核桃叶水浸提液对棉花生长及棉花枯萎病菌的化感效应

研究了不同浓度核桃叶水浸提液对棉花种子萌发、幼苗生长及对棉花枯萎病菌菌丝生长的化感效应。结果表明, 不同浓度核桃叶水浸提液对棉花种子萌发、幼苗生长及棉花枯萎病菌菌丝生长均体现出抑制效应, 且抑制作用整体随着浸提液浓度的增高而逐渐增强。浸提液对棉花种子发芽势、发芽指数的影响要大于对发芽率的影响, 20 mg·mL^–1以上浸提液浓度处理的棉花种子发芽势与发芽指数显著(P<0.05)降低, 而30 mg·mL^–1 的浓度下对种子发芽率的抑制仍不显著。浸提液浓度大于20 mg·mL^–1 时, 棉花幼苗根的生长及根系活力开始受到强烈抑制, 当浸提液浓度大于30 mg·mL^–1时, 幼苗总叶绿素含量显著降低, 导致幼苗的鲜、干重减少。同时, 在高浓度浸提液胁迫下(>30 mg·mL^–1), 还会造成棉花植株体内MDA 含量急剧增高。不同浓度浸提液对棉花枯萎病菌菌丝的生长均有一定的抑制作用, 40 mg·mL^–1 浓度浸提液的抑菌率达到最高, 为47.9%。     

番茄种子及其萌发期化感作用分析

采用种子发芽生物测试法,以发芽率、发芽势、发芽指数和活力指数为指标,对番茄(Lycopersicon esculentum Mill.)种子及其萌发期对大白菜[Brassica campestris ssp.pekinensis(Lour.)G.Olsson]、萝卜(Raphanus sativus Linn.)、黄瓜(Cucumis sativus Linn.)和番茄种子萌发的化感效应进行测定,并采用化感效应指数(RI)和化感综合效应(SE)对化感作用进行评价.结果表明:用30 mg·mL-1番茄种子浸提液培养大白菜、萝卜和黄瓜种子,各项发芽指标均低于对照;番茄种子萌发可导致套种的大白菜、萝卜和黄瓜种子的各项发芽指标降低;番茄幼苗分泌物对大白菜、萝卜和黄瓜种子的萌发也均有抑制作用;在4个发芽指标中,对种子活力指数的抑制效应最大.与对照相比,0.5和1.0g番茄幼苗模拟腐解物对大白菜、萝卜和黄瓜种子的发芽率有一定的促进作用,但均导致种子发芽指数和活力指数的降低;而1.5g番茄幼苗模拟腐解物对3种蔬菜种子各项发芽指标的抑制作用最大;随模拟腐解物质量的增加,番茄种子的发芽指标值也逐渐降低.8、16和24 mg·mL-1番茄幼苗浸提液对大白菜、萝卜、黄瓜和番茄种子的萌发有明显抑制作用,随浸提液浓度提高,受试蔬菜种子的各项发芽指标均逐渐降低.总体上看,在番茄种子萌发过程中对受试蔬菜种子萌发的RI值多数为负值、SE值均为负值.研究结果证实:番茄种子含有化感物质,在其萌发过程中分泌与释放化感物质并抑制胚根生长,且除抑制其他植物种子的萌发外还具有自毒作用.     

西芹种子浸提液处理后黄瓜枯萎病菌弱毒菌株的筛选

研究了西芹种子浸提液对黄瓜枯萎病菌菌落生长的抑制作用及浸提液处理后病菌致病力的变化.结果表明:在连续5代浸提液作用下,50 mg·mL-1的西芹种子乙醇、丙酮浸提液处理与其对照相比,显著抑制了黄瓜枯萎病菌菌落的生长;50 mg·mL-1的西芹种子蒸馏水浸提液处理在1～3代培养过程中,显著抑制了黄瓜枯萎病菌菌落的生长,而在4～5代培养过程中,与其对照相比,抑制菌落生长的差异不显著;用各代经西芹不同浸提液处理的黄瓜枯萎病菌接种到黄瓜上进行致病力测定,并于1周开始发病后调查病情,西芹种子丙酮、乙醇和蒸馏水浸提液处理的病情指数分别由第1代的26.7％、20.8％和22.5％降为第5代的17.5％、3.3％和18.3％;3种浸提液与其对照相比,其病情指数也表现降低,其中,乙醇浸提液处理与其对照差异达显著水平;接种至第5代时,乙醇浸提液处理的病情指数为3.3％,病菌毒力的致弱作用最强.综上所述,西芹种子浸提液不但抑制黄瓜枯萎病菌菌落的生长,而且还能弱化病菌的毒力.实验通过浸提液的连续处理获得了黄瓜枯萎病菌的弱毒菌株.     

