Mineralization of hydroxylated isoproturon metabolites produced by fungi

When exposed to the herbicide isoproturon, some soil fungi in pure culture metabolize the substance to hydroxylated metabolites. Hydroxylated metabolites of isoproturon have also been detected in soil studies. In an agricultural soil not previously exposed to isoproturon we found that the hydroxylated isoproturon metabolite N-(4-(2-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea mineralized faster than both isoproturon and its N-demethylated metabolite N-(4-isopropylphenyl)-N′-methylurea (MDIPU), thus indicating that mineralization of isoproturon is stimulated by fungal hydroxylation in this soil. In soils previously treated with isoproturon, in contrast, isoproturon and both its hydroxylated and demethylated metabolites mineralized at almost the same rate with up to 52% of the ¹⁴C-ring-carbon being degraded to ¹⁴CO₂ within 63 days. Thus hydroxylated metabolites of isoproturon do not seem to be more persistent than isoproturon, and hence may degrade before they can leach from topsoil and contaminate the aquatic environment. While an isoproturon-mineralizing bacterium Sphingomonas sp. SRS2 and a MDIPU-mineralizing mixed bacterial culture were able to deplete the medium of hydroxylated metabolites, little or no mineralization took place. This indicates that other bacteria must be present in the soil that are able to benefit from isoproturon being made available to mineralization by fungal hydroxylation.     

我国紫荆叶枯病研究初报

为了科学有效的防治该病害，并防止其扩展蔓延和远距离传播，笔者对紫荆叶枯病进行了研究。由受害紫荆上成功的分离和鉴定了紫荆叶枯病的病原，回接引起了相同的症状。通过对17个分离菌株的致病性及形态鉴定，确定它们分别属于Wl群的拟盘多毛孢属（Pestalotiopsis spp．）和Bl群的紫荆生茎点霉（Phomacercidicola P．Henn）真菌。     

抗Cd菌株的筛选及其对Cd的去除特性

从高Cd含量的闪锌矿土样中进行了抗Cd并富集Cd菌株的筛选,并对高效菌株的吸附和去除Cd特性作了分析。结果得到一株对Cd具有很强抗性和富集能力的茎点霉菌F2,该菌可在2000mg·L-1的Cd浓度下存活,在液体培养下对培养基中Cd尤其是高浓度Cd具有较好的去除作用,菌体Cd含量可达28%。F2干菌体对重蒸水中Cd的吸附动力学研究表明,吸附过程符合一级吸附动力学方程,同时计算了动力学参数。冷冻干燥菌体对Cd的吸附能力远大于烘干菌体,并在较大Cd浓度范围和pH值范围内对Cd具有较好的去除效果。     

新疆鸟类新纪录

本文报导隶属于7科、7属的9种新疆鸟类新纪录。其中除石鸻和红胸鸲两种(亚种)为国内首次正式纪录外,还包括有一个科级(石鸻科)、四个属级(石鸻属、八哥属、红胸鸲属和林鸮属)较高分类阶元的新疆新纪录。     

不同地区花生网斑病菌致病性鉴定及环境条件对致病力的影响

为了探明不同地区的花生网斑病菌致病力和筛选快速稳定的接种方法,以来自山东、云南和辽宁的6个不同地区的花生网斑病菌为材料,用孢子悬浮液对离体叶片和花生植株进行接种,结果表明致病力最强的菌株是WB-SY（分离自辽宁省沈阳市）。最佳接种条件为：开花末期使用高浓度孢子悬浮液（106/mL）,接种湿度保持在90%～100%之间持续保湿36h以上,温度在25～28℃之间,接种前黑暗处理24h,接种后近紫光（波长340～380nm）处理。本文筛选出的菌株和快速稳定的接种方法,将为抗病品种的筛选奠定基础。     

Differentiating A and B groups of Leptosphaeria maculans, causal agent of stem canker (blackleg) of oilseed rape

