魔芋软腐病病原菌TaqMan荧光探针PCR技术的建立及应用

为实现对田间土壤软腐病病原菌的定量检测,基于魔芋软腐病优势病原菌胡萝卜软腐果胶杆菌胡萝卜亚种Pectobacterium carotovorum subsp. carotovorum的FyuA基因序列,设计特异性引物PCC1/PCC2/PCC3,建立TaqMan荧光探针实时荧光定量PCR技术,并对魔芋根系土壤中软腐病病原菌进行动态监测。结果显示:基于FyuA基因序列设计的引物特异性好,仅能特异性检出胡萝卜软腐果胶杆菌胡萝卜亚种;当模拟带菌土壤中病原菌浓度低至1.88 CFU/g时也能检出,灵敏度高;发病魔芋根际土壤中软腐病病原菌检出率为100.00%,病原菌DNA浓度最高达到了7.52×10~7ng/μL,健康魔芋根际土壤中也存在病原菌,检出率为40.00%;不同种植模式中,林下魔芋土壤中软腐病病原菌数量较少;连作时间与病原菌数量、病情指数存在正相关关系,连作时间越长,病原菌积累越多,魔芋病情指数也越高,魔芋连作4年土壤中病原菌DNA浓度最高达到4.03×10~4ng/μL;对魔芋土壤软腐病病原菌进行全年监测,病原菌数量随着月份增长逐渐上升,在8—10月达到峰值543.20 ng/μL后下降,病原菌数量与魔芋病情指数变化规律一致,但田间魔芋软腐病的发生相对滞后。表明建立的TaqMan荧光探针实时荧光定量PCR技术可用于田间魔芋软腐病的监测。     

药剂拌种与温汤浸种对胡萝卜斑枯病防效研究

采用60℃温汤浸种10 min和0.3%三唑酮药剂拌种,可使胡萝卜斑枯病发病率比对照分别降低30.6%和46.0%;胡萝卜产量比对照分别增加0.2 kg/m2和0.4 kg/m2。     

胡萝卜新病害——胡萝卜斑枯病

胡萝卜是人们喜欢食用的蔬菜,在甘肃河西走廊各市、县都有种植,一般春季套种,秋季复种,年栽培面积8 000hm2以上.秋季栽培的胡萝卜9月中旬开始发病,下旬发病高峰,全田叶片枯黄,火烧状,田间发病率达56%,严重田块100%,减产20%～30%;贮藏期先根头腐烂,渐向根部发展,造成烂窖.经鉴定引起该病的病原菌为半知菌亚门,腔孢纲Coelomycetes,胡萝卜类腊肠茎点霉Allantophomoidescarotae S.L.Wei et T.Y.Zhang(<菌物系统>2003第1期),根据其症状特点,定名为胡萝卜斑枯病.     

福禄考斑枯病发生规律及药剂防治试验简报

1988-1990年间对严重影响福禄考观赏价值的福禄考斑枯病(Septoria divaricatae Ell.et Ev.)进行了病原菌种鉴定、发生规律及药剂防治试验。病原菌以分生孢子和菌丝状态在病残体上和土壤中越冬。在沈阳地区该病害每年有2-3个发病高峰期,降雨是影响病害发生的最主要的环境因子,室内和田间试验结果表明,40％多硫胶悬剂和50％多菌灵等药剂对病害的防效显著。     

辽宁轮叶党参斑枯病发生初报

本文首次报道了辽宁省药用植物轮叶党参斑枯病的发生危害、症状描述及病原菌的形态特征,并进行了病原菌的分离和纯化。分离得到的菌株按照柯赫氏法则进行了致病性测定。初步研究结果表明,轮叶党参斑枯病是由真菌党参壳针孢(Septoria codonopsidis Ziling)侵染所致。针对此病害的发生特点,本文初步提出了相应的防治建议。     

