不同地理和寄主来源的串珠镰孢的营养体亲和性研究

选用107个采自安徽、山东、江苏、湖北等不同地区棉花、玉米、水稻的串珠镰孢Fusarium moniliforme菌株,在含KClO3培养基上诱导筛选获得抗氯酸盐、不能还原利用硝酸盐的突变株(nitmutant)1081株,在MM、NM、HM等3种不同氮源培养基上划分出nitA、nitB、nitC、nitD四种突变类型,其中nitA出现频率最高,占总体76%;nitB和nitC其次,分别占12%和10%;nitD最少,占总体2%。采用nit突变体互补型配对技术,将供试菌株分别按地理来源和分离寄主进行配对培养,测得不同寄主群体内菌株的营养体亲合群(VCGs)数为56个,然后从每个VCG中随机抽取1个样本菌株,测定不同群体间菌株的VCG同一性,发现所抽取的56个菌株分属于54个VCGs,其中来自棉花的菌株Fm1、Fm2分别与来自玉米的菌株Fm19、Fm20属于同一VCG。按地理来源测定,4个群体共测得55个VCGs,其中来自山东的菌株Fm45和来自安徽的菌株Fm16发生亲和反应,属于同一VCG;107个菌株划分为54个VCGs。结果表明,串珠镰孢菌株群体内存在丰富的VCGs多样性。经多样性分析,不同地理来源的菌株平均1.9454个组成1个VCG,其P与Shannon-Wiener多样性指数分别为0.5140和1.0365;不同寄主上分离的菌株平均1.9107个形成1个VCG,P与Shannon-Wiener多样性指数分别为0.5234和0.9048。经t测验,两个群体Shannon-Wiener多样性指数H值间差异不显著(t=0.70小于t0.05=1.98),说明两个群体的VCG多样性无显著差异,相同地区来源的菌株的遗传相似性与相同寄主来源的遗传相似性相当。     

球孢白僵菌不同分离株的生物学及对小猿叶甲成虫致病性测定

球孢白僵菌Beauveriabassiana是一种寄主范围广、致病性强、适应性广的昆虫病原真菌。对采自广东阳山小猿叶甲Phaedonbrassicae的球孢白僵菌 6个分离株 (A ,B ,C ,D ,E ,F)的菌落生长速率、产孢量、分生孢子萌发率进行了实验 ,测定和比较了这 6个分离株对小猿叶甲成虫的致病力。结果表明 :各分离株在菌落生长速率上没有显著差异 ,但各分离株的孢子萌发率有显著差异 ,其中C ,D ,E分离株产孢量明显高A ,F分离株。用 5× 1 0 7分生孢子 mL的悬浮液处理小猿叶甲成虫 ,分离株间的致病力有显著的差异 ,以D分离株对小猿叶甲成虫的感染死亡率最高 ,为 86 67%。综合比较 ,产孢量和致病性较高的D分离株可作为进一步研究的材料。     

苎麻疫霉有性生殖导致菌落形态和生长速率在无性后代持续变异的研究

研究了苎麻疫霉菌株ＪＳ－５自交Ｓ１代单卵孢株的菌落形态和生长速率在其单游动孢子无性系后代的遗传与变异。结果表明,亲本菌株ＪＳ－５的菌落形态和生长速率在连续４代单游动孢子无性系后代稳定遗传,而该菌株的自交Ｓ１代的约２／３单卵孢株的上述性状在其单孢无性后代中发生分离,且上述性状的分离在无性单孢后代中至少可连续保持３￣４代。本研究结果提示,苎麻疫霉有性生殖导致上述性状的变异,除有性生殖过程中的基因重组外     

禾谷镰孢霉nit突变体的诱导及其生物学特性

将3个抗多菌灵和2个野生敏感型禾谷镰孢霉(Fusarium graminearum)菌株分别在含氯酸盐的MMC培养基上培养,共得到22个不能利用硝酸盐的营养缺陷突变体(Nitrate nonutilizing mutant, 简称nit突变体)。比较了各nit突变体与其亲本菌株之间在菌落生长速率、培养性状、产分生孢子能力、产子囊壳能力以及对多菌灵的敏感性等生物学特性方面的变化。结果表明,nit突变体均抗氯酸盐,在PSA平板上的生长速率没有改变,有性生殖能力没有下降,在Joffs 培养液和5%绿豆汤培养液中仍能产孢,但产孢量与亲本菌株有差异。此外,禾谷镰孢霉对氯酸盐和多菌灵之间没有交互抗药性。因此,可用nit作为遗传标记,研究禾谷镰孢霉有关性状的遗传学。     

