒性鉴定并对其基因组DNA进行SSR标记分析。结果显示：在中国鉴别寄主上供试菌系被区分为9个致病类型,在美国鉴别寄主上则得到24个毒性类型,在中美鉴别寄主上共得到30个毒性表型。通过中国鉴别寄主鉴定的CYR32、CYR33为优势小种,毒性比率分别达到35.9%和30.8%。SSR标记将这些菌系划分为36个基因型,毒性分析与     

条形柄锈菌34号生理小种的分子标记

条形柄锈菌Puccinia striiformis f. sp. tritici 34号生理小种(CYR34)是目前我国毒性谱最宽、毒性最强的生理小种,对小麦生产和抗病品种选育造成了极大的影响。本研究采用RAPD-SCAR分子标记技术,从300条RAPD随机引物中筛选到CYR34的特异引物,通过特异性片段回收、克隆和测序(GenBank登录号为OL907303),依据序列设计出了S2008F34/S2008R34特异性引物,能够从CYR34及接种CYR34的小麦发病叶片总DNA中都扩增出417 bp的目标片段。采用该特异性引物检测2021年陕西渭南、咸阳和宝鸡地区小麦条锈菌CYR34的流行频率分别为8.6%、6.0%和10.8%。该项研究为小麦条锈菌CYR34号生理小种的快速检测提供了技术支撑。     

小麦新抗源贵农775抗条锈性特征与遗传分析

发掘并利用不同类型抗条锈病基因,构建区域间抗病基因多样性差异布局,是阻遏条锈菌大区域传播、实现小麦条锈病持续控制的重要策略。为了明确小麦新抗源贵农775抗条锈性特征和抗性遗传规律,为其合理布局应用提供依据,文章利用10个条锈菌菌系进行苗期分小种鉴定;构建贵农775与感病品种Avocet(S)杂交后代F2:3及回交BC1遗传群体,利用小麦条锈菌流行小种CYR32和最近发现的对Yr26基因有毒性的新致病类型CH42,对贵农775进行抗条锈性遗传分析。结果表明,贵农775对包括CH42致病类型在内的所有10个供试菌系均表现为免疫或近免疫的抗病性反应,而中国当前主要条锈病抗源品种92R137、川麦42(YrCH42)、贵农22(YrGN22)及Yr24等均不抗CH42;抗病遗传分析结果表明,贵农775对小麦条锈菌小种CYR32和CH42的抗性分别由一对显性核基因控制,并且为不同的小种专化抗性基因。     

小麦抗条锈基因Yr69的连锁标记开发

抗条锈病基因Yr69对我国小麦条锈菌(Puccinia striiformis f.sp.tritici)小种具有广谱抗性,在小麦抗条锈病育种中具有重要价值.为提高分子标记辅助选择育种的效率,加快Yr69在小麦抗病育种中的应用,本研究利用条锈菌小种CYR34对包含340个小麦家系的'Taichung29/CH7086'...     

温室条件下条形柄锈菌体细胞重组的分子确证

为了获得温室条件下条形柄锈菌发生体细胞重组而导致毒性变异的直接证据,本研究选取7个美国条形柄锈菌小麦专化型菌系和2个美国条形柄锈菌大麦专化型菌系按照夏孢子颜色和专化型与毒性差异组成9对菌系组合,对于室内混合接种产生的子代菌系用具有不同抗性的小麦或大麦品种进行筛选,采用毒性分析及SSR分子标记技术对条形柄锈菌体细胞重组现象进行了研究。对获取的413个单孢子代菌系进行的毒性分析结果显示,有84个单孢子代菌系的毒性谱表现与亲本菌系不同,初步证明体细胞重组过程的存在。SSR标记分析结果显示,11对SSR引物中有6对引物在5对菌系组合的28个毒性谱不同的单孢子代菌系中,检测发现3个单孢菌系的扩增条带与其亲本菌系不同,且表现为亲本菌系扩增条带的重组,为体细胞重组菌系。这一结果从分子水平上证明了条形柄锈菌在室内接种条件下可以通过体细胞重组产生新小种而导致毒性变异。     

西科麦2028抗条锈性的遗传分析

西科麦2028是地理远缘小麦材料的杂交后代,具有突出的抗条锈病性能。为了解西科麦2028对小麦条锈病的抗性遗传规律,以西科麦2028和铭贤169的杂交群体为研究对象,采用我国目前小麦条锈菌流行小种CYR31、CYR32、CYR33、Su11-4对供试群体进行成株期接种,分析杂交后代的抗病性及分布情况。结果表明:西科麦2028对CYR31的抗病性由3对显性基因控制;对CYR32由2对显性和1对隐性基因控制;对CYR33由1对显性基因控制;对Su11-4由1对显性和1对隐性基因控制。     

