Histological investigation of stripe rust (Puccinia striiformis f.sp. tritici) development in resistant and susceptible wheat cultivars

The wheat cultivar Kariega expresses complete adult plant resistance against stripe rust, whereas cv. Avocet S is susceptible. Using confocal laser scanning microscopy, initial fungal penetration into flag leaves was identical in both cultivars, with directional germ-tube growth towards stomata that were penetrated without the formation of an appressorium, followed by differentiation of a substomatal vesicle, infection hyphae, haustorial mother cells and haustoria. During the following 4 days, further fungal development occurred more quickly in the resistant than in the susceptible cultivar. However, by 7 days postinoculation (dpi) the situation changed, with exponential growth of the pathogen occurring only in the susceptible line. Induced cellular lignification, a typical defence reaction of cereals, was observed at 4 dpi in the resistant cultivar, and 2 days later lignified tissue completely surrounded the fungal colonies. In the susceptible cultivar, isolated lignified host cells occurred at 6 dpi, and long, unbranched fungal hyphae outgrowing the resistance reaction were observed.     

小麦新抗源一粒葡抗条锈病的组织学和超微结构研究

 采用荧光显微镜、微分干涉显微镜和电子显微镜技术,系统研究了小麦新抗源一粒葡抗小麦条锈病的组织学和超微结构特征。结果表明:相对于感病品种铭贤169,一粒葡对条锈菌的侵染,在组织学和超微结构上均表现出明显的抗性特征。在组织学水平,表现为菌丝生长受抑,菌落发育延迟或败育,吸器母细胞和吸器数目明显减少;同时,侵染点的寄主细胞表现出不同程度的过敏性坏死症状。电镜观察发现,在一粒葡和感病品种中,条锈菌均可由芽管顶端直接进入或通过形成附着胞进入小麦气孔。其后,在一粒葡上,病菌胞间菌丝、吸器母细胞、吸器在细胞和亚细胞水平均发生了一系列异常变化,表现为原生质染色逐渐加深,液泡增多变大,逐渐消解原生质;胞间菌丝、吸器母细胞细胞壁不规则增厚;胞间菌丝线粒体肿胀,数目增多,逐渐解体;吸器母细胞细胞质逐渐空泡化后丧失其生理功能;吸器外质膜皱褶;吸器外间质加宽并有丝状或颗粒状物质形成,吸器体壁逐渐消解出现孔洞,吸器体最终畸形坏死。同时,寄主细胞产生一系列显著的结构防卫反应:形成胞壁沉积物、乳突、吸器鞘等结构,以及发生坏死,阻碍并抑制病菌的发育及扩展。     

Differences in reaction to Puccinia striiformis between first and second leaves in wheat crosses

Samenvatting In toetsingen van F1-en F2-kiemplanten van enige tarwekruisingen is gebleken dat het infectietype op het tweede blad tegenovergesteld kan zijn aan dat van het eerste. Dit verschijnsel zou verband kunnen houden met de invloed van het endosperm op de fysiologie van het eerste blad, terwijl de reactie van het tweede, blad bepaald wordt door het genotype van het embryo. De graduele verschillen in infectietypen op het eerste blad van F2-kiemplanten, een verschijnsel dat ook door Macer (1966) is gevonden, zouden het gevolg kunnen zijn van een gen-dosis effect in het endosperm.     

中国小麦生产品种对条锈菌不同生理小种抗病性分析

小麦条锈病是严重威胁我国小麦安全生产的病害,抗病品种培育和利用是经济、安全、高效的防控策略.通过对来自全国不同麦区的115个小麦生产品种进行苗期和成株期抗条锈病分小种鉴定的结果显示,供试小麦品种对条锈菌流行小种的抗病性存在明显差异.其中,苗期对7个条锈菌生理小种均表现抗病的品种9个(占参试品种的7.8%),均表现感病的品种23个(占20.0%);对条锈菌生理小种CYR32、CYR33和V26均表现全生育期抗性的品种13个(占11.3%)、成株抗性品种5个(占4.3%)和慢锈性品种3个(占2.6%).表明当前我国小麦主产区品种整体抗条锈性水平仍较低,需大力加强小麦抗条锈病育种工作,并对不同麦区小麦品种合理布局问题进行了讨论.     

