藓类提取物对植物病原真菌的抑菌性研究

以立枯丝核菌(Rhizoctonia)、尖孢镰孢菌(Fusarium oxysporum)、苹果轮纹病菌(Macrophoma kawatsukai)、梨黑星病菌(Fusicladium pirina)、草莓灰霉菌(Botrytis cinerea)等七种植物病原真菌为供试菌,通过生长速率法测定了24种藓类的乙醇提取物对病原真菌的抑制作用.结果表明,在提取物浓度为1.2mg干样/mL,大镰刀藓提取物对立枯丝核菌的抑制作用最强,抑菌率为67.8%.藓类提取物不仅对植物病原真菌有抑菌活性,而且还有多种藓类提取物对病原真菌菌丝有促进生长活性,如锐尖匍灯藓对立枯丝核菌菌丝生长的促进率为95.1%.选出大镰刀藓、扁灰藓、紫萼藓、山地水灰藓、疣小金发藓、橙色净口藓、锐尖匍灯藓和羊角藓对立枯丝核菌和灰霉菌的抑菌性或菌丝生长促进性进行了进一步研究,藓类提取物对病原菌的抑菌性或菌丝生长促进性在一定范围内随浓度的增加而增强,并且抑菌性随时间的延长呈下降趋势.     

两种秸秆醋液对尖孢镰刀菌和立枯丝核菌的抑菌作用

本研究以玉米秸秆醋液、水稻秸秆醋液为供试材料,研究不同稀释度的秸秆醋液对尖孢镰刀菌(Fusarium oxysporum)和立枯丝核菌(Rhizoctonia solani)的抑制作用,测定其可溶性蛋白和可溶性糖。结果表明,50倍稀释液对2种病原菌的抑制率为100%,即2种病原菌在50倍稀释处理的秸秆醋液中不能生长。玉米秸秆醋液对尖孢镰刀菌中可溶性蛋白的影响不显著,对立枯丝核菌中可溶性蛋白的影响表现为先升高后降低。水稻秸秆醋液对尖孢镰刀菌中可溶性蛋白的影响是先升高后降低,对立枯丝核菌中可溶性蛋白的影响是逐渐累积。高浓度的水稻秸秆醋液可提高2种菌体内可溶性糖含量,100倍稀释的玉米秸秆醋液可提高尖孢镰刀菌体内的可溶糖含量,玉米秸秆醋液对立枯丝核菌的可溶性糖含量基本不会产生影响。本研究为秸秆醋液在农业生产上的推广应用等提供科学依据。     

铅胁迫对3种藓类植物抗氧化酶活性的影响

采用水培实验研究了重金属Pb对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶(SOD、POD和CAT)活性的影响.结果表明,(1)在1~200 mg·L-1的铅胁迫浓度范围内,Pb对3种藓类植物的SOD活性均具有显著的促进作用,对Pb胁迫的种间敏感性差异为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)POD活性对Pb胁迫的反应趋势有一定差别,尖叶拟船叶藓和匍枝青藓的POD活性随Pb浓度的增加先升后降,湿地匍灯藓的POD活性变化较为平缓,种间敏感性差异为匍枝青藓>尖叶拟船叶藓>湿地匍灯藓;(3)在100 mg·L-1时Pb对湿地匍灯藓CAT活性表现为显著促进作用外,其余在低浓度下显示无显著影响,在高浓度下表现为抑制效应,种间敏感性差异为尖叶拟船叶藓>匍枝青藓>湿地匍灯藓.3种藓类植物的抗氧化酶体系中对Pb胁迫的抵抗起关键作用的是SOD,可作为藓类植物受Pb胁迫的敏感生理指标.3种植物中对Pb胁迫的反应较为敏感的是尖叶拟船叶藓.     

镉胁迫下3种藓类植物抗氧化酶活性变化的比较研究

采用水培实验研究了重金属Cd对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶系统(SOD、POD和CAT)的影响.结果表明,在1-100 mg·L-1的镉胁迫浓度范围内,Cd对3种藓类植物的SOD活性都具有显著的促进作用,SOD对Cd胁迫的种间敏感性顺序为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;3种藓类植物的POD和CAT活性对Cd胁迫均表现为先升后降,POD对Cd胁迫的种间敏感性顺序为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;高浓度Cd对CAT具有明显的抑制效应,CAT对Cd胁迫的种间敏感性顺序为湿地匍灯藓>尖叶拟船叶藓>匍枝青藓.在Cd长期胁迫下,SOD对3种藓类植物体内活性氧的清除起到关键作用,可作为藓类植物抗镉能力强弱的敏感生理指标;3种鲜类植物中匍枝青藓的抗镉能力最强,湿地匍灯藓次之,尖叶拟船叶藓最弱,并且这种抗性与cd在植物体内的积累成反相关.     

