Species from the Colletotrichum acutatum,Colletotrichum boninense and Colletotrichum gloeosporioides species complexes associated with tree tomato and mango crops in Colombia

Colletotrichum species cause typical anthracnose symptoms in tree tomato and mango. To characterize species of Colletotrichum in these two crops in Colombia, 91 isolates were collected from several localities. Phylogenetic analyses using nuclear gene sequencing of the ITS region and the glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) gene allowed the identification of three groups: acutatum, gloeosporioides and boninense. These three groups were further confirmed using two additional genomic regions (chitin synthase 1 and actin) for 30 isolates representative of the three previously identified complexes and one genomic region (ApMat) for the Colletotrichum gloeosporioides complex strains. The entire approach permitted a robust strain identification that allowed phylogenetic species recognition (PSR) based on the identification of well‐supported monophyletic clades and concordance between individual and multilocus phylogenies. Morphological and physiological assays were also conducted. Isolates that were morphologically identified as C. gloeosporioides showed high phenotypic diversity. Pathogenicity data revealed a considerable degree of host preference.     

Effects of antagonistic microorganisms on the post-harvest development of Colletotrichum gloeosporioides on mango

Potential microbial antagonists of Colletotrichum gloeosporioides were isolated from blossom, leaves and fruit of mango and screened using a series of assay techniques. In total 648 microorganisms, including bacteria, yeasts and filamentous fungi, were isolated and tested for their inhibition of growth of C. gloeosporioides on malt extract agar. In vitro , 121 organisms inhibited the fungus and were tested further for their ability to affect conidial germination. Of these isolates, 45 bacteria and yeasts inhibited germination. These were inoculated onto mangoes artificially infected with C. gloeosporioides and assessed for their potential to reduce the development of anthracnose lesions. Seven isolates were chosen for use in a trial in the Philippines using freshly harvested fruit. This final screening procedure yielded two potential candidates for further trials, isolate 204 (identified as Bacillus cereus ) and isolate 558 (identified as Pseudomonas fluorescens ). In post-harvest trials under commercial conditions, isolates 204 and 558 were both tested in combination with different application methods including the addition of adhesive material, peptone, fruit wax or sucrose polyester. Application of isolate 204 did not reduce disease development, whereas application of 558 significantly reduced anthracnose development. No additional benefit was achieved by incorporating the bacteria in adhesive material, peptone, fruit wax or sucrose polyester.     

芒果胶孢炭疽菌漆酶lac1与致病力的相关性分析

为了明确芒果炭疽病病菌(Colletotrichum gloeosporioides)漆酶与该菌侵染相关致病因子之间的关系,本文以愈创木酚为底物筛选获得的高产漆酶菌株A2为材料,测定了漆酶粗提液对芒果炭疽病病菌致病力的影响,并通过半定量RT-PCR法,分析了在不同侵染时段漆酶基因lac1和其他酶基因的表达。结果表明,漆酶粗提液单独不能致病,但能促进该病原菌在寄主中的扩展;在侵染过程中,lac1表达与黑色素合成酶(thd和scd)基因表达相关性更高,与细胞壁降解酶(ecg和pel)基因表达也有一定相关性,但不及前者高。芒果胶孢炭疽菌分泌的漆酶有助于该菌在侵染芒果过程中的扩展,且对侵染相关致病因子黑色素合成酶和细胞壁降解酶基因的表达有一定影响。初步推测,漆酶lac1除了能通过降解芒果组织中的酚类物质、促进病原菌的扩展之外,也可以通过干扰与致病力相关的黑色素合成和细胞壁降解酶的产生来影响芒果胶孢炭疽菌致病力。     

Multilocus identification and thiophanate-methyl sensitivity of Colletotrichum gloeosporioides species complex associated with fruit with symptoms and symptomless leaves of mango

