Studies on factor(s) in sweet potato which specifically inhibits germ tube growth of incompatible isolates of Ceratocystis fimbriata

Sweet potato root contained a factor or factors which differentiallyinhibited the growth of various isolates of Ceratocystis fimbriata.The factor scarcely inhibited germ tube growth of sweet potatoisolate, compatible to sweet potato. On the other hand, thegrowth of prune, oak, taro and almond isolates, all incompatibleto sweet potato, was strongly inhibited. The germ tube growthof coffee and cacao isolates, incompatible to sweet potato,were less inhibited. Inhibitory factor was distributed throughvarious fractions when centrifuged on a sucrose density gradient.The germ tube growth of pre-germinated oak isolate became lesssensitive to the inhibitory factor after being treated withpronase, suggesting the interaction of the factor with someprotein-containing surface structure of the fungal cell. Treatmentof the factor by phospholipase c, lipase and pronase causedno changes in its inhibitory activity, whereas periodate treatmentpartially inactivated the factor. These results suggest thatthis inhibitory factor constitutes one of the factors determiningthe specificity in sweet potato-C. fimbriata interactions. (Received July 18, 1977; )     

Studies on a Factor in Sweet Potato Root Which Agglutinates Spores of Ceratocystis fimbriata, Black Rot Fungus

A factor which agglutinated the spores of Ceratocystis fimbriata in the presence of Ca²⁺ was purified from sweet potato (Ipomea batatas Lam cv. Norin[1]) root. Element composition of the purified factor was as follows; analysis found: C (29.8%), H (3.97%), O (65.34%), N (0.81%): calculated for C₄₃H₆₉O₇₀N₁: C (30.02%), H (4.01%), O (65.15%), N (0.81%). The factor was mainly composed of galacturonic acid (53% of dry weight) and contained arabinose, fucose, and unidentified component as minor components. The factor also agglutinated A-, B-, AB-, and O types of human erythrocytes to almost the same degree in the presence of Ca²⁺. The differential spore-agglutinating activity of the factor depended on the pH of the assay medium; it agglutinated similarly the germinated spores of sweet potato and coffee strains at pH 7.5 and 5.5, whereas it displayed a distinct differential agglutinating activity at pH 6.5. The factor was assayed for spore-agglutinating activity at pH 6.5, using the germinated and ungerminated spores of seven strains of C. fimbriata; sweet potato, coffee, prune, cacao, oak, taro, and almond strains. The factor agglutinated ungerminated spores of all seven strains similarly, although small differences were observed among strains. On the other hand, a clear differential agglutination was observed among the germinated spores of various strains; sweet potato and almond strains were highly insensitive in comparison with other strains. The growth of the agglutinated spores of C. fimbriata was inhibited. These results are discussed in relation to host-parasite specificity.     

Growth, respiration and some enzymes of three strains of Ceratocystis fimbriata

Growth, respiratory activities and electrophoretic characteristicsof phosphatase and catalase in three strains of Ceratocystisfimbriata (sweet potato strain, coffee strain and prune strain)differing in pathogenicity on sweet potato roots were investigated.There were no significant differences in either growth kineticsor respiratory activity among the strains. Potassium cyanideand antimycin A inhibited oxygen uptake in sweet potato andprune strains. The oxygen uptake of endoconidia of coffee strainwas stimulated by these inhibitors. Mitochondria were preparedfrom endoconidia and mycelia of each strain, and enzyme activitiesof the electron transport system were measured. NADH₂: cytochromec oxidoreductase activity of coffee strain was higher than thatof the other strains. The electrophoretic phosphatase patternof coffee strain was identical with that of sweet potato strain,but differed from that of prune strain. On the other hand, thecatalase zymogram from prune strain was closely related to thatof sweet potato strain, but not to that of coffee strain. ¹This paper constitutes part 79 of the phytopathological chemistryof sweet potato with black rot and injury. (Received May 22, 1969; )     

Studies on factors in sweet potato root which induce spore germination of Ceratocystis fimbriata

