Impulsive Logistic Model for Gray Leaf Spots Caused by Cercospora zeae-maydi

[ Objectlve] Impulsive Logistic Model was used to simulate epidemic process of Gray Leaf Spots caused by C. zeae-maydi. [ Method] The pathogen was inoculated in different maize varieties, and the incidence were observed and recorded. Impulsive Logistic Model was used to simulate the development process of the disease, which was compared with actual incidence. [ Result] Artificial inoculation tests showed that impulsive Logistic Model could reflect time dynamic of C. zeae-maydi. Through derivation, exponential growth phase was from maize seedling emergence to eady July in each year, logistic phase was from early July to late August, terminal phase was from eady September to the end of maize growth stage. [ Conclusion] The derivation result from model was consistent with the development biological laws of C. zeae-maydi.

Culture Media Options for Growth and Morphological Characterisation of Cercospora coffeicola Affecting Coffee in Zimbabwe

Cercospora leaf spot is fast turning into a critically important disease in Zimbabwe.The disease is caused by Cercospora coffeicola which significantly reduces productivity and quality of coffee.Disturbingly,optimum sporulation of Cercospora coffeicola in culture remains a limiting factor for microbial analysis and quantitative studies of Cercospora leaf spot.Faced with this challenge,an in-vitro study was conducted at Coffee Research Institute,Manicaland,Zimbabwe to examine growth of Cercospora coffeicola in different nutrient media and to determine the best media for Cercospora coffeicola analysis.Six nutrient media were assessed(corn meal agar,oat meal agar,Czapek Dox agar,malt extract agar,yeast extract agar and potato dextrose agar)for the growth of Cercospora coffeicola.The laboratory-based experiment was duplicated,laid out in a Completely Randomized Design,replicated three times and based on Cercospora coffeicola nutrient inoculation.Data were collected on radial growth,colour and texture of mycelium at 3 and 6 days after inoculation.There were significant differences(p<0.05)in the growth of Cercospora coffeicola in media after 3 and 6 days.Malt extract agar had the greatest radial growth(34 mm and 32 mm)of Cercospora coffeicola for trials 1 and 2 respectively,whilst the least growth was in the oat meal agar(14.2 mm and 15.7 mm)for trials 1 and 2 respectively.There were variations in colour and texture of mycelium with malt extract agar,potato dextrose agar and oat meal agar associated with darker colours and rough texture while smooth white mycelia were found in corn meal agar.After considering all nutrient media,malt extract agar was found to be the best media for the growth of Cercospora coffeicola in-vitro.On the basis of our findings,the authors recommend the use of malt extract agar as the primary media for identification and characterisation of Cercospora coffeicola.

西瓜叶斑病病原菌的鉴定及室内药剂筛选

2022年在上海市浦东新区西瓜上发生一种深褐色、不规则至近圆形斑的叶部病害。采用组织分离法对病害样本进行分离,分离物SHCCC01经柯赫氏法则验证具有较强致病性。根据分离物的菌落特征、分生孢子形态、生物学特征以及基于核糖体内部转录间隔区(internal transcribed spacer,ITS)、组蛋白基因(histone,His)、真核翻译延伸因子1α(translation elongation factor 1α,TEF 1-α)和肌动蛋白(actin,Act)基因联合系统发育分析等,将病原菌鉴定为瓜类尾孢Cercospora citrullina。10种杀菌剂对该病原菌的毒力测定试验结果表明:氟啶胺、己唑醇、氟环唑、戊唑醇等4种药剂对病原菌的抑菌活性较高,其EC_(50)分别为0.3752、0.5754、1.4723、1.8902μg/mL。这些结果为西瓜尾孢叶斑病的防控和杀菌剂登记提供了重要依据。

