小麦抗赤霉病利器——他山之石

赤霉病是我国乃至世界小麦(Triticum aestivum)产区的重要病害, 给农业生产和人畜健康造成重大威胁。分离鉴定优质抗病基因、培育抗病品种, 是控制我国麦区赤霉病的重要手段。最近, 山东农业大学孔令让团队完成了二倍体长穗偃麦草(Thinopyrum elongatum)基因组的组装, 并在此基础上通过精细定位和图位克隆分离得到来自长穗偃麦草的抗赤霉病基因Fhb7。他们发现Fhb7编码1个谷胱甘肽转移酶, 对禾谷镰孢菌(Fusarium graminearum)分泌的包括呕吐毒素等在内的多种毒素具有解毒作用, 是1个广谱持久抗病基因。他们还发现Fhb7很可能最初源于内生真菌, 经过基因水平转移进入到偃麦草基因组中。此外, Fhb7不影响其它农艺性状, 且其抗性不受小麦遗传背景影响。这一系列工作揭示了作物抗病演化中的全新机制, 对小麦抗赤霉病育种以及更好地利用长穗偃麦草的丰富基因资源都具有重要意义。     

条锈菌诱导的抗锈小麦种质的基因表达分析

以条锈菌接种前后的抗条锈病种质N 95175的小麦幼苗叶片为材料,利用抑制消减杂交技术,构建了条锈菌接种初期小麦抗性种质叶片的SSH-cDNA文库。通过对文库中随机选取的50个阳性克隆提取质粒,进行测序,共获得已知功能的EST序列14条,如蛋白激酶、锌指蛋白、细胞色素P 450和OM T 1等抗病相关基因,它们涉及植物的信号传导、转录调控、丙烷代谢途径及防卫反应等方面。     

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'...     

两个紧密连锁的小麦苯丙氨酸解氨酶基因的分离与鉴定

利用一个小麦苯丙氨酸解氨酶基因PCR片段为探针,从小麦核DNA基因库中筛选出一个阳性噬菌体克隆,该克隆含有两个高度同源、紧密连锁、转录方向相同的小麦苯丙氨酸解氨酶基因PAL1与PAL2,它们之间的核酸序列同源性。为93％,相距约7kb,利用PAL1特异片段进行Southern分析,表明该基因在小麦基因组中具有多个拷贝。Northern杂交表明,经秆锈菌接种诱导,苯丙氨酸解氨酶基因在一对小麦抗-感近等基因系中差异表达：抗病等基因系中国春-Sr11携带与接种菌无毒性基因P11相对应的抗病基因Sr11,在接种4d后开始诱导表达,8d后表达量更高;而缺少抗病基因的感病系中国春-sr11接种6d后才开始表达,8d后的表达量与抗病系中6d时相当。用秆锈菌诱导物和几丁质寡聚物处理小麦悬浮细胞,均可在2h内激活苯丙氨酸解氨酶基因表达,但真菌诱导物在早期的诱导活性显著高于几丁质寡聚物。从转录水平证实了小麦苯丙氨酸解氨酶基因在秆锈菌诱导的抗性反应中具有重要作用。     

人工合成小麦CI184条锈病成株抗性基因的鉴定及分子标记定位

以硬粒小麦-粗山羊草人工合成小麦CI184、感病品种‘铭贤169’及其杂交组合的正反交F1以及CI184/‘铭贤169’F2、F2:3家系为材料,鉴定其条锈病抗性,对CI184条锈病抗性进行遗传分析;采用SSR分子标记技术和集群分离分析法进行多态性筛选,以F3抗病鉴定数据为依据,对CI184中条锈病抗性基因进行分子标记定位。结果显示:(1)CI184在苗期抗性鉴定中,对30种小麦条锈菌生理小种表现抗性,但对中国四川新出现的条锈菌生理小种V26表现苗期感病;在田间成株抗性接种鉴定中,CI184对中国流行的小麦条锈菌生理小种条中32、条中33、水源4、水源5、水源7和V26等表现出成株抗性。(2)CI184中条锈病抗性由隐性基因位点控制。(3)仅检测到一个控制条锈病抗性的QTL位点,位于1B染色体上Xgwm18和Xwmc626之间,暂时命名为Qyr.zz_1B,在四川和北京2个环境中可分别解释CI184中13.36%和18.07%的成株抗性贡献率。(4)Qyr.zz_1B位点的3个SSR标记和Yr15的1个SSR标记可以区分该位点与1B染色体上的其他抗条锈病基因,如Yr15、Yr24和Yr26/YrCH42。表明Qyr.zz_1B位点在小麦条锈病的抗病育种中具有潜在的应用价值。     