高温胁迫下两种藓类植物过氧化物酶活性的变化

在不同的高温胁迫条件下 ,对湿地匍灯藓 (Plagiomnium acutum)和大羽藓 (Thuidium cymbifolium)过氧化物酶 (POD)活性及其与处理时间和处理温度的关系进行了初步研究。结果表明 ,在一定的温度范围内 ,随着温度的升高 ,POD活性增加 ,二者成线形关系。在一定温度条件下 ,一般随着处理时间的延长 ,POD活性增加。但是当超过一定的温度 (4 5～ 5 0°C)以及一定的处理时间 (4～ 6h) ,POD活性有所下降。结果还表明 ,湿地匍灯藓的POD活性显著高于大羽藓。而且在高温胁迫下 ,湿地匍灯藓 POD活性变化比大羽藓活跃 ,其变化幅度也比大羽藓大。     

湖南藓类植物新资料

报道了湖南藓类7个新分布种:虾藓东亚亚种(Bryoxiphium norvegicum ssp. japonicum,隶属于虾藓科Bryoxiphiaceae,为湖南新记录科)、细拟合睫藓(Pseudosymblepharis duriuscula)、大叶真藓(Bryum pseudotriquetrum)、密叶匍灯藓(Plagiom niumconfertidens)、尖叶匍灯藓(P.cuspidatum)、石地青藓(Brachythecium glareosum)和毛叶梳藓(Ctenidium capillifolium,梳藓属为湖南新记录属)。并对它们的生境和地理分布进行了初步讨论。     

甘肃白龙江流域提灯藓科植物研究

对采自甘肃白龙江流域的180余份提灯藓科植物标本进行了分类研究,共鉴定出该科植物4属22种,其中瘤柄匍灯藓、大叶毛灯藓、细枝毛灯藓、具丝毛灯藓为甘肃省新记录种。同时,依据标本编制了白龙江流域提灯藓科植物的分属、分种检索表,列出了各个种的生境和分布,并对其区系成份进行了分析。     

铅胁迫对3种藓类植物细胞伤害及光合色素含量的影响

采用水培实验研究了重金属Pb2+胁迫下3种藓类植物[尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)]的细胞伤害、光合色素含量和Pb2+累积量的变化,以探讨藓类植物对Pb2+胁迫的反应敏感性和耐性强弱.结果表明:(1)Pb2+胁迫导致尖叶拟船叶藓、湿地葡灯藓和匍枝青藓叶细胞显著损伤的最低浓度分别为100、1和10 mg·L-1,叶细胞伤害随Pb2+浓度的升高而显著增加,它们对高浓度Pb2+的耐受性顺序为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)低浓度Pb2+胁迫(小于100 mg·L-1)对3种藓类植物的总叶绿素含量均没有影响,高浓度Pb2+胁迫则导致总叶绿素含量显著下降,降幅依次为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;叶绿素a/b值显示,高浓度Pb2+胁迫对尖叶拟船叶藓叶绿素b的抑制远大于叶绿素a,而对匍枝青藓和湿地葡灯藓使叶绿素a的抑制大于叶绿素b;当Pb2+胁迫浓度达到200 mg·L-1时3种藓类植物的类胡萝卜素含量显著降低;(3)3种藓类植物均能显著地富集Pb2+,高浓度Pb2+胁迫下,其富集能力急剧增加,而且与其耐受性呈正相关.     

一株拮抗立枯丝核菌的放线菌筛选、鉴定及生理特性

通过对峙实验,从采集自黄渤海海域的双齿围沙蚕(Perinereis aibuhitensis)中分离到一株内生放线菌SCF-18,并对其抑菌活性进行分析。SCF-18对立枯丝核菌(Rhizoctonia solani)和小麦根腐病菌(Bipolaris sorokiniana)都具有拮抗作用,且对立枯丝核菌生长的拮抗效果最为明显,生长抑制率为89.78%。抑菌试验结果表明:菌株SCF-18发酵滤液可以抑制立枯丝核菌丝的生长,发酵液浓度越高,抑制力越强;当发酵液浓度达到50%时,对两种病原菌的抑制率分别为89.78%和80.26%。菌株SCF-18生长特性试验结果表明:菌株SCF-18生长最适温度为30℃,最适pH值为7;放线菌SCF-18耐盐度可达5%。根据形态特征、培养特征、生理生化特性和16S rDNA序列分析,将放线菌SCF-18初步鉴定为淡紫灰链霉菌(Streptomyces lavendulae)。本研究发现,SCF-18菌株是防治立枯丝核菌等病原菌的潜在优良生防菌株,具有潜在的开发应用价值。     

