水稻纹枯病生防内生菌糖蜜草固氮螺菌的分离与鉴定

 本文首先对砂仁内生细菌进行分离,以水稻纹枯病菌(Rhizoctonia solani)为靶标菌对获得菌株进行离体拮抗活性、盆栽及田间试验测定。结果表明：获得的27株内生细菌中有4株具有较好的离体抑菌活性,其中SRJ2-4抑菌效果最好,抑菌带达到18 mm;SRJ2-4的盆栽防效及田间防效分别为80.7%与79.4%,与其它菌株相比达极显著水平。SRJ2-4处理的亩产量为488.79 kg,高于其他药剂处理。对该菌株形态、生理生化及16S rDNA序列进行分析,将该内生菌鉴定为糖蜜草固氮螺菌(Azospirillum melinis)。     

球毛壳ND35菌株在宿主植物上的侵染定殖

为了解球毛壳Chaetomium globosum ND35菌株在宿主植物上的侵染定殖方式和途径,以毛白杨组培苗为宿主植物,借助光学显微镜、扫描电镜、透射电镜,结合免疫荧光标记技术,研究了球毛壳ND35菌株子囊孢子萌发后在毛白杨上的侵染行为及其菌丝在组培苗根部的定殖。结果显示,子囊孢子萌发后形成的菌丝,能从杨树苗根、茎部表面细胞间的缝隙侵入或在根表面形成附着胞,进而形成侵染钉直接从表皮细胞侵入,在叶部主要从气孔侵入叶片内部。侵入根部的菌丝主要定殖于表皮细胞、外皮层细胞和细胞间隙,未进入内皮层和维管束组织。     

保存时间对中华羊茅种子内生真菌活力的影响

以分别保存于2004-2006年的带Epichloë内生真菌(E＋)中华羊茅Festuca sinensis为研究对象,探讨了随着保存时间的延长,内生真菌活力的变化。结果表明,随着保存时间的延长,中华羊茅种子带菌率、幼苗带菌率以及种子的发芽率、发芽指数、根长、苗长均有降低的趋势,同一年种子带菌率均高于幼苗带菌率,2006年带菌率最高,种子为95.80%,幼苗为93.10%;以3个年份的(E＋)中华羊茅草粉浸提液对细交链孢Alternaria alternata、燕麦镰孢Fusarium avenaceum和绿色木霉Trichoderma viride的抑菌活性研究表明,3个年份的带菌草粉浸提液对3种菌的菌落生长和孢子萌发均有一定的抑制作用,但保存时间越长,其抑菌能力越弱,2006年的抑菌率为63.51%,2004年为25.49%,而2006年的抑制产孢能力为69.25%,2004年仅为26.34%。同时,从不同保存年份分离到的内生真菌在相同条件下再培养结果显示,保存时间越长的内生真菌生长越缓慢,产孢能力越弱,2006年的菌落直径为26.4 mm,而2004年仅为17.4 mm。说明随着保存时间的延长,内生真菌活力在逐渐下降,导致自身生长以及促进种子生长,抑制真菌的活性也开始减弱。     

萝卜软腐病生防菌株Hy11的筛选、鉴定及定殖特性

为探讨银杏内生细菌对萝卜软腐病的防病作用,通过块根接种和温室盆栽试验筛选对萝卜软腐菌Pectobacterium carotovorum subsp.carotovorum具有高效抑制作用的生防菌株,共获得8株拮抗作用较强的内生细菌,其中菌株Hy11抑菌作用明显.对生防菌株Hy11进行了形态观察、生理生化特性测定、16S rDNA和gyrB基因序列分析,并应用绿色荧光蛋白基因标记菌株Hy11,研究该菌株在萝卜体内的定殖动态.结果显示,该菌株对萝卜软腐病具有较好的防效,对萝卜块根和幼苗的防治效果分别为77.9％和66.7％;对萝卜幼苗的促生率达113.28％.经鉴定,菌株Hy11为解淀粉芽胞杆菌Bacillus amyloliquefaciens.标记菌株Hy11-gfp在喷雾接种银杏叶片后0～3 d种群数量呈急剧下降趋势,10d后保持相对稳定;其在萝卜的根、茎和叶中均能够定殖,在根中的定殖数量最高可达1.2×104 CFU/g.     

Isolation,Identification and Distribution Characteristics of Fungal Endophyte in Delphinium grandiflorum L.