紫外线诱导小麦条锈菌毒性突变及突变体的RAPD分析

以夏孢子相对致死率90%左右作为紫外线处理最适时间,发现8min为小麦条锈菌条中29号单孢菌系(CY29-3)最适处理时间,其夏孢子相对致死率达88.97%。CY29-3的夏孢子经紫外线处理、扩繁、筛选品种筛选及4代的稳定选择后,获得了两个毒性变异的突变菌株。毒性突变产生的Jubi菌株对尤皮Ⅱ号的毒性增强,反应型由野生菌系的0型变为4型;非毒性突变产生的Funo菌株在阿夫上的反应型由野生菌系的4型变为2型。研究结果表明两突变菌株在鉴别寄主上的反应型和毒性范围也明显不同于野生菌系,说明紫外线诱导的小麦条锈菌变异是不定向和复杂的。对野生菌系和两个突变菌株进行RAPD分析后发现,两突变菌株与野生菌系之间的DNA多态性存在显著差异,多态率分别为10.58%和11.57%,说明紫外线可使小麦条锈菌基因组DNA发生较大的变化且突变位点比较复杂。     

条形柄锈菌小麦转化型夏孢子表面微观结构观测方法的建立

小麦条锈菌夏孢子表面微观结构的研究,对于夏孢子的萌发生长以及对条锈菌致病性的研究都具有很重要的意义。本研究以小麦条锈菌32号生理小种（CYR32）为材料,创新的采用硅片为基质,建立了利用原子力显微镜检测夏孢子样品表面的观测方法。结果表明,该方法优于其他基质材料,可以获得较为理想的扫描效果。为进一步研究小麦条锈菌夏孢子以及相近大小的病原体孢子表面特征提供了技术支撑。     

恶疫霉致病力和对甲霜灵敏感性的遗传与变异*

以分离自黑龙江腐烂苹果的恶疫霉Phytophthora cactorum Schroeter野生型菌株Ap14为亲本,采用菌丝块创伤接种法测定了恶疫霉对苹果的致病力在无性繁殖和有性生殖后代的遗传。结果是连续2代单游动孢子后代在苹果上所致病斑半径分别为22.4~24.1mm和21.8~23.4mm,与亲本所致病斑半径22.5mm无显著差异;而其20个自交后代个体所致病斑半径为21.4~25.8mm,与亲本有显著差异,其中2株致病力显著强于亲本,其余与亲本相似。表明恶疫霉对苹果的致病力在无性后代可稳定遗传,而在自交有性后代发生分离。同时在含甲霜灵0.05μg/ml的LBA平板上测定了恶疫霉菌丝生长对甲霜灵的敏感性在无性和有性后代的遗传。结果是恶疫霉对甲霜灵的敏感性在无性单孢后代无显著变异,而在50个自交有性后代中,上述浓度对其菌丝生长的抑制率分布范围为67.3~97.1%,与亲本78.3%有极显著差异,其中3株高于亲本,3株低于亲本,44株与亲本相似。表明恶疫霉对甲霜灵的敏感性同样在无性后代稳定遗传而在有性后代发生变异。上述结果提示,供试恶疫霉菌株中上述性状可能由细胞核杂合基因控制。     

The Puccinia striiformis effector Hasp98 facilitates pathogenicity by blocking the kinase activity of wheat TaMAPK4

The obligate biotrophic fungus Puccinia striiformis f. sp. tritici (Pst) employs virulence effectors to disturb host immunity and causes devastating stripe rust disease. However, our understanding of how Pst effectors regulate host defense responses remains limited. In this study, we determined that the Pst effector Hasp98, which is highly expressed in Pst haustoria, inhibits plant immune responses triggered by flg22 or nonpathogenic bacteria. Overexpression of Hasp98 in wheat (Triticum aestivum) suppressed avirulent Pst-triggered immunity, leading to decreased H₂O₂ accumulation and promoting P. striiformis infection, whereas stable silencing of Hasp98 impaired P. striiformis pathogenicity. Hasp98 interacts with the wheat mitogen-activated protein kinase TaMAPK4, a positive regulator of plant resistance to stripe rust. The conserved TEY motif of TaMAPK4 is important for its kinase activity, which is required for the resistance function. We demonstrate that Hasp98 inhibits the kinase activity of TaMAPK4 and that the stable silencing of TaMAPK4 compromises wheat resistance against P. striiformis. These results suggest that Hasp98 acts as a virulence effector to interfere with the MAPK signaling pathway in wheat, thereby promoting P. striiformis infection.     