长白山森林生态系统腐木生苔藓植物生态分布的DCA排序研究

应用除趋势对应分析（ＤＣＡ）对长白山不同森林类型腐木生苔藓植物分布研究表明,长白山红松阔叶混交林、暗针叶林以及两者之间的过渡林林下腐木生苔藓植物组成明显不同．红松阔叶混交林以尖叶匍灯藓、毛尖羽藓、细枝青藓等为主;过渡林以尖叶匍灯藓、鞭枝疣灯藓、羽藓、腐木藓、塔藓等为主;暗针叶林的以塔藓、钩枝镰刀藓、拟垂枝藓、曲背藓、毛梳藓等为主．暗针叶林林下腐木生苔藓植物发生量最大,物种的多样性也最高．海拔高度和林冠郁闭度是影响长白山森林林下腐木生苔藓植物生态分布的主要因素．     

Study of the aggressiveness of Rhizoctonia solani isolates

This paper presents an in vitro test to screen the pathogenicity of different Rhizoctonia solani isolates on a host range. The level of aggressivity of the different isolates was different for several host plants tested. There were significant differences between the crops and the isolates tested. In general, the disease level was higher on beans, lettuce and cabbage. In carrot and rye grass the level of infection was lower for the isolates of R. solani tested. The potato isolates of R. solani were less aggressive than the isolates coming from maize, fodder beet and sugar beet. The R. solani isolates were also biochemically characterized by pectic zymograms: the isolates Rs0401 (from maize) and Rs0504 (from sugar beet) belong both to the anastomosis group AG2-2.     

银杏外种皮提取物对几种蔬菜病原菌的抑制作用

以银杏外种皮提取物对几种蔬菜病原菌进行抑菌效果检测,结果表明,乙醇提取物、甲醇提取物的抑菌效果较好。乙醇提取物浓度为500 mg·mL^-1时,抑菌效果除对甘蓝黑斑病菌为88.5%外,对白菜炭疽病菌、茄子立枯病菌、茄子白绢病菌、黄瓜枯萎病菌均为100%。甲醇提取物浓度为500 mg·mL^-1时,对上述5种病菌的抑菌率均为100%。这为今后田间防治5种病菌及开发银杏植物源杀菌剂提供科学依据。     

Phenylacetic acid-producing Rhizoctonia solani represses the biosynthesis of nematicidal compounds in vitro and influences biocontrol of Meloidogyne incognita in tomato by Pseudomonas fluorescens strain CHA0 and its GM derivatives

