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1.
Charles P. Woloshuk Hugh D. Sisler Maria Chrysayi Tokousbalides Samson R. Dutky 《Pesticide biochemistry and physiology》1980,14(3):256-264
Tricyclazole (5-methyl-1,2,4-triazolo[3,4-b]benzothiazole) inhibits melanin synthesis in Pyricularia oryzae at concentrations less than 0.01 μg/ml. The primary site of inhibition in the biosynthetic pathway occurs between scytalone and vermelone. Accumulation of several metabolites derived from melanin precursors along branch pathways is associated with inhibition of melanin biosynthesis. At low tricyclazole concentrations (0.01–1 μg/ml), predominant accumulation of 2-hydroxyjuglone and 3,4-dihydro-3,4,8-trihydroxy-1-(2H)-naphthalenone (3,4,8-DTN) occurs as a result of the primary block between 1,3,8-trihydroxynaphthalene and vermelone. As the concentration of tricyclazole is increased from 1 to 10 μg/ml, flaviolin accumulation is markedly enhanced, whereas that of 3,4,8-DTN and 3,4-dihydro-4,8-dihydroxy-1-(2H)-naphthalenone is depressed, indicating possible secondary sites of inhibition in the main and branch pathways. Five melanin-deficient mutants of P. oryzae that phenotypically resemble the tricyclazole-treated wild-type strain were nonpathogenic or rarely infected two rice varieties. Three of the mutants studied were genetically defective in the melanin biosynthetic pathway at the site blocked by tricyclazole in the wild type. The wild-type strain converted both scytalone and vermelone to melanin; whereas the three mutants and the tricyclazole-treated wild type converted only vermelone to melanin. The data suggest a relationship between melanin biosynthesis and pathogenicity in P. oryzae. 相似文献
2.
Yasuyuki Kubo Kazumi Suzuki Iwao Furusawa Masaski Yamamoto 《Pesticide biochemistry and physiology》1985,23(1):47-55
Melanin biosynthesis by appressoria was studied in relation to their penetrating ability using tricyclazole [5-methyl-1,2,4-triazolo(3,4-b)benzothiazole], pp 389 [4,5-dihydro-4-methyltetra-zolo(1,5-a)quinazolin-5-one], and pyroquilon [1,2,5,6-tetrahydropyrrolo(3,2,1-i,j)quinolin-4-one], and color mutants of Colletotrichum lagenarium. Tricyclazole at 100 μM inhibited melanin biosynthesis by appressoria of C. lagenairum 104-T, and caused accumulation of 3,4-dihydro-4,8-dihydroxy-1(2H)naphthalenone (DDN) in the culture medium. By contrast, DDN was not detected in culture media of tricyclazole-treated mutant 8015, which is defective in the enzyme involved in the conversion of scytalone to 1,3,8-trihydroxynaphthalene (1,3,8-THN). Vermelone restored melanization of appressoria of albino mutant 79215 and of the parent strain 104-T treated with tricyclazole, pp 389, and pyroquilon; however, scytalone restored melanization only in appressoria of albino mutant 79215. These results indicate that tricyclazole, pp 389, and pyroquilon inhibit the conversion of 1,3,8-THN to vermelone in the melanin biosynthetic pathway of appressoria of C. lagenarium. Colorless appressoria formed in the presence of the three melanin-inhibiting chemicals germinated laterally on nitrocellulose membranes and rarely penetrated the membranes. On the other hand, when pigmented appressoria were restored by application of vermelone in the presence of the three chemicals, lateral germination of the appressoria was largely suppressed, and the membranes were effectively penetrated. From these results, it is concluded that the major effect of tricyclazole, pp 389, and pyroquilon on appressoria of C. lagenarium, causing failure of penetration, is the inhibition of melanization. Effects of the chemicals on other metabolic functions can be precluded as significant factors affecting the penetration process. 相似文献
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4.
玉米大斑病菌黑色素的一些理化性质和光谱吸收特征 总被引：7，自引：1，他引：7
黑色素是某些植物和动物真菌病害的致病相关因子,不同来源的黑色素其生物合成途径可能不同。对玉米大斑病菌细胞壁结合黑色素和从培养滤液中提取的黑色素进行理化性质、紫外吸收光谱和红外光谱扫描测定,并与标准品黑色素进行比较分析,明确了玉米大斑病菌黑色素具有与标准品黑色素相似的理化性质。DHN黑色素的特异性抑制剂——三环唑,对玉米大斑病菌0号和1号小种黑色素的产生均有抑制作用;以玉米大斑病菌基因组DNA为模板,通过PCR扩增,得到了1,3,8-三羟基萘还原酶基因的同源片段,推测玉米大斑病菌黑色素合成于DHN途径。 相似文献
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6.
