丛枝菌根真菌对黄瓜枯萎病的影响

盆栽条件下播种黄瓜Cucumis sativus同时接种丛枝菌根真菌Glomus etunicatum,4周后对接种处理和对照黄瓜苗分别浇灌Fusairum oxysporum f.sp.cucumerinum分生孢子悬液,2周后测定幼苗生物量、根内丙二醛、可溶性糖与游离脯氨酸含量及根围真菌和细菌数量。结果表明:接种Glomus etunicatum根系干重增加了9.3%,提高了根内可溶性糖和游离脯氨酸含量,显著减少了根围真菌数量,降低了黄瓜枯萎病的发病率和病情指数。而不接种Glomus etunicatum的黄瓜苗根系干重减少了28.0%。研究认为AM真菌Glomus etunicatum对黄瓜枯萎病具有一定的生防价值。     

拟康宁木霉T 51菌株对番茄枯萎病的生物防治及其机理研究

尖孢镰刀菌是番茄枯萎病的致病菌,该研究利用拟康宁木霉T 51菌株对尖孢镰刀菌展开对峙培养试验、防治最适温度、酸碱度筛选试验及生物防治效果试验,并测定防治试验中番茄幼苗叶片的生理生化指标和水杨酸、茉莉酸合成和信号途径关键基因表达量,探讨T 51菌株的生物防治机理。结果表明：(1)T 51菌株可显著抑制对峙培养中尖孢镰刀菌生长;随着环境温度和pH的增加,T 51菌株对尖孢镰刀菌的抑制率先升后降,并且在20 ℃、pH 7环境下效果最佳。(2)T 51菌株和尖孢镰刀菌混合孢子液处理番茄幼苗植株无明显的感病症状,植株生长状态与清水对照组无显著差异,枯萎病发病率和病情指数比单施尖孢镰刀菌孢子液处理显著大幅度降低,相对防效为87.5%。(3)与单施尖孢镰刀菌孢子液处理相比,混合孢子液处理番茄幼苗叶片的叶绿素荧光参数最大光化学效率、光化学淬灭系数和表观光合电子传递速率,以及抗氧化酶SOD、POD、CAT活性均显著增加,而非光化学淬灭系数和过氧化氢含量均显著降低。(4)与单施尖孢镰刀菌孢子液处理相比,混合孢子液处理番茄幼苗叶片的内源水杨酸(SA)显著降低,而茉莉酸(JA)含量显著升高,同时SA信号通路上的PR1和TGA2基因表达量均显著下调,JA合成基因LoxD的表达量显著上调。研究认为,拟康宁木霉T 51菌株对尖孢镰刀菌有显著的防治效果,并在20 ℃、pH 7环境下防治效果最佳;T 51菌株可能通过抑制尖孢镰刀菌侵染,增强番茄叶片抗氧化酶活性,提高叶片光合效率,以及调控水杨酸和茉莉酸合成和信号途径关键基因表达,调节内源水杨酸和茉莉酸含量,进而提高番茄植株的枯萎病抗病性。研究结果为番茄抗枯萎病提供了生防途径的理论依据。     

石灰碳铵熏蒸与施用生物有机肥对连作黄瓜和西瓜枯萎病及生物量的影响

采用稀释涂布平板计数法,研究了石灰碳铵及碳铵熏蒸对黄瓜和西瓜连作土壤尖孢镰刀菌数量的影响,以及熏蒸后施用生物有机肥对黄瓜和西瓜枯萎病的防控效果及植株生长的影响.结果表明:与对照相比,石灰碳铵及碳铵熏蒸后,连作土壤中黄瓜尖孢镰刀菌的数量分别下降95.4%及71.4%,西瓜尖孢镰刀菌的数量分别下降87.2%及64.2%;多因素方差分析表明,熏蒸、施用有机肥及作物种类均对土壤中尖孢菌数量、枯萎病发病率、防控率及生物量有显著影响;与未熏蒸施用普通有机肥对照相比,石灰碳铵熏蒸后施用生物有机肥能显著减少后茬黄瓜或西瓜土壤中尖孢镰刀菌的数量并显著降低枯萎病发病率,防控率高达91.9%及92.5%,同时显著增加了植株的株高、茎粗、SPAD值及干质量.表明石灰碳铵熏蒸及施用生物有机肥能够降低土壤中尖孢镰刀菌数量,有效防控黄瓜和西瓜枯萎病的发生并促进其植株生长.     

