多堆柄锈菌侵染不同抗性玉米的组织病理学研究

［目的］ 了解不同抗感玉米自交系对南方锈病的组织病理学反应,为今后筛选不同类型抗病自交系提供参考。［方法］ 采用曲利苯蓝透明染色法,以4个玉米自交系为材料,研究了玉米南方锈病致病菌—多堆柄锈菌在不同抗性材料上侵染过程的组织学特征。［结果］ 多堆柄锈菌侵入和定殖可以分为5个阶段：孢子萌发与芽管形成、附着胞形成、侵入细胞、胞内吸器产生、菌丝在细胞间扩展。在不同抗性的玉米材料上,病菌孢子萌发和芽管形成差别不明显,但侵入后病菌在不同抗性材料内的发育进程和发育程度具有显著差异。在抗病玉米材料上,病菌初生菌丝、吸器母细胞、次生菌丝的形成时间推迟,胞内吸器少,菌丝分枝少,菌丝生长缓慢。［结论］ 这些抗性特征与田间表现出的细胞过敏性坏死、叶片上夏孢子堆少的特征具有一致性。     

多堆柄锈菌侵染玉米的细胞学及超微结构特征

为明确玉米对多堆柄锈菌Puccinia polysora侵染后病理反应的细胞学特征,利用扫描和透射电镜技术分析了玉米自交系与多堆柄锈菌互作中二者的细胞变化过程。多堆柄锈菌对玉米的侵染主要以直接穿透叶片表皮侵入为主,少量可从气孔和细胞间隙侵入。接种后,病菌夏孢子在感病自交系叶片上快速并大量萌发,在叶表生长蔓延并侵入表皮组织细胞,7 d后形成夏孢子堆;在抗病自交系上,病菌萌发、菌丝生长均受到明显抑制,少量入侵的病菌也由于寄主细胞死亡而导致菌丝和夏孢子干瘪死亡。侵染早期在感病寄主细胞间隙出现菌丝并穿透细胞壁,在胞内产生分枝菌丝,此时寄主细胞结构正常;随着菌丝进一步扩展,叶绿体等结构发生紊乱,被侵染细胞逐渐死亡。在抗病自交系上,接菌24 h后寄主即出现过敏性坏死反应,侵入位点与周围细胞快速坏死,抑制菌丝生长蔓延;叶绿体中清晰可见深色颗粒状物质;72 h后细胞壁外侧产生大量致密的深色结晶体,应为与抗病反应相关的酚类物质。表明抗多堆柄锈菌的玉米材料可能存在2种抗病途径,即寄主与病菌互作中由分子识别引起的免疫反应和病菌侵入后的系统防卫反应。     

多堆柄锈菌孢子数量与病情以及气象因素的相关性分析

 为了解空气中引起玉米南方锈病病原菌多堆柄锈菌孢子数量与田间病情的关系以及气象因素对孢子和病情的影响,于2017年6 ~9月,在中国农业大学开封实验站,监测空气中多堆柄锈菌的孢子动态,并调查病情和记录气象数据,分别利用Pearson 和Spearman等级相关分析孢子数量与病情以及气象因素与孢子数量和病情的相关性,进一步利用多元逐步回归分析构建病害预测模型。结果表明,在调查日期内(8 月 5~26日),孢子数量呈现先升后降的趋势;孢子的空间分布和扩散方向与风向基本一致。8 d前和3 d前的孢子数量均与病情呈显著正相关(P＜0.01),相关系数分别为0.720和0.755。孢子浓度与温度(≥27℃)、日照时数呈显著负相关;8d 前的气象因素能够显著影响田间病情的发生。建立了玉米南方锈病病害预测模型:Y= 70.938+ 0.009 SC-2.180 MT(其中Y表示的是病情指数, SC表示孢子数量,MT表示日平均气温,R²为0.716),为病情预测提供指导。     