大豆灰斑病菌基因组学的研究进展

由Cercospora sojina K.Hara引起的大豆灰斑病菌具有生理小种多、爆发性强等特点。近些年随着抗病品种选择压力的增大,大豆灰斑病菌也随之变异,导致了生产上品种抗性丧失,化学防治效果差等诸多问题。前期国内外科学家主要把研究焦点集中在大豆灰斑病菌的抗病亲本筛选、生理小种鉴定及病害发生规律等传统研究手段上,目前随着分子生物学技术的快速发展,越来越多的新技术、新手段应用到大豆灰斑病菌的研究中,但相较于其它作物的病原菌,其研究不仅少而且不够深入。本文综述了近几年国内外大豆灰斑病菌基因组、比较基因组学及转录组学等最新研究成果,以期对大豆灰斑病菌的进化、侵染机制及与寄主互作机制的进一步研究提供参考。

水葫芦生防菌Cercospora piaropi菌株WH9BR的生物学性状

尾孢菌属的Cercospora piaropi是一种有潜力开发成为防治水葫芦的生物除草剂的真菌。文中研究了光照、温度、pH、碳源、氮源、湿度和介质对该真菌WH9BR菌株的生长、产孢和分生孢子萌发的影响。结果表明:全黑暗条件有利于WH9BR的菌丝生长和产孢,而全光照有利于其孢子萌发。WH9BR菌丝生长最适温度为25℃,产孢最适温度为25～30℃,孢子萌发最适温度为30℃。其生长、产孢和孢子萌发的最适pH分别为8.6、8.0～9.0和7.0。碳源中,甘露醇最适于WH9BR生长,葡萄糖和蔗糖有利于WH9BR产孢。以尿素作氮源时,WH9BR菌丝生长最快,而硝酸钠作氮源时,WH9BR产孢量最高。WH9BR的孢子在水滴中萌发率达到最高。玉米粉、蛋白胨、葡萄糖和蔗糖对WH9BR的孢子萌发有促进作用。

甘肃玉米灰斑病病原鉴定及遗传多样性分析

为掌握甘肃地区玉米灰斑病的发生分布、病原种类及遗传多样性,于2021-2022年调查了该病害在甘肃的分布范围,对采集的灰斑病样品进行分离与鉴定,并采用ISSR分子标记技术对甘肃玉米灰斑病菌的遗传多样性进行分析。结果表明,玉米灰斑病在甘肃陇南和陇东大部分地区均有发生,并已扩展至陇中地区;经形态学和分子生物学鉴定甘肃地区玉米灰斑病病原菌为玉米尾孢(Cercospora zeina);16条ISSR引物共扩增出74条条带,多态性条带73条,比例为98.65%。甘肃省陇南地区种群遗传多样性最为丰富,且与陕西省的遗传距离最小(0.021 4)、遗传相似度最高(0.978 9),陇东地区次之。在遗传相似系数为0.63时,可以将所有菌株分为4个亚群,亚群1中有28个菌株,其中包括16株陇南地区菌株、5株陇东地区菌株和7株来自陕西地区的菌株;亚群2中只有1个陇南地区菌株;亚群3中有10个菌株,包括陇南地区4个、陇东地区1个和5个陕西菌株;亚群4有2个菌株,陇东地区和陕西菌株各1个,4大类群分别包含来自不同地域的菌株。以上结果说明,同陇东地区相比,陇南地区与陕西地区的菌株遗传相似度更高,且亚群内遗传多样性与地理来源之间无明显的相关性。

大豆灰斑病菌(Cercospora sojina Hara)及其对寄主作用的研究

大豆灰斑病是一种世界性大豆病害,曾给我国的大豆生产造成重大的损失。本文主要从应用的角度论述了大豆灰斑病菌(Cercospora sojina Hara)的生物学特性、侵染循环、潜育期以及病害的预测,同时从病原物与寄主相互作用的角度,对大豆灰斑病生理小种的分化、抗性的遗传及代谢毒素等方面进行了综述,以期为该病害的防治及抗病育种研究提供资料与指导。

大豆灰斑病菌(Cercospora sojina Hara)毒素的初步研究

本试验主要从液体培养基的种类、培养温度、培养方式、培养天数、接种量和培养基的ｐＨ值及碳源等几个方面入手研究了大豆灰斑病菌最佳的产毒条件。利用大豆胚根伸长抑制率和单复叶萎蔫指数来测定毒素的产量。实验结果得出该菌的最佳产毒条件是利用Ｃｚａｐｅｋ 培养基，以蔗糖作为碳源，糖含量为３％ ，将培养基的ｐＨ调到６－ ７，接种三块直径为６ｍ ｍ 的新鲜菌丝块，于２５－ ２８℃下静止培养２５－ ２７ 天。