华重楼斑枯病病原鉴定

 2018年,四川汶川县重楼种植区的华重楼出现一种新的病害—华重楼斑枯病,该病害主要危害叶片,发生率为35%,天气适宜时可引起整株叶片枯死。为鉴定引起四川汶川县华重楼斑枯病的病原菌,本试验采用组织分离法对病原菌进行分离,利用科赫氏法则验证其致病性,依据菌株的形态学和基于rDNA-ITS和RPB2基因序列分析对病原菌进行鉴定。结果表明,分离菌株的菌落形态、分生孢子器和分生孢子形态与Didymella sp.相似;经分子生物学鉴定,该菌ITS-RPB2基因序列与亚隔孢壳属D. glomerata(登录号为FJ427013、GU371781)的同源性为100%。因此,将引起重楼斑枯病的病原菌鉴定为D. glomerata。     

土壤杆菌K1026对樱桃冠瘿病病原菌的抑制作用及田间防治效果

由致病性根癌土壤杆菌Agrobacteriumspp.侵染引起的根癌病对樱桃等果树生产造成严重的影响。利用双层平板、胡萝卜圆盘法和接种指示植物番茄等方法验证了澳洲生防菌株K1026对2种不同原生物型樱桃冠瘿病病原菌的抑制作用;检测了不同接种时间对病原菌侵染产生瘤状组织的影响,结果显示提前或者在病原菌接种后20h内接种K1026可抑制胡萝卜产生瘤状组织;研究了K1026对大樱桃根癌病的作用机制是产生土壤杆菌素和竞争附着位点;田间试验表明K1026蘸根处理,对‘中国樱桃’株系冠瘿病的防治效果达81.61%,使发病率降低至18.13%。     

土壤杆菌K1026对果树根癌病的生物防治

由致病性根癌土壤杆菌Agrobacterium spp.侵染引起的根癌病对山东及我国其他省份的樱桃、桃及其他果树生产造成严重的影响.土壤杆菌Agrobacterium rhizogenes K1026在澳大利亚已制成生防菌剂并在全球多个国家实现商品化,但在我国果树育苗和生产行业中还未得到广泛应用.本文从山东樱桃和桃树根癌组织及感病土壤中分别分离到100余株致病性土壤杆菌,经鉴定均属于生物Ⅱ型土壤杆菌;利用双层平板抑菌试验,检测了37株病原菌对菌株K1026的敏感性,结果显示,所有菌株均对K1026产生的抗生物质敏感,可以在Stonier,s培养基上产生5种以上不同类型的抑菌圈;胡萝卜切片试验显示,菌株K1026可完全抑制37株病原菌对胡萝卜的致瘤活性.上述结果为土壤杆菌K1026用于山东省樱桃及桃树根癌病的生物防治奠定了基础.     

土壤杆菌K1026对果树根癌病的生物防治（英文）

由致病性根癌土壤杆菌Agrobacterium spp.侵染引起的根癌病对山东及我国其他省份的樱桃、桃及其他果树生产造成严重的影响。土壤杆菌Agrobacterium rhizogenes K1026在澳大利亚已制成生防菌剂并在全球多个国家实现商品化,但在我国果树育苗和生产行业中还未得到广泛应用。本文从山东樱桃和桃树根癌组织及感病土壤中分别分离到100余株致病性土壤杆菌,经鉴定均属于生物Ⅱ型土壤杆菌;利用双层平板抑菌试验,检测了37株病原菌对菌株K1026的敏感性,结果显示,所有菌株均对K1026产生的抗生物质敏感,可以在Stonier’s培养基上产生5种以上不同类型的抑菌圈;胡萝卜切片试验显示,菌株K1026可完全抑制37株病原菌对胡萝卜的致瘤活性。上述结果为土壤杆菌K1026用于山东省樱桃及桃树根癌病的生物防治奠定了基础。     

