小麦赤霉病菌对多菌灵和不同杀菌剂敏感性的相关分析

为探明江苏省小麦赤霉病菌[Gibberella zeae (Schwein.) Petch]对多菌灵的抗药性和该药剂与其它杀菌剂的交互抗性,采用区分剂量法检测了采自江苏省26个县(市)的520株小麦赤霉病菌对多菌灵的抗药性,并采用菌丝生长速率法分别检测了对多菌灵不同敏感性的10个菌株对嘧菌酯、吡唑醚菌酯、肟菌酯、唑胺菌酯、氟环唑、己唑醇、灭菌唑和咯菌腈等杀菌剂的敏感性。结果表明,江苏省各县(市)菌株对多菌灵的抗性频率差异较大,总抗性频率为50.58%;通过EC₅₀值相关性分析,小麦赤霉病菌对多菌灵和上述杀菌剂之间不存在交互抗性。江苏省小麦赤霉病菌对多菌灵的抗性频率较高,迫切需要筛选新的杀菌剂防治小麦赤霉病。     

Localisation of the benzimidazole fungicide binding site of Gibberella zeae β2-tubulin studied by site-directed mutagenesis

BACKGROUND: The efficacy of benzimidazole fungicides is often limited by resistance, and this is the case with the use of carbendazim for controlling Fusarium head blight caused by Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum). Recent studies have shown that carbendazim resistance in field strains of G. zeae is associated with mutations in the β ₂‐tubulin gene. The aims of the present study were to validate this mechanism and research the binding sites of carbendazim on β ₂‐tubulin. RESULTS: This work used site‐directed mutagenesis followed by gene replacement to change the β ₂‐tubulin gene of a carbendazim‐sensitive field strain of G. zeae at residues 50, 167, 198 or 200. The transformants were confirmed and tested for their sensitivity to carbendazim. All the mutants were resistant to carbendazim, but the level of resistance differed depending on the mutation. Biological characteristics did not differ between the field strain and the site‐directed mutants. A three‐dimensional model of β ₂‐tubulin was constructed, and the possible carbendazim binding site was analysed. CONCLUSION: Mutations at codons 50, 167, 198 and 200 of G. zeae β ₂tub could cause resistance to carbendazim, and these codons may form a binding pocket. Copyright © 2010 Society of Chemical Industry     

RF－1小麦品系抗赤霉病机理初探

高抗赤霉病且丰产性较好的ＲＦ－１小麦品系和泗麦２号小麦比较后发现：该品种在扬花后残留的花药极少，穗形结构松散，麦穗主轴弯曲度大，穗轴表皮下机械组织排列紧密且层次多。室内离体麦穗接种的病情扩展较对照品种慢。     

小麦赤霉病特大流行年不同品种(品系)间抗性试验分析

田间对比试验结果表明,赤霉病特大流行年不同小麦品种对赤霉病的抗性存在极显著差异,可分为高感、中感和中抗3个类型。因此,生产上应以中抗品种扬麦158作为当家品种,适当示范种植扬麦11、扬麦13等抗病、耐病性较强、产量较高的品种,并加强测报,适时开展药剂防治,综合控制病害的流行为害。     

Sugar transporter (MfsX) of the major facilitator superfamily is required for flagella-mediated pathogenesis in <Emphasis Type="Italic">Dickeya dadantii</Emphasis> 3937

Dickeya dadantii (syn. Erwinia chrysanthemi) is a causal agent of soft-rot diseases on many crops. Here, we characterized a gene belonging to the major facilitator superfamily (MFS), which is involved in the symport, antiport, or uniport of various substrates, and the survival and virulence of many Gram-negative bacterial animal pathogens, for the possible involvement in the plant pathogenicity of D. dadantii. A marker-exchange mutant of this gene (mfsX) was constructed that had decreased maceration ability in Chinese cabbage, potato, and chicory. Observation with electron microscopy showed greatly reduced numbers of flagella per cell. This mutant had a significant reduction in swimming and swarming motility and a severe reduction in formation of biofilm. Because these phenotypes have been shown to be involved in plant pathogenicity of D. dadantii, mfsX seems to play an important role in pathogenesis of D. dadantii 3937 by its involvement in the expression of these pathogenicity-related phenotypes.     