两个不同抗性黄瓜品种和云南黑籽南瓜根系分泌物对黄瓜枯萎病发生的影响

研究了黄瓜品种津研4号（感枯萎病）、津春4号（抗枯萎病）和云南黑籽南瓜根系分泌物对津研4号黄瓜枯萎病发生的影响及其原因.结果表明:感病品种根系分泌物处理的黄瓜枯萎病发病早,接种后第15天病株率显著高于对照,至第20天时病株率与对照相近;而抗病品种根系分泌物处理的病株率一直显著小于对照.感病品种根系分泌物浇灌的植株株高、鲜质量降低,根系活力下降、电导度（伤害度）增加,而抗病品种和云南黑籽南瓜根系分泌物处理对植株影响较小.感病品种根系分泌物促进了黄瓜枯萎病菌的生长,而抗病品种和云南黑籽南瓜根系分泌物则抑制了病菌生长.     

酚酸物质对黄瓜幼苗及枯萎病菌菌丝生长的影响

研究了不同连作年限大棚土壤中酚酸物质的种类、含量及其对黄瓜幼苗和枯萎病菌菌丝生长的影响。结果表明:土壤中香草酸、对羟基苯甲酸及阿魏酸随黄瓜连作年限增加而呈现积累趋势;在连作7年的大棚土壤中3种酚酸类物质总量达29.8mg.kg-1干土,显著高于连作1年和3年土壤中的含量;酚酸物质可使黄瓜幼苗根长及茎粗显著降低,使株高及干物质量略有下降。与对照相比,酚酸物质使黄瓜幼苗体内过氧化物酶(POD)活性在短期内升高,5d后又呈下降趋势;对超氧化物歧化酶(SOD)活性的影响也表现出先升高后下降的变化趋势。高浓度酚酸使黄瓜幼苗丙二醛(MDA)含量持续升高。枯萎病菌菌丝生长测定表明:42h内,低浓度(≤50mg.L-1)酚酸对枯萎病菌丝生长有刺激作用;酚酸浓度高于50mg.L-1时,对菌丝生长有抑制作用;随酚酸处理时间延长,枯萎病菌对酚酸物质的耐受性增强,对高浓度酚酸的生长抑制作用表现不明显。     

外来入侵植物牛膝菊和野茼蒿水浸提液化感作用的生物测定

采用培养皿滤纸法,以小麦(Triticum aestivum L. )和玉米(Zea mays L. )为实验材料,以种子的发芽率、发芽指数、活力指数以及幼苗的株高和根长为测定指标,结合化感效应指数的综合效应值,对外来入侵植物野茼蒿[Crassocephalum crepidioides (Benth. ) S. Moore]和牛膝菊(Galinsoga parviflora Cav. )茎叶水浸提液的化感活性分别进行了测定.结果表明,随野茼蒿和牛膝菊水浸提液质量浓度(0.01～0.10 g·mL-1)的提高,小麦和玉米种子的发芽率、发芽指数、活力指数以及幼苗的株高和根长总体上逐渐减小;与对照组相比,0.01 g·mL-1牛膝菊水浸提液对小麦的幼苗株高以及玉米的种子发芽率和幼苗株高具有一定的促进作用,但对小麦和玉米的幼苗根长有显著抑制作用;而0.01 g·mL-1野茼蒿水浸提液仅对小麦种子的发芽率略有促进作用.0.04～0.10 g·mL-1野茼蒿和牛膝菊水浸提液对小麦和玉米种子萌发及幼苗生长的各项指标基本上均有显著的抑制作用;野茼蒿和牛膝菊水浸提液对玉米种子萌发和幼苗生长的抑制作用大于小麦.0.01～0.10 g·mL-1野茼蒿和牛膝菊水浸提液对小麦和玉米种子萌发和幼苗生长的化感效应指数的综合效应值均小于0,表现为抑制作用,并随2种植物水浸提液质量浓度的提高综合效应值逐渐降低,且前者的化感效应指数的综合效应值大于后者.研究结果显示,野茼蒿和牛膝菊水浸提液对小麦和玉米的化感活性均表现为抑制作用,且化感作用的强度与水浸提液的质量浓度相关;野茼蒿水浸提液的化感作用效应大于牛膝菊.     