绿色木霉TV41对尖孢镰刀菌FW0在西瓜植株空间分布和枯萎病防控效果的影响

【目的】为进一步探究盆栽试验条件下绿色木霉TV41 (Trichoderma viride TV41)对尖孢镰刀菌FW0 (Fusarium oxysporum FW0)在西瓜植株空间分布的影响以及对西瓜枯萎病的防控效果。【方法】通过定期检测不同处理西瓜根际/根表尖孢镰刀菌的数量、西瓜植株根内/茎内尖孢镰刀菌的数量以及植株侧根被侵染比例和尖孢镰刀菌在植株内的侵染进程,进行多次盆栽试验并统计发病率。【结果】当绿色木霉和尖孢镰刀菌接种量均为5×105孢子/g基质时,绿色木霉TV41在西瓜根际/根表的定殖数量明显高于尖孢镰刀菌FW0的数量,接种了绿色木霉TV41的处理,根际/根表尖孢镰刀菌的数量(103/g基质)显著低于仅接种FW0的对照(104/g基质);绿色木霉TV41不仅能够有效减缓尖孢镰刀菌在西瓜植株内的侵染进程,而且能够有效降低西瓜植株根内、茎内尖孢镰刀菌的数量。与对照(只接种FW0)相比,接种绿色木霉后西瓜枯萎病的发病率从66%降低到27%。【结论】绿色木霉TV41能够通过影响尖孢镰刀菌FW0在西瓜植株的空间分布,从而有效防控西瓜枯萎病的发生,防控效果达到60%。     

链格孢Alternaria alternata侵染导致瓜类幼苗白化的机制

用分离自无症状瓜类植物的27株链格孢属Alternaria真菌接种黄瓜,有14株引起了黄瓜幼苗的白化,这些菌株均属于链格孢A. alternata。为揭示A. alternata引起黄瓜幼苗白化的机制,对代表菌株5F29经固体发酵后提取其次级代谢产物,将粗提物按一定量混入基质进行盆栽实验。结果表明,黄瓜、丝瓜和甜瓜对该粗提物敏感,出现白化苗;小白菜和辣椒对粗提物不敏感,生长正常。植物幼苗用粗提物处理的结果与用产生菌接种的结果相一致。粗提物经硅胶柱层析、葡聚糖凝胶柱层析及高效液相色谱（HPLC）等方法分离纯化得到一种活性化合物,经测定该化合物引起黄瓜幼苗白化的最低浓度为12.5μmol/L。该化合物在此浓度下可引起黄瓜幼苗生长点白化,在15μmol/L的浓度下可引起黄瓜幼苗大部分组织白化,致使幼苗很快死亡。应用核磁共振和质谱技术,确定了该化合物的结构,鉴定为一种植物毒素——腾毒素（tentoxin）。研究结果揭示了A. alternata引起瓜类幼苗白化的机制以及不同植物对于腾毒素的不同敏感性。     

激光诱变玫瑰孢链霉菌结合链霉素抗性筛选法选育达托霉素高产菌株

将经过20 mW激光辐照20 min的达托霉素(Daptomycin)生产菌株-玫瑰孢链霉菌(Streptomyces roseosporus)D-38的孢子悬液倾注在含有1．9λg／mL链霉素的高氏一号培养平板上。通过链霉素抗性法筛选获得了10％正变率的突变株,其中突变株LC-54摇瓶发酵单位为81．2 mg／L,比出发菌株提高了39％。     

丝孢酵母与钙与杀菌剂配合对苹果采后病害的抑制效果

研究一种从桃果实上分离获得的拮抗菌－丝孢酵母（Trichosporon sp.)对苹果（Malus domestica Borkh.)采后病害的防治效果,包括接种不同浓度的拮抗菌与不同病菌之间的拮抗作用,以及拮抗菌与钙或与杀菌剂配合对苹果灰霉病和青霉病的抑制效果。结果表明,拮抗菌和病菌孢子的浓度都明显地影响其抑菌效果。拮抗菌的使用浓度越大,病菌孢子的接种浓度越低,其抑病效果越好。当丝孢酵母菌的使用浓度达到1068colony-forming units(CFU)mL时,可完全抑制接种在苹果上的灰霉菌（Botrytis cinerea Pers.)和青霉菌（Penicillium expansum(Link)Thom)的抑制效果明显地好于单独使用相同剂量的拮抗菌或杀菌剂。因丝孢酵母的悬液液中加入1％－2％CaCl2可显地提高拮抗菌对灰霉病和青霉病的抑制效果。     

