向日葵列当的内生细菌分离筛选与初步鉴定

为获得对向日葵菌核病有较强生防效果的拮抗细菌,从向日葵根部一年生全寄生杂草向日葵列当植株内分离纯化得到135株内生细菌菌株。依次采用平板对峙法、生长速率法、离体叶片防效试验、菌核萌发抑制试验筛选得到2株对核盘菌拮抗活性较好的内生细菌LIEH 92和LIEB54,用内生拮抗细菌菌株发酵液无菌滤液进行离体叶片防效试验发现,2个菌株的离体防效分别达68.48%和62.33%;LIEH 92和LIEB 54滤液处理过的菌核均不萌发,在防治向日葵菌核病方面具有良好的生防潜力。除木糖利用和V.P试验(Vopes-prokauer test)外,菌株LIEH 92与粘质沙雷氏菌的生理生化特征一致。16S r DNA序列分析鉴定,与菌株LIEH 92相似性大于99%的菌株归于肠杆菌科的沙雷氏菌属。以16S r DNA序列为基础构建系统发育树,发现菌株LIEH 92与各粘质沙雷氏菌同源性最高,因此认为菌株LIEH 92可能为粘质沙雷氏菌(Serratia marcescens)的新亚种。     

纳米银对大豆菌核病核盘菌的抑制作用研究

利用生长速率抑制法、显微观察和生物化学方法研究了纳米银离子对大豆菌核病核盘菌的抑菌效果及初步机理.结果表明:纳米银水剂对大豆菌核病核盘菌具有较好的抑制能力,在30mg·L-1浓度下可达到100%的抑制效果,其对大豆菌核病核盘菌的有效中浓度(EC50)为13.91mg·L-1;菌丝在纳米银有效中浓度下的生长受到很强抑制;经纳米银处理的核盘菌菌体中过氧化氢酶、总超氧化物歧化酶、超微量ATP酶的活力均发生相应变化,处理2h或12 h后,呈现增加趋势,但处理24 h后,则均表现为下降.因而纳米银对大豆菌核病菌的生长具有一定的抑制效果.     

拟康宁木霉对花生菌核病的生防机制

从黑龙江双城大田花生茎秆中采集的核盘菌菌核中分离得到1株拟康宁木霉(Trichoderma koningiopsis),通过平板对峙培养发现该木霉菌对花生核盘菌具有明显的抑制作用,木霉菌菌落可覆盖整个核盘菌菌落,产生大量分生孢子,并抑制核盘菌菌核的产生或分解已形成的菌核。显微观察发现该木霉菌丝可沿着核盘菌菌丝生长或侵入、缠绕在核盘菌菌丝上,抑制核盘菌菌丝的生长,最终使核盘菌菌丝消解、断裂。拟康宁木霉菌非挥发性代谢产物能有效抑制核盘菌的生长。因此,拟康宁木霉菌株TM对花生菌核病的主要生防机制是在重寄生过程中产生抗菌类代谢产物协同作用消解花生核盘菌菌丝,抑制菌核形成。     

防治小麦赤霉病有效药剂的筛选与田间药效试验

采用菌丝生长速率法测定97%咪鲜胺原药、97%戊唑醇原药、95%苯醚甲环唑原药、95%噻呋酰胺原药、95%甲基硫菌灵原药和70.3%春雷霉素原药6种杀菌剂及97%咪鲜胺原药与97%戊唑醇原药5种配比对小麦赤霉病菌的抑制作用,并对单剂和优选的复配制剂进行大田药效试验。试验结果表明:上述单剂EC 50值分别为0.054 3、0.627 2、1.313 5、0.319 7、6.439 0和17.521 9 mg/L,其中97%咪鲜胺原药对赤霉病的抑制作用最强,显著高于其他5种杀菌剂;97%咪鲜胺原药与97%戊唑醇原药5种配比均表现出增效作用,其中97%咪鲜胺原药与97%戊唑醇原药以2︰1比例复配时的共毒系数最高,为136.61,增效作用最明显。田间药效试验表明,25%咪鲜胺乳油(187.5 g/hm~2)、25%戊唑醇可湿性粉剂(105.5 g/hm~2)、400 g/L咪鲜胺·戊唑醇水乳剂(150.0 g/hm~2)、10%苯醚甲环唑水分散粒剂(450.0 g/hm~2)、240 g/L噻呋酰胺悬浮剂(60.0 g/hm~2)、70%甲基硫菌灵可湿性粉剂(750.0 g/hm~2)和40%多菌灵悬浮剂(400.0 g/hm~2)对小麦赤霉病的防治效果分别为66.60%、70.97%、74.92%、66.62%、61.78%、64.95%和63.87%,其中按照2︰1比例加工的400 g/L咪鲜胺·戊唑醇水乳剂对小麦赤霉病的防治效果最为突出,显著高于其他杀菌剂(P0.05)。因此推荐优先选用97%咪鲜胺原药、97%戊唑醇原药及其复配制剂防治小麦赤霉病。     