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。     

条形柄锈菌小麦专化型小种CYR29有性自交及毒性与无毒性基因的遗传分析

由条形柄锈菌小麦专化型（小麦条锈菌）Puccinia striiformis f. sp. tritici引起的条锈病是小麦上重大的生物灾害,严重威胁小麦安全生产。应用抗病品种是防治小麦条锈病最为经济有效的措施,但是条锈菌毒性的频繁变异,常常导致品种抗病性丧失,从而引发条锈病新的大流行。有性生殖是条锈菌毒性变异的重要途径,本文通过对小麦条锈菌流行小种CYR29在转主寄主小檗上的自交研究了有性生殖与病菌毒性变异之间的关系。通过诱导CYR29单夏孢子菌系形成冬孢子、萌发产生的担孢子接种转主寄主小檗,使其完成有性过程,由此共获得81个自交后代,对有性后代群体S1和亲本菌系在20个含单个抗病基因的近等基因系鉴别寄主上进行毒性鉴定。S1群体和亲本在Yr5、Yr8、Yr10、Yr15、Yr24、Yr32、YrSP、YrTr1和Yr26上均为无毒性,在Yr1、Yr31、Yr44和YrTye上均为毒性。S1群体在Yr6、Yr7、Yr9、Yr17、Yr27、Yr43和YrExp2这7个位点上出现了毒性分离,表明亲本在这些位点为杂合。81个自交后代可分为24种毒性表型,其中1种表型与亲本毒性一致,含22个菌系;其余23种毒性表型与亲本存在差异,含59个菌系,毒性变异率高达72.8%,且发生变异的子代均比亲本毒性谱更宽。结果表明该小种经过有性过程后产生了毒性增强的新菌系,进一步证实有性生殖是导致小麦条锈菌具有较高遗传多样性的原因之一。     

小麦叶锈病抗性基因在山西的有效性研究

采自山西省各地的小麦叶锈菌菌株分别接种在含有已知抗叶锈病基因的小麦近等基因系(或单基因系)上,测定其毒性频率,根据已知抗病基因对叶锈菌群体的抗性程度,对其进行抗性效能的评价。结果表明：抗性基因Lr9、Lr19、Lr24、Lr38的毒性频率较低,分别为23．08％、16．03％、12．82％和1．92％,为山西省小麦叶锈菌的有效抗病基因。在发现的诸多毒性类型中,THT、THK、PHT、TRT的出现频率居前四位,分别为19．23％、8．97％、7．05％、5．77％,为山西省目前小麦叶锈菌群体中的优势毒性类型。     

小麦叶锈病新抗源筛选

小麦叶锈病是小麦生产的主要病害之一,发病严重时往往导致大幅度减产。叶锈菌生理小种的变异易导致抗病基因抗性的丧失,因此不断获得新抗源对小麦抗病育种至关重要。小麦近缘植物中含有丰富的小麦育种所需的抗病基因。本研究从小麦-近缘植物双二倍体、附加系、代换系或易位系等创新种质中筛选出小麦叶锈病新抗源,为利用这些新抗源打下基础。苗期对116份供试材料人工接种美国堪萨斯州流行的小麦叶锈菌混合生理小种 (Lrcomp) ,其中部分材料人工接种09-9-1441-1等5个中国当前流行的叶锈菌生理小种进行抗性鉴定,筛选获得新抗源。116份种质中,31份免疫、近免疫或高抗Lrcomp。含有希尔斯山羊草、尾状山羊草、拟斯卑尔脱山羊草、两芒山羊草、卵穗山羊草、沙融山羊草、柱穗山羊草、顶芒山羊草、小伞山羊草、偏凸山羊草、中间偃麦草、茸毛偃麦草、长穗偃麦草、粗穗披碱草、栽培黑麦、非洲黑麦、提莫菲维染色质的部分种质免疫或高抗Lrcomp,而含二角山羊草、无芒山羊草、沙生冰草、多年生簇毛麦和一年生簇毛麦染色质的种质表现中感至高感Lrcomp。希尔斯山羊草4S染色体、尾状山羊草C#1和D#1染色体和两芒山羊草、顶芒山羊草中可能含有未被报道的抗Lrcomp的新基因,值得进一步向小麦转育。小麦-粗穗披碱草1HtS.1BL罗伯逊易位系对Lrcomp及 09-9-1441-1和09-9-1426-1等5个中国当前流行叶锈菌生理小种近免疫,值得利用染色体工程等方法获得小片段抗病易位系应用于我国小麦抗叶锈育种。     

