排序方式： 共有45条查询结果，搜索用时 312 毫秒
31.
中国南方八省（自治区）水稻纹枯病菌群体遗传结构的SSR分析 总被引：2，自引：0，他引：2
【目的】明确中国南方水稻纹枯病菌不同地理群体的遗传结构,为研究该病害的流行规律提供信息。【方法】采用8个SSR荧光标记对收集自中国南方8省（自治区）的188个水稻纹枯病菌进行检测。利用POPGENE version 1.31软件计算各项遗传多样性参数,近交系数由FSTAT 2.9.3软件估算。基于马尔可夫链模型,采用GENEPOP 4.2软件以卡方检验估计Hardy-Weinberg平衡。应用Arlequin 3.1软件进行分子方差变异分析,并通过遗传分化系数计算基因流。基于Nei’s遗传距离,利用MEGA5.0软件构建UPGMA树状图。使用STRUCTURE 2.3.3软件的贝叶斯聚类法进行群体遗传结构分析,并估计群体间遗传混杂程度。采用Mantel test检测遗传距离与地理距离的相关性。【结果】8个地理群体的平均观测等位基因数和有效等位基因数分别为4.025和2.071。Shannon’s信息指数为0.659-1.088,平均为0.859。等位基因丰富度为2.500-5.152,平均为3.858。观测杂合度为0.425-0.619,平均为0.506。期望杂合度为0.399-0.546,平均为0.472。总群体水平的近交系数（FIS = -0.069）为负值,表明总群体内杂合子过剩（纯合子缺失）。Hardy-Weinberg平衡检验表明,在6个群体中存在因杂合子的缺失或过剩引起的平衡偏离,暗示了水稻纹枯病菌同时具有克隆生长和有性繁殖,两种繁殖方式间的平衡因群体而异。AMOVA分析结果显示,有88.14%的遗传变异来自群体内部的个体间,表明遗传变异主要发生在群体内。Mantel检测发现,遗传距离与其地理距离之间呈显著正相关（r=0.422,P=0.025）。UPGMA聚类表明,所有群体可被划分为遗传分化明显的两个亚群（FST =0.209-0.624）,其中位于珠江沿岸的广宁和长塘群体为一个组群,而位于长江沿岸的6个群体为另一组群,与遗传结构分析结果一致。位于长江沿岸的群体遗传混杂明显,基因交流水平高（Nm=2.525-8.447）,群体分化程度较低（FST=0.029-0.094）。【结论】中国南方水稻纹枯病菌分布范围广泛、可能的混合繁殖模式以及菌核或菌丝具有远距离传播特性,是导致其遗传多样性水平较高的原因。长江亚群内部个体在不同群体之间的迁移所形成的基因流动,在一定程度上阻止了群体间的遗传分化。而长江亚群和珠江亚群之间存在明显的遗传分化,推测病原菌有限的长距离迁移可能是群体遗传变异空间结构形成的主要原因。 相似文献
32.
Rhizoctonia crown and root rot (RCRR), caused by Rhizoctonia solani Kühn AG 2-2 IIIB, is an important disease of sugar beet. While RCRR can be managed by agronomic practices, plant resistance remains the primary method for control. However, the molecular processes that mediate resistance to R. solani are largely unknown. The metabolic changes that occurred during susceptible and resistant R. solani interactions were compared and characterized using nontargeted metabolomic profiling. Metabolites from infected and healthy, root and leaf tissue, were taken at 0 and 7 dai and detected using reversed-phase UHPLC-MS and GC-MS. There was a clear distinction in the metabolome between tissue type and genotype, and in response to R. solani. 143 compounds were annotated and several metabolites associated with plant defense to fungi were identified in both germplasm. 相似文献
33.
不同品种种公牛繁殖性能分析 总被引：1，自引：0，他引：1
[目的]在相同的饲养环境条件下,分析不同品种种公牛之间繁殖性能及适应性的差异。[方法]通过对云南省家畜冷冻精液站四个品种的种公牛相关精液品质测量数据及终生冻精产量数据进行对比分析。[结果]经过对16头种公牛繁殖性能及适应性分析,荷斯坦种公牛原精活力及冻后活力都较其它种公牛表现出较明显的优势;荷斯坦种公牛在有效采精率及冻精产量上也明显高于其它品种公牛。 相似文献
34.
