棉花枯萎菌gDNA不同提纯方法的比较研究

以棉花枯萎菌菌株为试验材料 ,在CTAB法、SDS CTAB法等基础上加以改进 ,对 4种提纯棉花枯萎菌DNA的方法进行了比较研究。结果表明 :SDS CTAB法是适合于棉花枯萎菌DNA提取的方法。该方法提取的DNA纯度高 ,产率高 ,无明显降解现象 ,能很好地被限制性内切酶酶切 ,并用作PCR模板。

聚类分析在棉花枯萎菌生理小种鉴定中的应用

为找到一种较为客观地鉴定生理小种的方法 ,对采用鉴别寄主法鉴定枯萎病菌生理小种的一些数据运用UPGMA聚类分析的方法进行处理 ,结果两者基本一致 ,且聚类分析可将传统方法分类不明确的菌株有个较明确的归属。传统试验方法结合聚类分析能使棉花枯萎菌生理小种的划分更加科学。

河南省商丘地区棉花枯萎病菌的分子鉴定与致病力

以河南省民权县花园镇棉花枯萎病病株为材料,采用连续稀释法和单孢分离法得到枯萎菌单孢菌株,对该菌株进行形态学和显微形态学分析。采用真菌通用引物对所分离的菌株r DNA内转录间隔区(ITS)PCR扩增得到544 bp大小的片段(Gen Bank登录号为FJ715505),BLASTn分析结果显示,该序列与其他枯萎菌的ITS序列具有很高的同源性,将该ITS序列与Gen Bank中搜索到的同源性序列构建系统进化树,确定商丘地区棉花枯萎菌为尖孢镰刀菌(Fusarium oxysporum),对该分离棉花枯萎菌菌株进一步进行致病力生物学鉴定。

河北省棉花枯萎菌遗传多样性及致病力分化

为明确河北省棉花枯萎菌(Fusarium oxysporum f.sp.vasinfectum,FOV)变异及致病力分化情况,利用AFLP技术对采自河北省的75株FOV和3号、7号、8号生理小种的标准菌株进行遗传多样性分析,并比较了不同AFLP类群菌株对棉花品种冀棉11号的致病力差异。结果表明,78株FOV可划分为4个AFLP类群(AFLP groups,AGs),AGsⅠ为3号生理小种,AGsⅡ为8号生理小种,AGsⅢ包括7号生理小种和67株田间采集菌株,AGsⅣ包括8个田间采集菌株,该类群菌株与3号、7号、8号生理小种遗传差异较大。致病力初步测定表明,3号、7号、8号生理小种的标准菌株属中等致病力水平,而田间采集的75株枯萎菌菌株致病力存在明显差异,其中强致病力菌株占66.67%,中等致病力菌株占21.33%,弱致病力菌株占12%。表明河北省FOV群体遗传结构复杂,有遗传差异较大的新菌株出现,而且同一生理小种菌株之间存在显著的致病力分化。

不同腐解方式下棉秆腐解液对棉花枯、黄萎病菌的化感效应

采用自然腐解与接种微生物人工腐解两种方式分别处理棉秆,研究了两种腐解物水浸提液对棉花枯、黄萎病菌的化感效应。结果显示,两种腐解液对枯、黄萎病菌的菌丝生长及孢子萌发均具有较强的抑制作用,抑制强度整体上随着腐解液浓度的升高而增大。棉秆自然腐解液对枯、黄萎病菌菌丝生长的最大抑制率分别为58.17%、48.16%,对孢子萌发的最大抑制率分别为23.29%、16.22%,对枯、黄萎病菌毒力的有效中浓度(EC50)分别为33.20、45.20g·L-1;人工腐解液对枯、黄萎病菌菌丝生长的最高抑制率分别为71.63%、79.04%,对孢子萌发的最高抑制率分别为35.45%、42.74%,EC50分别为24.18、20.75g·L-1。表明棉秆腐解后具有作为植物源抑菌剂的开发潜力,并且采用人工方式腐解棉秆能有效提高腐解液对棉花枯、黄萎病菌的抑制强度。