水葫芦生防菌Cercospora piaropi菌株BA-57的生物学特性

尾孢菌属的Cercospora piaropi是一种水葫芦生防真菌,有潜力被开发成为防除水葫芦的真菌除草剂。本试验研究了该菌BA-57菌株的生物学特性。结果表明,BA-57菌丝生长、产孢和孢子萌发的最适温度都为30℃,最适pH分别为7.6、10.0和9.0。光照处理对BA-57的菌丝生长以及产孢量无显著影响,而全黑暗有利于孢子萌发。碳源中,甘露醇最适于BA-57菌丝生长,而葡萄糖和蔗糖有利于BA-57产孢。BA-57菌丝生长和产孢的最佳氮源都是硝酸钠。蛋白胨和玉米粉对BA-57的孢子萌发有促进作用。湿度条件,在水滴中BA-57的孢子萌发率最高。

水葫芦生防真菌Cercospora sp. FJ24的分离、鉴定及其分子生物学研究

从福建省得到被致病菌强烈感染的水葫芦植株,从中分离到致病菌菌株FJ24。形态学鉴定表明,该致病菌属于尾孢属。对该菌株的ITS区、EF-1、β-Tub、His-H3基因进行PCR扩增,测序结果显示其与目前已经分离、发现的多种尾孢属水葫芦致病菌存在着99%以上的序列相似性,可以认为其属于半知菌类(无性类)、丝孢纲、丝孢目、淡丛梗孢科、尾孢属的Cercospora piaropi。

不同水曲柳褐斑病病级叶片的微生物多样性

为探究染褐斑病不同程度的水曲柳叶片微生物多样性和主要致病微生物,分析防治方法以维护水曲柳人工林生态安全、提升其经济效益,在帽儿山实验林场采集染褐斑病不同程度的叶片,采用高通量测序技术,测定并分析水曲柳叶片微生物群落结构和物种组成。3组样品感病前后共得到1 026个真菌分类操作单元(Operational Taxonomic Unit,OUT)及322个细菌OUT。在细菌中,变形菌门和放线菌门为优势菌门;鞘氨醇单胞菌属、醋酸杆菌属、短根瘤菌属等为主要优势属。在真菌中,担子菌门和子囊菌门为优势菌门;维希尼克氏酵母属、壳针孢属、汉纳酵母属为优势菌属。3组样品细菌多样性及群落结构无明显差异,真菌多样性及群落结构差异性显著,初步推测尾孢菌属为病原菌,但其致病性有待进一步研究。

东北地区Cercospora属及相近属分类研究

本文报告了东北地区Cereospora属及相近属72个种,寄生于29科植物上,其中有5个新组合:忍冬短胖孢(Cercosporidium diervillae(Ell.et Ev.) Bai et Cheng);紫穗槐菌绒孢(Mycovellosiella passaloroides(Winter) Bai et Cheng);杯槐假尾孢(Pseudocercospora cladrastidis(Jacz.)Bai et Cheng);白头翁假尾孢(Pseudocercospora filiformis(Davis)Bai et Cheng);荚蒾假尾孢(Pseudocercospora varia(Peck)Bai et Cheng),及10个国内新记录种:假酸浆尾孢(Cercospora nicandrae Chupp);美女樱尾孢(Cercospora papillo(?)a Atkinson);苏子尾孢(Cercospora perillae Sawada);车前尾孢(Cercospora p(?)antaginis Sacc.);金光菊尾孢(Cercospora tabacina Ell.et Ev.);毛蕊花生尾孢(Cercospora verbascicola Ell.et Ev.);扁蓄假尾孢(Pseudocercospora avicularis(Winter) Khan et Shamsi);杜鹃假尾孢(Pseudocercospora handelii(Bubak)Deighton);一叶楸假尾孢(Pseudocercospora securingae(Togashi et Kats(?)ki) Deighton);芝麻假尾孢(Pseudocercospora sesami (Hansford) Deighton)。国内新寄主植物科2个;世界新寄主植物属2个;国内新寄主植物属12个;世界新寄主植物种11个;国内新寄主植物种16个。