Colletotrichum spp. are known causal agents of anthracnose in a broad host range, causing severe losses. Currently, the most effective way to reduce disease is by fungicide application, which could give rise to resistant populations. This study aimed to determine the Colletotrichum species present in conventional and organic mango orchards and to evaluate their pathogenicity and sensitivity to the benzimidazole fungicide thiophanate-methyl. Seventy-one isolates from fruit with symptoms and symptomless leaves were obtained. From these, 20 representative morphotypes were analysed based on glyceraldehyde-3-phosphate dehydrogenase partial gene sequencing. A subset of 10 isolates based on different species, isolation source, and fungicide sensitivity was used for morphological and multilocus phylogenetic analysis. Colletotrichum queenslandicum was only identified in conventional production systems, C. chrysophilum only in organic systems, and C. asianum and C. siamense in both. Pathogenicity tests showed all species were pathogenic, and only C. asianum caused symptoms via both unwounded and wounded inoculation methods. Overall, 25.3% of isolates (n = 18) that belong to C. siamense, isolated from a conventional orchard, grew on thiophanate-methyl amended media at 1,000 µg/ml, suggesting high resistance. Resistance was not correlated with any common point mutations at positions 198 and 200 of the β-tubulin 2 protein, as commonly found in other fungal pathogens resistant to benzimidazole. The 74.7% remaining isolates (n = 53) belonging to the other species were sensitive, reaching 100% inhibition at <10 µg/ml. Even with benzimidazole application, anthracnose symptoms persist due to the emergence of pathogenic Colletotrichum subpopulations that are resistant to thiophanate-methyl.     

The effect of climatic factors on Colletotrichum gloeosporioides, causal agent of mango anthracnose, in the Philippines

The epidemiology of the anthracnose pathogen of mango, Colletotrichum gloeosporioides, was studied over two growing seasons in the Philippines. This pathogen spreads within tree canopies as water-borne conidia during rainfall, and causes symptoms on young flush leaves, flowers and fruit. Infection studies with leaves and fruit incubated at different temperatures and humidities led to the derivation of a logistic regression model of the percentage of conidia forming appressoria. This model was compared with a similarly derived model from work in Australia; it appeared that the Philippine isolates of C. gloeosporioides were adapted to the higher mean temperatures of the Philippines. Conidia were observed to germinate and form appressoria at relative humidities (RH) between 95 and 100%, even though free surface moisture was only visible at 100% RH. This model was used retrospectively to estimate infection levels in two field trials which had been established to compare pre- and post-harvest practices in the control of the disease. Using this information to plan applications of a curative fungicide might have resulted in four fewer sprays in the first trial and one less in the second, compared with the standard protective spray programme employed.     

Anthracnose of Madagascar periwinkle caused by species belonging to the Colletotrichum gloeosporioides species complex

Severe blight of stems was found on Madagascar periwinkle (Catharanthus roseus) in Shizuoka and Okinawa prefectures, Japan, in July 2003 and September 2004, respectively. Similar fungi were isolated from the diseased plants. The isolated fungi caused the disease after inoculation and subsequently were reisolated from diseased tissues. The fungi were identified as species closely related to C. siamense or C. tropicale according to sequences of the β-tubulin-2 gene, indicating that they belong to the Colletotrichum gloeosporioides species complex. This is the first report specifying the genetic relationships of the pathogens of Madagascar periwinkle anthracnose in the complex.     

不同油茶种和品种对炭疽病的抗性观察

在林间调查了广东省内栽培的高州油茶、广宁红花油茶和39个品种的普通油茶对油茶炭疽病的抗病性,并在室内研究了高州油茶、广宁红花油茶和9个品种的普通油茶叶片对炭疽病的抗病性。林间自然状态下调查结果表明,广宁红花油茶对炭疽病的抗病性最强,普通油茶‘粤韶77-1号’、‘铁城1号’和‘湘林1号’抗性中等,其他品种均表现为感病;室内测定结果表明,广宁红花油茶属于抗病种类,‘铁城1号’和‘粤韶77-1号’属于中度抗病品种,其他为感病品种。     

Molecular and morphological characterization of Colletotrichum gloeosporioides from native Mexican Stylosanthes species

