一株分离自德国小蠊的贵州绿僵菌的鉴定及生物学特性

从安徽省宣城市麻姑山林场采集到自然罹病的德国小蠊僵虫，通过分离纯化获得一株绿僵菌RCEF6416，采用显微形态和分子生物学相结合方法将该菌株鉴定为贵州绿僵菌。本试验研究了在不同培养基、盐浓度、pH以及高温胁迫等条件下，该菌株的培养特征及产孢能力，以期为世界性卫生害虫德国小蠊的生物防治提供种质资源和理论依据。结果表明：该菌株在PPDA培养基上的生长速度较快，菌落直径平均日增量为4.94 mm/d，但在PDA培养基上产孢量最大，为5.1×10⁷孢子/cm²；在一定范围内，随着盐浓度增加菌落直径日增量增加，但是产孢量逐渐下降，且菌落逐渐产生白色菌丝圈；当pH为8时，菌株生长速度最快，产孢量最大；高温对菌株孢子萌发率影响很大，当水浴温度为45℃处理4 h后，其孢子萌发率仅为2.6%。     

The growth of a plant-parasitic bacterium,Clavibacter xyli subsp. cynodontis,is enhanced by xylem fluid components

Clavibacter xyli subspecies cynodontis is a gram-positive coryneform bacterium, originally isolated from Bermuda grass. The bacterium is xylem-limited, slow-growing and nutritionally fastidious. We found that extracts of Bermuda grass and maize, as well as xylem fluid collected from decapitated maize plants, enhanced the growth of the bacteria in vitro. The growth was enhanced even with 1% (v/v) maize xylem sap in a rich culture medium, giving both an increased growth rate and a higher stationary phase cell density. The relative increase in growth was inversely correlated with the size of bacterial inoculum. When liquid medium was stored for more than 2 months, the bacteria did not grow at all unless the medium was conditioned with a plant exudate. We fractionated maize xylem fluid by ultrafiltration and chromatographic methods and tested all the fractions for bacterial growth induction. The xylem sap was found to contain two distinct growth-enhancing compounds: a small hydrophilic compound and a proteinaceous compound of more than 10 kDa.     

In vitro Effect of the Phytoalexin Glyceollin I on Polygalacturonase and Oxalic Acid Production ofSclerotinia sclerotiorum

The polygalacturonase (PG) activity in culture filtrates fromSclerotinia sclerotiorum is reduced when glyceollin I, the major soybean phytoalexin, is present in the culture medium. When the enzyme activities in the culture filtrates are expressed per unit of fungal growth, PG activity decreases with increasing concentration of glyceollin I in the culture medium. The phytoalexin does not influence the isoenzyme pattern. This suggests that glyceollin I may inhibit quantitative but not qualitative enzyme production. Only the highest glyceollin I concentration tested inhibits oxalic acid production. The inhibitory effect on mycelial growth is confirmed. The data suggest a further hypothesis about the role of phytoalexin during pathogenesis.     

Antibiosis and Antagonism of Sclerotinia homoeocarpa and Drechslera poae by Pseudomonas fluorescens Pf-5 In Vitro and In Planta

ABSTRACT Pseudomonas fluorescens strain Pf-5, which produces several antifun-gal metabolites, including the antibiotics pyoluteorin, pyrrolnitrin, and 2,4-diacetylphloroglucinol, was tested for its ability to inhibit Sclerotinia homoeocarpa (causal agent of dollar spot) and Drechslerapoae (causal agent of 'melting-out') in vitro and in turfgrass; Tn5 mutants with altered antibiotic production also were tested. Inhibition in vitro differed with the medium used, but both fungi generally were inhibited by Pf-5. In most cases, a mutant deficient in pyoluteorin but not pyrrolnitrin or 2,4-di-acetylphloroglucinol was as inhibitory as Pf-5, whereas a pyrrolnitrin-deficient mutant was less inhibitory than Pf-5 in most fungus/medium combinations. High-performance liquid chromatography analysis of culture extracts showed that bacterial genotype and nutrition have an interactive effect on antibiotic production, such that conditions causing an increase in one antibiotic may increase or decrease another. The purported deficiencies for the pyrrolnitrin- and pyoluteorin-deficient mutants were confirmed. In S. homoeocarpa-infested grass clippings incubated in a moist chamber, Pf-5 reduced mycelial growth, whereas the pyrrolnitrin-deficient mutant did not and the pyoluteorin-deficient mutant was intermediate. In greenhouse experiments, Pf-5 reduced dollar spot disease incidence in bentgrass and bluegrass when sprayed over inoculated turf. In grass clippings infested with D. poae and incubated in a moist chamber under favorable conditions for spore production, Pf-5 did not reduce significantly the number of spores produced compared with the non-treated control. However, Pf-5 reduced melting-out disease incidence and severity in bluegrass inoculated with spores of D. poae under greenhouse conditions.     