Uredospore production and sporulation period of Puccinia recondita f. sp. triticina on primary leaves of wheat

Uredospore production per day and per sporulation period was measured under near-optimal conditions. Pustule density influenced time and rate of pustule opening, size of pustules, time of maximum sporulation, length of the sporulation period and the time and rate of tissue necrotisation. Within limits total dry weight of spores per leaf per sporulation period was independent of pustule density; it roughly equalled the dry weight of the spore producing leaf. The longest sporulation period observed was 65 days; at low pustule densities secondary pustules replaced exhausted primary pustules. Infectivity of the spores was normal up to 46 days after inoculation. The long sporulation period was epidemiologicaly interpreted as a survival mechanism.     

Identification of resistance genes to Puccinia striiformis in seedlings of Ethiopian and CIMMYT bread wheat varieties and lines

In a controlled environment, the reaction was observed of 42 bread wheat varieties and lines inoculated with 19 isolates of yellow rust differing in their virulence to 20 differential varieties. Five varieties and lines showed resistance to all isolates. The remaining ones appeared to have the genesYr2, Yr3, Yr4, Yr6, Yr7, Yr9 andYrA, either singly or in combination.Yr9 derived from rye was present in 67% of the varieties and lines.Yr4 is the only effective gene in that material as, in Eastern and Central Africa, yellow rust has virulence to the otherYr genes. Recognition of virulence toYr genes is enhanced by the use of a supplemental set of differential varieties supposedly carrying a single gene.Samenvatting Onder geconditioneerde klimaatsomstandigheden zijn 42 Ethiopische en CIMMYT rassen en lijnen van broodtarwe (Triticum aestivum) in het kiemplantstadium geïnoculeerd met 19 isolaten van gele roest die onderling verschilden in hun pathogeniteit voor 20 differentiërende tarwerassen waarvan de resistantie-achtergrond bekend is. De genom-gen relatie is toegepast om resistentiegenen te identificeren. Vier rassen en lijnen bleken resistent te zijn tegen alle isolaten. Verondersteld wordt dat hun resistentie berust op genen die niet eerder herkend waren of op een combinatie van bekende genen die niet compatibel was met de gebruikte isolaten. In het overige tarwemateriaal kon de aanwezigheid worden aangegeven van de resistentiegenenYr2, Yr3, Yr4, Yr6, Yr7, Yr9 enYrA. Het van rogge afkomstige en door het CIMMYT veel gebruikte resistentiegenYr9 was in 28 rassen en lijnen (67%) aanwezig. In het onderzochte tarwemateriaal isYr4 het enige voor Oost en Centraal Afrika effectieve resistentiegen omdat de daar voorkomende gele roest pathogeniteit bezit voor de overige genen. Het herkennen van pathogeniteit van gele roest voor bepaalde resistentiegenen is verbeterd door het toevoegen van tarwerassen met monogene resistentie aan het internatinale gebruikte tarwesortiment voor de determinatie van gele-roestfysio's.     

DON毒素在小麦赤霉病抗感品种麦穗组织中的积累分析

本研究采用单小花滴注和喷雾接种方法对3个抗病品种(‘望水白’、‘苏麦3号’、‘扬麦16’)和3个感病品种(‘周麦18’、‘矮抗58’、‘豫保1号’)的赤霉病抗性进行分析,并用ELISA测定了籽粒、颖壳和穗轴中的DON毒素水平。结果表明:两种方法接种后第20天,除‘望水白’外,抗病品种的病级日扩展速率和病小穗率都显著低于感病品种(P0.05);单小花滴注接种条件下,除‘周麦18’的籽粒和‘矮抗58’的穗轴外,抗病品种的籽粒、颖壳、穗轴中的DON毒素含量显著低于感病品种的籽粒、颖壳、穗轴中的DON毒素含量(P0.05);而喷雾接种条件下,抗病品种与感病品种的籽粒、颖壳中的DON毒素含量差异不显著,而穗轴中的DON毒素含量差异显著(P0.05)。除个别情况外,6个品种中,籽粒中DON毒素水平颖壳中DON毒素水平穗轴中DON毒素水平(P0.05)。     