黄淮麦区小麦品种(系)中Yr26基因的SSR检测

选用与Yr26紧密连锁的SSR标记Xgwm11和Xgwm18结合田间抗性鉴定,对239份黄淮麦区小麦品种(系)进行检测,以明确Yr26基因在黄淮麦区小麦品种资源中的分布.结果表明:共有35份品种(系)含有与Yr26紧密连锁的SSR标记Xgwm18或Xgwm11的特征带,占检测样本的14.6%.在这35份材料中,31份田间抗性鉴定表现免疫至中抗,4份表现中感.分子标记检测与田间抗病性检测吻合度较好,该标记可以用于Yr26基因的分子标记辅助选择.综合分子标记和田间鉴定,31份小麦(系)含有Yr26基因,占102份抗病材料的30.39%.     

Race analysis of Puccinia striiformis f.sp. tritici in Iran

The wheat stripe (yellow) rust is one of the most important diseases in Iran. In this study, 41 races out of 104 isolates in greenhouse were determined from 2008 to 2010. Races 6E6A+, 6E10A+ and 6E0A+ were more common. Races 0E0A+ was less aggressive than races 166E158A+ and 134E158A+ with virulence on 11 known genes. Virulence on plant/s with gene/s Yr1, Yr2, Yr4, Yr6, Yr7, Yr8, Yr9, Yr10, Yr25, Yr27, YrSU, YrSD, YrND, Yr3, Yr2+, Yr6+, Yr9+, Yr7+, YrCV and YrA was detected. The majority of isolates with high frequency (more than 70%) showed virulence on plant/s with Yr2, Yr7, Yr9 and YrA genes. No virulence was detected on plant/s with Yr3, Yr5 and YrSP. In greenhouse test, frequency of virulence to wheat genotypes with Yr1, Yr4, Yr10, YrCV (32+) and YrSD gene was less than 7%. Frequency of virulence to other wheat genotypes was between 8 and 100%.     

Molecular Detection of Stripe Rust Resistance Gene(s) in 115 Wheat Cultivars (lines) from the Yellow and Huai River Valley Wheat Region

Stripe rust (yellow rust), caused by Puccinia striiformis f.sp. tritici (Pst), is a serious disease of wheat worldwide, including China. Growing resistant cultivars is the most cost‐effective and environmentally friendly approach to control the disease. To assess the stripe rust resistance in commercial wheat cultivars and advanced lines in the Yellow and Huai River Valley Wheat Region, 115 wheat cultivars (lines) collected from 13 provinces in this region were evaluated with the most prevalent Chinese Pst races CYR32, CYR33 and the new race V26 at seedling stage. In addition, these wheat entries were inoculated with the mixed races of CYR32 and CYR33 at the adult‐plant stage in the field. The results indicated that 53 (46.1%) cultivars (lines) had all‐stage resistance to all the three races, and 16 (13.9%) cultivars (lines) showed adult‐plant resistance. The possible stripe rust resistance genes in these entries were postulated by the closely linked markers of all‐stage resistance genes Yr5, Yr9, Yr10, Yr15 and Yr26 and adult‐plant resistance gene Yr18. Molecular analysis indicated that resistance genes Yr5, Yr9, Yr10, Yr18 and Yr26 were found in 5 (4.3%), 38 (33.0%), 1 (0.9%), 2 (1.7%) and 8 (7.0%) entries, respectively. No entry was found to carry the Yr15 gene. In future breeding programs, Yr5, Yr15 and Yr18 should be used to pyramid with other effective genes to develop wheat cultivars with high‐level and durable resistance to stripe rust, whereas Yr9, Yr10 and Yr26 should not be used or used in a limited way due to the virulent races present in China.     

条形柄锈菌吸器特异效应蛋白Hasp68抑制寄主免疫并与小麦组织蛋白酶B互作

作为活体营养专性寄生真菌,条形柄锈菌（小麦条锈病）在侵染过程中通过形成吸器向寄主细胞释放效应蛋白,干扰寄主的防卫反应,促进其侵染与致病。因此,条形柄锈菌效应蛋白的鉴定与功能研究对揭示其毒性机理具有重要意义。本实验室前期完成了条形柄锈菌CYR31生理小种吸器转录组分析,从中鉴定得到一个吸器特异诱导表达分泌蛋白Hasp68,利用农杆菌侵染在烟草细胞中瞬时表达该基因,能够抑制小鼠促细胞凋亡蛋白Bax诱导的细胞程序性死亡,鉴定为条形柄锈菌候选效应蛋白。Hasp68基因全长318bp,编码105_aa,N-端包含20_aa的信号肽,无保守结构域。BlastX分析表明Hasp68为条形柄锈菌特有效应蛋白,在其他真菌中无同源蛋白,且在条形柄锈菌16个菌系中呈较低的序列多态性,表明其在条形柄锈菌的进化过程中相对保守。借助荧光假单胞菌EtHAn的三型分泌系统,在小麦细胞中过表达Hasp68能够抑制由非致病细菌引起的PTI（PAMP-triggered immunity）相关胼胝质的积累;同时,也能抑制小麦与无毒条形柄锈菌互作中ETI（effector-triggered immunity）相关的活性氧爆发和过敏性坏死反应,表明效应蛋白Hasp68具有抑制寄主免疫反应的功能。利用酵母双杂交系统筛选Hasp68在小麦中的互作蛋白,发现其与组织蛋白酶B（cathepsin B）TaCTSB互作,双分子荧光技术进一步验证二者在烟草细胞中共表达存在互作,初步揭示了效应蛋白Hasp68的互作靶标。     

