8种豆科灌木栽培种丛枝菌根真菌种类及分布

采集人工栽培决明(Cassia tora)、假木豆(Dendrolobium triangulare)、紫穗槐(Amorpha fruticosa)、白刺花(Sophora davidii)、猪屎豆(Crotalaria pallida)、多花木蓝(Indigofera amblyantha)、木豆(Cajanus cajan)和银合欢(Leucaena leucocephala)8种豆科灌木植物根际5-10、10-20和20-30 cm 3个土层的土样,研究其根际丛枝菌根(AM)真菌的侵染率、孢子密度、种类及多样性。结果表明,8种豆科灌木植物AM真菌侵染率普遍较高,最高的为猪屎豆,80.8%;土壤速效磷含量与侵染率呈显著负相关(r=-0.733,P=0.039);根际土壤中的AM真菌孢子主要分布于5-20 cm土层,5-10 cm土层猪屎豆孢子密度最大,为115.33个·10 g-1土壤;宿主植物种类与土壤层位对孢子密度交互效应影响显著(F=100.497,P0.001);AM真菌优势种枫香球囊霉(Glomus liquidambaris)、脆无梗囊霉(Acaulospora delicate)在8种豆科灌木植物的土壤中均有分布。本研究表明,喀斯特地区适生豆科灌木植物具有丰富的AM真菌资源,今后可以在喀斯特地区开展豆科灌木植物接种优势AM真菌和根瘤菌等相关研究,这将对农牧业生产和退化生态系统修复效应的影响具有重要意义。     

Biological control of trichostrongyles in calves by the fungus Duddingtonia flagrans fed to animals under natural grazing conditions

The present study was conducted in the 1993 grazing season with yearling calves exposed to a pasture with a natural mixed trichostrongyle larval infection. It was shown that daily feeding with the microfungus Duddingtonia flagrans during the first 2 months of the season led to a lowered herbage infectivity and a reduced acquisition of Ostertagia sp. and Cooperia sp. later in the season. In addition, the procedure delayed the onset of clinical disease. This was due to the nematode-destroying effects of the fungi in the dung excreted by the fungus-treated calves, as evidenced by results from a parallel in vitro assay on faecal larval cultures. The paper discusses future research needs before practical biological control can be implemented.     

Seasonal effects on the aerobic bacterial and fungal conjunctival flora of normal thoroughbred brood mares in Florida

Objective To evaluate seasonal effects on the presence or absence of fungal and aerobic bacterial flora of the conjunctival fornix of normal Florida Thoroughbred horses. Sample population Both eyes of 100 horses. Procedure Horses with normal anterior segment ophthalmic examinations from three farms in north central Florida were included. Each animal had the ventral conjunctival fornix of each eye swabbed with sterile culturettes. Samples were taken in October, January, April, and July (1999–2000). Aerobic and fungal cultures were plated. Bacterial cultures were reviewed at 24 and 48 h. Fungal cultures were reviewed weekly for 4 weeks. Logistic regression analysis with season as a factor and age of the horse as a covariate was performed. Statistical significance was set at P < 0.01. Results Horses ranged from 3 to 24 years of age, with a median age of 9 years. Twenty‐four genera of bacteria and 35 genera of fungi were recovered. Corynebacterium sp., Staphylococcus sp., Bacillus sp. and Moraxella sp. were the bacteria most frequently isolated. Mold species, dematiaceous mold species, Chrysosporium sp., Cladosporium sp., and Aspergillus sp. were the most frequently recovered fungi. Season did not have a significant effect on the presence of microorganisms isolated for individual horses adjusted for age. Younger horses had an increased incidence of gram‐negative rods and fungal isolates. The number of bacteria and fungi isolated are not uniform across seasons. Conclusion There were no significant differences between the number or type of organisms cultured during the sampling seasons in normal Florida horses. A large range of normal bacterial and fungal flora were isolated from these horses. The number of bacteria and fungi isolated are not uniform across seasons. The likelihood of detecting an organism depends on the horses’ age.     

甘肃棘豆内生真菌种群多样性

将采集于青海省祁连县甘肃棘豆的茎和叶部表面消毒后分别置于黑暗和光照条件以及PDA和BDA 2种培养基上进行内生真菌分离纯化,采用形态学和分子生物学分析技术鉴定种属,并计算多样性指数。结果显示,629块植物样品中共分离到内生真菌433株,分属9个科15个属28种,不同的培养条件下优势菌属不同;多样性指数计算结果显示,香农-维纳指数（H）为1.99,均匀度指数（E）为0.60,辛普森指数（D）为0.257。结果表明,采集于青海省祁连县的甘肃棘豆内生真菌多样性比较丰富,可为今后深入探讨甘肃棘豆内生真菌遗传多样性奠定基础,并为产苦马豆素目标菌株的筛选,提供丰富的内生真菌后备菌株。     

苜蓿种带真菌及其致病性测定

对来自我国新疆,内蒙古,吉林,陕西,甘肃,宁夏,山东,黑龙江,山西,河北和江苏等１１个省（自治区）苜蓿产区的３０个审定登记品种的３８个苜蓿种子样品进行了系统的种带真菌检测研究;测定了２１种２５个真菌分离物对苜蓿幼苗根组织的入侵性及１９种真菌对苜蓿种子萌发和幼苗生长的影响。     

