水稻稻瘟病抗性鉴定用菌株继代培养遗传变异研究

稻瘟病是最主要的水稻病害之一,人工接种鉴定是稻瘟病抗性鉴定的主要手段。接种鉴定用稻瘟病菌在继代培养过程中时常发生变异,为了解其变异特点,本研究通过在CM完全培养基和燕麦培养基中连续对10个稻瘟病菌田间菌株继代培养10代,对其每代的产孢量、菌落形态、生理小种及对24个丽江新团黑谷(LTH)单基因系致病性变化进行研究。结果表明,随着继代代数增加,多数菌株在第5代产孢量、生理小种及致病性都发生了部分变异,10个菌株中有6个菌株在第5代生理小种已发生变异,特别是菌株P10由ZA种群转变为ZC种群;菌株P3、P5和P8的生理小种从始至终没有变化,但菌株P3和P5对部分单基因系的致病性已发生改变。因此,在选择菌株进行稻瘟病抗性鉴定时,菌株继代应少于5代,尽量用原始菌株。     

大豆灰斑病菌生长和产孢高效培养方法探讨

为明确大豆灰斑病菌菌丝生长和产孢的有效方法,探讨了V8培养基组分中V8蔬菜汁和碳酸钙含量对大豆灰斑病菌菌丝生长速率和产孢量的影响及最佳组分配比。利用5种不同浓度V8蔬菜汁和5种浓度碳酸钙组成25种不同组分处理,以广泛使用的PDA培养基为对照培养基,接种大豆灰斑病7号生理小种进行暗培养,每2 d测量其菌落生长情况和产孢子量并进行对比分析。结果表明:25种不同组分V8培养基的菌落直径、生长速率、生长面积及产孢子量均大于PDA培养基的菌落。V8培养基菌落直径生长最快为3.47 mm·d^-1;孢子产量最多达每皿9.87×106个。培养第5天时,病原菌的生长活力最大。最适宜培养时间为11~13 d,其产孢量达到高峰。培养基组合A4b4碳酸钙含量为1.5 g·L^-1、V8蔬菜汁浓度为15%时,最适合菌落直径生长,菌落生长面积最大。培养基组合A4b3碳酸钙含量为1.5 g·L^-1、V8蔬菜汁浓度为12%时,产孢子量最多。     

大豆平头炭疽菌的产孢因素

为探讨不同因素对大豆平头炭疽病菌产孢量及其病菌致病力的影响,从不同培养基、光照条件、培养温度以及培养基蔗糖浓度等方面进行研究。结果表明,在供试的4种培养基中,在燕麦培养基上该菌产孢量最高;光照条件及培养温度对产孢量影响不明显;在以9g/L低浓度蔗糖为碳源的燕麦培养基上产孢量最高。回接实验表明,培养基蔗糖浓度的改变对病原致病力没有显著影响。大豆平头炭疽菌的产孢量受培养基类型、含糖量影响较大,光照及培养温度对产孢量影响不显著。     

内生解淀粉芽孢杆菌TB2液体发酵条件的研究

采用单因素试验和正交试验对具有广谱拮抗作用的内生解淀粉芽孢杆菌TB2菌株的摇瓶发酵培养基和发酵条件进行优化。结果表明,最佳培养基组份为:玉米淀粉1.0%、豆粉1.0%、(NH4)2SO40.5%、MgSO4·7H2O0.1%、FeSO4·7H2O0.03%、K2HPO4·3H2O0.02%、KH2PO40.01%;培养条件为:初始pH值为7.5,温度35℃,接种量3%,装液量50mL/250mL三角瓶,摇床转速200r/min,发酵周期22～26h。优化条件下发酵水平活菌数达到8.52×1010cfu/mL。     

橡胶树多主棒孢菌室内产孢条件的优化

对橡胶树多主棒孢菌株3种室内产孢方法进行了比较,通过产孢量、孢子大小、活力和致病力等方面的评价,发现菌丝打断法结果优于自然产孢法和纸片产孢法。进一步的研究结果表明:光暗交替、28℃、pH7、RH75%是孢子产生的最适条件;产孢时培养基越多,产孢量越高;菌丝打断后36h时产孢量达到最高。采用菌丝打断法共进行25个多主棒孢菌株的室内产孢试验,所有菌株产孢量均在6.1×105个/cm2菌落以上。     