条锈菌诱导的小麦叶片cDNA文库构建及表达序列标签分析

 以小麦品种水源11和条锈菌CY31号小种为材料,用SMARTTMcDNA Library Construction Kit构建条锈菌诱导的小麦叶片cDNA文库。得到原始文库的滴度为6×10⁶pfu/mL,扩增文库滴度9×10⁹pfu/mL,重组率98%,插入片段在0.5~2.2kb。随机挑取600个克隆,测序获得594条高质量ESTs,与GenBank序列进行BLASTx分析,已知功能ESTs与植物同源比例最高,占44%;其次为真菌,占32%;有18%ESTs在GenBank中没有匹配的同源产物。蛋白功能分析表明,PIG28编码蛋白、ABC转运子、金属硫因、泛素、质膜H⁺-ATPase和氨基酸透酶等可能参与了寄主与病原菌互作过程。     

小麦慢条锈品种成株期抗性组分分析

经2001-2003年对典型慢条锈品种成株期抗性组分测定结果表明,慢条锈品种具有如下特征:反应型和普遍率与快条锈品种差异不大,但病情指数低且上升速度缓慢;侵染点数少;潜育期相对较长;相对寄生适合度较小;对产量构成因素的影响不大等特点。提出了潜育期和病情指数是田间鉴定品种慢条锈性与否的简易、快速方法。     

小麦条锈菌中国鉴别寄主阿夫的抗条锈病基因单体分析

应用单体分析技术,用2E16单孢菌系对小麦条锈菌中国鉴别寄主阿夫进行抗条锈病主效基因分析及染色体定位。结果表明,阿夫对2E16菌系的抗性是由1对显性抗条锈基因控制,未发现其中含有与Sonalike相同的抗条锈病基因,确认阿夫中除含YrA外至少还含有1对未知的显性抗条锈病基因,并将其定位在3B染色体上,暂定名为YrFun。     

Effect of wheat cultivar mixtures on populations of Puccinia striiformis races*

This study quantifies the frequency of simple and complex races (races that can infect two or more components) of Puccinia striiformis in mixtures of wheat cultivars possessing different race-specific resistance genes. Treatments were designed so that the complex race changed depending on the host mixture, thus enabling us to observe the influence of pathogen complexity in different genetic backgrounds. Six cultivar mixtures and one pure stand of winter wheat were inoculated with three races of P. striiformis at two locations for two seasons. Potted plants of three winter wheat cultivars, each susceptible to one of the three races of the pathogen, were used to sample the pathogen during the field epidemics. Disease incidence on the differential cultivars was used to calculate the proportion of the three races in each treatment. The specific cultivars included in the mixtures influenced the frequencies of the three races. Increasing the number of virulent races in a mixture reduced the frequency of the complex race relative to the other two races. The results suggest that genetic background of the pathogen race, host composition, and interaction among pathogen races may be as important as cost of virulence in determining race frequencies in mixtures.     