胡萝卜黑腐病病原菌鉴定及生物学特性研究

胡萝卜黑腐病是影响山西省胡萝卜产业发展的主要病害。本文研究了胡萝卜黑腐病病原菌归属及其生物学特性。通过病原菌形态学特征鉴定胡萝卜黑腐病致病菌为Alternaria radicina。病原菌生物学特性测定结果表明,菌丝最适生长温度为28℃;最适pH为6;最适碳源和氮源分别为蔗糖和尿素;光照对菌丝生长影响较小。分生孢子萌发最适温度为30℃,水滴中萌发率最高,酸碱度和光照周期对分生孢子萌发影响较小。     

Pathogenicity of Colletotrichum gloeosporioides to carrot

Abstract

Colletotrichum gloeosporioides was identified as the causal agent of carrot umbel blight in Brazil. Pathogenicity was evaluated on carrot and other host plants, as well as compared with the pathogenicity of other C. gloeosporioides isolates on carrot. C. gloeosporioides isolated from carrot umbel was able to infect tomato plants and ripe fruits of tomato and sweet pepper, in addition to carrot umbels and seedlings. This appears to be the first report of C. gloeosporioides attacking carrots.     

Evaluation of carrot resistance to alternaria leaf blight in controlled environments

The objective of this study was to find a technique for plant resistance screening to alternaria leaf blight (ALB), caused by the fungus Alternaria dauci , in controlled environments. Glasshouse and laboratory screening methods were compared using three cultivars and F₂ genotypes segregating for ALB resistance evaluated against self-pollinated F₃ field-grown plants. Plant disease was assessed through a disease index obtained from the size and number of symptoms on carrot leaves. The results indicated the value of glasshouse evaluation and the inadequacy of detached leaf and hypocotyl assays for carrot screening for ALB resistance. Spearman's rank correlation, applied to results obtained with both F₂ plants and their progeny, indicated that the optimal evaluation stage for ALB resistance in carrot is 20 days after inoculation. This test was powerful enough to be used as a prescreening test in breeding programmes.     

Using crop canopy modification to manage plant diseases

Modifying crop canopies can suppress plant diseases in some crops. For example, in carrot, lateral trimming of the canopy by 30–40 % after canopy closure reduced sclerotinia rot (Sclerotinia sclerotiorum) to zero under moderate disease pressure without the use of fungicides. Trimming reduced relative humidity within the carrot canopy and increased air and soil temperature, inhibiting the formation of apothecia of S. sclerotiorum. Trimming also severed infected petioles, which reduced the opportunity for infection to progress to the carrot crown. Trimming combined with application of foliar fungicide was even more effective. Trimming reduced carrot leaf blights (Alternaria dauci, Cercospora carotae) in 1 of 3 years, when disease pressure was low. However, there was no advantage of combining trimming and fungicide sprays for leaf blight control. Canopy modification also reduces disease in legume crops. Soybean cultivars with reduced height and lodging, and early maturity, had up to a 74 % reduction in apothecia of S. sclerotiorum within the crop, and up to an 88 % reduction in disease incidence at harvest. In field pea, artificially supporting plants to reduce lodging, in combination with fungicide application, reduced the severity of mycosphaerella blight (Mycosphaerella pinodes) on pods by 67 % and increased seed yield by 54 %. In chickpea, paired-row planting that opened the canopy increased seed yield by 12 %, likely by increasing fungicide deposition. Modifications of the crop canopy can reduce disease, the need for fungicide sprays, and sometimes improve fungicide efficacy, but the results are often pathosystem-specific.     