不同产区板栗病原菌的种类及其致病力研究

从北京、山东、河北、湖南、湖北、江西、安徽、广西等板栗主产区的腐烂栗实中分离出146个分离物,经鉴定归属于11个属。不同产区栗实的自然带菌情况各异,带菌量和带菌种类有所不同,南方板栗产区的病原菌种类多于北方产区。回接实验研究了其中分布较普遍的6个属优势菌的致病力,表明不同菌的致病力强弱有较大差异,在相同培养条件下,Rhizoctoria使种仁的发病程度最严重,致病力最强,Penicilliumsp.的致病力最弱。不同接种方式对种仁侵染率的影响不同,种仁有伤接种的侵染率最高,达90%以上,而种皮接种和无伤滚动浸涂接种则不会使种仁发病腐烂。研究中还发现,不同病原菌所致板栗腐烂的病斑特征有所不同。     

丛枝菌根真菌对柳枝稷苗期生长作用机制的研究

柳枝稷(Panicum virgatum L.)存在苗期生长缓慢的现象,而菌根真菌与植物共生可以促进植物生长。为了探究菌根真菌对柳枝稷苗期生长的影响,我们以来自于柳枝稷低地型品种Alamo的2个品系Ma和Mg为材料,诱导丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)与柳枝稷共生,研究丛枝菌根真菌对柳枝稷苗期生长的影响及其分子机制。结果表明:丛枝菌根真菌可以侵入苗期柳枝稷根的内部形成共生菌根,并显著增加柳枝稷苗期的叶绿素含量、株高、叶片数和生物量。寄生植物瓜列当(Orobanche aegyptiaca)种子萌发和独脚金内酯(Strigolactones,SLs)合成标记基因检测实验表明,丛枝菌根真菌与柳枝稷共生可以抑制柳枝稷根系合成独脚金内酯,进而解除独脚金内酯对柳枝稷分蘖的抑制作用,促进柳枝稷苗期的生长。     

鸡舍真菌气溶胶潜在危害的定量评估

本文采用6级Andersen生物空气采样器和常用真菌计数培养基,在鸡舍入口处收集气溶胶真菌,经培养和纯化鉴定出78种真菌,其中包括黄曲霉、烟曲霉、黑曲霉及镰刀菌等在内的50余种真菌。研究表明鸡舍入口处空气真菌污染程度与鸡舍内没有显著差异。早晨气溶胶真菌浓度明显低于中午(P=0.07)和晚间(P=0.05)的浓度,且夏秋季节浓度相对较高,峰值在7月份。鸡舍内气溶胶真菌的年平均浓度为2.3×103 CFU/m3。黄曲霉、烟曲霉、黑曲霉在鸡舍空气中的浓度相对较高,分别超过真菌气溶胶组成平均浓度77.7 CFU/m3、63CFU/m35、7.1 CFU/m3,而镰刀菌是常见的空气真菌,其总平均浓度为74.6 CFU/m3,比平均值高出45.3 CFU/m3。平均CMD值分别为3.1μm;GSD分别为2.1。每分钟可沉积到支气管和直接侵入肺泡的活性真菌量分别是居室的3.4倍和3.3倍。本研究探讨了真菌气溶胶不同时间和季节的变化规律,并从其组成、浓度及粒子大小定量评估采样点鸡舍真菌气溶胶的危害,为有效控制禽类真菌病的流行提供科学依据和预警资料。     

菲和芘胁迫下AMF和PGPR对高羊茅生理生态的响应

旨在探究菲和芘胁迫下丛枝菌根真菌(AMF)与根围促生细菌(PGPR)对高羊茅生理生态的响应。以菲和芘1∶1混合处理浓度各0、50、100和150mg·kg^-1下对高羊茅接种AMF变形球囊霉(Gv)、PGPR荧光假单胞菌(Ps2-6)、Gv+Ps2-6和不接种对照共16个处理。结果表明,AMF、PGPR或AMF+PGPR处理均显著增加高羊茅生物量和菌根侵染率,增强植物光合作用,提高叶绿素含量,显著提高植物体内生理活性。在土壤中菲和芘100mg·kg^-1水平下,与对照相比,双接种Gv+Ps2-6处理的高羊茅叶片叶绿素a、b和总叶绿素含量分别提高57.7%、41.7%和51.8%;净光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)和气孔导度(Gs)分别增加70.6%、100.0%、4.5%和78.6%;最大光化学效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)分别提高2.2%和8.8%;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性、可溶性糖和脯氨酸含量分别是对照的1.6、1.5、2.3和2.7倍,丙二醛含量比对照下降46.0%;高羊茅株高和地上鲜重分别比对照增加63.0%和69.6%;接种PGPR处理能够增加AMF侵染率以及菌根依赖性。供试条件下,双接种Gv+Ps2-6处理增加高羊茅叶绿素含量和抗氧化能力,增强光合作用能力,降低膜脂过氧化水平,促进植物生长的作用最为显著。     

高羊茅种子内生真菌的消毒方法

在高羊茅Festuca arundinacea组织培养中最常用的外植体是成熟种子,而种子中共生的半知菌亚门内生真菌Neotyphodium coenophialum使消毒较为困难,污染率高.为了研究温水处理对富含内生真菌的高羊茅种子发芽率、污染率和出愈率的影响,以不同温度(40,50,60℃)、不同时间(10,20,30min)的温水浸泡和次氯酸钠配合使用处理高羊茅种子,并进行发芽率试验和愈伤组织培养.经统计学分析发现,适用于富含内生真菌的高羊茅种子的最佳消毒组合为50℃温水浸泡10min,再经70%酒精处理5min,然后用次氯酸钠处理15min.消毒方法在保证较高种子发芽率的前提下,可降低种子污染率,提高出愈率.该消毒技术对于解决高羊茅因内生真菌造成的严重污染、出愈率低等现象有重要作用,并为高羊茅再生体系构建奠定重要的试验基础.