Soil suppressiveness and functional diversity of the soil microflora in organic farming systems 总被引：1，自引：0，他引：1
Joeke Postma Mirjam T. Schilder Jaap Bloem Wiepie K. van Leeuwen-Haagsma 《Soil biology & biochemistry》2008,40(9):2394-2406
Arable fields of 10 organic farms from different locations in The Netherlands were sampled in three subsequent years. The soil samples were analysed for disease suppressiveness against Rhizoctonia solani AG2.2IIIB in sugar beet, Streptomyces scabies in radish and Verticillium longisporum in oilseed rape. In addition, a variety of microbial, chemical and physical soil characteristics were assessed. All data were correlated by multiple regression and multivariate analyses with the objective to find correlations between soil suppressiveness and biotic or abiotic soil characteristics. Significant differences in soil suppressiveness were found between the fields for all three diseases. Multiple regression indicated a significant correlation between suppressiveness against Rhizoctonia and the number of antagonistic Lysobacter spp., as well as with % active fungi and bacterial diversity. Grass-clover stimulated Rhizoctonia suppression as well as the presence of antagonistic Lysobacter spp. (mainly L. antibioticus and L. gummosus) in clay soils. Streptomyces suppression correlated with the number of antagonistic Streptomyces spp., % of active fungi and bacterial population size. The presence of antagonistic Streptomyces spp. correlated with a high fungal/bacterial biomass ratio. Verticillium suppression was only measured in 2004 and 2005, due to the inconsistent suppressiveness along the years. Nevertheless, a significant correlation with pH, potential nitrogen mineralization and bacterial biomass was found. Bacterial and fungal PCR-denaturing gel electrophoresis fingerprinting of bacterial and fungal communities, in general, did not significantly correlate with disease suppression. Highly significant explanatory factors of the composition of the dominating bacterial and fungal populations were % lutum, pH, C/N quotient, biomass and growth rate of bacteria. Additionally, the % of organic matter and years of organic farming were explaining significantly the composition of the bacterial population.Thus, significant correlations between several soil characteristics and suppressiveness of different soil-borne pathogens were found. For two of the three pathogens, suppression correlated with biotic soil characteristics combined with the presence of specific bacterial antagonists. Probably the soil suppressiveness measured in the organic fields is a combined effect of general and specific disease suppression. 相似文献
35.
微卫星序列包含有多种重复单元,在其两碱基重复的类型当中,CT／GA重复类型在功能基因组中比例较高。三疣梭子蟹是重要的养殖品种,对遗传种质的分析需要开发大量的分子标记,本文利用5’锚定引物PCT筛选三疣梭子蟹的CT／AG微卫星分子标记,测序的41个克隆子中,35条序列含有微卫星DNA序列,阳性克隆比率达到85．4％,共检测到55个微卫星位点,分布于20条序列中,其中19条序列检测到2个或2个以上微卫星位点。对所有筛选到的微卫星位点进行分类统计后表明,核心序列为（CT／AG）的有27个（50％1,27个位点为其他类型的重复。结果表明三疣梭子蟹CT／AG微卫星标记在三疣梭子蟹基因组中含量较丰富,5’锚定引物法在筛选特定标记的同时,还筛选了其他类型的微卫星标记,具有较强的筛选效率。 相似文献
36.
本研究对从海南岛尖峰岭热带雨林自然保护区的土壤样品中分离出的＆菌株S1478～1进行了特性鉴定,研究表明S1478—1分离株菌落形态和生长特征和励参照菌株HD73极其相似。16SrDNA序列分析表明,S1478—1分离株与其它＆thuringiensis、B．cereus和B.anthracis的16S rDNA序列相似性达到99％。分离株能产菱形伴胞晶体,SDS-PAGE蛋白电泳分析表明,菌株在生长后期,形成芽孢同时分泌130kD大小的晶体蛋白。生物测定表明S1478—1分离株对小菜蛾具有很高的毒杀活性,LC50值高达5．159×10^8cfu／mL。初步显示S1478—1分离株可作为防治鳞翅目害虫的生物农药菌株。利用PCR—RFLP方法鉴定S1478—1分离株含有cry1Ac同源基因,以PCR粘性端克隆方法扩增全长基因,序列测定表明该基因ORF为3537bp,编码1178个氨基酸,推定的编码蛋白分子量为133．3kD,与其它cry1Ac基因序列最高达到99％同源,因此,该基因可作为杀虫工程菌及培育转基因抗虫作物的候选基因。 相似文献
37.