转录因子基因TuGTγ-3参与乌拉尔图小麦对条锈病的抗性

小麦条锈病是由条形柄锈菌小麦专化型(Puccinia striiformis West. f. sp. tritici Eriks.＆Henn., Pst)引起的一种严重的真菌病害,发掘新的抗条锈病相关基因对于小麦抗病育种和抗病机理研究都具有重要意义。Trihelix是植物特有的转录因子家族,参与调控生长发育、形态建成、胁迫应答等过程。迄今,小麦属Trihelix家族与抗条锈病相关的研究尚未见报道。本研究从乌拉尔图小麦(Triticum urartu Tum., 2n=2x=14, AA)中克隆了Trihelix家族GTγ亚家族中的一个基因,命名为TuGTγ-3。序列分析表明,TuGTγ-3基因具有完整的开放阅读框(ORF),编码序列(CDS)全长1329 bp,编码442个氨基酸,推测其编码蛋白的分子量为50.31 kDa,理论等电点为6.12。生物信息学预测TuGTγ-3蛋白有一个单分型核定位信号(GLPMQKKMRYT),没有信号肽和跨膜结构域。TuGTγ-3蛋白的保守trihelix结构域的氨基酸序列位置为Q115~R187,第四α-螺旋位置为F234~Y241,CC结构域的位置为K362~K436。二级结构分析显示,TuGTγ-3蛋白由43.89%的α-螺旋、9.51%的伸展链、9.95%的β-转角和36.65%的不规则卷曲构成。利用普通小麦的基因组数据库BLAST分析表明,TuGTγ-3被定位于5A染色体长臂上。瞬时表达实验显示,TuGTγ-3蛋白主要定位在细胞核中,但细胞质中也有少量分布。表达谱分析表明,TuGTγ-3基因在叶片中的表达量显著高于根和叶鞘,且受小麦条锈菌小种CYR32的诱导而强烈上调表达。进一步通过大麦条纹花叶病毒诱导的基因沉默(BSMV-VIGS)实验证明,转录因子TuGTγ-3正向调控了乌拉尔图小麦对条锈病的抗性。     

Dr. Heinz rogoll‐70 Jahre

The wheat crop remains vulnerable to all three rust diseases (leaf rust, stem rust and yellow rust) caused by Puccinia spp. according to the prevalence of the pathogen in different wheat-growing areas worldwide. Stripe rust or yellow rust caused by Puccinia striiformis f. sp. tritici is the most significant rust pathogen which prefers cool, moist areas and highlands. The pathogen is recognised as responsible for huge production losses in wheat. Genetic variation in pathogen makes its control difficult. Therefore, resistance against all the races of the pathogen known as durable or race-non-specific resistance is preferred. The present study was carried out to identify durable resistance against stripe rust in selected wheat cultivars from Pakistan through seedling testing, field evaluation at adult stage, morphological marker studies and marker-assisted selection. Results revealed that 4% of the cultivars were resistant at the seedling stage while the rest were susceptible or intermediate. To confirm their field resistance, the same cultivars were evaluated under field conditions at Cereal Crops Research Institute Pirsabak (located in Khyber Pakhtunkhwa, KP) a hot spot of stripe rust in Pakistan. Observations exhibited that at the adult stage 4% of the cultivars were resistant, 70% intermediate or moderately resistant while the others were highly susceptible. Leaf tip necrosis was observed in 30% of the cultivars. Wheat cultivars showing susceptibility at the seedling stage were highly to moderately resistant at adult stage showing durable resistance. For further validation, morphological markers were also observed in cultivars indicating the presence of Yr18/Lr34 gene. Eleven cultivars (C-518, Mexipak, Kohinoor-83, Faisalabad-83, Zardana-93, Shahkar-95, Moomal-2002, Wattan-94, Pasban-90, Kiran-95, and Haider-2000) were identified, having durable or race non-specific resistance against stripe rust. These cultivars can further be utilised in wheat breeding programmes for deploying durable resistance to attain long lasting control against stripe rust.     