Characterization of tuber blight‐suppressive soils from four provinces of the Ecuadorean Andes

Late blight, caused by the oomycete Phytophthora infestans, is a threat to potato‐cropping systems worldwide. In the Ecuadorian Andes, despite a high late blight incidence in foliage, tuber blight is rare. In this work, the hypothesis that Ecuadorian Andean soils are naturally suppressive to P. infestans tuber infection was evaluated. Soils from four potato‐growing regions were assessed for disease suppressiveness by determining the effects of soil heat treatment on P. infestans sporangia and their ability to infect potato slices after 1, 8, 15 and 30 days of exposure to soils. Tuber infection after inoculation with P. infestans‐infested soils was consistently lower during the evaluation period compared with heat‐treated soils. Fresh, untreated soils affected germination and viability of P. infestans sporangia in a site‐dependent manner. In addition, the effect of heat treatment on soil bacterial communities was assessed through terminal restriction fragment length polymorphism analysis of the 16S rDNA gene region. Heat treatment disrupted bacterial community composition, and a subset of terminal restriction fragments (TRF) was either positively or negatively correlated with tuber infection. Bacterial TRF negatively correlated with tuber infection corresponded in fragment size to taxa with known ability to inhibit pathogens and promote plant growth. Finally, bacterial isolates obtained from untreated soils, which inhibited P. infestans growth in vitro, represented 22–47% of isolates recovered, and matched classes predicted by the TRFs. This work represents a first step in understanding the mechanisms behind the low incidence of tuber blight in Andean potato‐cropping systems.     

Seedling blight of Glycyrrhiza uralensis caused by Pythium myriotylum,P. aphanidermatum and P. spinosum and identifying primary inoculum sources using multiplex PCR detection

Pythium species, isolated from seedlings of Glycyrrhiza uralensis with blight, were identified as P. myriotylum, P. aphanidermatum, and P. spinosum on the basis of morphological characteristics and sequences of the internal transcribed spacer regions of rDNA. In pathogenicity tests, the isolates of the three Pythium species caused blight, producing the original disease symptoms. The primary inoculum source was determined using a multiplex PCR to detect the pathogen. All the Pythium species were detected in the soils of fields with the diseased plants and in soils of adjacent field soils.     

Influence of rate of soil fertilization on alternaria leaf blight (Alternaria dauci) in carrots

The possibility of suppressingAlternaria dauci (Kühn) Groves & Skolko, the causal agent of Alternaria leaf blight in carrot, by excess application of fertilizer was examined in greenhouse and field experiments. Reducing the rate of fertilization by one half from the optimal rate (100 ppm N, 19 ppm P and 74 ppm K) resulted in a 23–30% increase in the severity of Alternaria leaf blight. However, doubling the rate of fertilization resulted in only a 10–15% decrease in disease severity. Inoculating with different concentrations ofA. dauci spores (10³ or 10⁴ spores/ml) did not alter the response of the plants to the fertilization rate, although significantly higher disease severity was observed in plants inoculated with the higher spore concentration. These results were corroborated in the field, where neither disease severity nor harvested yield was significantly affected by tripling the amount of soil fertilization. Application of foliar fungicides, on the other hand, had substantial effects on both disease and yield. Therefore, it was concluded that carrot crops should be fertilized and maintained for optimum yield, and thatA. dauci should be managed by properly timed applications of fungicides during the growing season. Contribution no. 533/99 from the Inst. of Plant Protection, Agricultural Research Organization.     

干旱区绿洲土壤Cd-Zn复合污染下重金属形态及其生物有效性的研究

通过模拟基于Cd-Zn复合污染下干旱区绿洲土壤的胡萝卜盆栽试验,用Tessier连续提取法对胡萝卜土壤中Cd、Zn的形态分布进行分析,同时就生物利用性形态的变化研究了Cd、Zn的生物有效性。结果表明:1)原状土壤中Cd和Zn主要以残渣态存在,随着复合胁迫浓度的增加,Cd的主要赋存形态逐步转变为碳酸盐结合态和可交换态,Zn主要赋存形态逐步转变为以铁锰氧化态和残渣态,但有效态和潜在有效态的比例大大增加。2)胡萝卜对Cd、Zn的富集作用均为地上部分大于地下部分,对Cd的富集能力远远大于Zn。3)胡萝卜吸收的Cd和Zn不仅包括可交换态和碳酸盐结合态,还包括了在一定条件下释放出来的铁锰氧化态和有机结合态。     