多堆柄锈菌潜育期侵染量实时荧光定量PCR检测体系的建立

为快速及时诊断并定量监测玉米内多堆柄锈菌Puccinia polysora潜育期的侵染量,根据多堆柄锈菌的ITS序列和玉米Actin2基因序列,分别设计多堆柄锈菌特异性引物PpoF/PpoR和Taq Man探针PpoP以及玉米特异性引物ZmF/ZmR和Taq Man探针ZmP,对引物和探针的特异性和灵敏度进行测定,并用这2对引物和探针建立多堆柄锈菌潜育期的实时荧光定量PCR检测体系,定量监测接种后玉米叶片中多堆柄锈菌DNA量随时间的变化。结果表明,多堆柄锈菌和玉米的特异性引物和探针对各自靶标片段均具有良好的特异性,灵敏度分别为10^-3ng/μL和10^-2ng/μL;在接种后24 h,利用所建实时荧光定量PCR检测体系即可在玉米叶片中检测到多堆柄锈菌,且潜育期内多堆柄锈菌的侵染量随时间呈指数增长。表明所建实时荧光定量PCR检测体系可用于多堆柄锈菌潜育期侵染量的定量检测和监测。     

珊瑚菜柄锈菌性孢子阶段的发现及北沙参锈病研究简报

 北沙参(植物名珊瑚菜Glehnia littoralis)为名贵药材,锈病是北沙参的重要病害,其病原为珊瑚菜柄锈菌Puccinia phellopteri Syd.。该菌虽早有记述,但迄今只见有冬、夏孢子阶段的报道,对其生活史及侵染循环尚不清楚。     

玉米南方型锈病发生规律与防治技术初步研究

采用田间调查和试验的方法,着重研究了玉米南方型锈病病菌多堆柄锈菌夏孢子发芽与环境条件的关系,玉米不同生育期的感病性和病害的初侵染来源,并探讨了控制该病为害的主要技术途径。     

玉米南方型锈病夏孢子的侵染时期

玉米南方型锈病由多堆柄锈菌Puccinia polysora Underw引起,是浙江省20世纪以来发生较重的玉米病害[1-2],了解和掌握该病夏孢子的侵染时期,是最终控制其流行的关键所在.笔者采用夏孢子定点空中捕捉、不同恒温条件夏孢子发芽、玉米不同生育期感病性及田间病情消长动态观察等方法,研究了玉米南方型锈病的主要侵染期以及病情与温度、夏孢子数量、玉米感病生育期的吻合程度.     

玉米南方锈病发生温度范围测定

玉米南方锈病由玉米多堆柄锈菌(Puccinia polysora Underw.)引起,主要分布在热带和亚热带地区,但随着全球气候变暖,其发生范围不断扩大,对玉米生产的影响也随之扩大。对于该病害发病温度范围的测定有助于病害发生范围的区划和病害预防工作的进行。试验将多堆柄锈菌接种到供试玉米材料‘郑单958’上,置于不同温度下的光照培养箱中培养并观察发病情况,从而确定出玉米南方锈病的发病温度范围以及发病最适温度范围。试验结果表明:玉米南方锈病的发病温度范围为15~31℃,最适温度范围为24~27℃。     

薇甘菊柄锈菌生物学及其寄主专一性

在检疫温室条件下对外来入侵植物薇甘菊的寄生菌——薇甘菊柄锈菌的生物学及其寄主专化性进行了研究。结果表明，薇甘菊柄锈菌可以侵染植物叶片和叶柄等营养器官。受侵染部位起始出现褪绿斑，12～15d，自叶背产生黄色冬孢子堆，并逐步坏死和脱落，最终致寄主死亡。冬孢子黄至暗褐色，包埋在寄主组织中，无明显休眠期。高湿条件下，冬孢子易萌发产生担孢子进行再侵染。采用悬挂法对29个科、62个属的72种植物进行了寄主专化性测定，结果表明，薇甘菊柄锈菌在菊科植物天门冬、紫茎泽兰、向日葵、地胆草上形成褪绿斑，但未发现菌丝和吸器。薇甘菊柄锈菌可成功侵染薇甘菊和同属植物假泽兰。     