Modulation of host pH during the wheat–Fusarium culmorum interaction and its influence on the production and activity of pectolytic enzymes

The effect on ambient pH of Fusarium culmorum during its growth on mineral medium and in apoplastic fluids from infected wheat seedlings, and the effect on the production and activity of the enzymes pectin lyase (PNL) and polygalacturonase (PG), were investigated. Fungal development on a weakly buffered mineral medium in the pH range 5·0–8·0, with pectin as the sole carbon source, led to pronounced alkalinization, reaching values above 8·0. The increase in ambient pH was accompanied by enhancement of total PNL activity. Pectin lyase secretion was detected at pH 5·0 as a single isoenzyme. An additional isoenzyme was apparent during the increase in medium pH. Polygalacturonase was detected as a single isoenzyme only during early growth on medium buffered at pH 5·0. At this stage, the initial medium pH of 5·0, corresponding to the optimum pH for PG activity, appeared to be the most suitable for the activation of early production of this enzyme. During growth in acidified yeast extract medium the fungus secreted ammonia and increased medium pH. Similarly, in apoplastic fluids from inoculated seedlings the concomitant ammonia accumulation and rise in pH were recorded. This trend was accompanied by an increase in PNL, which could therefore function at close to its optimal pH. The results suggest that during infection of wheat seedlings by F. culmorum , pH modulation can lead to PNL production and activity, thus promoting colonization of host tissue.     

补水移栽对甜菜苗期生长及产量品质的影响

为明晰补水移栽对纸筒育苗甜菜苗期生长及产量品质的影响,研究比较了地下式补水与传统的地上式补水的土壤润湿结构特征,补水量对甜菜苗期地下部根系与地上叶片发育的影响,以及补水移栽在两种土壤条件下的甜菜产量与品质效应。结果表明,地下式补水创造了环裹于秧苗纸筒底部的土壤湿润球,利于向秧苗供水与田间有效保水。随补水量的增加,甜菜苗期侧根数、主根长、主根粗、根鲜重、叶片量、叶面积随之显著增长。在华北寒旱区砂质栗钙土农田,以成活率与壮苗为目标的甜菜移栽补水量为150～200 ml·株^-1、壤质草甸栗钙土农田为100～150 ml·株^-1为宜,较不补水甜菜块根增产68.78%～81.82%,糖产量提高65.57%～81.82%。地下式补水移栽,是提高甜菜成活率的关键;适量补水实现培育壮苗,成为甜菜高产的基础。     

Growth,microtuber production and physiological metabolism in virus-free and virus-infected potato in vitro plantlets grown under NaCl-induced salt stress

Viral diseases (a biotic stress) and salinity (an abiotic stress) have been/are the two major constraints for sustainable development of the world’s agricultural production including potato. Crops grown in field are often exposed simultaneously to abiotic and biotic stress, and responses of plants to co-stress by two or more factors may differ from those to each of the multiple stresses. Using in vitro cultures, we demonstrated that virus infection (singly and in combination) or salt, and co-stress by virus infection (singly and in combination) and salt significantly reduced growth and microtuber production, and caused severely oxidative cell damage determined by levels of O₂·^? and methane dicarboxylic aldehyde, and H₂O₂ localization in situ. Alterations in physiological metabolism by increasing total soluble sugar and free proline, and by decreasing chlorophyll content are responses of potato plantlets to virus infection (singly and in combination) or salt stress and co-stress by virus infection (singly and in combination) and salt. Oxidative cell damage and reduced chlorophyll content caused by virus and/or salt are believed to be responsible for the reduced growth, eventually resulting in decreased tuber yield. Results reported here would help us to better understand possible mechanism of reduced tuber yield by virus infection and/or salt stress.     