香蕉抗(感)病品种根系分泌物对枯萎病菌和枯草芽孢杆菌的生物效应

为明确香蕉根系分泌物对枯萎病菌及其生防枯草芽孢杆菌的生物效应,采用离位溶液培养法收集抗枯萎病香蕉品种(南天黄)和感枯萎病香蕉品种(桂蕉6号)的根系分泌物,研究根系分泌物对土壤微生物种群数量、香蕉枯萎病菌和枯草芽孢杆菌生长的影响。结果表明: 抗病品种根系分泌物能显著减少土壤真菌的数量,抑制枯萎病菌孢子的萌发;而感病品种根系分泌物能显著促进病菌菌丝生长和孢子的萌发,两个品种根系分泌物均能显著促进枯草芽孢杆菌的生长和生物膜形成。经抗(感)病香蕉品种根系分泌物处理,病菌菌丝生长速率分别为11.28和12.28 mm·d^-1,病菌孢子的萌发率分别为34.6%和79.5%;枯草芽孢杆菌培养12 h后菌体生长量的OD₆₀₀分别为1.27和1.14,生物膜形成量在静置培养72 h后OD₅₇₀分别达1.11和1.30,两个品种处理间的差异均达显著水平。枯草芽孢杆菌在香蕉感病品种根际中定殖的菌量显著高于抗病品种。通过对两个品种根系分泌物中可溶性总糖、游离氨基酸和有机酸的含量和组成分析,发现抗病品种根系分泌物中有机酸和游离氨基酸的含量明显高于感病品种,在各组成成分中,以乙酸和脯氨酸在抗(感)病香蕉品种根系分泌物中含量比值较高,分别达3.7和2.4倍。综上所述,抗病品种根系分泌物能抑制病菌生长,感病品种根系分泌物则会显著促进病菌生长,而两个品种根系分泌物均能显著促进枯草芽孢杆菌的生长和生物膜的形成。     

西芹挥发物对黄瓜枯萎病菌的化感作用

将定量的西芹种子、8～10叶期的叶片、叶柄、鲜根分别置于玻璃真空干燥器的下部,将在PDA培养基上接种黄瓜枯萎病菌的培养皿置于干燥器的上部,密封,利用生长速率法研究了不同西芹离体材料挥发物对黄瓜枯萎病菌的化感作用(各处理材料重量分别为50、100、150、200g)。结果表明:西芹挥发物对黄瓜枯萎病菌有化感抑制作用,且化感效果随着浓度的增加而增加;重量为200g的西芹种子、叶片、叶柄、鲜根挥发物处理黄瓜枯萎病菌144h后,化感效果分别为9.3%、10.9%、12.2%、18.7%;西芹鲜根挥发物的化感作用最强,其次为叶柄,叶片和种子最弱。对共培养后接种黄瓜枯萎病菌的黄瓜幼苗进行病害调查,处理为200株的西芹挥发物化感抑制效果最好,至接菌11d其发病株数为64株,化感效果为15.8%;西芹挥发物浓度越高,其抑制发病的效果越好,抑病效果随着时间的延长而减弱。     

外来杂草反枝苋对农作物的化感作用及其风险评价

利用改进的差时播种共培法,以麦田伴生恶性杂草播娘蒿为对照,在实验室条件下研究反枝苋根系分泌物及其不同浓度残枝浸提液对小麦、玉米、油菜种子萌发及生长的影响.结果显示:(1)反枝苋幼苗的根系分泌物能够显著抑制作物根长和苗高的生长;(2)反枝苋不同浓度浸提液均能抑制作物种子的萌发,其抑制作用随浓度的增加而增强;(3)除0.025 g·mL-1处理对小麦根长和苗高、玉米苗高有促进作用外,其余各浓度反枝苋浸提液对作物幼苗的根长和苗高有不同程度的抑制,且对根长的抑制作用更强;(4)反枝苋对作物幼苗的抑制作用强于恶性杂草播娘蒿,风险评估定量分析结果认定反枝苋为陕西省高度危险性植物.     

大蒜根系分泌物对不同受体蔬菜的化感作用

利用组织培养技术,在无菌条件下研究大蒜根系分泌物对莴苣、辣椒、萝卜、黄瓜、白菜和番茄等蔬菜作物的化感作用.结果表明：大蒜根系分泌物对6种蔬菜作物的发芽率、发芽指数、苗高及保护酶活性没有影响;对根长、地上部鲜质量及根鲜质量略有促进作用,其中,莴苣与对照差异达显著水平,化感效应指数分别为+0.163、+0.106、+0.318,白菜根长与对照差异达显著水平,化感效应指数为+0.120,其它受试作物与对照差异均未达显著水平;大蒜根系分泌物对受试作物叶绿素含量及根系活力有促进作用,与对照差异达显著水平,对萝卜的叶绿素含量促进作用最强,化感效应指数为+0.282,对黄瓜的根系活力促进作用最强,化感效应指数为+0.184;大蒜根系分泌物使受试作物对养分的吸收能力有所提高.     