薇甘菊柄锈菌在中国南方自然环境下的致病力

将薇甘菊柄锈菌接种于自然环境中,观察薇甘菊发病特征和侵染状况,研究薇甘菊柄锈菌在中国南方自然环境下的适应性和致病力。结果表明:薇甘菊柄锈菌在自然环境下有较好的适应性,接种后的薇甘菊叶片可以出现大量褪绿斑,随后产生黄褐色冬孢子堆,然后逐渐坏死和脱落;并且可以成功侵染野生薇甘菊,完成侵染循环。     

Reaction of leek cultivars to infection by Puccinia allii

Six components of susceptibility (incubation period, latent period, pustule size, infection frequency, sporulation intensity and reaction type) were measured for seven cultivars of leek following inoculation with urediniospores of Puccinia allii. Variation among cultivars was observed for each component. Sporulation intensity, latent period, infection frequency and reaction type were correlated and appeared to be better criteria for describing variation in host response than incubation period and pustule size. Cultivars Olaf and Kajak were'fast rusting'while cultivars Agria, Winterreuzen, Odin Longstanton, Gennevilliers Splendid and Platina exhibited varying levels of 'slow rusting'. The ';slow-rusting' cultivars Agria and Winterreuzen are of sufficiently high agronomic quality to be worthy of consideration for commercial production.     

Rice seedbeds as a source of primary infection by Rice yellow mottle virus

The effect of contamination of rice seedlings by Rice yellow mottle virus (RYMV) in seedbeds on the onset and spread of rice yellow mottle in the field was investigated. Rice seedlings were artificially contaminated in seedbeds at different rates (0.1, 0.5, and 2.5%) and pooled in bundles before transplantation, as done by farmers. RYMV was successfully transmitted through contaminated hands and bundling healthy and diseased seedlings together. Hand contamination was responsible for 4.5% infection. Disease incidence in the field after secondary spread reached 32% for 2.5% seedbed contamination rate but remained limited (less than 10%) for all other rates. Eradicating infected plants from seedbeds lessened disease incidence in the field. This technique may be used in conjunction with other prophylactic measures to efficiently control rice yellow mottle disease.     

Teleutospores as origin of systemic infection of Cirsium arvense by Puccinia punctiformis

Teleutospores ofPuccinia punctiformis were used for germination and inoculation experiments. The percentage of germination increased with increasing root extract concentration separately from the spore-suspension present in the same Petri dish.Volatile substances in root extracts of the thistle plant markedly promoted the germination of the teleutospores.Inoculation experiments showed that underground parts of plants ofC. arvense can be infected. The percentage of diseased shoots emerging from inoculated root segments was higher than of those emerging from seeds. Three types of systemically infected shoots could be distinguished.The development of spermogonia on the diseased shoots indicates that at first the hyphae are haploid, but later on become dikaryotic as shown by the formation of uredosori. Teleutospores are thus responsible for the systemic infection of the plants.Samenvatting Teleutosporen vanPuccinia punctiformis zijn gebruikt voor kiemings- en incubatieproeven.Vluchtige substanties, aanwezig in wortelextracten van de akkerdistel, hebben een grote invloed op de kieming van teleutosporen. Het percentage kiemende teleutosporen nam toe bij toenemende concentraties van het wortelextract, aanwezig in dezelfde petrischaal als de sporensuspensie.Inoculatieproeven toonden aan dat ondergrondse plantedelen vanC. arvense kunnen worden geïnfecteerd. Het percentage aangetaste scheuten opkomend uit wortelsegmenten was groter dan dat van scheuten verkregen uit zaden. Behalve systemisch geïnfecteerde scheuten werden ook enkele lokaal geïnfecteerde scheuten aangetroffen. De systemisch geïnfecteerde planten konden worden onderscheiden in drie verschillende types.De ontwikkeling van spermogonia op de systemisch aangetaste scheuten wijst er op dat het aanwezige mycelium haploid is, zoals ook te verwachten is bij infecties met basidiosporen. Pas later worden de hyphen dikaryotisch, zoals blijkt uit de vorming van uredosori.     