娄彻氏链霉菌HM85的鉴定及其对甜菜的防病促生作用

由甜菜尾孢菌(Cercospora beticola)引起的甜菜褐斑病是一种广泛发生、危害严重的真菌性病害,严重制约了我国糖料产业的发展。为挖掘对甜菜褐斑病具有生防应用潜力的拮抗菌株,从内蒙古自治区呼伦贝尔黑土地采集甜菜健康植株根际土壤样本,通过梯度稀释平板法和对峙培养法进行分离、纯化、筛选,获得1株具有良好拮抗效果的菌株HM85。基于其形态学特征和生理生化特征,结合16S rRNA基因序列分析将菌株HM85鉴定为娄彻氏链霉菌(Streptomyces rochei)。平板对峙试验结果显示,菌株HM85对甜菜尾孢菌HB2-2-2菌株的生长有明显抑制作用,抑菌率为58.68%。盆栽试验结果表明,HM85在防治甜菜褐斑病的同时对甜菜植株具有一定的促生作用,株高、株鲜重、根长、根鲜重和根直径与对照组相比分别增加22.73%、20.47%、36.10%、32.52%和75.03%。由此可见,娄彻氏链霉菌HM85具有作为促生菌剂和生防菌剂的研发潜力。

大豆紫斑病菌(Cercospora kikuchii)生物学特性研究

大豆紫斑病菌在ＰＤＡ培养基上生长速率最快，在大豆叶葡萄糖琼脂培养基和番茄培养基上产孢量比在ＰＤＡ上高２倍，此病菌生长发育最适温度为２５－２８℃，低于１５℃或高于３７℃均不适宜，在连续黑暗条件下有利于生长，ｐＨ４－９之间，均能生长和产孢，以ｐＨ＝７生长最适，ｐＨ＝７－８产孢最多，分生孢子在葡萄糖液中萌发最好，在１５－４０℃之间均能萌发，最适温度为３０－３３℃，ｐＨ＝３－９之间均能萌发，ｐＨ＝７－８萌发最好，黑暗条件有利萌发。

茶圆赤星病病原菌鉴定及其生物学特性研究

为明确高山茶园茶树病害病原菌及其生物学特性,采用组织分离法从病株中获得菌株HNSM-2,通过科赫氏法则、形态学特征及分子生物学技术鉴定并测定该菌株的最佳生长条件。结果表明,菌株HNSM-2回接茶树叶片30 d后出现红色点状病斑,随后扩展成圆形褐色病斑,与田间自然发病症状相同。该菌株菌落呈不规则圆形,中央着生白色致密菌丝,边缘浅墨绿色;分生孢子梗丛状,分子孢子顶孢圆锥形,具有3~14个隔膜;其ITS序列与Cercospora alchemillicola序列最为相似;结合形态特征和分子鉴定结果,确定其为尾孢菌属(Cercospora sp.)。该菌株的最适生长温度为24℃,最适pH值为6.0,最适碳源为蔗糖、葡萄糖和淀粉,最适氮源为硝酸钠;菌株对碳氮源的耐受性较强,在营养丰富条件下菌丝生长更快。

水葫芦生防菌Cercospora piaropi的病理学特性

尾孢菌属的Cercospora piaropi是一种有潜力开发成为防除水葫芦的生物除草剂的真菌。水葫芦原生叶片从被C.piaropi感染到完全死亡,需要约6周时间。C.piaropi接种水葫芦的适宜孢子浓度为105CFU/ml,适宜保湿时间为24h。30℃时C.piaropi感染水葫芦的原生叶片病害严重度最高。除水葫芦和鸭舌草外,C.piaropi对其他被测农作物和杂草均不产生病理作用,表现出较强的专一性。