小麦持久抗条锈品种斯汤佩利的遗传机制研究

对持久抗条锈小麦品种斯汤佩利进行了抗条锈特点研究和抗性遗传分析.斯汤佩利反应型0～1型,普遍率、严重度和病情指数3个抗性组分及其平均日变化率都很低,与三类对照品种之间有极显著差异.与中抗-中感为特征的、抗性由多基因或由主效基因与多基因共同控制的一般持久抗病品种相比,属于典型特例.其抗条锈性由2对显性基因互补控制,干尖性状由1对显性基因控制,二者之间不连锁,因此,干尖不能作为斯汤佩利抗锈性的辅助选择标记.     

An overview of stripe rust of wheat (Puccinia striiformis f. sp. tritici) in Pakistan

Stripe rust (yellow rust) caused by Puccinia striiformis f. sp. tritici has been an important disease of wheat in the Indian subcontinent since 1786. Currently, it prevails across all the wheat growing areas from north to south in the country. Due to the favourable weather conditions, the northern uplands have been historically hit by the severe disease epidemics. These epidemics caused significant losses to national wheat production. Acquisition of broader virulence pattern by the pathogen poses a serious threat to national agriculture. Although the deployed national wheat varieties have adequate resistance, these are developed around few major genes and are vulnerable to the new evolving strains of the pathogen. Utilisation of race non-specific durable resistance and seedling resistance via gene pyramiding, based on the current virulence scenario of the pathogen should provide sustainable control. This review focuses on the national milestones that recognise the economic significance of the disease and current status of stripe rust and its management in Pakistan.     

The Lr34 adult plant rust resistance gene provides seedling resistance in durum wheat without senescence

The hexaploid wheat (Triticum aestivum) adult plant resistance gene, Lr34/Yr18/Sr57/Pm38/Ltn1, provides broad‐spectrum resistance to wheat leaf rust (Lr34), stripe rust (Yr18), stem rust (Sr57) and powdery mildew (Pm38) pathogens, and has remained effective in wheat crops for many decades. The partial resistance provided by this gene is only apparent in adult plants and not effective in field‐grown seedlings. Lr34 also causes leaf tip necrosis (Ltn1) in mature adult plant leaves when grown under field conditions. This D genome‐encoded bread wheat gene was transferred to tetraploid durum wheat (T. turgidum) cultivar Stewart by transformation. Transgenic durum lines were produced with elevated gene expression levels when compared with the endogenous hexaploid gene. Unlike nontransgenic hexaploid and durum control lines, these transgenic plants showed robust seedling resistance to pathogens causing wheat leaf rust, stripe rust and powdery mildew disease. The effectiveness of seedling resistance against each pathogen correlated with the level of transgene expression. No evidence of accelerated leaf necrosis or up‐regulation of senescence gene markers was apparent in these seedlings, suggesting senescence is not required for Lr34 resistance, although leaf tip necrosis occurred in mature plant flag leaves. Several abiotic stress‐response genes were up‐regulated in these seedlings in the absence of rust infection as previously observed in adult plant flag leaves of hexaploid wheat. Increasing day length significantly increased Lr34 seedling resistance. These data demonstrate that expression of a highly durable, broad‐spectrum adult plant resistance gene can be modified to provide seedling resistance in durum wheat.     

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%.     

