Impact of alternative respiration and target-site mutations on responses of germinating conidia of Magnaporthe grisea to Qo-inhibiting fungicides     

Avila-Adame C  Köller W 《Pest management science》2003,59(3):303-309

Qo-inhibiting fungicides act as respiration inhibitors by binding to the Qo center of cytochrome b. Sensitivities of fungi to Qo inhibitors can be influenced by the induction of alternative respiration or by mutational changes of the cytochrome b target site. Previous studies on both mechanisms in Magnaporthe grisea (Hebert) Barr were focused on the mycelial stage of the pathogen. The present study describes the expression and impact of both resistance mechanisms during the stage of conidia germination. In the absence of a host, alternative respiration provided a >500-fold rescue from azoxystrobin during the germination of conidia derived from four wild-type isolates of M. grisea. This rescue potential during conidia gemination was substantially more pronounced than for mycelial growth. However, the pronounced effectiveness of alternative respiration during conidia germination was not apparent when barley leaves were protected with azoxystrobin prior to inoculation with conidia. In a comparison of a wild-type strain and an alternative respiration-deficient mutant, azoxystrobin efficacies in suppressing symptom development differed by a factor of two, with full disease control achieved for both genotypes at 1 microg ml(-1) azoxystrobin. In contrast, conidia derived from two QoI-resistant target site mutants were highly resistant to azoxystrobin and trifloxystrobin and fully capable of infecting leaf surfaces protected with 10 microg ml(-1) of azoxystrobin. Both target-site mutants had emerged spontaneously in the presence of high azoxystrobin doses when residual mycelial growth was supported by alternative respiration. The effective silencing of alternative respiration in protective applications of Qo-inhibiting fungicides might constitute a strategy of slowing the emergence of highly resistant target site mutants.  相似文献   

水杨酸对水稻幼苗抗瘟性的诱导作用   总被引：51，自引：3，他引：51  

蔡新忠  郑重 《植物病理学报》1996,26(1):7-12

 网室试验证明,水杨酸(SA)叶面喷雾可减轻水稻幼苗稻瘟病的发生。在平板培养中,SA对稻瘟菌分生孢子的萌发及菌丝生长均无明显抑制作用,因此认为SA处理后稻瘟病病情指数的下降是由于SA处理提高了水稻幼苗的抗瘟性,即稻苗产生了诱导抗性而引起的。SA诱发水稻幼苗产生对苗叶瘟诱导抗性的浓度为0.01~0.1mM。SA喷雾处理后2~4天接种,诱导抗性表现最强。0.01mMSA在接种前2天喷雾处理三叶一心期稻苗一次后,水稻叶片的病斑数目和大小比清水对照分别降低72.7%和55.4%,病指比对照降低59.8%,抗瘟性的持久期为15天(病指降低24.3%)。经0.01mMSA诱导处理后再用同浓度SA进行一次强化处理可增强诱抗效果,延长抗性持久期。用0.01mMSA处理水稻第一和第二叶可使未经处理的第三和第四叶上产生系统性抗瘟性。  相似文献   

Analysis of the Genetic Components of Peridial Tissue of Perithecia in the Blast Fungus     

Motoaki KUSABA  Mahito HASEGAWA  Yoshikatsu FUJITA  Hiroshi YAEGASHI 《Journal of General Plant Pathology》2001,67(3):200-204

To elucidate perithecial wall development in Magnaporthe grisea, monoconidial isolates were collected from the surfaces of six perithecia in five crosses. Genotypes of these isolates were characterized based on colony color, mating type and repetitive DNA elements. Each set of isolates from four perithecia possessed the genetic markers from only one parent in each cross. However, each set of isolates from the other two perithecia had markers from both parents. Tissues containing both parental genomic components may thus take part in construction of perithecial wall. Received 13 October 2000/ Accepted in revised form 12 March 2001  相似文献   