Evaluation of Pakistan wheat germplasms for stripe rust resistance using molecular markers

Wheat production in Pakistan is seriously constrained due to rust diseases and stripe rust (yellow) caused by Puccinia striiformis f. sp. tritici, which could limit yields. Thus development and cultivation of genetically diverse and resistant varieties is the most sustainable solution to overcome these diseases. The first objective of the present study was to evaluate 100 Pakistan wheat cultivars that have been grown over the past 60 years. These cultivars were inoculated at the seedling stage with two virulent stripe rust isolates from the United States and two from Pakistan. None of the wheat cultivars were resistant to all tested stripe rust isolates, and 16% of cultivars were susceptible to the four isolates at the seedling stage. The data indicated that none of the Pakistan wheat cultivars contained either Yr5 or Yr15 genes that were considered to be effective against most P. striiformis f. sp. tritici isolates from around the world. Several Pakistan wheat cultivars may have gene Yr10, which is effective against isolate PST-127 but ineffective against PST-116. It is also possible that these cultivars may have other previously unidentified genes or gene combinations. The second objective was to evaluate the 100 Pakistan wheat cultivars for stripe rust resistance during natural epidemics in Pakistan and Washington State, USA. It was found that a higher frequency of resistance was present under field conditions compared with greenhouse conditions. Thirty genotypes (30% of germplasms) were found to have a potentially high temperature adult plant (HTAP) resistance. The third objective was to determine the genetic diversity in Pakistan wheat germplasms using molecular markers. This study was based on DNA fingerprinting using resistance gene analog polymorphism (RGAP) marker analysis. The highest polymorphism detected with RGAP primer pairs was 40%, 50% and 57% with a mean polymorphism of 36%. A total of 22 RGAP markers were obtained in this study. RGAP, simple sequence repeat (SSR) and sequence tagged site (STS) markers were used to determine the presence and absence of some important stripe rust resistance genes, such as Yr5, Yr8, Yr9, Yr15 and Yr18. Of the 60 cultivars analyzed, 17% of cultivars showed a RGAP marker band for Yr9 and 12% of cultivars exhibited the Yr18 marker band. No marker band was detected for Yr5, Yr8 and Yr15, indicating a likely absence of these genes in the tested Pakistan wheat cultivars. Cluster analysis based on molecular and stripe rust reaction data is useful in identifying considerable genetic diversity among Pakistan wheat cultivars. The resistant germplasms identified with 22 RGAP markers and from the resistance evaluations should be useful in developing new wheat cultivars with stripe rust resistance.     

Remapping of the stripe rust resistance gene <Emphasis Type="Italic">Yr10</Emphasis> in common wheat

Key message

Yr10 is an important gene to control wheat stripe rust, and the search for Yr10 needs to be continued.

Abstract

Wheat stripe rust or yellow rust is a devastating fungal disease caused by Puccinia striiformis f. sp. tritici (Pst). Host disease resistance offers a primary source for controlling wheat stripe rust. The stripe rust resistance gene Yr10 confers the race-specific resistance to most tested Pst races in China including CYR29. Early studies proposed that Yr10 was a nucleotide-binding site, leucine-rich repeat gene archived as GenBank accession AF149112 (hereafter designated the Yr10 candidate gene or Yr10 _CG ). In this study, we revealed that 15 Chinese wheat cultivars positive for Yr10 _CG are susceptible to CYR29. We then expressed the Yr10 _CG cDNA in the common wheat ‘Bobwhite’. The Yr10 _CG -cDNA positive transgenic plants were also susceptible to CYR29. Thus, it is highly unlikely that Yr10 _CG corresponds to the Yr10 resistance gene. Using the Yr10 donor ‘Moro’ and the Pst-susceptible wheat ‘Huixianhong’, we generated two F₃ populations that displayed a single Mendelian segregation on the Yr10 gene, and used them to remap the Yr10 gene. Six markers were placed in the Yr10 region, with the Yr10 _CG gene now mapping about 1.2-cM proximal to the Yr10 locus and the Xsdauw79 marker is completely linked to the Yr10 locus. Apparently, the Yr10 gene has not yet been identified. Fine mapping and positional cloning of Yr10 is important for gene pyramiding for stripe rust resistance in wheat.