一种利用生理指标评价玉米弯孢菌叶斑病抗性的方法

本试验以4种不同抗性的玉米自交系幼苗为材料,比较了新月弯孢菌毒素浓度和处理时间对玉米主要防御酶系苯丙氨酸解氨酶（PAL）、过氧化酶（POD）和超氧化物歧化酶（SOD）比活力的影响。结果表明：在不同毒素浓度和胁迫时间下,PAL、POD和SOD比活力与品种抗病性的相关程度不一致。稀释200倍的毒素溶液处理玉米幼苗12h时,PAL比活力与抗病性呈极显著线性正相关,POD比活力与抗病性呈曲线正相关,SOD比活力与玉米抗病性呈极显著线性负相关。因此,可利用稀释200倍的新月弯孢菌毒素溶液处理12h时测得的玉米幼苗PAL、POD及SOD比活力估算玉米自交系弯孢菌叶斑病的抗性水平。     

月腺大戟根总黄酮对尖孢镰刀菌抑制作用的研究

采用生长速率法和孢子萌发法分别测定月腺大戟根总黄酮对尖孢镰刀菌菌丝生长和分生孢子萌发的抑制率,显微观察总黄酮处理尖孢镰刀菌后菌丝体形态结构的变化,并测定菌丝体相对电导率,菌丝体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性。结果表明:月腺大戟根总黄酮对尖孢镰刀菌菌丝生长和分生孢子萌发均有显著的抑制作用,抑制率随总黄酮浓度增加而增高,20 mg/L时抑制率达100%。总黄酮处理后的尖孢镰刀菌菌丝较细,分支减少,透明度差,液泡数量增多且形成较大的液泡;菌丝体细胞膜透性增加,SOD、CAT活性呈先上升后下降的趋势。以上实验结果可为植物病害生物防治及开发植物源农药方面提供理论依据和实验技术。     

中国弯孢属的分类研究Ⅱ.

报道弯孢属的两个新种,柱弯孢Curvularia cylindrica和拟棒弯孢Curvularia trachycarpi,前者生于葱Allium fistulosum上,后者生于棕榈Trachycarpus fortunei上。柱弯孢的分生孢子柱状细长,4个隔膜,这是区别于其它种的显著特征。拟棒弯孢的形态与棒弯孢Cclavata B．L．Jain近似,但是其分生孢子明显的大于后者。研究标本保存在山东农业大学植物病理学标本室（HSAUP）。     

亚精胺对黄瓜幼苗灰霉病的诱抗作用

采用根际基质注射结合叶面喷洒不同浓度亚精胺（Spd）的方法，测定了灰霉病菌侵染下黄瓜幼苗植株病情指数、防御酶活性和抗病相关物质含量等生理生化指标，以明确Spd对黄瓜幼苗抗灰霉病的诱导作用.结果表明：Spd处理黄瓜灰霉病病情指数比对照最高降低25.4%；苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）和多酚氧化酶（PPO）活性最高分别比对照提高48.4%、635.9%和38.9%；总酚、类黄酮和木质素含量也明显增加.表明Spd可诱导黄瓜幼苗对灰霉病的抗性，且最佳处理浓度为150 mg·L^-1.     

木霉防治灰霉病的研究进展

植物病害的生物防治是降低化学农药用量、减少环境污染的一种有效方式,木霉是现在普遍应用且生防潜力巨大的灰霉病防治真菌。目前,已经对防治灰霉的木霉菌株的筛选、应用及生防机制进行了大量而深入的研究。木霉的生防机制分为直接生防机制和间接生防机制,前者主要指木霉与灰霉病菌直接作用过程中所涉及的重寄生、抗生和营养竞争,后者是木霉通过诱导植物产生系统抗性来防治灰霉。本文对木霉直接防治灰霉病以及诱导植物产生系统抗性防治灰霉病所涉及的互作模式、信号传导途径以及所引起的防御反应进行综述,旨在通过机制的深入研究能够找到进一步提高木霉生防效果的技术方案。     