环腺苷酸对向日葵大丽轮枝菌生物学特性及致病力的影响

为探究环腺苷酸(cAMP,cyclic AMP)对向日葵大丽轮枝菌生物学特性及致病力的影响,在实验室条件下研究了外源添加cAMP(10mmol/L)后,向日葵大丽轮枝菌的菌落形态、生长速率、产孢量、分生孢子萌发率、微菌核数量、粗毒素分泌量以及致病力的变化。结果表明,外源cAMP使向日葵大丽轮枝菌分生孢子的产孢量提高了55.45%;而在含有cAMP的水琼胶培养基上培养24h后,大丽轮枝菌的分生孢子萌发率降低了69%;在含有cAMP的PDA上培养25d后,大丽轮枝菌微菌核形成的数量相比对照降低了46.8%;在含有cAMP的液体培养基中振荡培养15d后,大丽轮枝菌粗毒素的含量仅为0.156mg/mL,比对照培养液中毒素降低了35.27%。向日葵接种10mmol/L cAMP处理的大丽轮枝菌后,其病情指数为34.38,相比对照组降低了7.28%。因此,外源添加10mmol/L cAMP除了能够提高向日葵大丽轮枝菌的产孢量外,对其生长速率、分生孢子萌发率、微菌核形成的数量、粗毒素分泌量以及致病力均有不同程度的抑制作用,尤其是对微菌核形成的抑制作用最为明显。     

哈茨木霉TRI-5腐解油菜菌核及其施用方法

油菜机械收获后菌核病菌(核盘菌Sclerotinia sclerotiorum)的菌核会随着秸秆一起还田,给下茬油菜生长带来潜在危害。为降低菌核病发病率,研制哈茨木霉(Trichoderma harzianum TRI-5)可溶性粉剂,在油菜收获后立即喷施该粉剂。在实验室条件下,60h后TRI-5在菌核外表和内部均能生长良好,扫描电子显微镜结果显示,菌核的组织结构被彻底损坏。田间小区试验结果表明,喷施TRI-5可溶性粉剂30d后,与基质对照相比,核盘菌菌核萌发率下降22.06%,秸秆腐解率提高12.54个百分点,差异显著(P0.05);在水稻产量上,与基质对照相比,施用TRI-5可溶性粉剂提高水稻产量1.72%,但差异不显著(P0.05)。因此认为,哈茨木霉可溶性粉剂对油菜田间菌核病发生有生防效果。     

大豆菌核病菌生物学特性的研究

为有效控制大豆菌核病的发生、蔓延,从采自黑龙江省不同地区大豆菌核病菌中选取5个代表性菌株进行生物学特性的研究.结果表明:大豆菌核病菌菌丝生长的最适温度为20 ～ 25℃,而菌核在15 ～20℃时产生量最多;菌丝适于在中性和偏酸性条件下生长.病菌在PDA和大豆叶片汁培养基上生长较好,菌核的产生则在向日葵叶片汁培养基上最多;有无光照对菌丝生长影响不大,但光照有利于菌核的产生.子囊孢子萌发最适温度为25℃;萌发最适pH为7～8;大豆汁、向日葵汁和油菜汁可促进子囊孢子的萌发;有无光照对子囊孢子萌发无显著影响.不同地区大豆菌核病菌由于生态条件的不同,菌核萌发形成子囊盘能力和病原菌的致病力也存在差异.     

生防潜力菌H158与杀菌剂混配对水稻纹枯病菌毒力增效作用

采用菌丝生长速率法,分别测定了井冈霉素A、啶酰菌胺及两者间混配的毒力系数,及对生防潜力菌H158繁殖、生长的影响。结果表明,啶酰菌胺+井冈霉素A按1∶100、1∶200、1∶300和1∶400比例混配,对水稻纹枯病菌(Rhizoctonia solani)的EC50分别为5.5814、6.8186、5.2672、2.7772 mg/L,共毒系数分别为0.9716、1.5182、2.8210、6.8325,除1∶100表现为协同作用外,其他混合比例对纹枯病菌均表现为增效作用。啶酰菌胺对生防潜力菌H158的生长抑制作用不大,低浓度井冈霉素A对H158表现为相容性,较高浓度时有一定抑制作用。但两者混配药剂中加入H158,对其抑制情况与啶酰菌胺相似。混配剂中加入H158后对纹枯病菌的抑制率比未加H158时有所提高,均高于90.00%。     