源自不同寄主的灰葡萄孢生物学特性的比较研究

本研究以分离自番茄、辣椒、草莓、葡萄的灰葡萄孢Botrytis cinerea为供试菌株,从生长温度、pH适应性、碳源、氮源营养利用等方面对不同寄主来源的灰葡萄孢菌株的生物学性状进行了比较研究。结果表明,5个不同寄主来源的灰葡萄孢菌株的菌丝生长温度范围相同,均为0-35℃;但它们的最适生长温度和分生孢子致死温度存在差异,来自和县番茄菌株HX12最适生长温度为20℃,分生孢子致死温度为47℃ 10min,其余最适生长温度均为25℃,分生孢子致死温度均为48℃ 10min;不同菌株在相同温度下的生长速率有显著差异。pH对不同寄主来源灰葡萄孢菌株菌丝生长的影响存在差异,来自长丰辣椒的菌株LJ菌丝在pH2-9的范围内均能生长,以在pH3-6.5时生长较快,pH6时最快;其余4个菌株在pH2-12的范围内均能生长,以在pH3-9时生长较快,pH6左右最快。不同碳源、氮源营养对灰葡萄孢菌株菌丝生长和分生孢子产生均有显著影响,不同寄主来源的菌株间在碳源、氮源营养利用差异均极显著。在相同碳源、氮源营养条件下,不同寄主来源的菌株的线性生长、菌丝干重和分生孢子产量均有显著差异。     

苎麻疫霉有性生殖导致菌落形态和生长速率在无性后代持续变异的研究

研究了苎麻疫霉（PhytophthoraboehmeriaeSawada）菌株JS-5自交S1代单卵孢株的菌落形态和生长速率在其单游动孢子无性系后代的遗传与变异。结果表明,亲本菌株JS-5的菌落形态和生长速率在连续4代单游动孢子无性系后代稳定遗传,而该菌株的自交S1代的约2／3单卵孢株的上述性状在其单拘无性后代中发生分离,且上述性状的分离在无性单孢后代中至少可连续保持3～4代。本研究结果提示,苎麻疫霉有性生殖导致上述性状的变异,除有性生殖过程中的基因重组外,有性生殖还诱导产生了一种新的机制参与上述性状遗传与变异的调控。本研究还观察到供试菌株及其后代所产生的游动孢子绝大多数细胞内只含有1个细胞核,表明上述机制与异核现象无关。有性生殖导致生物学性状在随后的无性后代中发生持续变异可能是苎麻疫霉生物学性状遗传多样性的重要机制之一。     

苎麻疫霉有性生殖导致菌落形态和生长速率在无性后代持续变异的研究*

研究了苎麻疫霉（PhytophthoraboehmeriaeSawada）菌株JS-5自交S1代单卵孢株的菌落形态和生长速率在其单游动孢子无性系后代的遗传与变异。结果表明,亲本菌株JS-5的菌落形态和生长速率在连续4代单游动孢子无性系后代稳定遗传,而该菌株的自交S1代的约2／3单卵孢株的上述性状在其单拘无性后代中发生分离,且上述性状的分离在无性单孢后代中至少可连续保持3～4代。本研究结果提示,苎麻疫霉有性生殖导致上述性状的变异,除有性生殖过程中的基因重组外,有性生殖还诱导产生了一种新的机制参与上述性状遗传与变异的调控。本研究还观察到供试菌株及其后代所产生的游动孢子绝大多数细胞内只含有1个细胞核,表明上述机制与异核现象无关。有性生殖导致生物学性状在随后的无性后代中发生持续变异可能是苎麻疫霉生物学性状遗传多样性的重要机制之一。     