Antimicrobial peptaibols induce defense responses and systemic resistance in tobacco against tobacco mosaic virus

Trichoderma spp. are well-known biocontrol agents because of their antimicrobial activity against bacterial and fungal phytopathogens. However, the biochemical mechanism of their antiviral activity remains largely unknown. In this study, we found that Trichokonins, antimicrobial peptaibols isolated from Trichoderma pseudokoningii SMF2, could induce defense responses and systemic resistance in tobacco (Nicotiana tabacum var. Samsun NN) against tobacco mosaic virus (TMV) infection. Local Trichokonin (100 nM) treatment led to 54% lesion inhibition, 57% reduction in average lesion diameter and 30% reduction in average lesion area in systemic tissue of tobacco compared with control, indicating that Trichokonins induced resistance in tobacco against TMV infection. Trichokonin treatment increased the production of reactive oxygen species and phenolic compounds in tobacco. Additionally, application of Trichokonins significantly increased activities of pathogenesis-related enzymes PAL and POD, and upregulated the expression of several plant defense genes. These results suggested that multiple defense pathways in tobacco were involved in Trichokonin-mediated TMV resistance. We report on the antivirus mechanism of peptaibols, which sheds light on the potential of peptaibols in plant viral disease control.     

Induction of Volatile Organic Compounds of Lycopersicon esculentum Mill. and Its Resistance to Botrytis cinerea Pers. by Burdock Oligosaccharide

In the present study, we investigated the induction of volatile organic compounds （VOCs） of Lycoperslcon esculentum Mill. and its resistance to Botrytis cinerea Pers. by burdock oligosaccharlde. The disease severity of L. esculentum was evaluated 48 h after treatment with 0.6% burdock oligosaccharlde, followed by inoculation with a spore suspension of B. cinerea. The formation of O2＇, the activity of lipoxygenases （LOX）, peroxidase （POD）, cataiase （CAT）, and superoxide dismutase （SOD）, and the quantity and quallty of changes In VOCs were determined a period of time after treatment with 0.6% burdock ollgosaccharide. The results demonstrated that the disease index in treated plants was decreased by 42.5% compared with control 96 h after Inoculation. The production of O2＇ reached a maximum 6 h after treatment （1.36-fold compared with control）. There was an increase in LOX, POD, CAT and SOD activity in response to burdock oligosaccharide treatment and the enzymes showed different trends in the time-course of induction. At 120 h after treatment, （E）-2-hexenal was increased by 92% compared with control, whereas methyl salicylate showed a gradual Increase with induction period. Previous results had demonstrated that chitosan elicitor enhanced the production VOCs of L. esculentum and decreased plant susceptibility towards B. clnerea. Together, these findings suggest that increasing the production of VOCs in response to burrdock oligosaccharide may be an important mechanism for L. esculentumin its defense against pathogens, in addition, burrdock oligosaccharlde may act as a potent elicitor of resistance to disease in L. esculentum.     

Systemic acquired resistance in sunflower (Helianthus annuus L.)

Systemic acquired resistance (SAR) to infection by Botrytis cinerea in the leaves of sunflower (Helianthus annuus L.) plants was induced following cotyledon inoculation with B. cinerea or treatment with abiotic inducers. Salicylic acid (SA), benzo-(1,2,3)-thiadiazole-7-carbothioic S-methyl ester (BTH), 2,6-dichloroisonicotinic acid (INA) or EDTA protected sunflower plants against Botrytis infection, that was revealed by a reduction in the number and area of the necrotic lesions in upper leaves after challenge inoculation with the pathogen. SA and BTH were more potent inducers than INA, EDTA or pre-inoculation with the fungus. In addition to resistance to B. cinerea, the upper leaves have also developed resistance to maceration by a mixture of cell wall-degrading enzymes. Calcium nitrate inhibited both the protective effect and the resistance of leaf discs to cell-wall degrading enzymes. All the tested chemicals increased the synthesis and excretion of sunflower phytoalexins--coumarins scopoletin and ayapin and induced the PR-proteins chitinase and 1,3-beta-glucanase, being the inducer effect of each activator correlated with the level of protection against B. cinerea (BTH > SA > INA > EDTA). Thus, SAR induction is mediated by general increase of plant defence responses. This is the first report on SAR in sunflower.     