28种杀菌剂对大麦条纹病菌活性的室内测定

为了筛选防治大麦条纹病的新药剂,采用平皿法在室内测定了28种杀菌剂对大麦条纹病菌禾内齐蠕孢(Drechslera graminea)菌丝生长的抑制活性。结果表明,供试药剂对大麦条纹病菌的菌丝生长均有不同程度的抑制活性,其中95.3%戊唑醇TC、97.37%咪鲜胺TC、95%吡唑醚菌酯TC、98%二硫氰基甲烷TC、93%氟硅唑TC、99.4%咯菌腈TC、96.8%嘧霉胺TC、98%丙硫唑TC和84.39%啶酰菌胺TC显示有较高的抑菌活性,其抑制菌丝生长的EC50值分别为0.0019、0.0016、0.0254、0.0390、0.0057、0.0012、0.0788、0.1211、0.0773 mg/L。     

两种乙蒜素复配剂防治水稻稻瘟病的田间应用研究

35%乙蒜素.三唑酮乳油、35%乙蒜素.咪鲜胺乳油是防治水稻稻瘟病的新药,试验对这2种乙蒜素的复配剂进行了对比试验。结果表明,35%乙蒜素的三唑酮和咪鲜胺的复配剂较之单一三唑酮或咪鲜胺乳油具有显著增效作用,可在生产上推广使用。     

Sclerotinia and Phomopsis — two devastating sunflower pathogens

Cultivated sunflower (Helianthus annuus L.) is prone to many diseases caused by fungi, bacteria, and viruses, of which the most detrimental are those caused by fungi. Two of the most important fungal pathogens are Sclerotinia and Phomopsis. Within the genus Sclerotinia, both S. minor and S. sclerotiorum cause a basal stalk rot and subsequent wilt of sunflower, with S. sclerotiorum more widely distributed around the world. Sclerotinia sclerotiorum also incites a head rot and mid-stem rot of sunflower. Since Sclerotinia spp. have a very wide host range and can persist in soil as dormant sclerotia for up to 10 years, the pathogens have been extremely difficult to control with either generic resistance or fungicides. The most effective control is the use of long rotations, tolerant hybrids, and sclerotium-free seed. Gray stem spot is a relatively new disease of sunflower first observed in the early 1980s in Yugoslavia and now considered the most devastating sunflower disease in eastern Europe. Symptoms include large stem cankers and subsequent wilt. Phomopsis helianthi has been identified as one incitant of gray stem spot, but another Phomopsis species may also be involved, both in Europe and in the United States. Foliar fungicides can control gray stem spot, but the development of resistant hybrids has been much more cost-effective.     

硅对甘蔗黑穗病菌的体外抑菌效果研究

由鞭黑粉菌（Sporisorium scitamineum）引起的黑穗病是甘蔗（Saccharum spp.）生产上最重要的真菌病害。硅是植物生长过程中的有益矿质元素,能够提高植物对生物和非生物胁迫的抗性。目前,关于外源硅对甘蔗黑穗病菌的体外抑菌作用尚未见报道。本研究以硅酸钠（sodium silicate, Na₂SiO₃）和硅酸钾（potassium silicate, K₂SiO₃）处理甘蔗黑穗病菌,观察黑穗病菌的孢子萌发、菌落直径和菌丝生长情况,评价不同硅剂和pH对甘蔗黑穗病菌的体外抑菌效果。结果显示,0.5~20.0 mmol/L Na₂SiO₃和K₂SiO₃均完全抑制甘蔗黑穗病菌的孢子萌发,但1.0 mmol/L Na₂SiO₃促进甘蔗黑穗病菌菌落和菌丝的生长,10.0、20.0 mmol/L Na₂SiO₃和K₂SiO₃则显著抑制菌落和菌丝的生长,表明Na₂SiO₃和K₂SiO₃均会影响甘蔗黑穗病菌的生长,高浓度Na₂SiO₃和K₂SiO₃的抑菌效果明显。在不同pH条件下,低pH（5.87~10.86）处理下的甘蔗黑穗病菌孢子有萌发,但其萌发率随着pH的增大逐渐降低,高pH（≥10.96）完全抑制孢子萌发,此外,pH为9.40和11.57对菌落直径的抑制效果明显。调整pH为6.0的低浓度Na₂SiO₃（0~5.0 mmol/L）和K₂SiO₃（0~3.5 mmol/L）对孢子萌发影响小,但pH为6.0的高浓度Na₂SiO₃（7.0~20.0 mmol/L）和K₂SiO₃（5.0~20.0 mmol/L）显著抑制孢子萌发,表明相同pH水平下的K₂SiO₃比Na₂SiO₃及其对应pH处理对甘蔗黑穗病菌孢子萌发的抑制作用更为明显。研究结果为外源硅在甘蔗抗黑穗病的药效试验和防治机理研究提供参考。     