A total of 264 Stylosanthes spp. plants collected from 78 Stylosanthes spp. populations in seven southern Mexican states were analysed for the presence of Colletotrichum spp. Isolates were obtained from 64 plants collected from 36 Stylosanthes populations; 198 isolates produced straight conidia, while 72 isolates produced falcate conidia. Molecular identification was performed to confirm the identity of C. gloeosporioides for the straight-spored isolates. PCR amplifications using the primer CgInt, synthesized from an ITS1 fragment specific to C. gloeosporioides , and the universal primer ITS4 generated the target fragment for 120 Mexican isolates with straight conidia. The endonucleases Ava II and Sma I were used for restriction of the entire amplified ITS1 region of these 120 isolates. The tree constructed from the restriction data grouped 118 Mexican C. gloeosporioides isolates into three clusters containing reference isolates from Africa and Australia, and generated two additional clusters for two Mexican isolates. Conidial shape and growth rate on solid medium were used as the major morphological criteria for distinguishing types A and B. On the basis of 32 other morphological characteristics, a phenogram grouped the colonies into three main clusters. These clusters were partially related to the Stylosanthes species from which they were isolated, and to the molecular groups.     

中国芒果炭疽病菌复合种对苯醚甲环唑敏感性测定

芒果炭疽病是芒果上最严重的病害之一?本文采用生长速率法测定了来自不同芒果产区的芒果炭疽病菌对苯醚甲环唑的敏感性?结果表明, 苯醚甲环唑对供试的136个菌株的平均EC50为(1.46±0.14)mg/L, 其中, 最小值为0.09 mg/L, 最大值为9.74 mg/L, 其敏感性频率不符合正态分布?苯醚甲环唑对不同采集地区菌株的平均EC50无显著差异, 对贵州的菌株平均EC50最高, 对海南的最低?供试的芒果炭疽病菌包含13个种, 其中, 苯醚甲环唑对Colletotrichum cordylinicola的平均EC50最低, 对C.gloeosporioides 的平均EC50最高?     

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.     

芽胞杆菌SM905的鉴定及其对铁皮石斛胶孢炭疽菌的抑菌活性研究

芽胞杆菌Bacillus sp.SM905是本实验室分离并保存的一株活性细菌,为进一步明确其分类地位及其对铁皮石斛胶孢炭疽菌Colletotrichum gloeosporioides的抑菌活性,利用形态学、生理生化特性及16S rDNA和gyrB序列分析对SM905进行种属鉴定;采用菌丝生长速率法、插片法和琼脂平板法测定了不同浓度的SM905发酵上清液对靶标菌菌丝生长和孢子萌发的影响;并通过盆栽试验考察其防效。结果表明,SM905为贝莱斯芽胞杆菌Bacillus velezensis。不同稀释倍数的SM905发酵上清液对胶孢炭疽菌均有一定的抑制作用,其中5倍稀释液对菌丝生长的抑制率最高,为97.89%,20倍稀释液的抑制率也达90%左右。处理组残留胶孢炭疽菌气生菌丝表现为畸形、空洞、色素积累等,基内菌丝产生大量的分生孢子。SM905发酵上清液不影响胶孢炭疽菌孢子的萌发率,但是导致萌发后的菌丝生长稀疏、膨大。盆栽试验结果表明,SM905粉剂100倍液间隔7 d喷施2次对铁皮石斛炭疽病的防效为80.74%,优于10%苯醚甲环唑水分散粒剂800倍液。本研究表明,芽胞杆菌SM905可以作为铁皮石斛炭疽病生物防治用生防菌,具有良好的应用前景。     

Effect of humidity and temperature on conidial germination and appressorium development of two Philippine isolates of the mango anthracnose pathogen Colletotrichum gloeosporioides

