陕西省苜蓿茎点霉叶斑病病原菌的鉴定

近期发现了陕西省紫花苜蓿(Medicago sativa)一种苜蓿茎点霉叶斑病,为了准确鉴定该病害,开展了一系列病原鉴定试验。病叶片典型症状为叶尖上的深褐色斑点融合扩大呈“轮纹状”病斑;病原物的分生孢子无色透明,圆柱形,无隔单胞,大小为7×1.25 μm;以病原菌rDNA-ITS(核糖体DNA 内转录间隔区)序列的系统发育树的分析表明,病原菌与Phoma medicaginis var. Medicaginis(DQ109960)亲缘关系最近,NJ法中的相似性达到99%,UPGMA法中的相似性为98%;离体叶片接种验证病原菌具有致病性,结果表明:苜蓿茎点霉叶斑病的病原菌为苜蓿茎点霉(Phoma medicaginis var. Medicaginis)。     

草茎点霉毒素Ⅲ衍生物的合成与除草活性

[目的]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.[方法]以邻甲基苯甲酸为起始原料,经硝化、酰化等反应合成了16个新的苯甲酸酯类化合物,其结构均通过IR和1HNMR确证,并对合成的化合物进行除草活性筛选.[结果]在100μg/ml时,J-L-59对稗草Echinochloa crusgalli根的抑制率为93.7％;活体盆栽试验结果表明,在有效成分1000 g/hm2时,J-L-59对苘麻Abutilon theophrasti和反枝苋Amaranthus retroflexus的鲜重防效均达100％.毒力测定结果表示,J-L-59对反枝苋Amaranthus retroflexus的ED50值为有效成分94.06 g/hm2.[结论]J-L-59有较高的除草活性.     

国内外柑桔黑斑病研究进展

为了更好地了解和掌握柑桔黑斑病,笔者就国内外柑桔黑斑病研究进展进行较全面的综述。该病害自发现以来,其研究不断深入,至今已报道了4种症状类型,病原菌分类地位经历了数次变更,基于ITS的分子检测技术极大提高了病原菌检测的准确性,化学防治仍是主要防治手段,但还有一些问题如病原菌的潜伏侵染机制未研究清楚。目前柑桔黑斑病已扩散分布于南非、亚洲、澳洲、南美等地,危害表现日益严重,被欧美地区列为重要的检疫性病害,引起了相关部门的重视。     

山葵墨入病菌生物学特性研究

对山葵墨入病病株进行分离鉴定,明确其病原菌为山葵茎点霉菌(Phoma wasabiae Yokogi)。对该菌生物学特性研究结果表明,适宜该菌生长的培养基为PDA培养基,不同的温度、pH、光照等条件对山葵茎点霉菌的菌丝生长和产孢有显著的影响。该菌适宜的生长温度为19-25℃,最适温度为22℃;适宜生长的pH为6.0-9.0,最适pH7-8;该菌在黑暗条件下比在光照和光暗交替处理下生长快,且产孢的能力相对强;致死温度为55℃。10min。     

甜菜大龟甲与寄主植物的关系

强迫取食试验结果初步证实,甜菜大龟甲幼虫在藜科藜属杂草灰藜、小藜、杂配藜上能完成个体发育,取食甜菜时发育慢,死亡率高,幼虫个体间对甜菜的适应性差异大,赵冬代成虫出蛰期、一代卵及幼虫发生期与灰藜生长期的配合程度大于甜菜,但在田间灰藜等杂草数量少时,卵也可产生在甜菜叶片上,灰藜叶片被食光后幼虫转至甜菜为害。     

<Emphasis Type="Italic">Brassica napus</Emphasis> plants infected by <Emphasis Type="Italic">Leptosphaeria maculans</Emphasis> after the third to fifth leaf growth stage in south-eastern Australia do not develop blackleg stem canker

Blackleg (Phoma stem canker) caused by Leptosphaeria maculans is the most damaging disease of Brassica napus (canola, rapeseed, colza) worldwide and is controlled by sowing blackleg resistant cultivars and crop management strategies that reduce exposure to inoculum and fungicide application. In experiments in south-eastern Australia, canola cultivars inoculated after the three to five leaf growth stage did not develop stem canker. Although mature canola plants are known to be less susceptible to blackleg than seedlings, this highlights for the first time the specific importance of protecting seedlings up to the three to five leaf growth stage in Australia. This would typically correspond to a period of four to six weeks after emergence. Canola plants are likely to be significantly less vulnerable to infection after this growth stage. However, this timing may vary due to the influence of environmental conditions.     