Stem canker or blackleg of brassicas, caused by Leptosphaeria maculans , is one of the most damaging diseases of winter oilseed rape in the UK. Airborne ascospores, released in autumn and winter, initiate leaf infections which may lead to colonization of the petiole and, later in the season, formation of stem lesions and cankers. Although isolates of the pathogen differ in ability to cause damaging stem cankers, this is not readily apparent from leaf spotting or stem lesion symptoms. However, several cultural, biochemical and genetic characteristics appear to be associated with the ability to form damaging stem cankers and isolates can be assigned to one of two groups, termed A and B, on the basis of differences in these characteristics. To investigate the relationship between leaf spotting symptoms and subsequent stem canker formation, and to improve understanding of the epidemiology of this pathogen, it is desirable to differentiate between the stem canker forming A group and the less damaging B group of L. maculans . Characterization of isolate type is also important in seed testing and crop breeding programs, particularly in countries such as Canada and Poland where the A type is not ubiquitous. This article reviews methods, including plant assays, assessments of growth characteristics in vitro , isozyme analyses, secondary metabolite profiling, serology, and nucleic acid analyses, that can be used to differentiate the A and B groups.     

温度、湿度和光照对花生网斑病菌分生孢子萌发的影响

为了探明花生网斑病菌(Phoma arachidicola Marasas,Pauer&Boerema)侵染致病的条件,研究了环境因素包括温度、湿度、光照(黑暗、近紫光、全光照)对花生网斑病菌分生孢子萌发的影响.结果表明,在黑暗条件下,培养5.5h时分生孢子开始萌发,24 h时萌发率为100％.分生孢子萌发率与温度之间的拟合模型符合二项式y=-0.570x2+28.97x-277.1(R2=0.808).据此模型,得出分生孢子萌发的最低温为12.8℃,最适温为25.4℃,最高温为38.0℃.培养24 h时,水膜中分生孢子萌发率(35.4％)极显著大于空气相对湿度为l00％(8.8％)和98％(0％)的萌发率.培养24 h时,黑暗(100％)和近紫光(97％)条件下的分生孢子萌发率极显著大于全光照下的萌发率(91％).结论:分生孢子萌发的最有利条件是黑暗、温度为25.4℃,且有水膜存在.     

草茎点霉毒素Ⅲ衍生物的合成与除草活性

为了提高草茎点霉毒素Ⅲ(2-甲基-3,5-二硝基苯甲酸甲酯)的除草活性,对其结构进行衍生优化。以邻甲基苯甲酸为起始原料,经硝化、酯化等反应合成了34个新的苯甲酸酯类化合物,其结构均通过IR、1H NM R和GC-M S确证。杂草种子萌发试验结果表明,目标化合物对供试杂草根的抑制率明显高于茎,在100μg/m L时,4-15、4-16和4-26对反枝苋Amaranthus retroflexus根的抑制率分别为92.8%、92.0%和87.4%,有较显著的除草活性;活体盆栽试验结果表明,在有效成分1 000 g/hm2时,4-1对马唐Digitaria sanguinalis和反枝苋A.retroflexus的鲜重防效均达100%,有较高的除草活性;毒力测定结果表明,4-1对马唐D.sanguinalis的ED50值为有效成分94.89 g/hm2。     

草茎点霉粗毒素的产生条件及活性测定

为了寻求能够充分发挥草茎点霉粗毒素活性的最佳培养条件,笔者利用有机溶剂萃取草茎点霉发酵液,获得粗毒素,采用针刺法、种子萌发法确定草茎点霉毒素合适的提取条件及对鸭跖草的致病性。结果表明：草茎点霉胞外毒素活性较高,3种有机溶剂中乙酸乙酯萃取效果最好,产毒的最佳条件为：培养温度32℃、培养时间14天、培养方式为150 r/min震荡培养。粗毒素浓度在1000 μg/mL时种子萌发抑制率为26.09%,病斑面积达到6.85 mm2。萃取毒素采用有机溶剂的种类以及培养温度、培养时间、培养方式对草茎点霉粗毒素的活性影响很大。