桉苗灰霉病初步研究

按苗灰霉病(Botrytis cinerea Pers.ex Fr.)是近年在云南省新发现的病害,过去未曾报道。该病多发生在按苗幼嫩的茎上部和叶片上,可造成按苗迅速死亡。早春连绵阴雨,气温较低,致使该病易造成流行,该病的流行也与管理措施密切相关。采取平衡施肥,加强苗期管理是最有效的预防措施。发病期可施用75％百菌清可湿性粉剂1:500倍;或70％敌克松可湿性粉剂与等量的50％多菌灵可湿性粉剂混用,稀释1000倍常量喷雾,每7～10天一次,连续喷2～3次,可有效地控制按苗灰霉病蔓延流行。     

Age-related resistance to Pseudomonas syringae pv. tomato is associated with the transition to flowering in Arabidopsis and is effective against Peronospora parasitica

As plants mature it has been observed that some become more resistant to normally virulent pathogens. The ability to manifest the Age-Related Resistance (ARR) response in Arabidopsis to Pseudomonas syringae pathovars tomato (Pst) coincided with the transition to flowering in plants both delayed and accelerated in the transition to flowering. ARR was also associated with a change in PR-1 gene expression, such that young plants expressed PR-1 abundantly at 3 days post inoculation (dpi) while mature plants expressed much less. The Arabidopsis ARR response requires SA accumulation via isochorismate synthase (ICS1) [24]. ICS1 was expressed one dpi with virulent and avirulent Pst in both young and mature plants. The ARR response was also effective versus avirulent Pst providing an additional 4-fold limitation in bacterial growth. Arabidopsis ARR was found to be ineffective against two necrotrophs, Erwinia carotovora subspecies carotovora (bacterium) and Botrytis cinerea (fungus) and one obligate biotroph, Erysiphe cichoracearum (fungus). However, mature wild type, SA-deficient sid2 and NahG plants supported little growth of the obligate biotrophic oomycete, Peronospora parasitica. Therefore ARR to P. parasitica appears to be SA-independent, however the level of ARR resistance was somewhat reduced in these mutants in some experiments. Thus, there may be numerous defence pathways that contribute to adult plant resistance in Arabidopsis.     

咯菌腈对草莓灰霉病Botrytis cinerea的毒力及防效研究初报

用生长速率法测定了咯菌腈、多菌灵、硫菌·霉威、苯醚甲环唑4种药剂对草莓灰霉病Botrytis cinerea的毒力。结果表明,4种药剂对草莓灰霉菌菌丝的生长都有不同程度的抑制作用,随药剂浓度增加抑制作用增强,其EC50值分别为0.0472、95.7193、0.4854、1.3611 mg/L,其中咯菌腈的毒力最强。田间防治试验结果表明:2.5%咯菌腈FC每667 m2施药量120 mL时防效为83.7%,80 mL时防效为67.7%;65%硫菌·霉威WP每667m2施药量100 g时防效为65.3%。     

Further suppression of<Emphasis Type="Italic">Botrytis cinerea</Emphasis> disease in cucumber seedlings by chitosan-copper complex as compared with chitosan alone

Chitosan-copper complex compared with chitosan alone enhanced suppression ofBotrytis cinerea rot development on four-true-leaf cucumber seedlings in controlled growth chambers. This paper constitutes the first report of such enhancement. The optimal concentrations for the most effective suppression ofBotrytis development were 0.2 gl ⁻¹ chitosan and 1.6 mmole copper. After 12 days’ incubation, marked and significantly better disease suppression was obtained with chitosan-copper complex (75% suppression) than with chitosan alone. The chitosan-copper complex could be a very promising decay control agent for use in both conventional and organic agriculture. http://www.phytoparasitica.org posting Dec. 18, 2002.     

应用电导仪测定番茄灰霉病菌对多菌灵抗药性的初步研究

1.0 mg/L和5.0 mg/L多菌灵盐酸盐溶液处理灰霉病菌多菌灵敏感菌株和抗性菌丝体,用电导仪测定溶液电导率的动态变化,结果表明:在敏感菌株存在时,多菌灵盐酸盐溶液2 h后的电导率显著降低,而抗性菌株存在的溶液中电导率则未见下降。     

灰葡萄孢菌nit突变体的诱导及其在营养体亲和性测定中的应用初探

 从山西运城、临汾、长治、晋中、大同等地保护地黄瓜灰霉病病株上采集、分离的分属于3个不同菌丝融合群的8个灰葡萄孢菌单孢菌株,经氯酸盐诱导处理,共获得了抗氯酸盐的硝酸盐利用缺陷突变体(nit突变体)59株,其中nit1型38株,nit3型10株,nitM型11株。所有nit突变株分别在PDA斜面转管培养3次(21 d)后,除6株恢复成野生菌株外,其余多数nit突变菌株表现稳定。来源于同一野生菌株的不同类型nit突变体间或同一菌丝融合群不同野生菌株的nit突变体间可产生互补反应而形成异核体,其中以nitM型突变株互补性最好,在利用nit突变体测定灰葡萄孢菌营养体亲和性时应作为标准菌株。来源于不同菌丝融合群的nit突变体间不能产生互补反应。     