Spore germination of Ceratocystis fimbriata was studied in termsof host-parasite specificity. The sweet potato, coffee and cacaostrains of Ceratocystis fimbriata germinated well in a fractionof sweet potato root water extract which had been passed througha column of cation exchange resin. The results showed that germinationof these strains was independent of exogenous cations. On theother hand, the prune, oak, taro and almond strains requiredfor germination both the absorbed and unabsorbed fractions ofsweet potato root water extract which were separated from eachother with a cation exchange resin column. Divalent cationssuch as Ca²⁺ Mg²⁺, Mn²⁺ and Zn²⁺ were identified as the activeprinciples in the absorbed fraction and Ca²⁺ showed the highestinductive activity for spore germination in the presence ofthe unabsorbed fraction. The active principle(s) in the unabsorbedfraction has not yet been identified. There was no relationshipbetween the Ca²⁺ and Mg²⁺ contents of the spores and the requirementof exogenous Ca²⁺ for germination. Ca²⁺ appeared to functionas a trigger of spore germination, not as a normal nutrient.These results suggest that the divalent cations such as Ca²⁺and Mg²⁺ in sweet potato contribute to the establishment ofhost-parasite specificity of this system. (Received August 10, 1977; )     

Increased disease resistance and enzyme activity induced by ethylene and ethylene production of black rot infected sweet potato tissue

Exposure of root tissue from a susceptible variety of sweet potato to low concentrations of ethylene induced a resistance to infection by Ceratocystis fimbriata and an increase in the activity of peroxidase and polyphenoloxidase in the tissue. Susceptible tissue that was inoculated with a pathogenic strain of C. fimbriata or a nonpathogenic strain that can induce resistance liberated more ethylene into closed chambers than tissue inoculated with strains that did not induce resistance. It is suggested that ethylene may be a stimulus that diffuses from infected areas into adjoining tissue to initiate metabolic changes which may lead to disease resistance. Polyphenol oxidase but not peroxidase activity was increased in slices of potato tubers and parsnip roots treated with ethylene. The activity of these enzymes in root tissue of carrot, radish or turnip was not altered by ethylene treatment.     

The possible involvement of a spore agglutinating factor(s) in various plants in establishing host specificity by various strains of black rot fungus, Ceratocystis fimbriata

Extracts, possibly containing a factor(s) which agglutinatesspores of Ceratocystis fimbriata, were obtained from the sweetpotato, potato, taro, cucumber and kidney bean. The factor(s)seemed to be involved in the expression of host specificityby various strains of C. fimbriata. The agglutinating factor(s)from sweet potato root had a high molecular weight and was inactivatedby pronase or macerozyme treatment. (Received March 6, 1974; )     

Influence of exogenous ethylene on ipomeamarone accumulation in black rot infected sweet potato roots

Ipomeamarone accumulation in sweet potato (Ipomoea batatas) roots infected with Ceratocystis fimbriata (black rot) was decreased by one-third when roots were stored under 100 ppm ethylene. This effect of ethylene was not observed when infected tissue was also treated with benzylisothiocyanate. Ethylene treatment and long term infection were associated with the accumulation of 4-ipomeanol and 1-ipomeanol.     

Production of ethylene by sweet potato roots infected by black rot fungus

Ethylene production by sweet potato roots infected by the blackrot fungus, Ceratocystis fimbriata, increased strikingly afterinfection. The fungus grown on potato extract containing 1%sucrose or steamed sweet potato produced no ethylene. Thus,ethylene was proven to be produced from the host tissue affectedby fungus invasion. The ethylene production seemed to be stimulatedby carbon dioxide. Oxygen was essential for production, butexcess oxygen, probably over 80%, was found to be inhibitory.Apparent fungus growth on sweet potato was reduced under a hightension of oxygen, but this was not a cause of reduced ethyleneproduction in excess oxygen. When tissue plugs of infected sweet potato which were activelyproducing ethylene were sliced into thin discs, ethylene productionwas abolished with the exception that the first 1 mm discs atthe 1st and 2nd day stages produced a significant amount ofethylene. Similarly, plugs which were removed from fungus-invadedparts did not produce an appreciable amount of ethylene. Theproduction of ethylene was observed only by tissue plugs whichconsisted of both fungus invaded and noninvaded parts. Infected sweet potato tissue produced ethylene at a rate comparableto that in apples and may provide a goodsystem for the studyof ethylene biosynthesis. ¹Part 72 of the Phytopathological Chemistry of Sweet Potatowith Black Rot and Injury.     

Electrophoretic Study of Protein Metabolism in Sweet Potato Infected with Ceratostomella fimbriata

It was shown in previous papers that in sweet potato infected with Ceratostomella fimbriata, there occurred metabolic activations such as respiratory increase, polyphenols production, protein synthesis and organic phosphate accumulation. In this report on an electrophoretic experiment, forming a part of those studies, it is stated that the pattern of the protein components in the sound part, adjacent to the infected part of sweet potato attacked by the pathogen differs from that of sound sweet potato.     

