水稻旱育秧立枯病致病菌鉴定及药剂防治研究

从水稻旱育秧病苗上分离到67个菌株 ,经鉴定分属于镰刀菌58个、腐霉菌7个、丝核菌2个。经回接测定其致病性 ,结果表明致病的镰刀菌主要是串珠镰刀菌 (Fusarium moniliforme) ;腐霉菌中主要是盐腐霉 (Pythium salinum)、间生腐霉 (P .interedium)和顶生腐霉 (P .acrogenum) ;丝核菌为立枯丝核菌 (Rhizoctonia solani)。接种试验表明串珠镰刀菌在6～8d龄幼苗的根中部侵染发病率最高 ,腐霉菌和丝核菌在一叶一心期茎基部侵染发病率最高。药剂试验表明以浸种灵(二硫氰基甲烷)、土菌消(hymexazol)、甲霜灵(metalaxyl)等种子处理加土壤处理 ,防效优于单独种子处理或土壤处理。     

拮抗放线菌TA21对烟草根黑腐病菌的抑制及其控病作用

菌株TA21是一株从重庆烟区土壤中筛选出的对烟草根黑腐病菌Thielaviopsis basicola有较强拮抗作用的放线菌,为了明确其抑菌效果和控病作用及其在烟草根黑腐病生防中的应用潜力,本文进行了菌株TA21抑菌活性检测和温室控病测试;并通过形态学、生理生化和分子分类的方法确定其分类地位。室内测定试验表明,菌株TA21对烟草根黑腐病菌的抑菌带宽达12.5mm;温室控病试验发现其对烟草根黑腐病防治效果达85.3%。无菌滤液试验表明,在试验浓度范围内无菌滤液均能有效抑制烟草根黑腐病菌菌丝生长、减少孢子萌发。根据菌株形态特征、培养性状、生理生化特性、细胞组分及16S rDNA序列分析,确定菌株TA21为链霉菌属吸水链霉菌Streptomyces hygroscopicus。     

烟草尖孢镰刀菌拮抗真菌的筛选鉴定及促生作用研究

为获得烟草镰刀菌根腐病拮抗真菌菌株,试验以河南省豫中烟区烟草根际土壤为试材,以主要致病菌尖孢镰刀菌Fusarium oxysporum为主要靶标,采用稀释涂布平板法分离获得土壤真菌371株,平板对峙培养法测定获得1株具有明显抑制效果的拮抗菌株,利用形态学和分子生物学的方法将其鉴定为棘孢木霉Trichoderma asperellum Tr-0111。抑制效果测定表明,该菌株对尖孢镰刀菌的抑制率最高可达93.13%,对根串珠霉菌、拟茎点霉、链格孢菌等其他8种烟草病原菌均具有较强的抑制效果。促生作用测定结果表明,菌株发酵液使烟草种子萌发率提高5.34%,烟苗根长增长率为62.39%,对盆栽烟草的最大叶面积和地上部鲜重也具有显著的促生效果。为进一步相关机理的研究和生防菌剂的研制奠定了基础。     

烟草疫霉拮抗放线菌的生防潜力评价

由寄生疫霉烟草致病变种Phytophthora parasitica var. nicotianae引起的烟草黑胫病是连作烟田的重要土传病害之一,重发年份常给烟农造成巨大的经济损失。本研究通过稀释分离法从贵州省遵义市烟草黑胫病重病区的健康烟草根际土壤中共分离获得179株放线菌。通过平板对峙培养法筛选得到15株对烟草黑胫病菌菌丝生长有明显抑制作用的菌株。测定了这15个菌株代谢液对烟草疫霉菌丝生长的抑制作用,其中H-3菌株代谢液对烟草疫霉菌丝生长抑制率最高,达到85.68%。研究了H-3代谢液对烟草疫霉游动孢子萌发的抑制作用。结果显示培养6、12和24h对游动孢子萌发的抑制率分别为72.75%、65.20%和63.45%。结合形态特征及16S rDNA序列分析,初步鉴定H-3菌株属于链霉菌属Streptomyces sp.。盆栽防效和田间防效试验结果表明,施用H-3对烟草黑胫病具有一定的防效,当添加H-3固体发酵物22.5 kg/hm2时田间防效最好,防效可达70.42%。通过荧光定量PCR技术检测了烟草根际土壤中烟草疫霉的量,结果发现,随着H-3用量的增加,根际土壤中烟草疫霉的拷贝数呈下...     