Local dispersal of Puccinia striiformis f. sp. tritici from isolated source lesions

Understanding how disease foci arise from single source lesions has not been well studied. Here, single wheat leaves were inoculated with Puccinia striiformis f. sp. tritici urediniospores, and all wheat leaves within two intersecting 0.3 × 3.0 m transects were sampled in eight replicates over 3 years. The lesions observed on each of the top three leaves on plants within 1.5 m from the source lesion were three‐dimensionally mapped. The total number of lesions within a 1.5 m radius was estimated by dividing the number of lesions observed within each 0.025 m‐wide annulus by the fraction of the annulus sampled. The estimated total number of lesions produced within 1.5 m of a single source lesion ranged from 27 to 776, with a mean of 288 lesions. Eighty percent of the lesions were recorded within 0.69 m of the source infection. The proportion of total lesions observed at a given distance from the source was fitted well by the Lomax and Weibull distributions, reflecting the large proportion of lesions arising close to the source, and when fitted by an inverse power distribution had a slope (b) of 2.5. There were more lesions produced on leaves higher in the canopy than on lower leaves, with more lesions being detected above than below the point of inoculation. Simultaneous measurement of lesion gradients and spore dispersal in the final year of the study suggests that this pattern is due to greater susceptibility of upper leaves, rather than increased dispersal to upper leaves.     

油茶炭疽病初次侵染来源的研究

 12月和3月对14-17种病部和土壤进行三个病理检查,结果看出:1.炭疽病菌越冬场所主要在植株上部,而不是地面残落病部和土壤;2.病枝、病花芽痕、病叶芽和枯花苞等病部带菌率最高,产孢能力亦大。     

一串红穿孔病病原鉴定和初侵染源分析

 2021年夏季,受台风“烟花”影响,上海市奉贤区海湾镇大面积一串红种苗突发穿孔病,本文按照柯赫氏法则鉴定病原物并进行初侵染源分析。从田间病样中分离出的黄色分离物YchA回接一串红形成穿孔症状,在非寄主本氏烟草上可激发过敏反应。16S rDNA序列分析显示YchA为黄单胞菌属;以持家基因fyuA、gyrB、rpoD进行多位点序列分析(Multi-locus sequence analysis, MLSA)发现,菌株YchA与核桃细菌性黑斑病菌(Xanthomonas arboricola pv. juglandis, Xaj)亲缘关系最近;Biolog鉴定系统分析显示,一串红穿孔病病原为Xaj的可能性约为68%。对育苗基质、种子和灌溉水的检测发现,种子和灌溉水带菌。这些结果表明,一串红细菌性穿孔病的病原为树生黄单胞菌(X. arboricola),可能是一个新致病变种;种子带菌是病害的初侵染来源,灌溉水带菌扩散。     

Scanning electron microscopy of early infection in the uredial stage of Puccinia sorghi in Zea mays

An SEM study was made of the infection process of Puccinia sorghi in Zea mays. A uredospore germ tube grows across epidermal cells and along their anticlinal walls, often branching and altering direction of growth. The fungus, on attaining a stoma, delimits an appressorium over it. Infection peg initials enlarge linearly and centripetally along the appressorium base, forcing open the stomatal slit. Having penetrated the stomatal aperture, the infection peg develops a substomatal vesicle. From the vesicle, two short primary infection hyphae develop synchronously, a septum later forming between the vesicle body and each hyphal base. A further septum divides the primary hypha into two cells. Secondary infection hyphae emerge later from the fully expanded vesicle on the proximal side of each vesicle/primary hypha septum. Secondary hyphae are narrower than primary hyphae, form their proximal septum some distance along the hypha, develop asynchronously, and proliferate to form the intercellular mycelium. Infection processes and epidermal stripping are discussed.