禾谷镰孢霉nit突变体的诱导及其生物学特性

将3个抗多菌灵和2个野生敏感型禾谷镰孢霉（Fusarium graminearum)菌株分别在含氯酸盐的MMC培养基上培养,共得到22个不能利用硝酸盐的营养缺陷突变体（Nitrate nonutilizing mutant,简称nit突变体）。比较了各nit突变体与其亲本菌株之间在菌落生长速率,培养性状,产分生孢子能力,产生囊壳能力以及对多菌灵的敏感性等生物学特性方面的变化。结果表明,nit突变体均抗氯酸盐,在PSA平板上的生长速率没有改变,有性生殖能力没有下降,在Joff's培养液和5%绿豆汤培养液中仍能产孢,但产孢量与亲本菌株有差异。此外,禾谷镰孢霉对氯酸盐和多菌灵之间没有交互抗药性,因此,可用nit作为遗传标记,研究禾谷镰孢霉有关性状的遗传学。     

禾谷镰孢霉nit突变体的诱导及其生物学特性*

将3个抗多菌灵和2个野生敏感型禾谷镰孢霉(Fusarium graminearum)菌株分别在含氯酸盐的MMC培养基上培养,共得到22个不能利用硝酸盐的营养缺陷突变体(Nitrate nonutilizing mutant, 简称nit突变体)。比较了各nit突变体与其亲本菌株之间在菌落生长速率、培养性状、产分生孢子能力、产子囊壳能力以及对多菌灵的敏感性等生物学特性方面的变化。结果表明,nit突变体均抗氯酸盐,在PSA平板上的生长速率没有改变,有性生殖能力没有下降,在Joffs 培养液和5%绿豆汤培养液中仍能产孢,但产孢量与亲本菌株有差异。此外,禾谷镰孢霉对氯酸盐和多菌灵之间没有交互抗药性。因此,可用nit作为遗传标记,研究禾谷镰孢霉有关性状的遗传学。     

镰孢属几种植物病原真菌分子核型的研究

利用脉冲电场凝胶电泳（ｐｕｌｓｅｄ－ｆｉｅｌｄ ｇｅｌ ｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ,ＰＦＧＥ）,研究了４株串珠镰孢（Ｆｕｓａｒｉｕｍ ｍｏｎｉｌｉｆｏｒｍｅ）、１株尖镰孢（Ｆ．ｏｘｙｓｐｏｒｕｍ）．１株茄镰孢（Ｆ．ｓｏｌａｎｉ）和１株Ｆｕｓａｒｉｕｍ ｓｐ的分子核型以及不同地域和寄主来源的串珠镰孢种内菌株间的分子核型差异。以凝胶包埋法（不破除分生孢子细胞壁）制备供试菌株电泳样本,采用３组条件组     

苎麻疫霉生物学性状遗传与变异研究

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉（PhytophthoraboehmeriaeSawada）的菌落形态、菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在3种类型：（1）在单游动孢子后代和自交后代均可稳定遗传;（2）在单游动孢子后代稳定遗传而在自交后代发生变异;（3）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂合基因控制,也可以由细胞核纯合基因控制,还可能由细胞质因子控制。试验结果还指出,苎麻疫霉的同宗配合性状在单游动孢子和单卵孢后代均可稳定遗传,表明在供试的苎麻疫霉菌株中控制该性状的遗传因子是纯合的。     

苎麻疫霉生物学性状遗传与变异研究*

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉（PhytophthoraboehmeriaeSawada）的菌落形态、菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在3种类型：（1）在单游动孢子后代和自交后代均可稳定遗传;（2）在单游动孢子后代稳定遗传而在自交后代发生变异;（3）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂合基因控制,也可以由细胞核纯合基因控制,还可能由细胞质因子控制。试验结果还指出,苎麻疫霉的同宗配合性状在单游动孢子和单卵孢后代均可稳定遗传,表明在供试的苎麻疫霉菌株中控制该性状的遗传因子是纯合的。     

Suppression of maize root diseases caused by Macrophomina phaseolina, Fusarium moniliforme and Fusarium graminearum by plant growth promoting rhizobacteria.