小麦条锈病菌非亲和性小种诱发小麦抗锈性研究

 在水源11、洛夫林10等7个品种上分别选择小麦条锈菌CY17、CY28等9个生理小种中非亲和小种进行诱发接种,亲和小种为挑战小种。观察发病后的病情指数并与单独接种诱发小种和单独接种挑战小种处理的病情指数进行比较。证明诱发抗病现象是比较普遍的,但表现程度因小麦品种、诱发小种和挑战小种而不同。诱发抗病性的表达时间可持续8 d,以诱发接种后1~2 d表达最强。诱发接种量与诱发抗病性表达呈指数函数关系,也间接证明这种诱发抗性是局部的。作者认为:诱发抗病性在品种、诱发和挑战小种不同组合之间的差异在小种动态中会起一定的作用。     

小麦品种温度互作中抗条锈微效基因的表达

初步研究了不同温度下小麦品种抗条锈性的表达机制 ,结果分析表明 :品种间、温度间及品种×温度间差异均达到了极显著水平。试验进一步证明京核 1号小麦温敏微效基因的存在。在高温潜育发病条件下有利于微效基因抗性的表达。接种前高温处理 1～ 2d ,在常温下潜育发病 ,对温敏基因抗性的表达没有显著影响 ;接种后高温处理 1～ 2d ,在常温下潜育发病 ,对温敏基因抗性的表达有一定的诱导作用。而接种后在常温下处理 1～ 2d ,再于高温下潜育发病 ,更有利于微效基因抗性表达     

小麦品种对小麦条锈病抗病性试验评价

2006～2007年对13个小麦品种在自然发病情况下进行抗条锈病试验,结果表明,对小麦条锈病表现为抗病的品种有淮麦17、96.23粉质、云杂3号、繁19、宜麦1号,其中96-23粉质、宜麦1号的产量较高,繁19、淮麦17的产量居中;对小麦条锈病表现为耐病的品种有川麦107、楚麦3号,且产量较高.绵阳19、白粒5号对小麦条锈病高度摩病.     

Predicting epidemics of yellow rust (Puccinia striiformis) on the upper canopy of wheat from disease observations on lower leaves

Data from field experiments were used to test whether disease observations on lower leaves of wheat were good predictors of future epidemic development in the upper canopy. Fungicide treatments to replicated plots in 1994 and 1995 caused variation in levels of initial inoculum of urediniospores of yellow rust ( Puccinia striiformis ). Observations of symptom severity were made on individual leaf layers throughout the season. Sporulating lesions on lower leaves were considered to be a measure of inoculum source strength for transfer to upper culm leaves. Low source strengths were associated with delays in epidemic development on the upper leaves, as quantified by a location parameter, t _m, the time at which severity reached half of the asymptote value in logistic fits to disease progress data on the upper leaves. However, there was much unexplained variation, probably due to extraneous variation in upward transfer efficiency of inoculum and rates of epidemic development. Vanderplank's sanitation ratio theory was used to account for variation in inoculum transfer and epidemic rate. The analysis revealed that if the aim is to predict disease on a newly emerged culm leaf, during the period when it can be treated effectively with fungicide, then observations of disease two leaves further down the culm were of the greatest predictive value ( R ² = 86%). These observations, however, need to be integrated with information about factors affecting upward inoculum transfer and rates of epidemic development if acceptable predictive precision is to be achieved.     

不同培养载体对小麦条锈菌夏孢子人工萌发的影响

为探索适合小麦条锈菌寄主体外萌发的载体,并建立基于不同研究目的的小麦条锈菌夏孢子人工萌发技术,采用超声波水雾培养法,以小麦条锈菌生理小种CYR32为供试材料,探讨了不同培养载体对小麦条锈菌夏孢子萌发特性的影响.在最适温度和湿度条件下,以4种不同材料为培养载体,小麦条锈菌夏孢子的萌发率、芽管生长率和外观显示情况有显著差异.在尼龙纱网上的夏孢子萌发速度和芽管伸长速度最快,12 h内萌发率最高可达93.40％,芽管最长可达446.71 μm;亲水滤膜上夏孢子的萌发率和芽管长仅次于纱网;亲水塑料膜和PVDF膜上夏孢子的萌发率均高于普通亲水载玻片,而芽管长度低于普通亲水载玻片.采用侧光照明时,在亲水滤膜和PVDF膜上极易清晰观测到夏孢子及其芽管内的黄色颗粒物.在亲水塑料膜上,还可观察到夏孢子萌发12 h后,芽管尾部膨大形成类似附着胞的结构.结果显示,超声波水雾可使条锈菌夏孢子处于水分饱和的环境,而纱网纤维组成的小格具有很好的保水结露功能,能使夏孢子萌发快,萌发效率高,芽管生长快;另一方面,使用其他培养载体还可满足观测条锈菌夏孢子内黄色颗粒物向芽管内转移和芽管尾部形成类似附着胞结构的目的.     