玉米螟高毒力白僵菌菌株紫外线诱变选育

对自然选育、综合性状表现较好的白僵菌BC6菌株进行紫外线诱变处理,获得产孢量高于亲本菌株的突变菌株4株(Z01、Z09、Z18、Z19)。突变菌株经继代培养,产孢量及产孢特性表现稳定,每代突变体菌株的产孢量均显著高于对应代数的对照亲本菌株,诱变菌株没有回复亲本菌株的表现。经生物测定,菌株Z19和Z09致病力高于对照。Z19菌株校正死亡率高于对照10个百分点以上,差异极显著。     

甘蔗二点螟杀虫真菌绿僵菌的筛选与毒力测定

从椰心叶甲僵虫上分离得到10株对甘蔗二点螟具有较好致病性的绿僵菌,其中MC3的致病性最好,校正死亡率为89.16%,且甘蔗二点螟的校正死亡率随着MC3菌株孢子浓度的增加而逐渐提高,当浓度为1.0×107个/mL时,其死亡率为93.02%。MC3菌株在SDAY培养基菌丝生长及产孢效果最好,孢子萌发的最适温度是25～28℃。     

枯草芽孢杆菌(Bacillus subtilis)CS27液体发酵条件优化

从提高细胞生物量并降低发酵生产成本的目的出发,本文采用单因素试验和正交试验方法,对已筛选出的枯草芽孢杆菌CS27菌株进行液体发酵培养基和工艺条件优化。得到最佳培养基配方为:1.5%黄豆粉、0.5%糖蜜、0.8%氯化铵、1.0%氯化钠、0.1%柠檬酸钠、0.5%碳酸钙、0.1%七水合硫酸镁;最佳发酵条件为:发酵温度32℃,最佳装液量50 mL/250 mL,最适接种量10%,初始pH7.0。在优化后的培养基发酵条件下细胞生物量可以达到1.75×10~9 cfu/mL,为枯草芽孢杆菌CS27菌株规模化生产及应用提供科学依据。     

花生褐斑病菌培养基筛选及生理性状和致病性研究

花生褐斑病菌(Gercosporaarachidicola Hori)在花生杆培养基上的产孢量优于前人推荐的3种培养基。在6种供试培养基中,菌丝生长量则以前人推荐的花生叶斑病尾孢菌培养基最大。培养过程中,不同光照处理对病菌生长和产孢不敏感;不同温度处理产孢量有显著差异。2 %葡萄糖液有促进孢子萌发作     

花生褐斑病菌产孢条件的研究

花生褐斑病菌(Cercospora arachidicola Hori)在花生秆汁培养基上的产孢量优于前人推荐的3种培养基。培养过程中,不同光照处理对病菌产孢不敏感;不同温度处理产孢量有显著差异。     

Inoculation of potato tubers withErwinia carotovora during simulated commercial washing and fluming practices

The potential for bacterial soft rot in potato tubers was affected by laboratory simulation of some components of fluming and washing practices at commercial packinghouses. The potential was expressed as disease severity (average percentage surface decayed) after a standard 4-day incubation at 20°C in a mist chamber. Increased disease resulted when there was an increase in the following factors: a) duration of immersion of tubers in water; b) population of bacteria suspended in water; c) hydrostatic pressure on submerged tubers, and d) concentration of a surfactant (Triton X-100) in the suspensions. A sample of tubers from each tuber lot was uniformly moistened with tap water and then incubated to determine a base-level disease severity. Disease severity in Russet Burbank tubers from commercial storage increased from the base-level of 0.8% to 76% when tubers were immersed in 5 × 10⁶ colony-forming units (cfu)/ml ofErwinia carotovora pv.carotovora (Ecc) for 64 min prior to incubation. Disease severity was 64% when tubers were immersed in a similar suspension for only 0.1 min, but with a hydrostatic pressure of 230 cm of water. Severity values fourto fivefold above control levels (from immersion in water) resulted from an immersion for 5 min in 5 × 10³ cfu/ml with hydrostatic pressures of 5, 180, or 370 cm of water. A 20-fold increase in severity occurred when Red LaSoda tubers were immersed briefly (less than 5 s) in 5 × 10⁶ cfu/ml. Rinsing these tubers with tap water after inoculation, but prior to incubation, did not affect the subsequent development of decay. Thus, the high potential for bacterial soft rot in tubers that have been flumed or washed by water concentrated with soft rotErwinia cannot be reduced by washes or rinses with clean water.     