Dispersal routes of Cercospora zeina causing maize gray leaf spot in China

The gray leaf spot caused by Cercospora zeina has become a serious disease in maize in China.The isolates of C.zeina from Yunnan,Sichuan,Guizhou,Hubei,Chongqing,Gansu,and Shaanxi were collected.From those,127 samples were used for genetic diversity analysis based on inter-simple sequence repeat(ISSR)and 108 samples were used for multi-gene sequence analysis based on five gene fragments.The results indicated that populations of C.zeina were differentiated with a relatively high genetic level and were classified into two major groups and seven subgroups.The intra-population genetic differentiation of C.zeina is the leading cause of population variation in China,and interpopulation genetic similarity is closely related to the colonization time and spread direction.The multi-gene sequence analysis of C.zeina isolates demonstrated that there were nine haplotypes.Genetic diversity and multi-gene sequence revealed that Yunnan population of C.zeina,the earliest colonizing in China,had the highest genetic and haplotype diversity and had experienced an expansion event.With the influence of the southwest monsoon in the Indian Ocean,C.zeina from Yunnan gradually moved to Sichuan,Guizhou,Shaanxi,Gansu,and Chongqing.Meanwhile,C.zeina was transferred directly from the Yunnan into the Hubei Province via seed and then came into Shaanxi,Henan,and Chongqing along with the wind from Hubei.

Early Detection of <i>Cercospora</i>Species in Soybean Plants: Immunologic and Molecular Methods

Late-cycle diseases (LCD) cause a significant deterioration in quality and reduce yields in soybean crops. In Argentina, in particular, leaf blight and purple seed stain, caused by the agent Cercospora kikuchii, and frog eye spot, caused by C. sojina, are the prevailing sources of diseases. The early, rapid and accurate detection of these phytopathogens becomes essential, and would contribute to preserving both the environment and the health of humans and animals by preventing the wasteful or improper use of chemicals such as pesticides. In order to detect Cercospora species in soybean plants at an early stage, immunochemical and molecular techniques were developed in this work. Strains from the NITE Biological Resource Center collection (Japan): Cercospora kikuchii NBRC 6711 and Cercospora sojina NBRC 6715 and regional isolates of C. kikuchii were used. To develop Dot-Blot and PCR techniques, experiments with plants undergoing different treatments were carried out: those experimentally inoculated with these fungi, those treated with sterile water and healthy plants as well. Both techniques allowed the detection, at early stages, of Cercospora species involved in two of the most frequent LCD in the country, when the cercosporin concentration produced by the fungus was higher than 3.93 ± 0.39 nmol·cyl-1 ±SD. The sensitivity between both techniques was very different. While Dot-Blot allowed the detection of the disease 4 days after inoculation, PCR detected it after 4 hours, even without visible symptoms of the disease.

抗褐斑病甜菜种质资源和生防菌株的初步筛选

甜菜是我国重要的糖料作物,甜菜褐斑病的发生给甜菜产业带来巨大的危害。为研究防治褐斑病的有效方法,本研究对抗褐斑病甜菜种质资源和生物防治菌株进行筛选。通过分析接种甜菜尾孢菌后的发病开始时间和叶片比值发现,种质资源‘780041B/2丰’、‘780020A/优’、‘780016A优’和‘780016B/12优’对甜菜尾孢菌HL001抗性较强;种质资源‘780016A优’、‘780016B/12优’、‘7412丰’、‘Polanwice-p’、‘N98113’、‘H735A’和‘bopa0237丰’对NM001抗性较强;种质资源‘N98102’、‘7412丰’和‘780016A优’对XJ001抗性较强。‘780016A优’对3株甜菜尾孢菌均具有较强抗性。绿僵菌001对3株甜菜尾孢菌的抑菌半径为0.97~1.33 cm,抑菌率为20.27%~26.31%;绿僵菌002对3株甜菜尾孢菌的抑菌半径为1.37~1.63 cm,抑菌率为28.63%~32.60%。绿僵菌002对3株甜菜尾孢菌的拮抗效果优于绿僵菌001。本研究为甜菜抗褐斑病遗传育种和褐斑病生物防治奠定了基础。