几丁质降解放线菌对棉花枯、黄萎菌的作用

对从土壤中分离到的58株放线菌进行了皿内拮抗试验及利用几丁质能力测定,在此基础上筛选出了F104,F1052株产几丁质酶的菌株,并测定了其对棉花枯、黄萎菌的离体和活体抑制作用。皿内观察发现,F104和F105均可寄生于棉花黄萎菌,F105还可寄生于棉花枯萎菌。平皿扩散试验结果发现,F104和F105的培养滤液无论经高温处理与否,均能使棉花黄萎菌呈现畸形菌丝,而经高温处理的F104还可使棉花枯萎菌表现为畸形菌丝。抑制靶标致病菌寄主活体定殖作用的研究结果表明,F104和F105处理均表现出不同程度的超前接种防治黄萎病的作用,超前接种F105的间隔期与棉苗中枯萎菌的检出率呈负相关。

1株拮抗棉花枯、黄萎病菌的纤维素分解菌筛选

为获得具有拮抗棉花枯、黄萎病菌的棉杆促腐菌剂,进行棉杆纤维素分解菌分离及拮抗菌株的筛选,采用平板对峙法测定菌株对棉花枯、黄萎病菌菌丝生长的影响,通过生长速率法和孢子萌发法测定菌株发酵液对2种病原菌菌丝生长以及孢子萌发的影响,并对筛选得到的菌株进行鉴定。结果获得1株具有抑菌效果的棉杆纤维素分解菌SJ-3,其羧甲基纤维素酶活(CMCase)达到69.1 U/mL,滤纸酶活(FPase)达到48.5U/mL。该菌对棉花枯、黄萎病菌菌丝生长均有显著抑制,抑制率分别达到24.7%、23.1%。其发酵液具有抑菌活性,较高的发酵液浓度能增强对病原菌的抑制作用,发酵液对枯萎病菌孢子萌发的抑制作用较强,最高抑制率为21.6%,而对该病原菌菌丝生长的抑制较弱,最高抑制率仅为6.2%;发酵液对黄萎病菌的菌丝生长和孢子萌发均有较强的抑制作用,最高分别达到32.2%、21.4%。经鉴定,菌株SJ-3为普通青霉(Penicillium commune)。

生防菌株SC11的鉴定、定殖及对棉花枯萎病防治效果研究

通过生物学特性观察和16S rDNA基因序列分析鉴定菌株SC11为壮观链霉菌（Streptomyces spectabilis）。该菌可在棉花根际土壤以及棉花根部长期定殖,30 d的定殖密度分别为1.38×105 CFU/g和2.95×103 CFU/g。2011年和2012年的大田防治试验显示,SC11菌粉对棉花枯萎病防效分别为42.51%和36.70%,与对照50%多菌灵（WP）的防效相比无显著差异,施用90～150 d的防效分别显著高于多菌灵（P〈0.05）。与清水对照相比,田间施用SC11菌粉棉花倒三叶面积显著提高52.6%,籽棉和皮棉产量分别增加21.9%和23.0%（P〈0.05）。研究结果表明,壮观链霉菌SC11是一株对棉花枯萎病具有应用前景的生防菌株。

Screening for Siderophore-producing Endophytic Bacteria against Fusarium oxysporum

[Objective] With a strain of endophytic antagonistic bacteria with good disease control efficacy in pot as trial material,the paper was to explore the antagonistic mechanism of siderophore against Fusarium oxysporum.[Method] Whether the strain produced siderophore and its fluorescent property was judged by MSA（Modified Sugar-Aspartic acid） plate.The siderophore activity of strains in liquid MSA medium was determined through the absorbance values at particular wavelength.The inhibition effects of it siderophore against F.oxysporum under different concentrations of Fe3＋ were compared.Then the strain was preliminarily identified based on morphological,physiological and biochemical characteristics [Result] The fluorescent siderophore produced by the endophytic bacteria in MSA medium had a strong inhibition effect against F.oxysporum.With the increasing concentration of Fe3＋,the inhibition effect against the pathogen weakened.The preliminary analysis showed these strains belonged to Bacillus.[Conclusion] Bacillus could compete the absorption of Fe3＋ by secreting siderophore to inhibit the growth of F.oxysporum.