Ahmed A. Kheder Yasunori Akagi Hajime Akamatsu Konomi Yanaga Nitaro Maekawa Hiroshi Otani Takashi Tsuge Motoichiro Kodama 《Journal of General Plant Pathology》2012,78(1):30-38
The tomato pathotype of Alternaria alternata (A. arborescens) produces the dark brown to black pigment melanin, which accumulates in the cell walls of hyphae and conidia. Melanin has
been implicated as a pathogenicity factor in some phytopathogenic fungi. Here, two genes of the tomato pathotype for melanin
biosynthesis, ALM1 and BRM2-1, which encode a polyketide synthetase and a 1,3,8-trihydroxynaphthalene (THN) reductase, respectively, have been cloned and
disrupted in the pathogen. The gene-disrupted mutants, alm1 and brm2-1, had albino and brown phenotypes, respectively. The wild-type and the mutants caused the same necrotic lesions on the leaves
after inoculation with spores. These results suggest that melanin is unlikely to play a direct role in pathogenicity in the
tomato pathotype A. alternata. Scanning electron microscopy revealed that the conidia of both mutants have much smoother surfaces in comparison to the
wild-type. The conidia of those mutants were more sensitive to UV light than those of the wild-type, demonstrating that melanin
confers UV tolerance. 相似文献
7.
《Pesticide biochemistry and physiology》1987,29(3):244-251
Appressorial penetration of onion epidermal walls by wild-type strains P-2 and O-42 of Pyricularia oryzae was more sensitive to fthalide (4,5,6,7-tetrachlorophthalide) than penetration by wildtype strain 4091-5-8 and black mutant strain BL-3 of Pyricularia grisea. Cerulenin completely blocked appressorial penetration by P. oryzae strain P-2 or P. grisea strain BL-3, but penetration capacity of these appressoria could be largely restored with 0.1 mM scytalone. Fthalide and tricyclazole inhibited the conversion of 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN) to 1,3,8-trihydroxynaphthalene (1,3,8-THN) and 1,8-dihydroxynaphthalene (1,8-DHN) as well as the conversion of scytalone to 1,8-DHN by cell-free extracts of P. oryzae or P. grisea. These inhibitors blocked the NADPH-dependent reductase reactions involved in the conversion of 1,3,6,8-THN to scytalone and the conversion of 1,3,8-THN to vermelone in the melanin biosynthetic pathway to 1,8-DHN. The two reductase reactions in extracts from P. oryzae P-2 were about 10 times as sensitive to fthalide or tricyclazole as those in extracts of P. grisea. Reductase activity with either 1,3,6,8-THN or 1,3,8-THN as substrates was present in only trace amounts in cell-free extracts of the buff mutant, P. oryzae P-2 m-1. 相似文献
8.
Tricyclazole (EL 291), 4,5-dihydro-4-methyltetrazolo [1,5-a] quinazolin-5-one (PP 389), and pyroquilon (CGA 49104) were studied to determine the effects on growth and melanin biosynthesis by Pyricularia oryzae in vitro. The three fungicides were essentially devoid of toxicity to P. oryzae at concentrations up to 50 ug ml?1 but each selectively inhibited melanin biosynthesis at much lower concentrations. Inhibition of melanin biosynthesis resulted in the accumulation of 2-hydroxyjuglone and flaviolin. The study indicated that the three compounds act by a similar mechanism in P. oryzae.. 相似文献
9.
多主棒孢霉(Corynespora cassiicola)是世界范围内重要的植物病原真菌,其引起的草莓棒孢霉叶斑病对草莓产业的健康发展具有潜在威胁。小柱孢酮脱水酶(scytalone dehydratase,SCD)是真菌多聚二羟萘类(DHN)黑色素生物合成途径中的关键酶,在植物病原菌致病过程中发挥重要作用。本研究通过同源重组的方法获得了草莓多主棒孢霉小柱孢酮脱水酶基因(CcSCD1)的敲除突变体,并进行了回补和RT-PCR验证。与野生型相比,敲除突变体△CcSCD1-2表现为菌落无色素沉积、菌丝稀疏、产孢量显著下降、分生孢子无色较小以及致病力明显减弱。结果表明,CcSCD1参与调控多主棒孢霉的黑色素生物合成、营养生长、分生孢子产量及致病力。 相似文献
10.
为明确DHN黑色素合成抑制剂三环唑对玉米大斑病菌Setosphaeria turcica致病力的影响,通过含毒介质系统研究了三环唑作用下玉米大斑病菌的黑色素生物合成量、附着胞的细胞孔径、膨压和病菌的致病力。结果显示,当三环唑浓度≤5μg/mL时,玉米大斑病菌菌落生长量和产孢量变化不显著,但黑色素的生成量降至对照菌株的43%;三环唑处理的病菌附着胞细胞壁孔径增大至2.7～3.3 nm,膨压降至3.75 MPa,侵染率下降37.5%,同时病斑面积显著减小。表明三环唑通过抑制玉米大斑病菌DHN黑色素合成,降低了病菌附着胞的膨压,从而导致致病力下降。 相似文献
11.