In Vitro Physiological Responses of Fusarium oxysporum f. sp. niveum to Exogenously Applied Syringic Acid

ABSTRACT. Plant–microbe interactions are often accompanied by allelochemicals, such as syringic acid, released from the host plant. To explore the role of phenolic acids released from crop host plants in response to pathogen invasion, we examined the allelopathic effect of an artificially applied syringic acid on Fusarium oxysporum f. sp. niveum . We demonstrated that the growth and the conidial germination rate of F. oxysporum f. sp. niveum were stimulated at lower concentrations of syringic acid, though inhibited by higher dosage compared with control. The yield of fungus mycotoxin was increased from 60.9% to 561.5%. We conclude that syringic acid can be considered as a allelochemical inducer, stimulating the relative virulence factors of invading pathogens.     

尖孢镰刀菌四个专化型细胞核的初步研究

本文对尖孢镰刀菌(Fusarium oxysporum)的4个专化型12株菌的孢子萌发、核分裂时间及核DNA含量进行了比较,结果表明:不同专化型菌株孢子萌发速度基本一致,而萌发过程中发生第一次核分裂的时间不同。黄瓜、西瓜、荸荠、大豆各专化型第一次核分裂时间分别为:5.67hr、5.45hr、7.35hr、7.82hr,其核DNA含量分别为:0.321pg、o.306pg、0.177pg 0.174pg。测定结果显示出不同专化型菌株的孢子核DNA含量可能存在倍数关系,并推测F.oxysporum的黄瓜专化型与西瓜专化型为同一类型,而荸荠专化型与大豆专化型为同一类型。     

Microconidia germination of the tomato pathogen Fusarium oxysporum in the presence of root exudates

Abstract

In this study we assessed microconidia germination of the tomato pathogens F. oxysporum f. sp. lycopersici (Fol) and F. oxysporum f. sp. radicis-lycopersici (Forl) in the presence of root exudates. Tomato root exudates stimulated microconidia germination and the level of stimulation was affected by plant age. Treatment of root exudates with insoluble polyvinylpolypyrrolidone, which binds phenolic compounds, indicated that tomato root exudates contain phenolic compounds inhibitory to F. oxysporum microconidia germination. Our study indicates that tomato root exudates similarly stimulate microconidia germination of both Fol and Forl. However, individual F. oxysporum strains differ in the degree of germination response to the root exudates. Furthermore, root exudates from non-host plants also contain compounds that stimulate microconidia germination of Fol. In general, the effects of root exudates from non-host plants did not differ considerably from those of tomato. The ability of phenolic compounds to inhibit germination of Fol seems not to be plant-specific.     

生防枯草芽孢杆菌B29菌株抗菌物质的初步研究

通过检测生防枯草芽孢杆菌除菌上清液对黄瓜枯萎病菌Fusarium oxysporium f．cumerinum菌丝生长和分生孢子萌发的抑制作用,初步研究了生防枯草芽孢杆菌B29菌株抗菌物质的活性。结果表明,枯草芽孢杆菌B29菌株分泌的抗菌物质不仅抑制病原菌的生长;并可抑制尖孢镰刀菌孢子的萌发,使分生孢子萌发畸形。研究确定了该菌株抗菌物质产生的最佳条件：培养温度30℃;培养基初始pH值7.5;装液量为250ml三角瓶装液75ml培养基;培养时间120h。经30%~70%硫酸铵沉淀获得的抗菌粗提物对60℃处理具有稳定性（活性达97.8%）;对蛋白酶K具有部分耐受性,对胰蛋白酶和胃蛋白酶较敏感。     

Effects of Membrane Filtering of Tomato Root Exudates on Conidial Germination of Fusarium oxysporum f. sp. lycopersici

The effect of different membrane filters on the bioactivity of tomato root exudates was tested in an in vitro assay addressing the germination of microconidia of the soil-borne fungus Fusarium oxysporum f. sp. lycopersici . Membrane filtration of unsterile root exudates with filters of different membrane materials and filter brands resulted in an increased microconidia germination. This effect varied depending on the used membrane filter but was lacking when sterile root exudates were used. The alteration of the bioactivity of unsterile root exudates therefore seems to be due to the presence of microbial contaminants. The varying effects of different filter brands may be due to their differential potential of retaining inhibitory compounds. When working with root exudates, such effects of membrane filtration have to be taken into account.     