Evaluation of potato clones for severity of Verticillium wilt, yield and specific gravity in Maine

In 1994 and 1995, the effect of Verticillium wilt, caused byVerticillium dahliae andV. albo-atrum, on tuber yields, number and weight of U.S. No. 1 and B size tubers, and specific gravity was studied in northern Maine, an area with a short growing season. Seven clones (four resistant and three susceptible) were evaluated in a split-plot design with three replications. Clones were the whole-plot factor, and seed pieces in sub-plots were either uninoculated or inoculated with 50 ml of 4 × 10⁴ cfu/mlVerticillium spp. at planting. Individual plants were scored for Verticillium wilt symptoms before harvest on a 1= <3% wilt to 10= >97% wilt. Differences among clones for wilting and specific gravity were significant. The inoculation treatment had no effect on any of the tuber traits measured. However, there were significant clone x inoculation interactions for most tuber traits. Reductions in yield, weight and number of U.S. No. 1 potatoes, and specific gravity were greater in the Verticillium wilt susceptible clones than in the resistant clones. These results suggest that breeding clones with resistance toVerticillium spp. will reduce yield losses, while maintaining tuber size and specific gravity under disease pressure.     

A simple and efficient method to assess susceptibility of potato to stem rot byErwinia carotovora subspecies

Limited development of blackleg resistant potato cultivars has been ascribed to the lack of an effective and reliable test for large scale blackleg resistance screening. A method using leaf petioles was developed for assessing susceptibility of potato stems to blackleg pathogens (Erwinia carotovora subspeciesatroseptica andE. c. subspeciescarotovora). Fifty grams of sterile autoclaved silica sand in Magenta jars (GA-7 vessel, Magenta Corp., Chicago, Illinois) was drenched with bacterial suspension, (17 ml, 2.6 × 10 to 2.6 × 10⁷ cfu/ml) and freshly cut petioles from 5 to 6 week-old plants were inserted to about 5 mm into the sand. The Magenta jars with lids closed were kept on a laboratory bench (20 ±2 C, 16 hours light). The arrangement provided near ideal post-inoculation incubation environment of high humidity for pathogen multiplication and rot development in the petioles. Length of rot was recorded 72 hours after inoculation. Linear regression of rot development on inoculum concentration had R² ≥ 0.80. The petioles inoculated and incubated by this method produced measurable rot lesions with a bacterial concentration as low as 2.6 × 10⁴ cfu/ml and differentiated between the resistant cultivar Russet Burbank and the susceptible cultivar Sangre at all the inoculum concentrations used. Furthermore, susceptibility ranking of five cultivars obtained by this method agreed in general with their reported field reactions. The method is simple and sensitive, and could be used for large scale screening for stem rot resistance in wildSolanum species and early generation breeding populations.     

一株对茶丽纹象甲高毒力白僵菌菌株的筛选、鉴定与培养研究

茶丽纹象甲（Myllocerinus aurolineatus）是一种重要的茶树害虫,当前对其防治仍以化学手段为主。为寻找一种高效、安全和可持续的生物防治方法,本研究采用浸虫法从12株原寄主为鞘翅目昆虫的白僵菌Beauveria spp.中筛选出一株对茶丽纹象甲成虫高毒力的Bbr1552菌株。室内生物测定结果表明,用每毫升含5.0×10⁷个孢子的孢悬液（25℃）处理茶丽纹象甲成虫的LT₅₀值为4.49 d,处理7 d,茶丽纹象甲的累计校正死亡率为100%,僵虫率为69.44%,LC₅₀值为每毫升1.55×10⁶个孢子。对菌株Bbr1552进行形态学鉴定与rDNA-ITS序列和Bloc序列分析,明确其为布氏白僵菌Beauveria brongniartii。此外,对该菌株的最适培养基和培养温度研究发现,其最适生长和产孢培养基均为PPDA培养基;最适生长和产孢温度均为25℃。     