PEG胁迫下85份引进柱花草种子的萌发特性

为探究不同柱花草的抗旱性强弱,构建柱花草资源抗旱评价体系,以85份引进柱花草为试验材料,分别测定0（CK）、10%和20%质量浓度的PEG-6000渗透液胁迫下萌发期的相对发芽势、相对发芽率、相对胚根长、相对胚轴长、萌发抗旱指数共5项指标,分析不同干旱胁迫对柱花草种子萌发的影响,并结合隶属函数法综合评价柱花草抗旱性能。结果表明：低浓度的PEG对柱花草种子的萌发有一定促进作用,高浓度PEG降低了柱花草种子的相对发芽势和相对发芽率,阻碍了胚芽和胚根的生长,种间表现出较大差异。其中抗旱型材料为头状柱花草CIAT 2250、大头柱花草CIAT 2113和CIAT 1942、蔓性柱花草CIAT 10182,不耐旱材料有墨西哥柱花草CIAT 1590、卡尔奇柱花草CIAT 1616和CIAT 1624。本研究结果为引进柱花草资源抗旱性评价、抗旱品种选育及其机理研究提供了理论依据。     

Occurrence of resistant strains of Botrytis cinerea to anilinopyrimidine fungicides in table grapes in Chile

Effort to control gray mold caused by Botrytis cinerea failed in a table grapevine (Vitis vinifera) vineyard near Santiago, Chile where cyprodinil (Vangard 50 WP), a new fungicide of the anilinopyrimidine group, had been applied alone up to four times per year during two growing seasons. A relatively high frequency (38.5%) of resistant isolates of B. cinerea (EC₅₀ for mycelial growth inhibition varied from 2.9 to 4.84 μg ml⁻¹) may explain the partial loss of field control efficacy obtained. Resistance was correlated with a complete loss of in vivo sensitivity to cyprodinil. Resistant isolates of B. cinerea showed cross resistance to the anilinopyrimidines fungicides mepanipyrim and pyrimethanil. Cyprodinil partially impaired conidia germination and differentially affected conidial germination of resistant and sensitive isolates. Significant differences (p<0.05) in growth rate, sclerotia production and osmotic sensitivity were found among isolates of B. cinerea, but no correlation could be drawn between these biological differences and resistance or sensitivity. This indicates a disruptive selection characteristic of monogenic resistance. Thus, strategies were implemented to avoid the further development and spread of resistance in B. cinerea to the anilinopyrimidine fungicides. To our knowledge this constitutes the first mention of resistance in B. cinerea populations to anilinopyrimidine fungicides in South America.     

Relationship between leaf injury and colonization of cabbage by Sclerotinia sclerotiorum

Mechanical and insect feeding injuries of cabbage provided sites for ingress by Sclerotinia sclerotiorum. In field studies, injuries sustained by hitting cabbage heads with a blunt object penetrated several leaf layers and were readily infected by S. sclerotiorum. Incidence of Sclerotinia rot ranged from 15 to 36% infected plants in the hitting treatment. Disease incidence was low (0–5%) when wounds were created by allowing lepidopterous larvae (the imported cabbageworm, Pieris rapae L., the diamondback moth, Plutella xylostella L., and the cabbage looper, Trichoplusia ni Hubner) to feed on cabbage leaves. The incidence of colonization of lepidopterous larvae feeding sites by S. sclerotiorum was greater in greenhouse studies (5–60% infected feeding sites) than in field studies. In greenhouse studies, disease incidence was significantly greater in plants receiving hitting injuries than tearing injuries. There was little evidence of inoculation day or injury day effects. Colonization frequency of tissue injured mechanically was similar whether wounds were inoculated immediately or 4 days later. Plants that were incubated in a dry environment developed fewer infections than plants held in a moist environment. Inoculated plants that were not injured did not develop disease.     