辣椒疫病拮抗菌株筛选、鉴定及其防效

从疫病发病严重田块的健康辣椒植株根际分离到98株拮抗菌,从中筛选出两株具有广谱抗性并可在贫营养条件下生长良好的高效拮抗菌株HL-3和LZ-8.通过形态观察、生理生化特性和16S rDNA序列分析,确定HL-3为多粘类芽孢杆菌,LZ-8为短小芽孢杆菌.HL-3和LZ-8对辣椒疫霉菌丝生长抑制率分别为72%和68%.HL-3和LZ-8还对黄瓜枯萎病菌、辣椒枯萎病菌、棉花黄萎病菌、黄瓜立枯病菌、烟草黑胫病菌和番茄青枯病菌具有显著的抑制作用.盆栽试验表明,HL-3和LZ-8对辣椒苗期疫病防治效果分别为72%和83%,且对辣椒生长表现出明显的促生作用.     

Allelopathy of rice (Oryza sativa L.) root exudates and its relations with Orobanche cumana Wallr. and Orobanche minor Sm. germination

Allelopathy has been considered not only as an environmentally friendly approach for weed control but also a potential reason causing autotoxicity in crop production. In this study, the responses of seeds of lettuce, wheat, rice, clover broomrape (CB), and sunflower broomrape (SB) to the root exudates of rice cultivars were studied. Lettuce germination was promoted by root exudates of Yliangyou 3218 and I-Kung-Pao. Wheat seedling growth was inhibited by all nine rice species. I-Kung-Pao and Ganxin 203 exerted greater autotoxicity than other cultivars. Yongyou 15 and I-Kung-Pao induced the highest germination rate of CB, while Yongyou 13, Zhongzao 22, and I-Kung-Pao induced the highest germination rate of SB. A significantly correlation was noted between germination-inducing ability on broomrape seeds and allelopathic effects on target plants. It is suggested that using broomrape seeds germination is a better receptor for the identification of rice allelopathic potential.     

AM真菌和镰刀菌对西瓜根系几种酶活性的影响*

在温室盆栽条件下研究了丛枝菌根(Arbuscular Mycorrhiza, AM)真菌Glomus versiforme和西瓜枯萎镰刀菌Fusarium oxysporum f.sp. niveum对西瓜根系中过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、β-1,3-葡聚糖酶和几丁质酶活性的影响。结果表明,接种AM真菌的西瓜根系中4种酶的活性均高于对照,先接种G. versiforme,后接种F. oxysporum f.sp. niveum处理的4种酶的活性均高于只接种F. oxysporum f.sp. niveum 的处理,且酶的活性峰值出现较早。表明接种G. versiforme 能预先诱导这4种酶的产生,提高其活性,从而提高西瓜对F. oxysporum f.sp. niveum侵染的抗性。接种G. versiforme的感枯萎病西瓜品种“郑杂5号”酶的增加幅度大于抗病品种“京欣1号”的接种处理,说明G. versiforme对提高感病西瓜品种酶活性的作用更大。     

Allelopathic effects of root exudates from watermelon and rice plants on Fusarium oxysporum f.sp. niveum

Root exudates have a key role in communication between plants and microbes in the rhizosphere. Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum (Fusarium oxysporum), drastically reduces watermelon yields in continuous cultivation systems, but it can be significantly alleviated using watermelon/aerobic rice intercropping system as shown by the research carried out in this laboratory. It is important to evaluate the interaction between root exudates from the two crops and the pathogen and thus to clarify the mechanism of disease suppressiveness in the intercropping system. The effects of phenolic acids, sugars and free amino acids in root exudates from watermelon (REW) and rice (RER) on the growth of Fusarium oxysporum were studied. The results obtained are listed as follows: (1) REW significantly increased spore germination and sporulation, whereas RER had inhibitory effects on those two parameters. (2) HPLC analysis showed that salicylic acid, p-hydroxybenzoic acid and phthalic acid were identified in exudates from both plants, but p-coumaric acid was only detected in rice and ferulic acid only in watermelon. Moreover, of the total rice exudates a high proportion (37.9 %) of p-coumaric acid was detected and the total amount of phenolic acids was 1.4-fold as high as that in watermelon. (3) Considerable differences in the components and contents of both sugars and amino acids were found between REW and RER exudates. (4) Exogenously applied alanine (Ala) increased spore germination and sporulation. In contrast, addition of exogenous p-coumaric acid reduced spore germination and sporulation, relative to controls. It was concluded that the rice root exudates had anti-fungal properties while that from watermelon promoted pathogen growth. This discovery provided a scientific basis for practicing watermelon/aerobic rice intercropping to control Fusarium wilt in watermelon.