两株毒力不同的核盘菌产草酸、果胶酶的比较

对强弱毒力不同的核盘菌Ep-1PNA5和Ep-1PN的主要致病因子草酸和果胶酶的产生进行了比较研究。结果发现强毒力的Ep-1PNA5和弱毒力Ep-1PN都可产生草酸,并且在发病油菜活体组织上,弱毒力Ep-1PN的病组织中的草酸含量高于Ep-1PNA5病组织;两个菌株在发病油菜活体组织上的果胶酶产量没有差异,但在诱导培养基中Ep-1PN菌株比Ep-1PNA5的果胶酶产量高。这一结果表明弱毒力Ep-1PN菌株毒力的衰退并不是因为其所携带的dsRNA因子抑制了草酸和果胶酶所产生的。     

Sclerotinia sclerotiorum growth and oxalic acid production on selected culture media

Abstract Two isolates of Sclerotinia sclerotiorum , the highly aggressive (B24) and the weakly aggressive (SS41), were grown on liquid media containing one of the following carbon sources: purified cell walls obtained from onion or sunflower, pectin, polygalacturonic acid, carboxymethylcellulose, xylan or arabinogalactan. Isolates were equally able to utilize these substrates for mycelial growth but differed in their ability to utilize them for oxalate production. B24 produces oxalic acid always to a substantial extent, SS41 only in traces. The poor ability to produce oxalic acid by SS41 seems to be due to a lower efficiency in the synthetic pathway.     

组学技术在核盘菌研究中的应用

核盘菌Sclerotinia sclerotiorum是一种典型的死体营养型植物病原真菌,全球分布且寄主范围广泛,严重危害多种植物,对农业生产造成严重损失。核盘菌研究主要集中在真菌生物学及病理学等方面。近年来,随着高通量分析技术的不断改进,多种组学技术为系统生物学研究提供了平台。文中主要综述利用多种组学研究方法在植物病原真菌核盘菌研究中的应用及研究进展,探讨开展植物病原物及病害发展的系统性研究思路,以期为核盘菌的分子生物学及致病机理等研究提供参考,同时也为其他植物病原物及病害系统研究提供理论依据。     

Enzymatic oxalate decarboxylation in isolates of Sclerotinia sclerotiorum

Abstract Sclerotinia sclerotiorum isolates B24 (virulent) and SS41 (hypovirulent) possess oxalate decarboxylase. Production was regulated by composition and pH of culture medium and required the presence of oxalate or its precursor, succinic acid, as inducers. Mycelia of both isolates contain equivalent amounts of enzyme.     

利用SRAP分析核盘菌遗传多样性

核盘菌(Sclerotinia sclerotiorum)是危害油菜等多种经济作物的重要病原真菌.研究不同地区、相同或不同寄主核盘菌的遗传多样性对了解核盘菌的遗传演化过程和指导病害防控具有重要意义.我们采用序列相关扩增多态性(sequence-related amplified polymorphism,SRAP)标记对不同地理来源、不同寄主来源的76个核盘菌菌株的遗传多样性进行了分析.7对SRAP引物共获得260个位点,其中114个为多态位点,占43.85%.UPGMA聚类结果显示,在相似性系数为0.64时,76个核盘菌菌株分为4个组,每组包含的菌株数分别为54、18、2和2.聚类及主成分分析结果显示,来源于春油菜生态区和冬油菜生态区油菜上的核盘菌菌株可以明显分为两簇,而油菜、大豆、莴苣等不同寄主植物上的核盘菌菌株没有明显的遗传分化.分子变异分析(AMOVA)结果显示.不同地理来源、不同油菜生态区和不同寄主来源的核盘菌群体内的变异率分别为75.2%、81.2%和97.6%,均达到极显著水平(P<0.001);不同地理来源和不同油菜生态区的核盘菌群体间的变异率分别为24.8%和18.8%,也达到极显著水平(P<0.001);不同寄主来源的核盘菌群体间的变异率仅为2.4%,变异不显著(P=0.8673).研究结果表明,来源于春油菜生态区的核盘菌的遗传多样性高于冬油菜生态区.     