The Adsorption of a Polygalacturonase Isoenzyme of Botryodiplodia theobromae on Plant Tissues and the Implication on the Pathogenicity of the Fungus

The polygalacturonase isoeazyme (PG 3) of Botryodiplodia theobromae extracted from rotted sweet potato was adsorbed by sweet potato, potato, carrot, bean stem and tomato fruit to various degrees. Adsorption was greater with sweet potato and tomato fruit tissues. Carrots, bean stem and potato absorbed the enzyme to more or less the same degree. The enzyme was not adsorbed on tomato stem. A spore/mycelial suspension of B. theobromae infected the test tissues to various degrees. The enzyme completely macerated sweet potato roots, potato tubers and tomato fruits within 5 h while the bean stem and onion tissues were little affected by the enzyme. The tomato stem was neither infected by the fungus nor macerated by the enzyme.     

Oxidative Enzymes of Ceratocystis fimbriata Isolates Differing in Host Specificity

Eight isolates of Ceratocystis fimbriata differing in pathogenicity on sweet potato roots were compared in vitro for peroxidase, catalase and polyphenol oxidase activities. Pathogenic isolates were generally lower in specific activities of peroxidase and catalase than the nonpathogenic isolates. Cultures of pathogenic isolates were distinguished by black culture liquid compared to the yellow color of nonpathogenic isolates. No consistent differences among the isolates were apparent when the specific activity of polyphenol oxidase preparations were compared on various phenolic substrates. The peroxidase of C. fimbriata had an approximate molecular weight of 81,000 when compared with known protein standards on a column of Sephadex G-100 dextran gel. Its substrate specificity differed from horseradish peroxidase in that it was nonreactive with guaiacol.     

特基拉芽孢杆菌XK29挥发物2-甲基丁酸对甘薯长喙壳菌的抑制作用研究

【目的】研究特基拉芽孢杆菌挥发物2-甲基丁酸对甘薯长喙壳菌的抑制作用,评价2-甲基丁酸对甘薯黑斑病的防治效果。【方法】采用I-分隔平皿和气相抑菌体系,研究不同剂量的2-甲基丁酸对甘薯长喙壳菌菌丝生长和孢子萌发的抑制作用;使用乳酸酚棉蓝染色观察2-甲基丁酸对甘薯长喙壳菌显微形态的影响;利用荧光探针钙荧光白和溴化丙锭检测2-甲基丁酸对甘薯长喙壳菌细胞壁结构与细胞膜通透性的影响;使用荧光探针2,7-二氯荧光素二乙酸酯检测甘薯长喙壳菌胞内活性氧含量变化;测定谷胱甘肽含量分析病原菌应对氧化损伤能力的改变;通过线粒体脱氢酶活力和丙酮酸含量的检测,分析2-甲基丁酸对甘薯长喙壳菌线粒体功能和能量代谢的影响;评价2-甲基丁酸在甘薯黑斑病防治中的使用效果。【结果】2-甲基丁酸显著抑制甘薯长喙壳菌菌丝生长和孢子萌发,降低其产孢能力,导致菌丝折叠弯曲并形成不连续的空腔。2-甲基丁酸使甘薯长喙壳菌的细胞壁结构改变,细胞膜通透性增加,胞内活性氧含量升高,谷胱甘肽含量显著降低,使病原菌应对氧化损伤的能力下降,线粒体脱氢酶活力和丙酮酸含量显著降低,诱发线粒体功能障碍,干扰细胞能量代谢,最终导致细胞死亡。此外,2-甲基丁酸对甘薯黑斑病也具有良好的防治作用。【结论】2-甲基丁酸对甘薯长喙壳菌具有显著的抑制作用,可作为安全高效的气相抑菌材料用于新型熏蒸制剂的研发。     

Host specificity,pathogenicity and the presence of virulence genes in Iranian strains of Pseudomonas syringae pv. syringae from different hosts