武夷菌素对番茄灰霉菌的抑制作用及对番茄抗病性相关酶活性的影响

采用凹陷载玻片法测定了武夷菌素对番茄灰霉菌分生孢子萌发的抑制作用,在离体番茄叶片上测定了被武夷菌素处理后的番茄灰霉菌菌丝和分生孢子致病性的变化以及武夷菌素对番茄幼苗体内抗病性相关酶活性的影响。结果表明:武夷菌素对番茄灰霉菌的分生孢子有较强的抑制作用,其EC₅₀为14.1μg／mL。浓度为100μg／mL的武夷菌素可完全抑制孢子的萌发。武夷菌素能使灰霉菌菌丝和分生孢子的致病性明显下降,同时还能诱导番茄体内抗病性相关酶(SOD、POD、PPO、PAL)活性的增强,提高番茄幼苗的抗病性。     

Transgenic cucumber expressing an endogenous class III chitinase gene has reduced symptoms from Botrytis cinerea

A class III chitinase gene (CHI2) is induced in cucumber plants (Cucumis sativa L.) in response to infection by pathogenic microorganisms. Infection of Botrytis cinerea, causal agent of gray mold disease on cucumber, also induces CHI2 expression. To investigate whether CHI2 is involved in resistance to gray mold disease, transgenic cucumber plants were produced to overexpress the CHI2 gene. One line was analyzed in detail in terms of disease resistance. The transgenic cucumber plant (CC2) constitutively expressed CHI2 and reduced the symptoms of B. cinerea for 4 days after inoculation compared with nontransgenic plants. However, this inhibitory effect was not absolute, and CC2 eventually developed serious disease symptoms. Chitinase activity of the crude extract from CC2 leaves was higher than that from nontransgenic plants. A high-molecular-weight fraction containing CHI2 from CC2 leaves had fungistatic activity against B. cinerea. Interestingly, the low-molecular-weight fraction from CC2 leaves with CHI2 removed also had fungistatic activity against B. cinerea. Not only the introduced chitinase activity but also the endogenous defense reactions activated by overexpression of CHI2 may be involved in the enhanced gray mold disease resistance in CC2.     

The salicylic acid-dependent defence pathway is effective against different pathogens in tomato and tobacco

The role of salicylic acid (SA) was investigated in basal defence and induced resistance to powdery mildew ( Oidium neolycopersici ) and grey mould ( Botrytis cinerea ) in tomato ( Lycopersicon esculentum ) and tobacco ( Nicotiana tabacum ). A comparison of NahG transgenic tomato and tobacco (unable to accumulate SA) to their respective wild types revealed that in tomato, SA was not involved in basal defence against O. neolycopersici but NahG tobacco showed an enhanced susceptibility to O. neolycopersici infection, the effect becoming more obvious as the plants grew older. In contrast, SA played no role in the basal defence of tobacco against B. cinerea , but seemed to contribute to basal defence of tomato against B. cinerea. Activation of the SA-dependent defence pathway via benzothiadiazole (BTH) resulted in induced resistance against O. neolycopersici in tobacco but not in tomato. Microscopic analysis revealed that BTH treatment could prevent penetration of the Oidium germ tube through tobacco leaves, whereas penetration was successful on tomato leaves irrespective of BTH treatment. In contrast, soil or leaf treatment with BTH induced resistance against B. cinerea in tomato but not in tobacco. It is concluded that the SA-dependent defence pathway is effective against different pathogens in tomato and tobacco.     

灰霉菌侵染对番茄幼苗活性氧积累及抗氧化酶活性的影响

为进一步分析活性氧和抗氧化防御系统在番茄抗病信号调控机制中的作用,为提高产量和品质提供科学依据,以4叶1心的番茄幼苗为试验材料,比较番茄幼苗受灰霉菌侵染后叶片O_2~-·以及抗氧化酶、内源褪黑素等的变化。结果表明:番茄幼苗接种灰霉菌后,随着时间的延长,幼苗叶片上病斑斑点逐渐增多,灰霉菌含量显著增多,叶色逐渐变浅,植株表现明显的发病症状;灰霉病菌侵染后番茄体内O_2~-·活性爆发,超氧化物歧化酶(SOD)和过氧化物酶(POD)活性下降,过氧化氢酶(CAT)和谷胱甘肽还原酶(GR)活性上升,褪黑素含量增加;上述变化都是番茄幼苗为了抵御灰霉菌的生物胁迫而发生的应激反应。综上,植物在遭受病原菌等生物胁迫时不能简单地推断SOD、CAT和POD等抗氧化酶活性一定升高,植物抵御病原菌侵染更多地依赖于抗性信号路径中信号物质的激活和积累。