Improved antifungal activity of a mutant of Trichoderma harzianum CECT 2413 which produces more extracellular proteins

Trichoderma harzianum is a well-known biological control agent against fungal plant diseases. In order to select improved biocontrol strains from Trichoderma harzianum CECT 2413, a mutant has been isolated for its ability to produce wider haloes than the wild type, when hydrolysing pustulan, a polymer of beta-1,6-glucan. The mutant possesses between two and four times more chitinase, beta-1,3- and beta-1,6-glucanase activities than the wild type, produces about three times more extracellular proteins and secretes higher amounts of a yellow pigment (alpha-pyrone). This mutant performed better than the wild type during in vitro experiments, overgrowing and sporulating on Rhizoctonia solani earlier, killing this pathogen faster and exerting better protection on grapes against Botrytis cinerea.     

茉莉酸对棉花单宁含量和抗虫相关酶活性的诱导效应

以植物生长调节物茉莉酸(Jasmonic acid,JA)为诱导子,以常规棉为研究对象,探讨了外源茉莉酸对棉花幼苗单宁和蛋白酶抑制素以及其它抗虫相关酶活性诱导的浓度依赖性和持久性,讨论了棉花抗虫相关物质的抗虫效果.结果表明,0.01、0.1和1.0 mmol/L茉莉酸都能在2周内诱导棉花单宁和胰蛋白酶抑制素(Proteinase inhibitors,PIs)含量增加,诱导多酚氧化酶(Polyphenol oxidase,PPO)、苯丙氨酸解氨酶(Phenylalanine ammonia-lyase,PAL)、过氧化物酶(Peroxidase,POD)和过氧化氢酶(Catalase,CAT)活性升高.对3种浓度茉莉酸的诱导效应进行分析表明,0.1 mmol/L茉莉酸对于诱导PIs、PPO、POD和CAT最有效,0.1和1.0 mmol/L茉莉酸对于诱导棉花单宁和苯丙氨酸解氨酶等效,二者的诱导效应均高于0.01 mmol/L.对茉莉酸诱导抗性的持久性进行分析表明,最佳诱导效应发生的时间各不相同:POD活性在JA处理后第1天最高,随后呈下降趋势,PIs和单宁含量分别在JA处理后第7天和第14天达最大值;JA处理后第1天和第7天的PPO活性无明显差异,但明显高于第14天;JA处理后第7天和第14天的PAL活性无明显差异,但明显高于第1天;JA处理后第1、7和14天棉花叶片的CAT活性均无明显差异.以上结果表明,茉莉酸可通过增加棉叶单宁和PIs含量、提高棉叶PAL、PPO、POD和CAT活性等增强棉花幼苗的抗虫性.     

外源Ca2+对水杨酸诱导番茄抗灰霉病的增效机制

探讨了外源Ca²⁺对水杨酸(SA)诱导番茄抗灰霉病的增效机制.以番茄灰霉病敏感型品种‘L402’幼苗为材料,分别进行H₂O(对照)、SA、SA+Ca和SA+EGTA(Ca²⁺螯合剂)处理,期间(1～5 d)分析各处理植株叶片活性氧(ROS)含量,苯丙氨酸解氨酶、几丁质酶和β-1,3-葡聚糖酶活性,以及病程相关蛋白编码基因PR1、PR2和PR3表达水平的变化,并调查处理3 d后灰霉病情指数.结果表明： 与对照(病情指数为74.8)相比,SA、SA+Ca和SA+EGTA处理的植株叶片灰霉病的病情指数分别为46.9、38.5和70.3;SA处理明显提高叶片ROS含量以及苯丙氨酸解氨酶、几丁质酶和β-1,3-葡聚糖酶活性,这些参数在SA+Ca处理的植株中被进一步提高,但在SA+EGTA处理的植株中则被降低;SA处理明显提高了PR1、PR2a和PR3b的表达水平,Ca²⁺进一步加强了这一效果,而EGTA则起抑制作用.SA或SA+Ca处理期间的PR2b和PR3a表达较未处理的对照上调了1～2倍,而PR1、PR2a和PR3b上调了2～5倍.表明Ca²⁺对SA诱导番茄抗灰霉病具有增效作用,其机理至少与Ca²⁺和SA协同作用促进ROS形成有关,而ROS作为信号分子增加植株抗病相关酶活性以及PR1、PR2a和PR3b等防卫基因的表达.