Thiabendazole as an iatrogenic agent in carrot black rot

Negligible amounts of carrot (Daucus carota L.) seed were produced in Brazil prior to the release of cv. Brasilia in 1982. This cultivar is tolerant of high temperature and resistant to leaf blight caused by Alternaria dauci (Kühn) Groves & Skolko (Vieira et al ., 1983). Since 1982 technology for production of Brasilia seed has developed rapidly and over 40 t of seed have been produced, representing more than 8000 ha planted. Fungicides are widely used on carrot root crops and growers have naturally extended their use to carrot seed crops. Mancozeb, thiabendazole, captafol and chlorothalonil, applied at weekly intervals, are the most common fungicides used although their efficacy in this new situation has not been evaluated.
A survey of pathogens associated with carrot seed production (Reifschneider & Della Vecchia. 1983) has shown that the most common fungal pathogen is Alternaria radicina Meier, Dreschler & Eddy, a species which is a common seed-borne pathogen in the USA (Rader, 1952) and has been present in Brazil since 1970 or earlier (Luz, 1970).
Since information concerning the control of A. radicina in carrot seed crops is lacking we established a preliminary fungicide experiment in July 1982 within a 5-ha commercial field planted with artificially vernalized roots of which 90% were infected, to varying degrees, with A. radicina . Plots were 25 m2 and each treatment (Table 1) was replicated five times, in a completely randomized design. Seeds were harvested manually at maturity and dried by forced air at c. 30°C. Infection by A. radicina was detected using the method of Soteros (1979) in which heat-treated seeds (100°C for 1 h) are plated on malt agar. A total of 200 seeds per plot (20 seeds per plate) were used. Identification of A. radicina was based on conidium and conidiophore morphology (Ellis & Holliday, 1972).     

适应水稻秸秆还田的抗稻纹枯病拮抗菌株的筛选

[目的]筛选适应水稻秸秆还田的抗水稻纹枯病的拮抗菌株.[方法]从土壤中分离出4株芽胞杆菌和9株木霉,测定其对水稻秸秆的降解能力,对具有较好降解能力的菌株测定其对水稻纹枯病菌的抑制效果和对水稻秸秆的适应性.[结果]芽胞杆菌B4菌株和木霉T3、T5、T6和T9菌株对水稻秸秆有较好的降解效果,其中木霉T5和T9的降解效果最好;芽胞杆菌B4菌株对水稻纹枯病菌的抑制率达40.48％,而且抑菌带能持久地保持,木霉T3、T5、T6和T9菌株对水稻纹枯病菌的抑制率较高,抑制率分别为46.48％、45.63％、50.99％和53.38％,这5种拮抗菌的代谢物都能抑制菌丝的生长和完全阻止菌核的形成,而且这5株菌株对水稻秸秆都有一定的适应能力.[结论]木霉T5和T9具有较好的秸秆降解和抑制稻纹枯病菌的双重效果.     

湖北省蔬菜根结线虫病发生特点

调查了武汉、沙市、宜昌、恩施、孝感、黄岗、襄樊、荆门、十堰９地市郊的３４种蔬菜根结线虫病发生特点。结果表明,葫芦科、豆科和茄科蔬菜受害最重,发病级别达３～４级;红萝卜等１１种蔬菜受害较轻,病株率为２０％～５０％,病级１～２级;大蒜等１０种蔬菜未见发病。南方根结线虫（Ｍｅｌｏｉｄｏｇｙｎｅｉｎｃｏｇ－ｎｉｔａ）是引起我省蔬菜发病的优势虫种。５～３０ｃｍ的耕作层土壤中根结线虫群体数量较大,受害根常形成须根团,在５ｃｍ深度的土层中延伸达５０ｃｍ。