菌核病防治研究进展

菌核病是一种寄主种类广泛的重大植物病害,可侵染450多种重要作物和草类,在我国每年给油菜、大豆以及多种蔬菜带来10～30亿元的损失.介绍了菌核病的症状、危害以及致病机理等,概述了主要的防治措施,并报道了国内外在关于菌核病生物防治、转基因育种、分子机理等方面的研究进展.     

Suppression of carbendazim-susceptible and -resistant Sclerotinia sclerotiorum with Macleya alkaloids

Macleaya alkaloids (abr. MCA), an extract from aerial parts of Macleaya cordata, was investigated on suppressing Sclerotinia stem rot disease. The median inhibitory concentrations (EC₅₀) of MCA on mycelia growth were 5.21 μg mL^?1 to carbendazim-susceptible (Ss01) and 6.34 μg mL^?1 to carbendazim-resistant (Hm25) S. sclerotiorum, and there was no cross-resistance between MCA and carbendazim. MCA blocked the mycelial membrane leakage and regulated the exo-secretion of the reducing sugar and oxalate in a concentration-dependent manner. Moreover, MCA also significantly destroyed the redox balance including superoxide dismutase, peroxidase and catalase in Sclerotinia mycelia. In pot experiments, MCA showed an excellent antifungal efficacy on protecting rapeseed leaves from the infection of Ss01 and Hm25 isolates. The results suggested a potential possibility to develop MCA as an agro-chemical to control Sclerotinia stem rot disease and manage carbendazim resistance.     

核盘菌AROM蛋白的三级结构分析

核盘菌编码AROM蛋白的arom基因已经被克隆测序,本文根据该基因翻译的氨基酸序列用同源模建方法和从头模建方法分析了AROM蛋白各结构域的三级结构和功能位点,以及该蛋白二聚体可能的组装方式。结果表明,核盘菌AROM蛋白的脱氢奎尼酸合酶结构域进一步由N-端含有一个Rossmann折叠的α/β结构域和C-端的α螺旋结构域组成;5-烯醇丙酮酰莽草酸-3-磷酸合酶结构域则由两个相似结构域组成,每个结构域含有不同拷贝数的β折叠和α螺旋;莽草酸激酶结构域的N-端由三个β折叠组成;脱氢奎尼酸酶结构域为(α2β2)3多肽,在N-端有一对反平行的β链,在C-端有loop环;莽草酸脱氢酶结构域含有一个由α/β组成的催化结构域和一个含有Rossmann折叠的NADPH结合结构域。     

Secretion of pectic isoenzymes by Sclerotinia sclerotiorum

Abstract Cultures of Sclerotinia sclerotiorum grown on different pectin-related polysaccharides (citrus pectin, apple pectin, sodium polygalacturonate), carboxymethylcellulose (CMC) or glucose as the only carbon source were examined daily for polygalacturonase and pectinase activities. Electrophoretic forms of polygalacturonase and pectin methylesterase activities were revealed using analytical IEF and sodium polygalacturonate and citrus pectin as substrates in overlay gels. A sequence in the production of pectic enzymes and isoenzyme synthesis was found in pectic-polymer cultures corresponding to the induction of several isoenzymes. Enzyme activities in glucose media were associated with three polygalacturonase and two pectinmethylesterase isoforms which were produced constitutively. Sodium-dodecyl-sulphate polyacrylamide-gel electrophoresis followed by immunoblotting with polyclonal antibodies against an exo-polymethylgalacturonase and an exo-polygalacturonase revealed that these exo-enzymes were secreted from the beginning of cultivation in the different culture media showing characteristics of constitutive enzymes.     