寡雄腐霉发酵液对烤烟生长的影响及对烟草黑胫病的防治作用

为了探索对烟草黑胫病高效、稳定的生防制剂,利用寡雄腐霉工程菌株制备发酵液,采用温室盆栽试验研究该发酵液对烟苗生长的影响和对烟草黑胫病的防治作用。寡雄腐霉发酵液可提高正常烟苗生物量达22.6%,促进烟苗氮、磷、钾吸收;带病烟苗的发病率和病情指数分别降低了61.6%和64.2%,相对防治效果达64.2%;施用发酵液明显降低带病烟苗的细胞膜透性和丙二醛含量,提高烟叶多酚氧化酶、超氧化物歧化酶和苯丙氨酸解氨酶活性。说明寡雄腐霉发酵液可诱导烟株的防御作用,并提高其抗病能力和促生作用。     

寄生玉米的6种腐霉及其致病性研究

 从国内12省、自治区、直辖市玉米植株上分离出腐霉菌菌株,依据形态特征、培养性状、生长抑制温度,以及产生的有性与无性器官,鉴别出6个腐霉种:棘腐霉(Pythium acanthicum Drechsler),瓜果腐霉(P.aphanidermatum(Edson)Fitzpatrick),强雄腐霉(P. arrhenomanes Drechsler),禾生腐霉(P.graminicola Subramaniam),肿囊腐霉(P.inflatum Matthews),寡雄腐霉(P.oligandrum Drechsler),其中肿囊腐霉出现频率高,分布广泛。回接玉米表明,腐霉能够侵染玉米并引起病害,肿囊腐霉、禾生腐霉、强雄腐霉、棘腐霉是玉米青枯病的重要致病菌;瓜果腐霉能够引起玉米中部茎节腐烂;寡雄腐霉虽寄生玉米,但对玉米成株无致病力。     

荧光假单胞菌拮抗菌株对烟草疫霉的抑菌机制及控病效果

为探讨烟草根际生防细菌对烟草疫霉Phytophthora nicotianae的抑菌机制,从重庆地区连作烟田健康烟株根际土壤分离获得5株荧光假单胞菌Pseudomonas fluorescens拮抗菌株。通过平板对峙及代谢产物抑菌试验筛选对烟草疫霉具有高效拮抗作用的菌株,其中,P-72-10菌株抑菌效果最强,抑菌带半径达13.0 mm,相对抑制率为68.57%,且该菌株代谢产物对烟草疫霉菌丝生长有明显的抑制作用,相对抑制率达25.39%～46.03%;显微观察发现该菌株可引起烟草疫霉菌丝的分支增多,菌丝顶端膨大呈畸形,多数菌丝中间或顶端细胞的细胞壁加厚、原生质浓缩和产生类似厚壁孢子的细胞。在温室盆栽条件下P-72-10菌株对烟草黑胫病也表现出良好的控病效果,对抗病和感病品种的相对防效分别为53.57%和66.37%。     

木霉对烟草黑胫病菌的拮抗机制

采用平板对峙法、水解酶平板活性测定、圆孔滤液法与游动孢子萌发检测、挥发性抑菌物检测等方法探讨木霉生防菌株对烟草疫霉Phytophthora nicotianae Brada de Hann的拮抗作用机制。结果表明,TR13、TR14、TR17对烟草疫霉有竞争、重寄生和抗生作用,但不同木霉菌株对烟草疫霉的拮抗作用有所不同,TR13、TR14的竞争作用较强;水解酶平板活性测定表明,3个木霉菌株均产生β-1,3-葡聚糖酶、纤维素酶,两种酶均参与烟草疫霉细胞壁的消解,以TR13与TR14酶的活性较高;3个菌株均产生非挥发性抗生素抑制烟草疫霉菌孢子萌发,但对疫霉菌菌丝的生长影响不大;TR13、TR14几乎不产生挥发性抗生素,TR17则产生挥发性抗生素,明显抑制疫霉菌生长。     

防治烟草根黑腐病拮抗芽孢菌株的筛选

由基生根串珠霉菌(Thielaviopsis basicola)引起的烟草根黑腐病是烟草生产上重要根部真菌病害,近年在我国烟草种植区有加重危害的趋势,目前防治措施主要依赖化学药剂,给卷烟卫生带来一系列问题[1].探索该病生物防治途径,克服农药残留和病原菌抗药性十分重要.芽孢杆菌是土壤和植物微生态区系的优势生物种群,具有优良生防特性[2],采用芽孢杆菌作为烟草根黑腐病生防因子尚未见报道.本研究从烟草根际土壤中分离筛选对烟草根黑腐病病菌有较强拮抗作用的芽孢菌株,研究其抑菌活性、控病作用及其分类学地位.     