大白菜抗感品种间作提高感病品种抗病毒病能力研究

为了探讨通过抗感品种间作栽培方式来提高大白菜品种抗病毒病的能力,采用小区试验和对黑龙江大白菜区试与生试结果分析。结果表明,抗感品种间作可提高感病大白菜品种抗病毒病能力;抗性不同的品种间作使同一品种在区试、生试中表现出不同的抗性,与对照相比表现出不同增产幅度。     

条锈病侵染对小麦抗氰呼吸和活性氧代谢的影响

 以不同抗病性的小麦为材料,观察了条锈病菌侵染小麦幼苗叶片时活性氧代谢和抗氰呼吸发生、运行的变化。讨论了二者在长期病程下的平衡关系。实验显示:接种8d后,感病小麦中H₂O₂含量开始高于抗病小麦,O₂^-·含量变化差异不明显。SOD、CAT和POD活性整体上表现为接种后的前4d有所上升,接种4d之后呈下降的趋势;感病小麦中3种抗氧化酶的活性均高于抗病小麦。条锈菌侵染下小麦幼苗抗氰呼吸容量和运行活性的变化在两类小麦中与H₂O₂的变化一致,在侵染初期上升缓慢,以后迅速上升;aoxl的mRNA水平仅在侵染后4d的幼苗叶片中略有上升,在以后的侵染过程中没有发生显著的变化。我们推测,活性氧可以在多种水平上参与条锈病菌侵染下抗氰呼吸的诱导,而抗氰呼吸也在某种程度上参与小麦在条锈病菌侵染下活性氧的清除与机体的生理保护机制。     

The effect of temperature and light intensity on growth and sporulation of Puccinia striiformis on wheat

Urediniospore production by Puccinia striiformis on wheat per unit leaf area infected was much lower at low light intensities than at high light intensities. The number of pustules per unit area of infected leaf and the daily sporulation rate per pustule increased linearly with increasing light over the range 10–50 W/m². Increasing temperature between 7 and 20°C shortened latent period and reduced the longevity of sporulating leaves. Colonization rate and the frequency of pustules per unit area of infected leaf increased between 7 and 15°C but declined markedly at 20°C. Spore production reached its peak earlier and declined more rapidly with increasing temperature between 7 and 15°C. this decline being less marked in the highly susceptible cultivar Maris Beacon than in the more resistant Maris Nimrod and Maris Huntsman.     

Genes for race-specific resistance to yellow rust (Puccinia striiformis) in Indian wheat cultivars

Seedlings of Indian wheat cultivars (Kalyansona, Sonalika, WL711 and eight others released commercially) were tested with 13 British and four alien races of Puccinia striiformis. The data indicated the probable presence of the resistance gene Yr2 in the three cultivars named above and in six of the others. Reactions of the remaining two cultivars, PWB12 and WL2265, were consistent with the presence of the gene 177. The presence of Yr2 in Kalyansona, Sonalika and WL711 was supported by evidence from crosses between them and with Heines VII, which is known to carry Yr2. In crosses of Sonalika with a susceptible cultivar, Kharchia Local and also with WL711, tests of F1, F2 and F3 generations indicated that, in addition to Yr2 , Sonalika possesses at least two other genes. Both these genes were difficult to detect but the F3 data supported the hypothesis that there is a single partially recessive gene giving resistance to alien race 6E16 and a different, possibly complementary, gene system effective against another alien race, 39E134. The presence of resistance in addition to Yr2 was also detected in WL711 and HD2329.