向日葵菌核病拮抗菌XRK5的筛选与鉴定

从向日葵根际分离了640个细菌分离物,以向日葵菌核病菌(Sclerotinia sclerotiorum)为靶标菌,通过平板对峙法获得了18个具有拮抗性能的细菌,其中XRK5具有较强拮抗能力,且拮抗性能稳定,具有较好的生防应用潜力。经过形态观察、生理生化特征及16SrRNA序列分析,将XRK5鉴定为辣椒溶杆菌(Lysobacter capsici),XRK5的16SrRNA序列在GenBank中的注册号为FJ959348。     

Colonisation of sclerotia of Sclerotinia sclerotiorum by a fungivorous nematode

Aphelenchoides saprophilus nematodes fed on sclerotia, mycelium, and alginate-formulated pellets of Sclerotinia sclerotiorum, mycelium of Trichoderma harzianum, and mixed fungal cultures. As many as 500 nematodes were found inside individual sclerotia. Results suggest potential impacts of fungivory on S. sclerotiorum and its ecological interactions with plant hosts and biocontrol fungi.     

A sunflower leaf antifungal peptide active against Sclerotinia sclerotiorum

A 5-kDa antifungal peptide (APS) was isolated from Helianthus annum L. (line HA89) leaves infected with a virulent isolate of Sclerotinia sclerotiorum (Lib.) de Bary. AP5 was purified by gel filtration, cation exchange chromatography and reverse phase FPLC and HPLC. This peptide in vitro inhibits ascospores germination of the fungal pathogen S. sclerotiorum or produces mycelial growth inhibition, depending on its concentration. The effective concentration of AP5 giving 50% growth inhibition (IC₅₀) against S. sclerotiorum was 0.4 μM. The antifungal efficacy of AP5 is higher than that of other antimicrobial proteins already described that have no appreciable effect on S. sclemtiorum below 4 μM. The relevance of this finding with regard to the function of AP5 in sunflower resistance to pathogens is discussed.     

Detection of Sclerotinia sclerotiorum in Planta by a Real-time PCR Assay

Stem rot caused by Sclerotinia sclerotiorum is a very serious disease on oilseed rape worldwide. In this study, a pair of polymerase chain reaction (PCR) primers was designed based on the nucleotide sequence of a DNA region amplified by a microsatellite primer M13. The primer pair amplified a 252-bp fragment from all S. sclerotiorum isolates collected from oilseed rapes at different locations in different years, but not from any other fungus tested. Using this pair of primers, a real-time PCR assay was developed to rapidly detect early infection of S. sclerotiorum on petals of oilseed rape. The real-time PCR assay developed in this study could help growers make a timely decision on fungicide application.     

油菜菌核病菌对速克灵的抗药性风险研究

在室内条件下通过菌丝生长速率法测定了分离自安徽省10个县市的油菜菌核病菌（Sclerotinia scleroti-orum）对速克灵的敏感性。结果表明,速克灵对各供试菌株的EC50值分布范围为0.0899-0.4966μg/mL,平均为0.2541μg/mL,且供试菌株在含速克灵质量浓度为10 000μg/mL的PDA平板上菌丝生长几乎完全被抑制。表明各供试菌株对速克灵十分敏感,但其敏感程度地区间存在较大差异。通过室内药剂直接诱变法,获得了抗速克灵突变株。抗性突变株抗性测定结果表明,某些地区的抗性菌株抗性消失,有些地区的抗性菌株抗性继续保持。结果显示安徽省油菜菌核病菌对速克灵具有潜在的抗药性风险。     

稀土元素对油菜菌核病菌生长及其生化性状影响的研究

研究了氧化镧 (La2 O3 )对油菜菌核病菌 (Sclerotiniasclerotiorum ,Ss)生长及其生化性状的影响 .结果表明 ,La2 O3 浓度在 3 0～ 45 0mg·L-1时 ,固体培养和液体培养中对Ss生长均呈明显抑制作用 ,且生长抑制率 (Y)随La2 O3 浓度增加而相应增加 .液体培养中油菜菌核病菌产生的果胶酶活性随溶液中La2 O3 浓度增加而相应增加