禾谷镰孢Tri12基因敲除突变体的致病力

Tri12是镰孢菌Fusarium编码单端孢霉烯族毒素(trichothecenes,以下简称“单族毒素”)输出泵的基因,而产毒基因Tri5编码的单端孢霉二烯合酶催化毒素生物合成中的第一步反应。以禾谷镰孢FusariumgraminearumSchw.野生型菌株NRRL29169为亲本,获得Tri12敲除的转化子MT12。与NRRL29169相比,MT12在PDA培养基上生长慢,生长量小(P<0.01),大分生孢子较长。致病力测定结果显示,NRRL29169致病力最强,所致病害可以自接种点向上下扩展至其他小穗,而MT12的致病力极弱。我们由此推测,Tri12的敲除导致病菌产生的毒素不能被泵出体外毒害寄主,进而在病菌体内积累抑制自身生长和毒素的进一步产生,从而降低病菌的致病力。     

三种毛茛科植物提取物及原白头翁素的活性研究

采集打破碗花花、毛茛和白头翁3种毛茛科植物样品76个,以水、人尿、乙醇等作溶剂,用浸泡法、蒸馏法和回流萃取法等方法提取,进行生物测定,结果表明:上述植物提取物具有较低的杀虫活性,较高的离体抑菌活性,对鱼低毒从植物中提取或人工合成的原白头翁素、白头翁素(经UV、IR、NMR分析与文献值符合)等样品16个。研究证明,原白头翁素,在水溶液中性质不稳定,容易发生聚合反应,其聚合物的生物活性明显下降,但以乙醇为溶剂时,则较为稳定。     

水稻与基腐病菌互作中的活性氧代谢

对水稻与基腐病菌互作中活性氧及其相关酶系与抗性关系进行了研究。结果表明:超氧阴离子自由基(O2.-)、H2O2、MDA在接种后24 h达到高峰,且抗病品种的含量比感病品种高;SOD在抗感品种接种病菌24 h后活性增加,均达到高峰,然后开始下降,但总趋势为抗病品种低于感病品种;CAT在接种后24 h和96 h,感病品种出现2个高峰,而抗病品种的活性在整个过程中变化不明显。     

PIRA-PCR for detection of Fusarium graminearum genotypes with moderate resistance to carbendazim

PIRA-PCR ( p rimer- i ntroduced r estriction a nalysis PCR) was developed to detect isolates of Fusarium graminearum with moderate resistance to carbendazim, a methyl benzimidazole carbamate (MBC)-group fungicide. Two primer pairs were designed and synthesized according to the nucleotide sequence of the β ₂-tubulin gene from F. graminearum. Fragments of 164 bp were amplified by nested PCR from isolates differing in carbendazim sensitivity. A Hin dIII restriction enzyme recognition site was introduced artificially by inner primers to detect a mutation at codon 167, and Taa I ( Tsp 4CI) restriction enzyme was used to detect a mutation at codon 200. The sensitivity of isolates to carbendazim was determined by analyzing electrophoresis patterns of the resulting PCR products after simultaneous digestion with both Hin dIII and Taa I. Results from PIRA-PCR and a conventional method (mycelial growth on agar) were identical but PIRA-PCR required only 7–8 h while the conventional method required 5–7 days. This study demonstrates that PIRA-PCR not only monitors the appearance of moderately resistant isolates, but can be useful for detecting genotypes of F. graminearum with moderate resistance to carbendazim.     

甘薯茎腐病菌的遗传多样性及致病力差异分析

为了解不同地区甘薯茎腐病菌Dickeya dadantii种群遗传多样性水平及致病力差异,采用重复序列PCR基因指纹(repetitive element palindromic PCR,REP-PCR)技术和薯片接种方法,对采自广东省、广西壮族自治区和重庆市的6个市区县的59株菌株进行分析。结果表明,5对引物对59株菌株扩增出41个清晰的条带,其中36个为多态性条带,每对引物的扩增条带数在4～10之间,平均为7.2。在物种水平上,有效等位基因数、Nei’s基因多样性指数和Shannon信息指数分别为1.4768、0.2801和0.4186,其中湛江种群多样性最高,南宁种群多样性最低;当遗传相似系数为0.79时,59株菌株可被划分为5个类群,类群划分与菌株来源地间有一定的相关性。此外,不同地区病菌种群间存在明显的致病力差异,其中合浦种群与湛江种群致病力最强,万州种群致病力较弱。表明甘薯茎腐病菌种群具有丰富的遗传多样性,不同地区的病菌种群存在明显的遗传多样性与致病力差异。