葡萄组织培养回顾与展望

葡萄是一种历史悠久、种植广泛、品种繁多的园艺果树,又是一种用途极广、价值很高的经济作物,堪称果树之王,葡萄生产在世界果树生产中占有举足轻重的地位。植物组织培养这一种神奇的生物技术手段与葡萄常规育种的有机结合,是实现综合育种目标所必需,它将进一步推动全球的葡萄生产,从而使葡萄这一古老的植物进一步造福于全人类。     

Essential oil production increased by using virus-free patchouli plants derived from meristem-tip culture

For the production of virus-free patchouli ( Pogostemon cablin ), isolated meristem tips were cultured on a medium supplemented with 0·2 ppm 6-benzylaminopurine. Multiple shoot proliferation was initiated during the culture. Complete plantlets were regenerated by transferring multiple shoots to a medium devoid of phytohormones. Plantlets thus produced were transplanted to soil with a high rate of survival and tested by enzyme-linked immunosorbent assay (ELISA) to check elimination of patchouli mild mosaic virus. Following further propagation by stem cuttings, virus-free plants were grown in the northern and southern parts of Mindanao Island, Philippines. Significant increases in biomass and essential oil yield were observed in virus-free plants grown at both localities. Using gas chromatographic analyses, a full set of major sesquiterpenes was detected in the essential oils recovered from virus-free patchouli plants. Reinfection of healthy clones with the virus took place within 4 months of cultivation in the field.     

Ridge-furrow plastic mulching with a suitable planting density enhances rainwater productivity,grain yield and economic benefit of rainfed maize

Soil surface mulching and planting density regulation are widely used for effective utilization of limited rainwater resources and improvement of crop productivity in dryland farming.However,the combined effects of mulching type and planting density on maize growth and yield have been seldom studied,especially in different hydrological years.A field experiment was conducted to evaluate the effects of mulching type and planting density on the soil temperature,growth,grain yield(GY),water use efficiency(WUE)and economic benefit of rainfed maize in the drylands of northern China during 2015-2017.Precipitation fluctuated over the three years.There were four mulching types(NM,flat cultivation with non-mulching;SM,flat cultivation with straw mulching;RP,plastic-mulched ridge plus bare furrow;RPFS,plastic-mulched ridge plus straw-mulched furrow)and three planting densities(LD,low planting density,45.0×10^3 plants/hm^2;MD,medium planting density,67.5×10^3 plants/hm^2;HD,high planting density,90.0×10^3 plants/hm^2).Results showed that soil temperature was higher with RP and lower with SM compared with NM,but no significant difference was found between RPFS and NM.More soil water was retained by soil mulching at the early growth stage,but it significantly varied at the middle and late growth stages.Maize growth was significantly improved by soil mulching.With increasing planting density,stem diameter,net photosynthetic rate and chlorophyll content tended to decline,whereas a single-peak trend in biomass yield was observed.Mulching type and planting density did not have significant effect on evapotranspiration(ET),but GY and WUE were significantly affected.There were significant interacting effects of mulching type and planting density on biomass yield,GY,ET and WUE.Compared with NM,RPFS,RP and SM increased GY by 57.5%,50.8%and 18.9%,and increased WUE by 66.6%,54.3%and 18.1%,respectively.At MD,GY increased by 41.4%and 25.2%,and WUE increased by 38.6%and 22.4%compared with those of at LD and HD.The highest maize GY(7023.2 kg/hm^2)was observed under MD+RPFS,but the value(6699.1 kg/hm^2)was insignificant under MD+RP.Similar trends were observed for WUE under MD+RP and MD+RPFS,but no significant difference was observed between these two combinations.In terms of economic benefit,net income under MD+RP was the highest with a 9.8%increase compared with that of under MD+RPFS.Therefore,we concluded that RP cultivation pattern with a suitable planting density(67.5×10^3 plants/hm^2)is promising for rainwater resources utilization and maize production in the drylands of northern China.     

枯萎病菌毒素培养滤液对唐菖蒲幼苗毒性的初步研究

 对唐菖蒲枯萎病菌进行了产毒培养基的筛选,研究毒素培养滤液对胚根生长的抑制作用、对幼苗根系活力的影响及对幼苗的致萎作用。结果表明：唐菖蒲枯萎病菌在Czapek培养基中培养15 d所产生的培养滤液对唐菖蒲胚根的抑制作用最强,胚根生长抑制率高达99.79%;而菌丝干重在PD培养基中培养13 d达到最高值1 242.27 mg;毒素培养滤液经121℃灭菌20 min后对唐菖蒲胚根仍有很强的抑制作用,表现出较高的热稳定性;与对照相比,毒素培养滤液能够显著降低唐菖蒲幼苗根系活力,随处理时间的延长和处理浓度的增加,萎蔫级数逐渐增加。说明枯萎病菌毒素培养滤液是唐菖蒲枯萎病的致病因子,可以利用其筛选唐菖蒲抗枯萎病品种。     