AIMS: The aim of the present investigation was to determine the influence of Rhizoctonia solani and its pathogenicity factor on the production of nematicidal agent(s) by Pseudomonas fluorescens strain CHA0 and its GM derivatives in vitro and nematode biocontrol potential by bacterial inoculants in tomato. METHODS AND RESULTS: One (Rs7) of the nine R. solani isolates from infected tomato roots inhibited seedling emergence and caused root rot in tomato. Thin layer chromatography revealed that culture filtrates of two isolates (Rs3 and Rs7) produced brown spots at Rf-values closely similar to synthetic phenylacetic acid (PAA), a phytotoxic factor. Filtrates from isolate Rs7, amended with the growth medium of P. fluorescens, markedly repressed nematicidal activity and PhlA'-'LacZ reporter gene expression of the bacteria in vitro. On the contrary, isolate Rs4 enhanced nematicidal potential of a 2,4-diacetylphloroglucinol overproducing mutant, CHA0/pME3424, of P. fluorescens strain CHA0 in vitro. Therefore, R. solani isolates Rs4 and Rs7 were tested more rigorously for their potential to influence biocontrol effectiveness of the bacterial agents. Methanol extract of the culture filtrates of PAA-producing isolate Rs7 resulting from medium amended with phenylalanine enhanced fungal repression of the production of nematicidal agents by bacteria, while amendments with zinc or molybdenum eliminated such fungal repression, thereby restoring bacterial potential to cause nematode mortality in vitro. A pot experiment was carried out, 3-week-old tomato seedlings were infested with R. solani isolates Rs4 or Rs7 and/or inoculated with Meloidogyne incognita, the root-knot nematode. The infested soil was treated with aqueous cell suspensions (10(8) CFU) of P. fluorescens strain CHA0 or its GM derivatives or left untreated (as a control). Observations taken 45 days after nematode inoculation revealed that, irrespective of the bacterial treatments, galling intensity per gram of fresh tomato roots was markedly higher in soil amended with isolate Rs4 than in Rs7-amended soils. Soil amendments with R. solani and the bacterial antagonists resulted in substantial reductions of the number of galls per gram of root. These results are contradictory to those obtained under in vitro conditions where culture filtrates of PAA-positive Rs7 repressed the production of nematicidal compounds. Plants grown in Rs7-amended soils, with or without bacterial inoculants, had lesser shoot and root weights than plants grown in nonamended or Rs4-amended soils. Moreover, amendments with Rs7 substantially retarded root growth and produced necrotic lesions that reduced the number of entry sites for invasion and subsequent infection by nematodes. Populations of P. fluorescens in the tomato rhizosphere were markedly higher in Rs7-amended soils. CONCLUSIONS: PAA-producing virulent R. solani drastically affects the potential of P. fluorescens to cause death of M. incognita juveniles in vitro and influences bacterial effectiveness to suppress nematodes in tomato roots. SIGNIFICANCE AND IMPACT OF THE STUDY: As most agricultural soils are infested with root-infecting fungi, including R. solani, it is likely that some PAA-producing isolates of the fungus may also be isolated from such soils. The inhibitory effect of PAA-producing R. solani on the biosynthesis of nematicidal agent(s) critical in biocontrol may reduce or even eliminate the effectiveness of fluorescent pseudomonads against root-knot nematodes, both in nursery beds and in field conditions. Introduction of bacterial inoculants, for the control of any plant pathogen, should be avoided in soils infested with PAA-producing R. solani. Alternatively, the agents could be applied together with an appropriate quantity of fungicide or chemicals such as zinc to create an environment more favourable for bacterial biocontrol action.     

菊芋叶片提取物抑菌活性与化学成分的研究

为了开发新型植物源杀菌剂和充分利用菊芋(Helianthus tuberosus L.)资源,本文尝试用石油醚、乙醚、乙酸乙酯和水等4种溶剂对菊芋叶片进行平行提取,采用生长速率法测定菊芋叶片提取物对水稻纹枯菌(Rhizoc-tonia solaniKühn)、小麦赤霉菌[Gibberella zeae(Schw.)Petch]、番茄早疫菌[Alternaria solani(Ellis et Martin)Jones et Grour]和番茄灰霉菌(Botrytis cinerea Pers.)生长量的抑制活性;并通过试管法和滤纸法对菊芋叶片内化学成分进行初步预试。抑菌实验结果表明:(1)菊芋叶片各溶剂提取物处理与对照处理相比差异显著;(2)菊芋叶片水提取物处理与各有机溶剂提取物处理差异也基本显著;(3)菊芋叶片各溶剂提取物同浓度处理对水稻纹枯菌、番茄早疫菌和番茄灰霉菌抑制效果较好;(4)菊芋叶片乙酸乙酯提取物抑菌效果最为显著,浓度为20mg/mL时对番茄早疫菌和番茄灰霉菌已达到完全抑制,对水稻纹枯菌抑制率也达到77.91%。初步化学预试结果说明,菊芋叶片中含有蛋白质、氨基酸、还原糖类、有机酸、酚类和鞣质、黄酮类、内酯类、强心甙以及油脂等化学成分。     

贝莱斯芽胞杆菌HN-Q-8菌株发酵液稳定性测定及抑菌活性成分分析

【背景】贝莱斯芽胞杆菌(Bacillus velezensis) HN-Q-8菌株是本实验室前期获得的能有效拮抗立枯丝核菌(Rhizoctonia solani)的生防细菌。【目的】明确贝莱斯芽胞杆菌HN-Q-8菌株的抑菌活性物质。【方法】采用菌丝生长速率法检测其发酵液对5种马铃薯病原菌的拮抗能力以及稳定性,利用基质辅助激光解吸电离飞行时间质谱技术对HN-Q-8菌株活性物质进行鉴定。【结果】HN-Q-8菌株对立枯丝核菌(Rhizoctonia solani)、尖镰孢菌(Fusarium oxysporum)、茄链格孢(Alternaria solani)和致病疫霉(Phytophthora infestans)具有良好的抑菌活性,抑菌率可达50%-90%。发酵液分别经紫外照射35min、自然光照射10 h以及100°C高温处理后,相对抑菌率分别为74%、92%和98%;发酵液的抑菌活性不受胰蛋白酶和蛋白酶K的影响;但不耐强酸、强碱,其适宜pH为4.0-10.0,表明HN-Q-8菌株活性物质具有良好的稳定性。活性成分能使立枯丝核菌菌丝形态畸形扭曲,从而抑制立枯丝核菌的生长,经鉴定活性物质为丰原素(fengycin)和表面活性素(surfactin)。【结论】贝莱斯芽胞杆菌HN-Q-8菌株发酵液具有较好的稳定性和较强的抑菌活性,具有良好的开发价值和应用前景。     