腐霉菌对荧光假单胞菌株LT6代谢物的敏感性变异

为了探明不同靶标病原菌对生防菌荧光假单胞菌株LT6及其代谢物的敏感性差异，在1／5TSA平板上测定了荧光假单胞菌株LT6对69株腐霉菌的拮抗效果，在试验中观察到菌株LT6对不同种腐霉与同种腐霉不同菌株的拮抗效果存在明显差异，抑菌带最宽的为终极腐霉Pythium ultimum菌株，达7．5mm，对未知种腐霉菌株抑菌带宽最小，均小于3．0mm。腐霉菌株对由LT6产生的抗生素吩嗪-1-羧酸（PCA）的敏感性存在变异，被测的54株腐霉，当PCA浓度为7．0μg／mL时，敏感的为28株，高抗的为15株。用不同的培养液培养LT6所得的代谢物，在相同浓度下，对同一腐霉菌菌丝体生长的抑制效果不同，培养液1／5 TSB和NB明显强于KMB。综合所获结果可以看出，靶标病原菌对生防菌敏感性不一致；不同的培养基产生不同的代谢产物，对病原菌的抑制作用有明显差异。     

Pathogenicity, Electrophoretic Characterisation and In planta Detection of the Cocoyam Root Rot Disease Pathogen, Pythium myriotylum

Cocoyam (Xanthosoma sagittifolium), an important staple food crop for many people in the tropics and subtropics, suffers great losses from a root rot disease which is most probably caused by Pythium myriotylum, although it has been claimed that a complex of three root pathogens is needed to cause the disease. In this study, we compared two Pythium isolates from diseased cocoyam roots, CRPm and Bokwai, with other putative P. myriotylum isolates from culture collections and from Cameroonian soil, with respect to host range and isozyme patterns. Pathogenicity was tested on tomato, bean, cowpea, tobacco and cocoyam. CRPm and Bokwai were only pathogenic to tobacco and cocoyam. On cocoyam, these isolates caused typical symptoms within 48h on 100% of the inoculated plantlets. Only two other isolates of P. myriotylum from culture collections were moderately to weakly pathogenic to cocoyam. Isolates of P. myriotylum were very variable in their pathogenicity to bean, cowpea, tomato and tobacco. Isozyme patterns of - and -esterases were used to differentiate CRPm and Bokwai from all other isolates. Unlike the other P. myriotylum strains, cocoyam isolates were unable to grow at 37°C. Malate dehydrogenase isozyme bands originating from CRPm were consistently detected in CRPm-infected cocoyam roots grown in vitro and in vivo. These findings indicate that CRPm can penetrate cocoyam roots and cause disease in the absence of other root pathogens. This study also indicates that P. myriotylum from cocoyam developed a certain degree of host specialisation.     

山东省烟草黑胫病菌生理小种研究

 1982-1984年该省14个主要产烟县采集分离出烟草黑胫病菌104个菌系.接种方法试验表明,用游动孢子悬浮液注射接10叶期烟苗的烟茎或茎基部对于鉴定该菌的生理小种是比较好的方法.根据各菌系在L8、NC1071和NiCotiananudicaulis上的病害反应划分生理小种。结果是供试的104个菌系中有两个菌系为生理小种1号,约占1.9%;另有两个菌系虽不是0、1和3号小种,但是否为2号小种,还是其他小种,有待进一步研究;其余的菌系为0号小种,约占供试菌系的96.2%,目前为该省优势小种.     

Diversity of Virulence in Phytophthora parasitica on Tobacco, as Reflected by Nuclear RFLPs

ABSTRACT A worldwide collection of P. parasitica isolates was investigated for the ability to infect tobacco and tomato, as related to elicitin production. Elicitin was produced by all nontobacco isolates, and nonproducing strains all were isolated from tobacco. In addition, producing strains were isolated from tobacco and coexisted with nonproducing (TE ) strains. Elicitin production generally was associated with low virulence on tobacco and frequent pathogenicity on tomato, whereas TE isolates generally were highly virulent and specialized to tobacco. Analysis of both mitochondrial and nuclear DNA restriction fragment length polymorphisms indicated, for the first time, that black shank isolates can be distinguished from other P. parasitica isolates on the basis of genetic criteria. Our results suggest that severe black shank is caused by a limited number of TE strains that have been disseminated by clonal evolution. Mutations in the TE phenotype seem to have arisen independently in several genetic backgrounds and distinct geographic areas. The fortuitous absence of elicitin production has precluded population replacements in areas of intensive tobacco cultivation. Thus, monitoring the loss of elicitin production in developing tobacco areas should be considered in disease management.     

