Selection and characterization of a new switchgrass (Panicum virgatum L.) line with high somatic embryogenic capacity for genetic transformation

Switchgrass (Panicum virgatum L.) is used horticulturally as an ornamental and agronomically as an animal feedstock and a putative bio-energy crop. Genetic transformation, using somatic embryogenic (SE) callus derived from mature seeds, is one strategy for improving switchgrass traits. A superior switchgrass line, HR8, was developed in this study using recurrent tissue culture selection from cv. Alamo. Eighty two percent of HR8 seeds germinated after harvest comparing to 26.8% for unselected ‘Alamo’. HR8 seeds that germinated produced 84.9% SE callus. HR8 seeds had higher endogenous abscisic acid (ABA) contents and responded differently to exogenous additions of ABA in culture. Endophytes were isolated from switchgrass seeds and callus. HR8 callus had less endophytic contamination than that of ‘Alamo’ callus. HR8 SE calli were genetically transformable using Agrobacterium. Therefore, HR8 is a superior line for generating SE callus and Agrobacterium-mediated transformation.     

黄芪根腐病生防菌株的筛选鉴定及其防效评价

以沙棘根瘤内生细菌为材料,筛选对黄芪根腐病具有生防效果的菌株,以期为黄芪根腐病的生物防治提供优质菌种。采用平板对峙法,筛选得到抑菌性能较强的沙棘根瘤内生细菌TT14,并检测其对4株黄芪根腐病原菌的抑菌活性;根据形态和培养特征,生理生化特性及16S rRNA基因序列分析,对菌株TT14进行鉴定;通过盆栽试验,测定菌株TT14发酵液对黄芪根腐病的防治效果。结果显示,25株沙棘根瘤内生细菌中,11株具有抑制黄芪根腐病的能力,其中5株对供试的4株黄芪根腐病病原菌都表现出较好的抑菌效果,在这5株内生菌中TT14抑菌效果最佳,其对4株病原菌的抑菌率均在54.52%以上;经鉴定菌株TT14为特基拉芽孢杆菌(Bacillus tequilensis);盆栽试验显示菌株TT14发酵液对黄芪根腐病有明显的生防效果,其防治效果达65.68%,较对照组提高38.08%。综上可见,沙棘根瘤内生细菌TT14具有较强的抑制黄芪根腐病的活性,并具有较好的生防效果。     

特殊生境微生物脂肪酶及其在生物柴油中的应用

脂肪酶在精细化工、洗涤、医药、食品和生物柴油等领域有着巨大的应用潜力,是最有经济价值的生物催化剂之一。然而当前的脂肪酶并不能满足所有的工业需求,因此从特殊生境中发掘新型微生物脂肪酶,是近年来脂肪酶催化领域的热点。     

Effect of the endophyte <Emphasis Type="Italic">Neotyphodium lolii</Emphasis> on susceptibility and host physiological response of perennial ryegrass to fungal pathogens

The effect of the endophyte Neotyphodium lolii on susceptibility of perennial ryegrass (Lolium perenne) to ten fungal pathogens in detached leaves was studied. The pathogens were Alternaria alternata, Ascochyta leptospora, Bipolaris sorokiniana, Curvularia lunata, Fusarium acuminatum, F. avenaceum, F. chlamydosporum, F. solani, F. oxysporum, and Gliocladium roseum. In addition, the effect of the endophyte on four pathogens (A. alternata, B. sorokiniana, Curvularia lunata and F. avenaceum) in living plants was studied, and changes in host superoxide dismutase (SOD) or peroxidases (POD) activity were examined. The total lengths of lesions on detached leaves were greater (P < 0.05) on E- plants than on E+ plants except for A. leptospora although differences between E+ and E- were not consistently significant at all sample times (days after inoculation).The numbers of lesions were greater (P < 0.05) and the lesions were larger (P < 0.05) on intact E- plants than on intact E+ plants for all of the four pathogens. SOD enzyme activity was significantly greater (P < 0.05) in E+ plants than in E- plants only for A. alternata, C. lunata, and F. avenaceum. POD enzyme activity was significantly greater (P < 0.05) in E+ plants than in E- plants only for C. lunata, B. sorokiniana and the uninoculated control.     