Rice blast fungus isolates were collected in Kyushu to investigate resistance to scytalone dehydratase inhibitors of melanin biosynthesis (MBI-D). In 2001, failure of control of rice blast was reported in the Saga prefecture, where MBI-Ds have been used since 1998. At that time, the distribution of resistant isolates was mainly limited to that area. However, in 2002, resistant isolates were detected in all prefectures of Kyushu. DNA fingerprinting analysis showed that the mutation causing resistance to MBI-Ds had arisen independently in each area. These data suggest that resistant isolates may occur in any area and become dominant under continuous selection pressure for MBI-Ds. Nevertheless, resistant strains can be controlled by reductase inhibitors of melanin biosynthesis (MBI-R) or commercial rice seed disinfectants. 相似文献
12.
小柱孢酮脱水酶(scytalone dehydratase,SCD)及羟基萘还原酶(hydroxynaphthalene reductase,HNR)是真菌多聚二羟奈类(DHN)黑色素生物合成途径中的关键酶。根据已知真菌的小柱孢酮脱水酶及羟基萘还原酶的保守结构域设计兼并引物并利用RACE技术,获得桑椹菌核病菌(核地仗菌,Scleromitrula shiraiana)SsSCD1和Ss4HNR1的DNA和c DNA序列。SsSCD1和Ss4HNR1均含2个内含子和3个外显子,分别编码169和263个氨基酸残基。进化分析表明SsSCD1和Ss4HNR1与灰葡萄孢和核盘菌中小柱孢酮脱水酶和四羟基萘还原酶基因的亲缘关系最近。DHN黑色素合成特异性抑制剂三环唑处理核地仗菌,结果显示三环唑可抑制核地仗菌菌丝生长和黑色素合成,对SsSCD1的表达无显著影响,但Ss4HNR1的表达水平显著提高。这些结果表明三环唑能够特异性的抑制四羟基萘还原酶,且DHN黑色素是核地仗菌生长发育的重要产物。 相似文献
13.
The capacity of Monilinia laxa (Aderh. et Ruhl.) Honey to induce peach twig blight was lost in an albino mutant and in a wild-type strain of the pathogen treated with pyroquilon, a melanin biosynthesis inhibitor. Pyroquilon (10 ù ml?1) inhibited melanin biosynthesis but did not inhibit mycelial growth of the pathogen or the albino mutant in vitro. These observations indicate that the compound interferes in some manner with the infection process of host cells. 相似文献
14.
ABSTRACT During formation of appressoria produced from conidia and ascospores of Venturia inaequalis, a dark brown ring structure was detected at the base of appressoria. This melanized appressorial ring structure (MARS) was attached to the leaf surface like a sealing ring and formed the fungus-plant interface; it is believed to be required for pathogen penetration of the cuticle. Neither germ tubes nor infection structures beneath the cuticle were found to be visibly melanized. MARS were formed not only on apple leaves but also on leaves of nonhost plants and artificial surfaces differing in hydrophobicity; the formation of appressoria and MARS was confined to hard surfaces. The melanin nature of the ring was confirmed by using melanin biosynthesis inhibitors. Applications prior to inoculation largely inhibited the melanization and reduced infection rate by 45 to 80%; curative applications were not effective. Transmission electron microscopy verified a localized melanization of the cell wall around the penetration pore, and melanin was incorporated into all layers of the fungal cell wall. Appressoria without MARS were not able to infect the plant, suggesting that this structure can be considered to be a pathogenicity factor in V. inaequalis. 相似文献
15.
4HNR (1,3,6,8-tetra-HN reductase) gene of melanin biosynthesis in Setosphaeria turcica had been cloned successfully by RT-PCR in this study. Both sequences of DNA and cDNA of 4HNR were 807 bp and there was no intron in the sequences. This gene only had single copy in genome through Southern blotting analysis. A 2 285 bp for the flanking sequence of 5' had been obtained and it had promoter structure through the software analysis. 相似文献
16.
Anja Maier Andrea Golz Hartmut K. Lichtenthaler Norbert Meyer Günter Retzlaff 《Pest management science》1994,42(3):153-161
Cyclohexane-1,3-diones such as the herbicides cycloxydim, sethoxydim, alloxydim and clethodim are known to be specific inhibitors of the plastid-located acetyl-CoA carboxylase (ACCase) in Poaceae, a key enzyme of de-novo fatty acid biosynthesis in higher plants. Using several new cyclohexane-1,3-dione derivatives and known herbicides, the relationships between chemical structure and enzyme inhibition have been studied. The basic cyclohexane-1,3-dione structure was modified at three different positions. These compounds were tested for inhibition of the de novo fatty-acid biosynthesis in test systems of etioplasts isolated from Avena sativa L. and Hordeum vulgare L. seedlings and also for inhibition of the isolated barley ACCase. The I50 values of these cyclohexane-1,3-diones were determined. The influence of the modification of alkyl chains (length and type of substituent) on the degree of ACCase-inhibition is discussed. Several new compounds were found that were about two orders more active than the known herbicides cycloxydim or sethoxydim in the etioplast and ACCase test systems but not necessarily on the level of whole plants. 相似文献
17.