金耳有效原种的配方和品种筛选

将生产中用到的两个金耳品种作为研究对象,将不同配方培养基中的菌丝、子实体生长状况进行对比,挑选出更适宜大规模生产的金耳品种,并探究麦麸在金耳有效原种制备中的必要性。研究结果显示,金耳1号菌丝较金耳2号更粗壮,长势更好,菌丝满瓶速度更快,子实体形态更好,更适合作为大规模生产的品种进行推广,且添加麦麸的配方更适合金耳1号原种生长。     

Epigallocatechin gallate,a major tea catechin,induces biofilm formation of <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv. <Emphasis Type="Italic">theae</Emphasis>

Plants constitutively produce a variety of secondary metabolites that have antimicrobial activities against phytopathogens; however, interactions between these performed antimicrobial compounds and phytopathogens were poorly understood. In this study, interactions between epigallocatechin gallate (EGCg), which was a major tea catechin that had antimicrobial activities against varieties of bacteria, and Pseudomonas syringae pv. theae (P.s. theae), the causal of bacterial shoot blight of tea, were investigated. EGCg had less antimicrobial activity against P.s. theae; however, subinhibitory concentrations of EGCg induced biofilm formation. Because biofilms are induced in the presence of sucrose in the culture medium but not by P.s. theae strains deficient in exopolysaccharide levan production, biofilm induction by EGCg and levan production are closely related. EGCg increased survival of P.s. theae under dry conditions on nonwounded leaf surfaces in the presence of sucrose. These data indicate the possibility that tea catechins affect the survival of P.s. theae on the phyllosphere. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Variability in aggressiveness,cultural characteristics,cercosporin production and fatty acid profile of Cercospora piaropi,a biocontrol agent of water hyacinth

The extent of variation in aggressiveness, growth and pigmentation in culture, phytotoxin production and fatty acid profile were determined in a population of 55 isolates of Cercospora piaropi, a fungus used as a biocontrol agent of the aquatic weed water hyacinth (Eichhornia crassipes). Besides differences in the colour of mycelium and diffusible pigments in culture, isolates of C. piaropi grown under standard conditions differed significantly in their ability to produce the phytotoxin cercosporin, as well as in aggressiveness and growth rate. A positive correlation existed between the ability of the isolates to produce cercosporin and their aggressiveness, and a negative correlation between growth rate and cercosporin production or growth rate and aggressiveness. Based on thin‐layer chromatographic separation of extracts and comparison with beticolin‐1, used as a standard, there was no evidence of production of beticolins. In discriminant analysis, fatty acid methyl ester (FAME) profiles had low resolution for differentiating populations among isolates of the fungus, and the level of resolution was influenced by the age of the colonies. Diffusible pigments in culture and cercosporin production are useful adjuncts to aggressiveness screening for choosing the most effective isolate of C. piaropi for biological control.     

Effects of the fungus Crinipellis perniciosa, causal agent of witches' broom disease, on cell and tissue cultures of cocoa (Theobroma cacao L.)

The symptoms of witches' broom disease in cocoa, caused by the Basidiomycete fungus Crinipellis perniciosa , are pronounced swelling of the terminal and axillary buds followed in the long term by necrosis of this tissue. The direct effect of C. perniciosa on cocoa cells was examined under controlled conditions by growing primary and secondary phase cultures of the fungus separately and also with callus cultures and with cell suspensions. Both primary and secondary phase mycelium reduced growth of callus cultures by about 47% after one week compared with the controls. However, cell suspensions containing primary phase mycelium showed initial growth double that of the uninfected controls after 5 days, but then growth was reduced below that of the control and particularly when the primary phase became secondary phase mycelium. This change in fungal development coincided with the time that the cell culture reached the stationary growth stage. Cell cultures inoculated with stationary phase mycelium showed the same growth as the control after 5 days but then growth was reduced to 50% of the control after 19 days incubation and remained at this low level subsequently. The inhibitory effect of secondary phase mycelium was examined by incubating callus and cell suspensions with culture filtrate from liquid cultures of the secondary phase. Inclusion of 50% by volume of culture filtrate from the secondary phase in the growth medium for callus and cell suspensions, respectively, resulted in a reduction in growth of the plant tissue cultures. Addition of fungal culture filtrates also led to loss in potassium and loss of viability of cell suspensions and of isolated cells as represented by protoplasts. The necrotrophic mode of the secondary phase may be achieved through the production of phytotoxins acting on the host cell membrane.     