Fungi on roots and stem bases of asparagus in the Netherlands: species and pathogenicity

A survey was made to identify the most important soilborne fungal pathogens of asparagus crops in the Netherlands. Ten plants were selected from each of five fields with a young (1–4 y) first planting, five fields with an old (6–13 y) first planting and five fields with a young replanting. The analysis included fungi present in the stem base and the roots of plants with symptoms of foot and root rot or showing growth decline without specific disease symptoms. Isolates of each species were tested for pathogenicity to asparagus on aseptically grown plantlets on Knop's agar. Symptoms were caused byFusarium oxysporum, F. culmorum, Botrytis cinerea, Penicillium verrucosum var.cyclopium, Cylindrocarpon didymum, Phialophora malorum, Phoma terrestris andAcremonium strictum. F. oxysporum was by far the most common species and was isolated from 80% of the plants. Not all of its isolates were pathogenic to asparagus. Symptoms were caused by 67%, 78% and 93% of the isolates obtained from young first plantings, old first plantings and replantings, respectively.F. culmorum was isolated from 31% of the plants. Two other notorious pathogens of asparagus,F. moniliforme andF. proliferatum, did not occur in our samples.Species causing symptoms in the vitro test that were found on more than 5% of the plants were additionally tested for their pathogenicity in pot experiments.F. oxysporum f.sp.asparagi caused severe foot and root rot, significantly reduced root weights and killed most of the plants.F. culmorum caused lesions on the stem base often resulting in death of the plant.P. terrestris, a fungus only once reported as a pathogen of asparagus, caused an extensive root rot, mainly of secondary roots that became reddish. The fungus was isolated in only a few samples and is not to be regarded as an important pathogen in Dutch asparagus crops.P. malorum caused many small brown lesions on the stem base and incidentally also on the upper part of small main roots. This is the first report of its pathogenicity to asparagus. The fungus is one of the organisms inciting spear rust and it reduced crop quality rather than crop yield.P. verrucosum var.cyclopium andC. didymum did not cause symptoms in pot experiments.Because of its predominance on plants with foot and root rot and its high virulence,F. oxysporum f.sp.asparagi was considered to be the main soilborne pathogen of asparagus in the Netherlands.     

Isolation and expression analysis of differentially expressed genes in stem tissue of the Greek lemon cv. Adamopoulou

Lemon (Citrus limon (L.) Burm. f.) is susceptible to mal secco, a serious vascular disease caused by the fungus Phoma tracheiphila (Petri) Kant. and Gik., as well as low temperatures. The greek lemon cultivar Adamopoulou, thought to be derived from the Portuguese cultivar Lisbon, exhibits enhanced resistance to mal secco and cold as opposed to cv. Lisbon. Suppression subtractive hybridization (SSH) was employed for the isolation of differentially expressed genes in lemon stem tissue. A subtractive cDNA library was constructed and a total of 296 clones were sequenced. The obtained sequences were edited, resulting in 56 non-redundant ESTs. Sequence analysis revealed homology to previously identified genes involved in defense mechanisms against biotic and abiotic stresses, as well as sequences with no significant similarity in the GenBank. Selected ESTs were analyzed by real-time PCR for confirmation purposes. This analysis revealed significant expression differences between the two cultivars for genes expressing allantoinase, ultraviolet-B-repressible protein, 4-coumarate:CoA ligase and other proteins that are known to be upregulated under biotic and abiotic stress conditions.     

茶树新病害病原菌Phoma segeticola var. camelliae的形态学特征及系统学分析

正我国主要茶树病害种类近100种,对茶叶产量和品质带来较大的影响[1～3]。2016年3月至5月,受低温阴雨等天气因素影响,贵州部分高海拔地区的茶树病害发生率较高。课题组在贵州省石阡县茶园发现一种茶叶斑点病,对茶叶产量和品质影响较大。该病害初期表现在嫩叶或新梢,成叶也可被     

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens

Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.