解淀粉芽孢杆菌B9601-Y2提高玉米生长和产量的效应

采用促进植物生长的解淀粉芽孢杆菌B9601-Y2拌、浸玉米种子和浇灌土壤后均能显著提高玉米生长速度和生物量。3×101～3×105 cfu/mL浓度菌液浸泡玉米种子1 h,播种后5 d苗高比对照(清水)提高119.88%～168.85%;浸种2 h,3×104 cfu/mL和3×105 cfu/mL处理则有抑制作用。采用1.6×108、6.2×107、3.9×107 cfu/mL菌液浇灌土壤,播种后7 d苗重比对照增加20.75%、27.36%和33.96%。以3.9×107～1.6×108 cfu/mL浓度菌液拌种处理,15 d苗龄的植株重量比对照增加4.03%～29.35%,在收获期株高增加6.00%～16.29%,产量增加5.76%～11.81%。高浓度处理促生长效果不如中浓度处理。     

Bacterial ring rot disease development in resistant and susceptible cultivars

In two greenhouse tests, we compared cell populations ofCorynebacterium sepedonicum in inoculated cultivars which had failed to show symptoms in field inoculation tests against cultivars that produce well-defined symptoms. Both population studies showed that cell numbers as high as 1 × 10⁹ colony-forming units per gm of fresh weight (cfu gm^-1) were reached in some cultivars prior to symptom development. In one of these tests, conducted when day length averaged 14 1/2 hrs, some cultivars failed to show symptoms 11 wks after inoculation but were found to have cell populations as high as 3.2 × 10⁸ cfu gm^-1 7 wks after inoculation. In another study, root and seed piece inoculations were compared in susceptible and resistant cultivars and only minor differences in symptom expression due to mode of entry of the pathogen were found.     

金龟子绿僵菌菌株培养基的改良

采用液体振荡与固体平板双培养的方法,对金龟子绿僵菌MA4,MAIml两菌株的培养基进行改良.研究结果表明:MA4,MAIml菌株的最适复合碳源均为玉米粉、最适氮源为蛋白胨、最适碳氮比为4:1(m:m,下同)、碳浓度分别为0.5,1.0mol/L,即改PPDA培养基为:MA4菌株以11.8g/L的玉米粉代替蔗糖,17.1g/L的酵母浸膏代替蛋白胨;而MAlml菌株的则以23.6g/L的玉米粉代替蔗糖,蛋白胨由10.0g/L更换为16.2g/L.     

In vitro Utilization of Gold and Green Kiwifruit Oligosaccharides by Human Gut Microbial Populations

We examined the effects of whole kiwifruit on gut microbiota using an in vitro batch model of gastric-ileal digestion and colonic fermentation. Faecal fermentations of gold and green kiwifruit, inulin and water (control) digests were performed for up to 48?h. As compared to the control, gold and green kiwifruit increased Bifidobacterium spp. by 0.9 and 0.8 log(10) cfu/ml, respectively (P?相似文献   

玉米瘤黑粉病抗性鉴定技术的评价

选用西北灌区生产上具有代表性的10个玉米品种,采用不同接种方法及接种浓度在玉米不同生育时期人工接种玉蜀黍黑粉菌,研究抗性鉴定技术,筛选出一整套重复性好、发病完全、受外界因素干扰小的接种技术体系。结果表明,供试玉米品种接种玉蜀黍黑粉菌的最佳方法是注射法,最佳接种时期为6叶1心期,最佳接种浓度为9×10³～10×10³个孢子/mL。     

Long-term dry preservation of viable mycelia of two mycoherbicidal organisms

The production of large amounts of fungal spores for preservation and formulation are considered constraints to effective use of fungal biocontrol agents. Few successful attempts have been made to store fungal mycelia alone. Late log-phase liquid fermenter cultured isolated mycelia of two Fusarium spp. specific to the parasitic broomrapes (Orobanche spp.) from fermenters were formulated in alginate beads or in ‘Stabileze’ (starch, sucrose, corn oil, and silica) and air-dried. ‘Stabileze’ formulations exhibited <30% loss of mycelial viability for >9 months and retained pathogenicity to the weed for over a year, while mycelia harvested earlier, and conidia from liquid culture exhibited >40% loss of viability. Mycelia from liquid culture yielded >20 times more colony forming units (cfu) of F. arthrosporioides and >2 times more cfu of F. oxysporum than spores at late log phase. Efficient formulation of mycelia should significantly change the economics of biocontrol.