In order to explore the species of endophytic fungi from a poisonous plant, Delphinium grandiflorum L. In this experiment, surface disinfection was used for separation, morphological identification was used, and phylogenetic tree was constructed using ITS sequence to determine the species of endophytic fungi. The results showed that 22 species of endophytic fungi were isolated from D. grandiflorum L., they were mainly divided into two groups according to their phylogenetic relationship, belonging to 6 classes, 6 orders, 6 families, and 7 genera. Among them, Alternaria sp. was the dominant species (accounting for 31.82% of the isolated strains, mainly distributed in flowers and leaves), endophytic fungi are most commonly distributed in flowers (accounting for 40.91% of the isolates), followed by leaves (31.82%), roots (22.73%) and stems (4.55%). The results indicated that the distribution of endophytic fungi in D. grandiflorum L. is different in different tissues.     

拮抗内生细菌B20-006菌株对玉米主要防御酶系的影响

笔者通过对玉米纹枯病拮抗内生细菌筛选研究发现,利用拮抗内生细菌B20-006进行种子包衣处理,对玉米纹枯病的防效最高达67．9％。同时通过抗利福平B20-006突变菌株回接再分离及利用免疫胶体金银染色技术证明,B20-006菌株可通过根系侵人,具有沿维管束进行转运的能力。为进一步明确其生防机理,本文系统研究了B20—006菌株与宿主玉米相互作用过程中主要防御酶系苯丙氨酸解氨酶、过氧化物酶、超氧化物歧化酶及酯酶等的比活性变化。     

Induction of systemic resistance to Agrobacterium tumefaciens by endophytic bacteria in grapevine

Crown gall disease of grapevine, caused by Agrobacterium tumefaciens, often results in severe economic loss to grape production worldwide. This study demonstrated the ability of the endophytic bacteria Pseudomonas sp. Sn48 and Pantoea sp. Sa14 isolated from domesticated and wild grapevines to induce resistance in both above- and belowground tissues of grapevines infected with A. tumefaciens. Our results provide evidence that both strains can colonize roots and/or shoots. We showed that the strains Pseudomonas sp. Sn48 and Pantoea sp. Sa14 are capable of inducing stilbenic phytoalexin production in grapevine tissues and to further prime plantlets for enhanced phytoalexin production after A. tumefaciens inoculation. We also showed that in the majority of treatments, polyamine accumulation remained unchanged or slightly increased in plantlets treated with Pseudomonas sp. Sn48 and Pantoea sp. Sa14 compared with the control. Our findings indicated that the levels of polyamines remain unchanged or significantly decrease in plantlets treated with endophytic bacteria after A. tumefaciens challenge compared to the control and plantlets treated with individual endophytic bacterial strains. PR1, PR2, and PR4 gene expression levels of plantlets treated with Pseudomonas sp. Sn48 and Pantoea sp. Sa14 significantly increased after A. tumefaciens inoculation. The findings revealed the efficacy of the selected endophytic bacteria in triggering grapevine resistance against A. tumefaciens and the possible use of these strains as an alternative to chemical control methods in grapevine crown gall disease management.     

内生短短芽胞杆菌011可湿性粉剂的研制

以植物内生短短芽胞杆菌011为研究对象,通过对载体、润湿剂、分散剂、稳定剂、保护剂的筛选,确定了内生短短芽胞杆菌011可湿性粉剂最佳配方：滑石粉10%,木质素磺酸钙7%,DBS 3%,CMC-Na 2%,糊精0.1%。结果显示制备的短短芽胞杆菌011可湿性粉剂在25 ℃室温下芽胞含量为1. 8×1010 cfu/g,pH 6.8,悬浮率76%,润湿时间52s,细度通过率98%。能有效降低化学农药在农业生产中的使用率,减少农药对生态环境的破坏。     

野生大豆内生细菌多样性及其杀线虫活性分析

为探明河北昌黎野生大豆内生细菌的多样性,寻找新的具有杀线虫活性的微生物资源,采用平板稀释法从野生大豆根、茎、叶等组织中分离内生细菌,结合形态特征以及16S rDNA基因序列进行比对分析,并对大豆孢囊线虫Heterodera glycines进行杀线虫活性比较.从野生大豆分离获得内生细菌180株,分属于7大类群:变形菌门α亚群、变形菌门β亚群、变形菌门γ亚群、厚壁菌门、放线菌门、酸杆菌门和疣微菌门,其中变形菌门α亚群和厚壁菌门为优势类群,分别占分离细菌总株数的48.9％和18.9％,野生大豆组织内生细菌Shannon-Wiener多样性指数为2.11 ～2.91.内生细菌Bacillussubtilis WSR93和B.megaterium WSR22菌株能明显地抑制大豆孢囊线虫卵的孵化,相对抑制率分别为97.9％和98.2％,对2龄幼虫也有较强的毒杀作用,校正死亡率分别为88.9％和90.9％.研究表明,野生大豆组织中内生细菌具丰富的多样性,其胞外分泌物中存在天然杀线活性物质.