Pseudomonas syringae pv. syringae (Pss) strains were isolated from almond, apricot, peach, pear, sweet cheery and wheat in Kohgiluye and Boyer-Ahmad, Kordestan, Fras and Chaharmahal and Bakhtiari provinces of Iran. The strains were examined for host specificity, the presence of virulence genes and pathogenicity on different hosts. After inoculation of isolates, in compatible reactions bacterial populations increased within six days of inoculation and final cell numbers increased several-fold over initial inoculum levels, but in incompatible reactions, bacterial populations declined within four days of inoculation. Almond, sweet cherry and wheat isolates induced progressive necrotic symptoms on almond leaves and stems. Apricot, peach and sweet cherry isolates induced necrotic lesions when inoculated on apricot leaves. On pear leaves and stems, only the pear isolate incited pathogenic reaction and isolates from other hosts did not. The syrB gene was detected in all of the tested isolates. Almond and pear isolates did not have the syrD gene. The sypA gene was detected in the almond, peach, pear and sweet cherry isolates while the sypB gene was detected in the apricot, peach, sweet cherry and wheat isolates. Almond, apricot, pear and wheat isolates gave negative results for the detection of nit gene. The gene Ach, was detected only in the peach isolate and gene hrmA, was detected only in the wheat isolate. This study indicates that host specificity exists among different Pss strains, and genes responsible for syringomycin and syringopeptin production contribute to the virulence of Pss strains.     

The Isolation and Properties of a Factor in Taro Tuber that Agglutinates Spores of Ceratocystis fimbriata, Black Rot Fungus

A factor which agglutinates spores of Ceratocystis fimbriatain the presence of Ca²⁺ was isolated from taro tuber (Corocasiaesculenta Schott, cv. Shiro). The elemental composition of theisolated factor was as found by analysis: C (33.27%), H (4.27%),O (61.90%), N (0.56%); as calculated for C₆₉H₁₀₆O₉₇N₁: C (33.13%),H (4.27%), O (62.04%), N (0.56%). This factor is composed mainlyof galacturonic acid (85% of its dry weight) and contains arabinose,fucose and an unidentified component as its minor components. The differential spore-agglutinating activity of this factordepends on the pH of the assay medium, differential agglutinatingactivity being present at pH 6.5 toward germinated spores ofvarious strains of C. fimbriata. The differential agglutinationof the spores of these strains changed with the growth stage:Ungerminated spores and hyphae of the strains tested were agglutinatedto the same extent, whereas the germinated spores of these strainswere agglutinated differently. When ungerminated and germinated spores of the strains weretreated with pronase, Macerozyme or phospholipase D, their reactivityto the factor changed. Sonication also caused changes in thereactivity of the spores to the factor; germinated spores ofthe sweet potato strain became highly sensitive to it. Insensitivityto the factor was restored in sonicated spores incubated witha substance released from the spores during sonication. Theseresults are discussed in relation to host-parasite specificity. (Received May 19, 1982; Accepted November 9, 1982)     

一株感染家蚕的高致病性白僵菌的筛选及复合诱变

【背景】白僵蚕中的生物活性物质在医疗、保健品及化妆品行业有着广泛的应用。目前,许多人工养殖僵蚕基地在实际生产中使用的菌种多为未进行纯化优选的自然感病死亡僵蚕孢子粉且无固定的施用浓度,使得蚕的僵化死亡率难以保证。提高白僵菌菌株的致病力并筛选性状优良的高毒力菌株是工厂化生产白僵蚕研发的重要方向。【目的】利用紫外-微波复合诱变技术筛选高毒力菌株,为僵蚕工厂化生产提供优良菌株。【方法】利用孢子稀释法从山西省养殖农户中自然感染白僵菌的家蚕中分离获得一株原始白僵菌,运用紫外-微波复合的方式对该菌株进行诱变,并比较诱变前后菌株的产孢量及对家蚕的致病力。【结果】分离得到的原始菌株经鉴定为球孢白僵菌(Beauveria bassiana),命名为Beauveria bassiana Bb1003。通过对致死率和正突变率的考察,确定紫外-微波复合诱变的最佳诱变条件为紫外(功率为15 W)照射30 min,微波(功率为800 W、额定微波频率2 450 MHz)辐照60 s。筛选后得到6株复合诱变菌株(UMCM1、UMCM2、UMCM3、UMCM4、UMCM5和UMCM6)。菌株UMCM2对家蚕的僵化率高达...     