A plant growth-promoting isolate of a fluorescent Pseudomonas sp. EM85 and two bacilli isolates MR-11(2) and MRF, isolated from maize rhizosphere, were found strongly antagonistic to Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina, causal agents of foot rots and wilting, collar rots/stalk rots and root rots and wilting, and charcoal rots of maize, respectively. Pseudomonas sp. EM85 produced antifungal antibiotics (Afa+), siderophore (Sid+), HCN (HCN+) and fluorescent pigments (Flu+) besides exhibiting plant growth promoting traits like nitrogen fixation, phosphate solubilization, and production of organic acids and IAA. While MR-11(2) produced siderophore (Sid+), antibiotics (Afa+) and antifungal volatiles (Afv+), MRF exhibited the production of antifungal antibiotics (Afa+) and siderophores (Sid+). Bacillus spp. MRF was also found to produce organic acids and IAA, solubilized tri-calcium phosphate and fixed nitrogen from the atmosphere. All three isolates suppressed the diseases caused by Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina in vitro. A Tn5:: lacZ induced isogenic mutant of the fluorescent Pseudomonas EM85, M23, along with the two bacilli were evaluated for in situ disease suppression of maize. Results indicated that combined application of the two bacilli significantly (P = 0.05) reduced the Macrophomina-induced charcoal rots of maize by 56.04%. Treatments with the MRF isolate of Bacillus spp. and Tn5:: lacZ mutant (M23) of fluorescent Pseudomonas sp. EM85 significantly reduced collar rots, root and foot rots, and wilting of maize caused by Fusarium moniliforme and F. graminearum (P = 0.05) compared to all other treatments. All these isolates were found very efficient in colonizing the rhizotic zones of maize after inoculation. Evaluation of the population dynamics of the fluorescent Pseudomonas sp. EM85 using the Tn5:: lacZ marker and of the Bacillus spp. MRF and MR-11(2) using an antibiotic resistance marker revealed that all the three isolates could proliferate successfully in the rhizosphere, rhizoplane and endorhizosphere of maize, both at 30 and 60 days after seeding. Four antifungal compounds from fluorescent Pseudomonas sp. EM85, one from Bacillus sp. MR-11(2) and three from Bacillus sp. MRF were isolated, purified and tested in vitro and in thin layer chromatography bioassays. All these compounds inhibited R. solani, M. phaseolina, F. moniliforme, F. graminearum and F. solani strongly. Results indicated that antifungal antibiotics and/or fluorescent pigment of fluorescent Pseudomonas sp. EM85, and antifungal antibiotics of the bacilli along with the successful colonization of all the isolates might be involved in the biological suppression of the maize root diseases.     

Host-range Characterization of Two Pratylenchus coffeae Isolates from Brazil

Two isolates of Pratylenchus coffeae were collected from coffee roots (in Marília, São Paulo State, Brazil) and Aglaonema (in Rio de Janeiro City, Rio de Janeiro State, Brazil) and maintained in the laboratory on alfalfa callus. Twenty-four plants were tested in the greenhouse to characterize the host preference of these isolates. The host ranges of the isolates differed from each other and, interestingly, coffee, banana, and citrus were not among the better hosts of either isolate. Rather, sorghum, maize, rice, millet, okra, melon, eggplant, and lettuce were the best hosts of the Marília isolate. Poor hosts included French marigold, Rangpur lime, banana, sesame, peanut, sunflower, cotton, French bean, onion, and small onion. The best hosts of the Rio de Janeiro isolate were sesame, soybean, sorghum, castor oil plant, watermelon, squash, eggplant, and melon; the poorest hosts were French marigold, coffee, Rangpur lime, banana, sunflower, peanut, maize, millet, French bean, cotton, onion, sweet pepper, lettuce, okra, and small onion. These isolates have important molecular and morphological differences, suggesting host preference is linked to these characteristics.     

橡胶炭疽病病原菌生物学特性初步研究

测试了7个来自云南省版纳地区的橡胶树炭疽病菌的菌株在不同培养基、温度及pH条件下的生长速率,观察了这些菌株在PDA上的菌落和分生孢子形态,测定了这些菌株的致病力。发现这些菌株的最适生长的培养基、温度、pH和对橡胶树的致病力存在明显的差异,对橡胶树的致病力有明显不同,菌落和分生孢子形态也存在可观察到的差异。     

Moniliformin production and toxicity of different Fusarium species from Southern Africa.