Inhibitive Activity of the Extracts of Plants in Artemisia against Fusarium oxysporum f. sp. vasinfectum and Fusarium momiliforme

[Objective]The aim was to provide theoretical basis for the control of cotton Fusarium wilt and cotton boll rot disease.[Method]The inhibitory activity of the extracts from three species of plants(Artemisia annual L.,Artemisia capillaris Thunb.,Artemisia argyi Levl.et Vant)against Fusarium oxysporum f.sp.vasinfectum and Fusarium moniliforme were studied under the condition of laboratory.[Result]The extracts of all the three plants in Artemisia showed strong antifungal activity against the tested pathogenic ...

Effect of Chitinase-Producing Strain V-8 on Controlling Cotton Fusarium Wilt

[Objective] This study aimed to screen endophytic bacteria which is antag- onistic to cotton Fusarium wilt. [Method] Fresh cotton plants collected from cotton- growing areas in Jingzhou City, Hubei Province were used as experimental materials to isolate endophytic bacteria. Through chitinase test and co-culturing both micro-or- ganisms side by side on the same PDA culture plate, antagonistic strains to cotton Fusarium wilt were screened. [Result] A total of 83 bacterial isolates were obtained from cotton plants grown in the fields, six of which were chitinase-productive bacte- ria. Through chitinase test and co-culturing both micro-organisms side by side on the same PDA culture plate, strain V-8 which had the strongest antagonistic effect on Fusarium oxysporum f. sp. vasinfectum was screened. Strain V-8 had a wider anti- fungal spectrum with certain inhibitory effect on all the six important pathogenic fungi including Fusarium oxysporum f. sp niveum; it colonized stably in the rhizospheric soil of cotton, with a colonization density of up to 6.2x10s cfu/g fifty days after inoc- ulation; the relative effect on controlling cotton Fusarium wilt in pot test was 73.2%. The Findings of this study suggested that strain V-8 had great potential for biological control of cotton Fusarium wilt and could be taken as a substantial material for the cloning of chitinase genes. [Conclusion] The results from this study provides bases for the control of cotton fusarium wilt, as well as the exploitation of endophytic bac- teria resources in cotton and the development of novel biological pesticides.

2-（1H-1，2，4-三唑-1-基）咪唑啉酮衍生物的制备及杀菌活性

通式（Ⅰ）所示的2-（1H-1，2，4-三唑-1-基）咪唑啉酮衍生物具有杀菌活性，对稻瘟菌、水稻纹枯菌、芦笋褐斑菌、苹果轮纹菌、小麦赤霉菌及棉花枯萎菌具有良好的抑制活性，可用做杀菌剂。

VdPKS1 is required for melanin formation and virulence in a cotton wilt pathogen Verticillium dahliae

Verticillium dahliae is a soil-borne phytopathogenic fungus that causes vascular wilt disease in a broad range of hosts. This pathogen survives for many years in soil in the form ofmelanized microsclerotia. To investigate the melanin synthesis in V.. dahliae, we identified a polyketide synthase gene in V. dahliae, namely VdPKS1. PKS1 is known to involve in the dihydroxynaphthalene melanin synthesis pathway in many fungi. We found that VdPKS1 was required for melanin formation but not for microsclerotial production in E dahliae. The VdPKS1 gene-disruption mutant （vdpksl） formed melanin-deficient albino microsclerotia, which did not affect the fungal colonization in host tissues but significantly reduced the disease severity. Gene transcription analysis in the wild-type and the vdpks1 strains suggested that VdPKS1 gene-disruption influenced the expression of a series of genes involved in ethylene biosynthesis, microsclerotial formation and pathogenesis. Our results suggest that the VdPKS1-mediated melanin synthesis is important for virulence and developmental traits of E dahliae.