甘薯脱毒技术及增产效果研究

作者于１９８８～１９９５年研究了甘薯病毒及甘薯脱毒技术,明确了侵染山东甘薯的主要病毒种类是甘薯羽状斑驳病毒和甘薯潜隐病毒,在国内首次分离侵染甘薯的烟草花叶病毒,探明了其生物学特性。筛选出适合山东甘薯茎尖培养基的最佳激素配比,浓度,ｐＨ值。探索了脱毒薯的增产机理和增产效果,提出了组织培养,茎尖苗检测,脱毒薯速率与推广应用的配套技术规程,培养出徐薯１８等１２个品种的脱毒苗,平均增产４２．９％出干率提高     

Fusaric acid: phytotoxicity and in vitro production by Fusarium oxysporum f.sp. lilii,the causal agent of basal rot in lilies

The production of phytotoxins byFusarium oxysporum f.sp.lilii, a pathogen causing bulb and scale rot in lilies, was investigated. To determine the toxic activity of culture filtrate, a bioassay with in vitro grown scale bulblets or with callus was set up. The fungus produces toxic components in different culture media. The highest toxicity was observed in Czapek Dox medium. HPLC and GC/MS analyses revealed the presence of fusaric acid at toxic concentrations in this medium. The production of fusaric acid in time coincides with the increase of toxic activity in the culture filtrate. It is concluded that at least part of this toxicity is due to fusaric acid.     

一株高毒力刀孢蜡蚧菌最适培养条件的优化及其对桃蚜的毒力测定

刀孢蜡蚧菌Lecanicillium psalliotae是一种重要的昆虫病原真菌,在害虫生物防治中应用广泛.为明确刀孢蜡蚧菌生长和产孢的最适培养条件,本文对一株刀孢蜡蚧菌HFLP006菌株的培养条件进行优化,比较了不同培养基种类、初始接菌量、培养温度、供试碳源和氮源对该菌株产孢量的影响.结果 表明,在SDAY液体培养...     

高粱新病害顶腐病的初步研究

 我国高粱上发生的新病害顶腐病是由亚粘团串珠镰孢(Fusarinm moniliforme var.subglutinans Wr.&Reink.)侵染引起的。病菌生长的适宜温度为25~30℃,适宜pH值为6~8。小型分生孢子萌发的适宜温度为25~28℃,适宜pH值为6~7。病菌在Bilai培养基上,pH4~11间均易产生大型分生孢子。黑光灯和日光灯照射对大型分生孢子形成有促进作用,且黑光灯优于日光灯;在光照处理下最适宜产生大型孢子的培养基为小麦粒和高粱粒。病菌在PSA培养基上培养10~12天后可产生厚垣孢子。病菌能利用多种碳源,以半乳糖、甘露糖为佳,乳糖、木糖、葡萄糖次之。对氮源利用远不及碳源。人工接种条件下,病菌能侵染高粱、苏丹草、哥伦布草、玉米、谷子、珍珠粟、薏苡、水稻、燕麦、小麦、狗尾草等禾本科植物。     

稻曲病菌离体培养体系的构建与优化

稻曲病是水稻穗期的一种重要病害,严重影响稻米的产量和品质。稻曲病菌Ustilaginoidea virens 在离体培养条件下生长缓慢,严重制约了杀菌剂室内生测试验的观察和高效筛选。本研究以稻曲病菌培养基为研究对象,通过筛选、组合和优化固体培养体系的氮源、碳源、凝固剂以及阳离子浓度,以期构建适合稻曲病菌生长的室内培养体系。结果发现:在5种常见的商品化培养基中,稻曲病菌的生长速率仅为0.7~2.3 mm/d;而在18种配制培养基中,有77%的培养基对稻曲病菌表现出不同程度的生长促进效应,其中蛋白胨蔗糖结冷胶 (PSGG) 培养基的促进效果最显著 (P < 0.05),生长速率达3.4 mm/d,且其对不同地理分布的稻曲病菌菌株均有生长促进效应。此外,在以结冷胶作为凝固剂的培养基中添加质量分数为0.02%的硫酸镁 (Mg2+),可有效提高培养基的凝固程度,且对菌丝体的生长速率无影响。在适合稻曲病菌生长的PSGG培养基中,蛋白胨和蔗糖是合适的氮源和碳源组合,结冷胶是合适的凝固剂。此研究结果可提高室内培养稻曲病菌的生长速率,为进一步理解稻曲病菌在离体条件下的生长机制及提高室内杀菌剂生测试验的效率提供了重要参考。