Four new moniliformin-producing species of Fusarium were found, viz., F. acuminatum, F. concolor, F. equiseti, and F. semitectum. Isolates of F. acuminatum and F. concolor produced large amounts of moniliformin (3.4 and 9.5 g/kg, respectively), whereas isolates of the other three species yielded less than 30 mg/kg. The production of moniliformin by isolates of F. oxysporum and F. avenaceum from southern Africa is described. All 14 toxic isolates of F. oxysporum produced moniliformin. Most isolates of F. fusarioides and all six isolates of Fusarium moniliforme va. subglutinans tested produced moniliformin, as did 28 of 36 toxic isolates of F. moniliforme. A number of F. moniliforme isolates produced greater than 10 g/kg, and one isolate yielded 33.7 g/kg in corn after incubation for 5 weeks at 25 degrees C. Moniliformin production in the field in corn ears was shown by inoculating plants with known moniliformin-producing isolates of three Fusarium species. Yields of up to 645 mg/kg were recorded. Isolates of F. acuminatum, F. equiseti, F. fusarioides, and F. moniliforme were found that were highly toxic to ducklings but which did not produce moniliformin.     

In vitro studies on the potential for biological control of Aspergillus flavus and Fusarium moniliforme by Trichoderma species

Culture filtrates of Trichoderma viride and Trichoderma harzianum were inhibitory of Fusarium moniliforme and, to a lesser extent, Aspergillus flavus. The degree of inhibition was, however, dependent on the carbon or nitrogen source incorporated into the medium. Scanning electron microscopy revealed the development of abnormal fruiting structures on exposure to some Trichoderma culture filtrate, while macroscopically, growth restriction and, in the case of A. flavus, altered colony colouration were observed. Based on the results of inverted colony culture, it would appear that some isolates of Trichoderma produce inhibitory volatile compounds. The production of possible antibiotics was also demonstrated. The aggressive behaviour (towards A. flavus and F. moniliforme) demonstrated by Trichoderma spp. may be partly explained by the liberation of extracellular enzymes by these fungi. An isolate of T. viride exhibited amylolytic, pectinolytic, proteolytic and cellulolytic activity. Based on the results of the present investigation, Trichoderma spp. are potential candidates for biocontrol of some mycotoxin-producing fungi, but there exists some doubt as to their osmotolerance within the air-dry seed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of some phytopathogenic fungi and their metabolites on growth of Heliothis virescens (F.) and its host plants

Eleven fungal isolates and their secondary metabolites incorporated into artificial diet were tested for oral toxicity to the tobacco budworm (TBW) by examining larval weight, efficiency of conversion of ingested food to body tissue (ECI), pupal weight, days to pupation, and mortality. Two isolates of Altemaria alternata, two isolates of Fusarium moniliforme, three isolates of F. oxysporum and an isolated of F. solani reduced larval weight 90–99% after 7 days and inhibited pupation. ECI was reduced 34–96% in control groups. One isolate of A. alternata reduced pupal weight by 67% and increased the time to pupation three‐fold. One isolate of Cladosporium cladosporioides reduced larval weights by 56% and pupal weights by 7%. In a preference test of these isolates incorporated at a 1:4 ratio into artificial diet, 48% of the larvae were found on diet cubes containing autoclaved rice, 19% on standard diet, 10% on C. cladosporioides, 6–9% on F. solani, 8% on A. alternata and 3% on F. moniliforme. The fusarial toxins, T‐2 and diacetoxyscirpenol (DAS), were the most active compounds against TBW larvae among the 10 microbial toxins tested. T‐2 toxin reduced larval weight by 87%, reduced ECI by 62%, reduced pupal weight by 33% and delayed pupation by 1 week DAS caused similar but less severe effects than T‐2 toxin. AAL‐toxin inhibited larval growth and reduced pupal weights by 20% and 13%, respectively. A. alternata, F. moniliforme and F. solani were also phytotoxic to alfalfa (Medicago sativa,), crimson clover (Trifolium incarnatum) and wild geranium (Geranium dissectum,), which are early season plant hosts of TBW.