水稻主要抗瘟基因对福建稻瘟菌群体的抗性分析   总被引：3，自引：0，他引：3  

刘文德  阮志平  郑士琴  赵长江  郑武  鲁国东  王宗华 《植物病理学报》2005,35(6):526-531

 用1995-2003年间在福建省水稻产区采集的稻瘟菌代表菌系的108个分离菌,它们在CO39近等基因系上测定被划分为30个毒性类型,用它们在30个水稻抗稻瘟病近等基因系或单基因系品种上进行抗病性测定。结果表明水稻抗稻瘟病基因Pi-k^h抗性最强,抗性频率高达98.15%,Pi-1和Pi-9(t)也具有较高的抗性频率,是较好的抗源;对2个和3个Pi基因的联合抗性频率的分析,发现一些联合抗性频率极高,甚至有达到100%的组合,表明抗瘟育种采用多个Pi基因聚合,易于获得抗性强的品种。根据抗病基因与供试菌株互作的亲和性,对供试30个Pi基因可能的系统关系分析得到的初步信息可为抗病基因的聚合与布局策略提供参考。  相似文献   

Significance of PWT4–Rwt4 interaction in the species specificity of Avena isolates of Magnaporthe oryzae on wheat     

Kenji Hirata  Yukio Tosa  Hitoshi Nakayashiki  Shigeyuki Mayama 《Journal of General Plant Pathology》2005,71(5):340-344

We examined whether PWT4, an avirulence gene of Avena isolates of Magnaporthe oryzae toward wheat, corresponded to Rwt4, a resistance gene identified in wheat cultivar Norin 4, in a one-to-one manner. Twelve wheat cultivars were inoculated with 65X1, an F₁ culture with PWT4 derived from a cross between an Avena isolate (Br58) and a Triticum isolate (Br48). Three wheat cultivars (Norin 26, Shin-chunaga, Cheyenne) were resistant and therefore selected as possible carriers of Rwt4. The three cultivars were then inoculated with a population derived from a backcross of 61M2 carrying PWT4 with Br48 carrying pwt4. Segregation analyses revealed that PWT4 operates against the three cultivars. If PWT4 corresponds to Rwt4 in a one-to-one manner, all three cultivars should carry Rwt4. To test if this is the case, the three cultivars were crossed with Chinese Spring (a noncarrier of Rwt4) and Norin 4. When F₂ seedlings from Chinese Spring × Norin 26, Chinese Spring × Shin-chunaga, and Chinese Spring × Cheyenne were inoculated with 61M2, resistant and susceptible seedlings segregated in a 3 : 1 ratio. On the other hand, crosses between the three cultivars and Norin 4 yielded no susceptible F₂ seedlings. These results indicate that all three cultivars carry Rwt4. Considering all results, we concluded that PWT4 corresponds to Rwt4 in a one-to-one manner. An inoculation test with Chinese Spring–Cheyenne chromosome substitution lines indicated that Rwt4 is located on chromosome 1D.  相似文献   

2002年黑龙江省部分稻区稻瘟病菌生理小种鉴定   总被引：7，自引：0，他引：7  

张亚玲  靳学慧 《植物保护》2006,32(2):31-34

用中国7个统一鉴别品种对2002年在黑龙江省部分地区采集的57个单孢分离菌株进行了生理小种鉴定。共鉴定出6群10个生理小种,即ZA17、ZA49、ZB1、ZB19、ZB25、ZC9、ZD1、ZD5、ZE1和ZF1生理小种,其中ZD1为优势小种,出现频率为36.8%。生理小种的组成由1996年商世吉报导的4群7个生理小种发展到6群10个生理小种,优势小种也由ZE1转变为ZD1。其中ZA17、ZA49强致病型的生理小种开始出现。所鉴定出的10个生理小种对4个粳稻鉴别品种有较强的致病力。地域较近的地区稻瘟病菌的生理小种群体组成也有较大差异。  相似文献   

DNA fingerprinting of Pyricularia grisea by rep-PCR using a single primer based on the terminal inverted repeat from either of the transposable elements Pot2 and MGR586     

Fumihiko Suzuki  Michiyoshi Arai  Junichiro Yamaguchi 《Journal of General Plant Pathology》2006,72(5):314-317