The TIR–NBS but not LRR domains of two novel N-like proteins are functionally competent to induce the elicitor p50-dependent hypersensitive response

The tobacco N protein recognizes the helicase domain (p50) of the Tobacco mosaic virus (TMV) replicase as an elicitor and mediates hypersensitive response (HR). We obtained two cDNA clones encoding novel N-like (NL) proteins NL-C26 and NL-B69 from Nicotiana tabacum cv. Samsun NN. NL-C26 and NL-B69 had a Toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (TIR–NBS–LRR) structure and showed 78% and 73% identities to N, respectively. The NL-C26 and NL-B69 genes were also expressed in N. tabacum cv. Samsun nn, which lacks the N gene. Unlike N, NL-C26 and NL-B69, when coexpressed with p50, failed to induce HR on the sites of agroinfiltration in Samsun nn leaves. However, the elicitor-dependent HR in Samsun nn was induced efficiently by chimeric N proteins with the continuous TIR–NBS domains of NL-C26 and NL-B69. On the other hand, the efficiency of HR induction varied significantly among chimeric N proteins with either of the TIR and NBS domains of the NL proteins. In contrast, chimeras carrying the LRR domains of the NL proteins did not induce HR. Thus, the TIR–NBS domains of NL-C26 and NL-B69 could functionally adapt to the LRR domain of N, which may determine the specificity for the elicitor. We speculate that the NL genes are potential HR-inducing resistance genes for undetermined pathogens other than TMV.     

马铃薯Y病毒HC-Pro第182位赖氨酸残基参与引起烟草叶脉坏死

马铃薯Y病毒(potato virus Y,PVY)是侵染烟草的最重要病毒之一.不同PVY株系侵染烟草可引起不同症状,有些PVY株系可引起烟草叶脉坏死,严重影响烟草的产量和品质.PVY A12分离物属于NTN-NW株系,但侵染珊西烟(Nicoti-ana tabacum cv.Xanthi)不能引起叶脉坏死.分析发现,...     

烟草品种对烟草花叶病毒和黄瓜花叶病毒的抗性鉴定

 2010-2011年采用大田人工接种鉴定的方法,对生产中大面积推广使用的24份烟草品种进行了烟草花叶病毒（TMV）和黄瓜花叶病毒（CMV）的抗性鉴定。结果表明,供试品种对TMV和CMV的抗病性存在较大差异,对TMV表现抗病的有Coker86、吉烟5号、Coker176、CV87、辽烟8号、CV91、中烟90等7份材料;表现中抗的有秦烟98、双抗70、C151等3份材料;表现中感的有秦烟96、G80、金星6007、龙江981、K326、秦烟201、NC89等7份材料;表现感病的有G28、云烟97、净叶黄、红花大金元、RG11、云烟85、云烟87等7份材料。对CMV表现抗病的有Coker86、龙江981、C151、秦烟201、云烟87等5份材料;表现中抗的材料是金星6007;表现中感的有CV91、RG11、Coker176、中烟90、K326、红花大金元、净叶黄、G80、G28等9份材料;表现感病的有秦烟98、云烟85、秦烟96、NC89、双抗70、云烟97、CV87、辽烟8号、吉烟5号等9份材料。其中兼抗TMV和CMV两种病毒病的材料有2份,分别是Coker86和C151。同时研究还发现,抗病性不同的烟草品种在受到病毒危害以后,对烟叶的产量和品质的影响也不同。明确了中国24个烟草品种的抗病性水平,为抗病品种的利用与品种合理布局提供科学依据,同时为烟草抗病毒病育种的亲本选择提供抗源信息。     

Molecular Markers Dispute the Existence of the Afro-Andean Group of the Bean Angular Leaf Spot Pathogen, Phaeoisariopsis griseola

ABSTRACT Coevolution of the angular leaf spot pathogen, Phaeoisariopsis griseola, with its common bean host has been demonstrated, and P. griseola isolates have been divided into Andean and Mesoamerican groups that correspond to defined bean gene pools. Recent characterization of P. griseola isolates from Africa has identified a group of isolates classified as Andean using random amplified polymorphic DNA (RAPD), but which are able to infect some Mesoamerican differential varieties. These isolates, designated Afro-Andean, have been identified only in Africa. Random amplified microsatellites, RAPD, and restriction digestion of amplified ribosomal intergenic spacer region were used to elucidate the relationships among the Afro-Andean, Andean, and Mesoamerican groups of P. griseola. Cluster and multiple correspondence analysis of molecular data separated isolates into Andean and Meso-american groups, and the Afro-Andean isolates clustered with Andean isolates. Analysis of molecular variance ascribed 2.8% of the total genetic variation to differences between Afro-Andean and Andean isolates from Africa. Gene diversity analysis revealed no genetic differentiation (G(ST) = 0.004) between Afro-Andean and Andean isolates from Africa. However, significant levels of genetic differentiation (G(ST) = 0.39) were observed between Afro-Andean or Andean isolates from Africa and Andean isolates from Latin America, revealing significant geographical differentiation within the Andean lineage. Results from this study showed that Afro-Andean isolates do not constitute a new P. griseola group and do not represent long-term evolution of the pathogen genome, but rather are likely the consequents of point mutations in genes for virulence. This finding has significant implications in the deployment of resistant bean genotypes.     