锰、水杨酸与内生真菌互作对醉马草种子萌发的影响

本研究通过纸上芽床发芽试验,明确不同浓度的Mn处理对带(E+)与不带内生真菌(E-)醉马草(Achnatherum inebrians)种子萌发的抑制作用以及外源水杨酸(salicylic acid, SA)对Mn胁迫的缓解作用。结果表明,与添加Mn处理相比,E+醉马草种子发芽率和发芽指数均显著(P<0.05)高于E-醉马草种子,随着Mn处理浓度的增大,E+醉马草种子的萌发率均显著降低(P<0.05),而E-醉马草种子发芽率和发芽指数无显著差异;随着Mn处理浓度的增加,E+和E-醉马草根长均呈明显的下降趋势,而芽长无显著差异;在外源SA各处理浓度下,E+醉马草根长均显著(P<0.05)高于E-醉马草根长,在10mg·L^-1Mn处理液中分别添加不同浓度的外源SA,结果显示外源SA对Mn处理具有缓解作用。综上所述,内生真菌本身影响醉马草种子的萌发,重金属胁迫对醉马草种子萌发具有一定的抑制作用,而外源SA可以适当地缓解这一胁迫。     

抗肿瘤药用植物及其内生菌活性代谢产物的研究

综述近年来药用植物及其内生菌抗肿瘤活性代谢产物的研究成果。药用植物内生菌的次生代谢产物中,具有抗肿瘤作用的成分主要包含萜类化合物、生物碱类化合物、苯丙素类化合物、黄酮类化合物等多种活性物质,该研究结果为利用药用植物内生菌开发抗癌药物提供一条新的途径。     

植物内生菌活性成分研究进展

植物内生菌是一种新的微生物资源,近年来通过内生菌途径得到的活性物质不仅种类繁多,而且有许多未开发的新化舍物,其中一些化合物在抗菌、抗肿瘤、抗病毒等方面有较高的活性,特别是新近筛选出对心血管疾病、艾滋病病毒显示活性的内生菌,引起广大科学工作者的重视。介绍了植物内生菌的生物多样性、产活性物质的内生菌种类、活性筛选策略。     

内生真菌对草坪型高羊茅草弯孢霉叶斑病的影响

研究了草坪型高羊茅品种CrossfireⅡ的含有内生真菌（简称带菌）和不含内生真菌（简称不带菌）植株,接种新月弯孢霉病原菌后叶斑病的发生情况。结果表明：带菌植株的发病率和病情指数明显低于不带菌植株,抗病效果达30%以上。叶片保护酶活性测定结果表明,过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）酶活性在接种病原菌前,带菌植株低于不带菌植株;接种病原菌后,带菌植株这2种酶的活性均显著增加,增加的幅度和速度均较不带菌植株叶片相应酶活性大;多酚氧化酶（PPO）酶活性的变化没有规律性。     

茄类内生菌的分离及拮抗细菌的筛选(英文)

[Objective] The aim of this study was to isolate the endophyte of three solanaceae fruits and vegetables such as tomato, pepper and eggplant, to screen and identify the bacterial wilt antagonistic bacteria. [Method] According to the lapping liquid culture method, the endophyte of three plants was isolated by the selective medium and purified by the plate streaking method, so the purified endophyte was screened by the hyphal pieces confront culture method. Furthermore, the screened antagonistic and endophyteic bacteria was identified and classified through culture characteristics of isolates and morphological features of thallus, Gram stain as well as physiological and biochemical reactions. [Result] Fifty-three endophytic bacteria, fifty-three endophytic fungi and forty-four endophytic actinomycetes were separated from the endophyte of three plants. The screened fourteen endophytic bacteria with strong antagonistic effect on the bacterial wilt were classified to Bacillus, Escherichia, Klebsiella, Agromonas, Erwinia and Curto Bacterium respectively. Especially, Bacillus was the dominant species, which had the strongest antagonistic effect on the bacterial wilt. [Conclusion] This study provides an effective way for biological control of the bacterial wilt in solanaceae.     

茄类内生菌的分离及拮抗细菌的筛选

1材料与方法 1．1植株及病原菌 健康的番茄、辣椒及茄子植株,采自茂名市郊区菜园;茄科雷尔氏菌（Ralstonia solanacearum）由茂名学院生物技术与食品工程实验中心分离得到。