We investigated the use of single primers complementary to sequences in the terminal inverted repeat (TIR) of either Pot2 or MGR586, transposable elements found in Pyricularia grisea, for DNA fingerprinting by repetitive-element-based polymerase chain reaction (rep-PCR). Under standard amplification conditions, rep-PCR with each single primer generated distinct fingerprint patterns among rice-infecting P. grisea isolates collected in Japan. With the Pot2-TIR primer, bands ranging in size from 0.2 to 8 kb and in number from 8 to 13 per isolate were amplified. Although fewer bands were amplified with the MGR586-TIR primer, this molecular technique should be more reliable to identify and classify P. grisea isolates by combining the data of fingerprint patterns from each TIR primer. In a cluster analysis based on DNA fingerprints from this rep-PCR with the Pot2-TIR primer, 10 reference isolates and 12 field isolates from Saga Prefecture in 2002 were separated into six clonal lineages. We also demonstrated that the 12 field isolates belonged to one clonal lineage. Thus, this rep-PCR method using the single primer Pot2-TIR will be useful for the analysis of the population structure of rice blast pathogens.  相似文献   

Molecular and Pathotype Analysis of the Rice Blast Fungus in North Vietnam     

Nguyen Thi Ninh Thuan  Joseph Bigirimana  Ed Roumen  Dominique Van Der Straeten  Monica Höfte 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(4):381-396

Rice blast caused by Pyricularia oryzae is a devastating disease worldwide. In Vietnam, rice blast is especially severe in the Red River Delta in the North. The genetic diversity of 114 P. oryzae isolates collected from rice in 2001 in the Red River Delta and nine additional Vietnamese P. oryzae isolates was analysed using Amplified Fragment Length Polymorphism (AFLP). DNA similarity and cluster analysis based on 160 polymorphic AFLP markers showed twelve different AFLP genetic groups among the 123 field isolates. Isolates collected from japonica hosts clustered separately from indica host isolates with at least 60% dissimilarity with little evidence for gene flow between the two populations. In the 2001 population originating from indica hosts, three genetic groups were predominant and represented 99% of the isolates sampled. One predominant clonal lineage represented 59% of the 2001 indica host population and was found in eleven provinces in the Red River Delta of North Vietnam. Significant genotype flow could be demonstrated between the indica population south of Red river and the indica population north of Red river. There was significant linkage disequilibrium between the AFLP loci within the indica population, indicating that this is not a random mating population. Pathogenicity tests of 25 isolates selected from the 12 AFLP groups on a set of 29 differential rice lines revealed two avirulent isolates and 23 pathotypes. Different combinations of known resistance genes were found to have potential for blast resistance breeding for North Vietnam. First two authors contributed equally  相似文献   

Dynamics of spatial and temporal population structure of Pyricularia oryzae in Taiwan     

Yi-Nian Chen  Dong-Hong Wu  Mei-Chun Chen  Meng-Ting Hsieh  Woei-Shyuan Jwo  Guo-Cih Lin  Rong-Kuen Chen  Hau-Ping Chou  Pei-Chen Chen 《Pest management science》2023,79(11):4254-4263

  相似文献   

三环唑防治稻瘟病的应用技术及防效影响因素研究   总被引：6，自引：0，他引：6  

黄星  周明国  张传清  傅峰  张永慧 《农药学学报》2005,7(2):131-134

在实验室条件下研究了三环唑防治稻瘟病的应用技术与导致药剂防效下降的因素。三环唑喷雾或浸根处理对稻瘟病都有显著防效,浸根处理优于喷雾处理;喷雾或浸根处理后5 d内表现较高防效,持效期达10 d;三环唑处理3 d后再次喷雾处理,不但可以提高防效,还可使持效期延长至15 d;在稻瘟病菌尚未侵入稻苗时用10 μg/mL三环唑喷雾处理,防效达81.3%,在稻瘟病菌完成侵入后再用三环唑处理,10 μg/mL药剂防效仅为35.6%。若水稻叶片有伤口,三环唑对稻瘟病则失去防效。药剂喷雾后1 h内降雨会导致防效显著下降, 3 h后降雨则对防效无影响。  相似文献