抗植物病毒剂对烟草和甜菜病程相关蛋白的诱导作用

 本文用7种抗植物病毒剂在烟草(Nicotiana tabacum L. "Samsun" NN)和甜菜(Beta milgaris L.)上进行了病程相关蛋白(Pathogenesis-Related Proteins,PRs.)的诱导试验。结果表明,所有参试的抗植物病毒剂都可以在烟草和甜菜上诱导产生一些PR蛋白。抗病毒物质在烟草和甜菜上分别最多可以诱导产生7种PR蛋白。这可能对植物的诱导抗性有一定的贡献。但在产生的PR蛋白的种类和含量上有一定的差别,同一种药剂在不同植物上诱导产生PR蛋白的能力也有所不同。多种成份的药剂与单一成份的药剂相比,可诱导产生的PR蛋白种类和含量较多。     

2012年部分麦区小麦白粉菌群体对三唑酮敏感性及其与毒性的关系

 抗病品种和化学防治是控制植物病害最有效的两种措施,病原菌在长期选择压下可改变其群体结构,以逐步适应品种抗性和杀菌剂压力。本研究采用拌种离体叶段法对 2012年采自我国9个省(市)的129个小麦白粉病菌Blumeria graminis f. sp. tritici单孢堆分离物进行了三唑酮敏感性检测,同时采用31个已知抗病基因品种(系)对其进行苗期毒性测定,并对二者之间的相关性进行分析结果表明:129个供试菌株对三唑酮的EC₅₀为 109.97 mg/L,平均抗药性水平达到52.62倍,变异系数为 107.2。所有供试菌株中,99.22% 的菌株产生了抗药性,其中高抗菌株占58.91%,中抗菌株占37.98%。北京菌株的抗药性水平明显高于其他8个省市。利用Popgen1.32软件对9个省(市)小麦白粉病菌群体的毒性多样性分析结果表明,四川群体毒性基因多样性水平最高,Nei基因多样性H值为0.224 1,浙江群体最低,H值为0.096 8。小麦白粉菌群体对三唑酮的敏感性和毒性的相关性分析表明,EC₅₀或EC₅₀变异系数与毒性多样性之间均不存在显著的相关性,但EC₅₀与毒性基因数目之间的关系符合对数方程。此结果可为杀菌剂和抗性品种的合理利用提供依据。     

Greater aggressiveness in the 2_A1 lineage of Phytophthora infestans may partially explain its rapid displacement of the US-1 lineage in east Africa

The displacement in east Africa of the US-1 clonal lineage of Phytophthora infestans by 2_A1 clonal lineage has been very rapid. This study tested the hypothesis that dominance of 2_A1 could be due, at least in part, to the increased aggressiveness of 2_A1 over US-1, using both a detached leaf assay (DLA) and a tuber slice assay. The assays were conducted in Uganda and Kenya but US-1 was only assayed in Uganda, because isolates could not be moved across borders and no potato US-1 isolates were available in Kenya. All isolates were collected from potato and compared on two potato cultivars (Kachpot-1 and Sarpo Mira), with the 2_A1 isolates also tested on tomato cultivar Rio Grande. Additionally, a tuber slice assay was done to test whether the capacity to infect tubers differed between 2_A1 and US-1. The aggressiveness of the isolates in the DLA varied significantly both within and among isolates classified according to clonal lineage and for type of host. The 2_A1 isolates were significantly more aggressive than US-1 isolates on both potato varieties evaluated. There were no significant effects of clonal lineage or potato cultivar used in the tuber assay. No significant correlation between foliar and tuber pathogenicity was observed. The 2_A1 isolates were significantly more aggressive on potato than on tomato. An effect of location was also observed in the DLA, on both hosts. It can be concluded from this study that greater pathogenicity of 2_A1 is at least partly attributable to its increased aggressiveness on potato.