甘蔗黑穗病的防治药剂筛选及产量评价

由甘蔗鞭黑粉菌引起的甘蔗黑穗病是我国甘蔗生产中危害最大的病害,给甘蔗产业造成严重的产量和经济损失。化学防治是作物病害综合防治的重要措施之一,开展甘蔗黑穗病高效、低毒、低残留防治药剂的筛选,进行田间防治试验,对甘蔗黑穗病的有效防治和提高甘蔗产量具有重要意义。为筛选适合大田防治甘蔗黑穗病的推荐化学药剂,通过测定11种杀菌剂对甘蔗鞭黑粉菌的抑菌试验,采用扫描电镜解析有效杀菌剂的抑菌机理,通过新植蔗和宿根蔗的甘蔗黑穗病大田防治试验,评价杀菌剂的防治效果和对产量、株高、茎径、公顷有效茎数、锤度、单茎重等甘蔗主要农艺性状的影响。结果表明,经室内生物活性测定,获得4种杀菌剂对甘蔗鞭黑粉菌单倍体生长、有性配合、冬孢子萌发有抑制作用,分别是42.4%唑醚·氟酰胺悬浮剂、75%肟菌·戊唑醇水分散粒剂、250 g/L吡唑醚菌酯乳油和325 g/L苯甲·嘧菌酯悬浮剂。扫描电镜显示,这4种杀菌剂均对甘蔗鞭黑粉菌冬孢子和单倍体孢子细胞组织造成不同程度的破坏,使甘蔗鞭黑粉菌失活。在大田新植蔗的甘蔗黑穗病防治试验中,42.4%唑醚·氟酰胺悬浮剂、75%肟菌·戊唑醇水分散粒剂、250 g/L吡唑醚菌酯乳油和325 g/L苯甲·嘧菌酯悬浮剂的防治效果分别为91.81%、82.84%、81.76%、70.92%,各药剂防治区产量分别比对照增产20.84%、17.13%、15.92%、13.35%。在宿根蔗的甘蔗黑穗病防治试验中,以上杀菌剂防治效果分别为89.35%、82.21%、81.51%、70.18%,其产量分别比对照增产30.15%、24.05%、20.33%、16.58%。新植蔗和宿根蔗药剂防治区的甘蔗其他农艺性状均优于对照区。这4种杀菌剂对甘蔗黑穗病均有良好的防治效果和增产作用,可作为大田防治甘蔗黑穗病的推荐杀菌剂。     

五种杀菌剂对花生褐斑病菌室内毒力的影响和田间药效

为了筛选对花生褐斑病田间防治效果好的杀菌剂,结合室内毒力测定(菌丝生长速率法和载玻片萌发法)和田间小区药效试验对四种杀菌剂与常规使用的杀菌剂多菌灵进行了比较。结果表明,室内毒力测定中,多菌灵对菌丝的抑制效果最强,抑菌率为91.4%;其余四种供试杀菌剂中以咪酰胺效果最好,抑菌率达85.6%;王铜效果最差;多菌灵对分生孢子的抑制率为60.9%,其余四种杀菌剂效果差异不显著。田间药效试验结果显示,咪酰胺2 000mg/kg对花生褐斑病的田间防治效果达60.62%,远远高于对照药剂多菌灵(15.53%)以及其它三种供试杀菌剂(王铜、爱可和戊唑醇)。此外咪酰胺比清水对照增产32.28%,也远远高于其它几种药剂。通过室内毒力试验和田间药效试验表明,田间杀菌剂防治花生褐斑病时,咪酰胺比对照药剂多菌灵具有更好的防治效果,适用于花生褐斑病重病地区。     

核盘菌Ss160的基因克隆与功能初探

由核盘菌（Sclerotinia sclerotiorum）引起的菌核病是油菜等十字花科作物的重要病害,对油菜的产量品质造成严重影响。本研究基于转录组数据筛选到一个核盘菌基因Ss160 (Sscle04g035160),发现Ss160在接种油菜的核盘菌中高度表达。生物信息分析表明该基因具有信号肽,且序列在真菌界高度保守。亚细胞定位显示Ss160无特异性的定位,烟草叶片瞬时表达Ss160在核盘菌离体叶接种实验中病斑扩展显著小于表达空载体的和野生型烟草叶片,暗示异源表达Ss160能够提高植物的菌核病抗性。基于酵母系统的体外实验证明Ss160具有转录激活能力。该研究结果为后续Ss160在核盘菌-植物互作中功能机制的研究提供基础,也为油菜菌核病的研究提供借鉴和参考。     

木薯褐斑病菌的室内药剂筛选

采用孢子萌发法对分离自海南的木薯褐斑病菌进行了10种杀菌剂的室内筛选。结果表明,国光多菌灵(50%多菌灵WP)和咪鲜胺(25%咪鲜胺EC)的EC50值最小,抑菌效果最好;腐霉利(50%WP)的EC50值最大,抑菌效果最差。建议生产上使用多菌灵和咪鲜胺等来防治木薯褐斑病。