A comparison of rates of germination and appressorium formation by an isolate of Colletotrichum gloeosporioides on mango leaves, fruit surfaces and cellophane membranes showed that behaviour was broadly similar on all three substrates. Frequency of appressorium formation was slightly higher on cellophane membranes, and both hyaline and melanized appressoria were formed. Only melanized appressoria were formed on mango surfaces. In vitro experiments on membranes showed comparative differences in physiological behaviour with temperature for two Philippine isolates of C. gloeosporioides . The most stimulatory temperature for production of appressoria differed in isolates I-2 and I-4 (25 and 20°C, respectively). At 30°C more appressoria became melanized than at lower temperatures, but the frequency of formation of penetration pegs was highest at 25°C. Conidia of C. gloeosporioides germinated on cellophane membranes at relative humidities as low as 95%, but the percentage of conidia germinating and forming appressoria increased as the RH approached 100%. Approximately 18% of conidia of C. gloeosporioides I-2 held at 62 and 86% RH for 4 weeks retained viability, and some were capable of forming appressoria when placed at 100% RH. These results have implications for epidemiological models for disease control.     

红掌胶胞炭疽菌的分子检测

 胶胞炭疽菌是引起红掌炭疽病的病原菌。根据GenBank中炭疽属不同种的ITS序列差异,设计了胶胞炭疽菌的特异性引物E1/E2,由此建立的PCR检测体系可以从38个胶胞炭疽菌菌株中扩增得到329 bp的特异性条带,而扩增其它近似或相关菌株时没有相应的特异性条带。该检测体系对胶胞炭疽菌基因组DNA的扩增灵敏度达到10 pg。将引物E1/E2与ITS区通用引物进行套式PCR扩增后,检测灵敏度至少提高10 000倍。当土中胶胞炭疽菌分生孢子达到200个/g土时可检测出。进一步利用此检测体系对携带病原菌的灌溉水、发病组织进行检测,均能快速稳定地检测出病原菌。     

纳米材料二氧化钛对胶孢炭疽菌的抑制作用

对纳米材料TiO2的性质及其对胶孢炭疽菌的抑制作用进行了研究。TiO2在190～240nm处有强的吸收峰。在短波光日光灯和蓝光下TiO2具有较强的抑菌作用，TiO2A对胶孢炭疽菌的菌丝生长、产孢量及孢子萌发抑制率分别为15．21％、54．68％、80．68％，TiO2 B为30．84％、39．70％、86．70％。TiO2 A和TiO2 B的最适抑菌浓度分别为0．5和0．4mg／ml。     

枸杞炭疽病药剂防治药剂筛选

为有效防控厚皮甜瓜细菌性果斑病的发生,提出一套综合防控技术,通过田间开展各单项防控技术的重要性试验,建立标准化综合防控技术体系.结果表明:各单项技术可提高对细菌性果斑病的防效.与对照相比,72％农用硫酸链霉素可溶粉剂浸种可使防效提高16％,病果率降低3％;标准化喷药能使防效提高17％以上,病果率降低3.1％;整枝打杈前后进行防控能使防效提高39％以上;厚皮甜瓜整个生育期不浇水,能够减少病果的数量;在此基础上组装而成的标准化综合防控技术体系防效达89.2％以上,病果率仅为2％.     

火把对柑桔炭疽病菌的室内毒力试验

采用菌丝生长速率法,用杀菌剂火把对柑桔炭疽病菌进行了室内毒力测定,测得火把对柑桔炭疽病的EC50值为0.8110μg/mL,EC98值为10.5435μg/mL,确定了其在室内有效抑菌浓度。本试验有利于指导进一步的室外药效试验以确定实际应用中的最佳施用浓度。     

Blackening on yam in response to Colletotrichum gloeosporioides

A blackening confined to the cuticle and/or outer epidermal cell walls of mature leaves of Dioscorea alata was found to be associated with the appressoria of the fungus Colletotrichum gloeosporioides on plants subjected to high levels of inoculum in the field and to dense spore suspensions in controlled tests. The blackening occurred with little evidence of fungal penetration into the host cells. Preliminary analyses of the nature of the blackening detected melanin-like compounds and suggest the involvement of phenolic compounds and water-soluble chemicals, possibly enzymes, in the blackening process.