1-异丙基-3-酰基-5-甲氧基苯并咪唑酮衍生物的合成及抑菌活性 总被引：1，自引：1，他引：0
以4-甲氧基-2-硝基苯胺（1）为起始原料,经烷基化、硝基还原和环化反应制得中间体1-异丙基-5-甲氧基苯并咪唑酮（4）,再经N-酰化反应得到24个1-异丙基-3-酰基-5-甲氧基苯并咪唑酮衍生物（5a~5x）,通过核磁共振氢谱及元素分析对其结构进行了表征。初步抑菌活性测定结果表明,所有目标化合物对番茄灰霉病菌Botrytis cinerea的孢子萌发均有不同程度的抑制作用,其中5i（2-乙基丁酰基衍生物）和5q（2-甲基苯甲酰基衍生物）活性最高,在50 μg/mL时的抑制率分别为95.9%和93.4%。 相似文献
18.
多菌灵、三环唑对大丽轮枝菌微菌核、黑色素形成及致病力的影响 总被引：8，自引：0，他引：8
在离体和活体条件下测定了多菌灵、三环唑对大丽轮枝菌的微菌核黑色素形成的影响,以及经2种杀菌剂处理产生的形态变异菌株对棉苗的致病力。结果表明:多菌灵在培养基内含量超过0.1μg/ml时,即可抑制大丽轮枝菌微菌核的形成,随着培养基内多菌灵浓度的增加,微菌核形成时间逐渐延长,形成量逐渐减少;三环唑浓度为0.5μg/ml时,可抑制微菌核的黑色素形成,微菌核从黑色变为浅红至红褐色。三环唑对微菌核黑色素形成呈可逆抑制,变色的微菌核菌落移入不含药的培养基后,大多可恢复形成黑色素。培养基内三环唑浓度的提高,也可抑制大丽轮枝菌微菌核的形成;因2种杀菌剂的抑制而丧失形成微菌核的白色菌丝体移入不含药的培养基,微菌核形成能力也不能恢复。多菌灵和三环唑经棉株吸收后均能抑制植株内大丽轮枝菌微菌核的形成,但对微菌核色素的形成未见有明显影响。2种杀菌剂处理产生的形态变异菌株的致病力与野生型菌株致病力差异不显著。 相似文献
19.
Isoxaflutole or pyrazolate inhibition of tocopherol and plastoquinone biosynthesis in the green alga Chlamydomonas reinhardtii Dang leads to the inactivation of photosystem II and the degradation of its reaction centre D1 protein when exposed to strong light. Cell-permeable short-chain derivatives of plastoquinone and tocopherol were tested in the reversal. Addition of decyl-plastoquinone reverses herbicide-induced inhibition of photosynthesis and inactivation of photosystem II in short-time (1 h) exposure of the algae to high light. In high light longer than 1 h, decyl-plastoquinone alone loses effectiveness, but a synthetic permeable tocopheryl derivative retards the inhibitory effects on photosystem II and on the degradation of the D1 protein. This indicates that tocopherol deficiency induced by the herbicides makes a major contribution to their secondary mode of action in high light stress. 相似文献
20.
水稻稻瘟病菌不同发育阶段对7种QoI类杀菌剂的敏感性 总被引：2，自引：2，他引：0
以嘧菌酯为对照药剂,研究了6种中国自主创制的QoI类杀菌剂对水稻稻瘟病菌Magnapothe grisea不同发育阶段的影响。结果表明,供试药剂对水稻稻瘟病菌菌丝扩展均表现出良好的抑制作用,EC50值为0.10 ~2.89 μg/mL;对病菌产孢量和孢子萌发的抑制作用明显,EC50值分别为0.10 ~4.92和0.75 ~7.14 μg/mL。在1.0 μg/mL的含药平板上,烯肟菌酯、嘧菌酯、丁香菌酯、SYP-2815对水稻稻瘟病菌产孢量的抑制率均大于90%;对病菌孢子芽管伸长也具有一定的抑制作用,EC50值为1.67 ~34.76 μg/mL。在1.0 μg/mL的含药平板上,7种QoI类药剂对水稻稻瘟病菌菌丝形态无明显影响,但可明显抑制其黑色素的产生。 相似文献