Characterization of emerging populations of Fusarium oxysporum f. sp. conglutinans causing cabbage wilt in China

Fusarium oxysporum f. sp. conglutinans (FOC) causes Fusarium wilt, a disease of cabbage that has brought about significant economic loss throughout northern China since it was first detected in 2001. To characterize the Chinese FOC isolates, we compared the cultural characteristics, pathogenicity and races between the Chinese isolates and the type strains (race 1: 52,557 and race 2: 58,385). The Chinese FGL‐03‐6 isolate had cultural characteristics similar to those of strain 52,557, including colony growth rate, colony and spore characteristics and responses to temperature changes, while the strain 58,385 grew faster, produced more pigment and spores and was more adaptable to temperature fluctuations. The lethal temperature for all strains was 60°C, and the optimal temperatures for pathogen growth on potato dextrose agar and pathogenicity on plants were 25°C and 25 to 30°C, respectively. Tests for race and pathogenicity indicated that different cabbage cultivars had similar resistance reactions to FGL‐03‐6 and 52,557. However, the pathogenicity of FGL‐03‐6 was similar to that of 58,385, which infected quickly and caused more severe disease symptoms. This study further provides information regarding characterizing different strains of F. oxysporum f. sp. conglutinans.     

Induction of Furano-terpene Production and Formation of the Enzyme System from Mevalonate to Isopentenyl Pyrophosphate in Sweet Potato Root Tissue Injured by Ceratocystis fimbriata and by Toxic Chemicals

When sweet potato (Ipomoea batatas) root tissue was infected by Ceratocystis fimbriata, activity of the enzyme system from mevalonate to isopentenyl pyrophosphate, especially of pyrophosphomevalonate decarboxylase (EC 4.1.1.33), was increased in the noninfected tissue adjacent to the infected region, preceding the furano-terpene production in the infected region. Cutting and incubation of sweet potato slices did not produce furano-terpenes, and only slightly increased the activity of the enzyme system from mevalonate to isopentenyl pyrophosphate. The enzymic activity in diseased tissue was localized in the soluble fraction, and was higher in the tissue from the surface to a depth of about 5 mm with gradual decrease toward the inner part.     

发根农杆菌介导药用甘薯西蒙1号的遗传转化

用发根农杆菌A4分别感染药用甘薯西蒙1号的叶片、茎切段、叶柄等外植体,诱导出毛状根,并对毛状根进行了离体培养.采用L9(34)正交设计法优化甘薯西蒙1号的毛状根诱导条件;PCR扩增检测转化毛状根;用高效液相色谱仪检测了毛状根中咖啡酸的含量.结果表明:转化中茎切段是最合适的外植体,最佳感染时间20 min,共培养最佳时间为2天;PCR扩增检测表明发根农杆菌Ri质粒的T-DNA片段已整合进植物的基因组中;经高效液相色谱仪证实毛状根中含有咖啡酸,含量为0.03792 mg/g.     

Isolation and Characterization of Factors in Sweet Potato Root Which Agglutinate Germinated Spores of Ceratocystis fimbriata, Black Rot Fungus

A factor which agglutinates the germinated spores of Ceratocystis fimbriata was isolated from the sweet potato root. The factor is a glycoprotein with a molecular weight of 1.6 × 10⁶ daltons and required divalent cations such as Ca²⁺, Mn²⁺, Ni²⁺, and Mg²⁺ for activity. The activity of the factor was pH-dependent. The factor also agglutinated rabbit erythrocytes and is classified as a phytohemagglutinin or lectin. The factor agglutinated germinated spores of seven strains of C. fimbriata to almost the same degree. The factor showed differential agglutinating activity toward the strains in the presence of unidentified low molecular weight factor(s) in the sweet potato root. These results support our earlier suggestion that the spore-agglutinating factors in host plants function as the determinants of specificity in some host-parasite interactions.     

The pathogenicity of six strains of Helminthosporium sativum to three cereals with special reference to barley

Summary The pathogenicity of 6 strains ofHelminthosporium sativum P.K. & B. isolated from either oats, wheat or barley was studied. Oats was resistant to all strains followed by wheat while barley was susceptible. Barley variety Balder was the most resistant while Piroline was the most susceptible. Susceptibility of Piroline was manifested by higher percentage infection, bigger necrotic areas and wilting of the infected leaf. Toxic filtrates of the different strains could reproduce necrosis, wilting or chlorosis on cut leaves. Response of Balder and Piroline was similar in the filtrates of three strains, while in those of the other three Balder was more resistant. Formation of at least 2 toxic substances in the host tissues, one responsible for wilting and the other for necrosis, was suggested. No correlation was found between the dimensions of the spore or the number of its constituent cells and the virulence of the strain.