Genetic research as the valid base of strategies for breeding rust resistant wheats

It is known that few wheat cultivars maintain their resistance to rust diseases for a long period of time, particularly when crop populations become genetically more uniform. A number of genetically diverse, so far unexploited, sources of rust resistance in the natural as well as mutagenized population of wheat cultivars were identified. Several of these genes were placed in agronomically superior well-adapted backgrounds so that they could be used as pre-breeding stocks for introducing genetic diversity for resistance in a crop population. Some of these stocks when employed as parents in several cross combinations in a breeding programme have generated a number of promising cultivars with diversity for resistance.Many presently grown wheats in India, near-isogenic lines each with Lr14b, Lr14ab, Lr30 and certain international cultivars were identified as possessing diverse sources of adult plant resistance (APR) to leaf rust. Prolonged leaf rust resistance in some of the Indian cultivars was attributed to the likely presence of Lr34 either alone or in combination with other APR components. Tests of allelism carried out in certain cultivars that continue to show adequate levels of field resistance confirm the presence of Lr34, which explains the role that this gene has played in imparting durability for resistance to leaf rust. Also, Lr34 in combination with other APR components increases the levels of resistance, which suggests that combination of certain APR components should be another important strategy for breeding cultivars conferring durable and adequate levels of resistance. A new adult plant leaf rust resistance source that seems to be associated with durability in Arjun has been postulated. Likewise, cultivars possessing Sr2 in combination with certain other specific genes have maintained resistance to stem rust.Further, non-specific resistances that were transferred across widely different genotypes into two of the popular Indian wheats provided easily usable materials to the national breeding programmes for imparting durable resistance to stripe rust.     

Molecular mapping of a non-host resistance gene YrpstY1 in barley (Hordeum vulgare L.) for resistance to wheat stripe rust

Cultivated barley (Hordeum vulgare L.) is considered as a non-host or inappropriate host species for wheat stripe rust caused by Puccinia striiformis f. sp. tritici. Most barley cultivars show a broad-spectrum resistance to wheat stripe rust. To determine the genes for resistance to wheat stripe rust in barley, a cross was made between a resistant barley line Y12 and a susceptible line Y16. The two parents, F(1) and 147 BC(1) plants were tested at seedling stage with Chinese prevalent race CYR32 of Puccinia striiformis f. sp. tritici by artificial inoculation in greenhouse. The results indicated that Y12 possessed one dominant resistance gene to wheat stripe rust, designated YrpstY1 provisionally. A total of 388 simple sequence repeat (SSR) markers were used to map the resistance gene in Y12 using bulked segregant analysis. A linkage map, including nine SSR loci on chromosome 7H and YrpstY1, was constructed using the BC(1) population, indicating that the resistance gene YrpstY1 is located on chromosome 7H. It is potential to transfer the resistance gene into common wheat for stripe rust resistance.     

Durable resistance to wheat stem rust needed

The recent outbreak of a new wheat stem rust race capable of parasitizing many commercial wheat cultivars highlights the need for durable disease resistance in crop plants. More advanced breeding approaches using quantitative disease resistance genes and resistance gene pyramids are being used to combat wheat stem rust and other diseases, though widespread adoption of these breeding methodologies is needed to maintain resistance efficacy. Advances in understanding the molecular basis of plant disease resistance at both host and nonhost levels offers further possibilities for stem rust resistance using biotechnological approaches. However, truly durable resistance to wheat stem rust and other phytopathogens seems an unlikely prospect in the face of continually evolving pathogen populations.     

小麦抗条锈病基因YrCN19的诊断检测和遗传分析

用小麦条锈病抗性基因YrCN19的诊断标记Xgwm410对19个小麦品种或品系进行PCR筛选,其中川农19、新抗5号、爱民5号和爱民6号扩增出与条锈病抗性基因YrCN19共分离的特征片断,其大小为391个碱基,而在其他的小麦品种或品系中未能检测到该片断。系谱分析和抗性鉴定结果表明川农19、新抗5号、爱民5号和爱民6号含有小麦条锈病基因YrCN19。抗性遗传分析发现小麦条锈病抗性在川农19,新抗5号和爱民5号中的遗传符合单个显性基因的遗传规律(3抗:1感);杂交组合烟辐188/爱民6号的抗性遗传也符合单个显性基因的遗传规律,而另外一些杂交组合(如R25/爱民6号,鲁955159/爱民6号和苏3110/爱民6号)中的抗性分离则符合两对基因互补的遗传规律(9抗:7感)。本研究揭示了小麦条锈病抗性基因YrCN19在不同遗传背景和杂交组合的抗性表达和分离有差异,从而加速YrCN19在小麦抗条锈育种中的开发与利用。