水稻纹枯病时空生态位施药干扰研究

以施药作为干扰因子,研究干扰条件下水稻纹枯病菌的时间和空间生态位变化.结果表明,各施药处理与对照纹枯病菌的空间生态位存在差异,其中孕穗期施药+齐穗期施药和孕穗期施药+灌浆期施药两处理的空间生态位宽度指数分别为0.520、0.572,与对照的空间生态位宽度指数0.8563相差最大;分蘖盛期一次施药处理的空间生态位宽度指数为0.8577,与对照相差最小.各施药处理和对照的时间生态位宽度无显著差异,表明施药对纹枯病菌的时间生态位宽度影响不大.空间生态位宽度指数、病叶(鞘)率、病情指数及防治效果等计测结果表明,两次施药对病害的控制好于一次施药,其中两次施药中以孕穗期施药+齐穗期施药和孕穗期施药+灌浆期施药对病害的控制作用最强.施药不但压缩了水稻纹枯病菌的空间生态位宽度,限制了其在产量形成较为重要的上部叶位的扩张,而且压缩了水稻纹枯病菌的时间生态位宽度,限制了其在水稻产量形成时期的扩张.但施药只改变了病菌生态位的分布,调整压缩了水稻产量形成期的病害生态位,病菌生态位势的总和不变.     

亚麻立枯病拮抗菌的筛选、生防效果及发酵条件优化

【目的】从健康亚麻植株的根际土壤中筛选对亚麻立枯病菌具有较强抑菌作用的拮抗菌,优化其产生抑菌活性物质的发酵条件,为其生防利用奠定基础。【方法】采用稀释平板涂布法和对峙培养法进行拮抗菌的筛选;根据菌株形态学特征、生理生化特性以及16S r RNA基因序列分析对其进行鉴定;利用温室抗病实验确定其生防效果;通过单因素实验和均匀设计实验优化其发酵条件。【结果】分离筛选到一株对亚麻立枯病菌具有显著拮抗作用的细菌HXP-5,且其对另外7种植物病菌真菌均有拮抗作用;鉴定菌株HXP-5为枯草芽孢杆菌;温室抗病实验结果表明其生防效果可达71.22%;其产生抑菌活性物质的最佳发酵条件为:葡萄糖为2.3%,胰蛋白胨+酵母粉(3:1)为0.25%,Na Cl为0.18%,发酵时间为72 h,发酵温度为27°C,转速为210 r/min,250 m L摇瓶装液100 m L,接种量为1.7%。【结论】经鉴定,对亚麻立枯病病菌具拮抗作用的菌株HXP-5为枯草芽孢杆菌,且对亚麻立枯病具有较强的防治效果,发酵条件进行优化后其对亚麻立枯病病原菌显示出更强的拮抗作用。     

Structure, production characteristics and fungal antagonism of tensin - a new antifungal cyclic lipopeptide from Pseudomonas fluorescens strain 96.578

AIM: To study the antagonistic activity by Pseudomonas fluorescens strain 96.578 on the plant pathogenic fungus Rhizoctonia solani. METHODS AND RESULTS: Strain 96.578 produced a new cyclic lipopeptide, tensin. High tensin production per cell was detected in liquid media with glucose, mannitol or glutamate as growth substrate while fructose, sucrose and asparagine supported low production. Tensin production was nearly constant in media with different initial C levels, while low initial N contents reduced production. When applied to sugar beet seeds, strain 96.578 produced tensin during seed germination. When challenged with strain 96.578 or purified tensin, Rhizoctonia solani reduced radial mycelium extension but increased branching and rosette formation. CONCLUSION: The antagonistic activity of strain 96.578 towards Rhizoctonia solani was caused by tensin. SIGNIFICANCE AND IMPACT OF THE STUDY: When coated onto sugar beet seeds, tensin production by strain 96.578 could be of significant importance for inhibition of mycelial growth and seed infection by Rhizoctonia solani.