为检测Janus激酶/信号转导与转录激活子(JAK/STAT)信号通路抑制剂α-氰-3, 4-二羟基-N-苄基肉桂酰胺(AG490)对单核细胞增生李斯特菌(LM)感染小鼠脑微血管内皮细胞和小鼠的影响,将不同浓度抑制剂AG490与细胞共同孵育,然后将LM分别感染细胞,MTT法检测不同浓度抑制剂AG490对细胞活性的影响;利用菌落计数法计算LM的侵袭率和胞内细菌数量,检测AG490对LM介导的小鼠生存曲线的影响;利用试剂盒检测抑制剂AG490对LM介导的乳酸脱氢酶(LDH)、白细胞介素-1β(IL-1β)、干扰素-γ(IFN-γ)和白细胞介素-6(IL-6)分泌的影响;利用实时定量PCR检测AG490对LM介导的炎性小体NLRP3的mRNA水平影响。结果:抑制剂AG490在5、10或15μmol/L浓度时未见对细胞活性有明显影响,AG490显著抑制了LM的侵袭、胞内和脏器内细菌数量,提高小鼠成活率,显著提高LM介导的LDH、IFN-γ、IL-6、IL-1β和NLRP3的mRNA水平。本研究表明,JAK/STAT信号通路抑制剂AG490可调控细胞内LM的存活,增强LM介导的细胞炎性小体水平,为调查LM引起脑膜炎的致病机制提供科学依据。 相似文献
38.
39.
H. Ellen 《Soil & Tillage Research》1984,4(5):471-484
Rotary tillage experiments were carried out under laboratory conditions in 3 types of Dutch soil. The moisture contents were set at 6 levels. Two tools were used; a knife blade and a tine. The energy required to work the soil was assessed with a pendulum.The specific energy requirement was expressed in units per volume of loosened soil, EV (kJ m?3) and also in units per surface area of loosened soil, EA (kJ m?2). In silty clay loam EV ranged between 153 and 160 kJ m?3 for the knife blade, and increased from 170 to 280 kJ m?3 for the tine, when the moisture content increased from 17 to 22%. EA increased from 2.5 to 9 kJ m?2 × 10?1 for the knife blade and from 3.8 to 10.5 kJ m?2 × 10?1 for the tine, when the moisture content increased from 17 to 22%.In sandy loam EV decreased from 110 to 75 kJ m?3 for the knife blade and from 165 to 130 kJ m?3 for the tine, when the moisture content increased from 9.5 to 17% EA increased from 1 to 2.5 kJ m?2 × 10?1 for the knife blade and increased from 2.7 to 2 kJ m?2 × 10?1 for the tine, when the moisture content increased from 9.5 to 17%.In silty loam EV decreased from 117 to 95 kJ m?3 for the knife blade and from 170 to 137 kJ m?3 for the tine, when the moisture content increased from 17 to 22%. EA increased from 3.7 to 5 kJ mm?2 × 10?1 for the knife blade, and from 3 to 5.5 kJ m?2 × 10?1 for the tine, when the moisture content increased from 17 to 22%.The energy requirement was related to penetration resistance, shearing resistance and modulus of elasticity. In silty clay loam the penetration resistance decreased from 3.9 to 2.6 MPa × 10?1, the shear resistance hardly changed and ranged between 0.8 and 0.9 MPa × 10?1, and the modulus of elasticity decreased from 46 to 23 MPa × 10?1, when the moisture content increased from 17 to 22%.In sandy loam the penetration resistance decreased from 5.5 to 1.9 MPa × 10?1, the shear resistance decreased from 0.6 to 0.4 MPa × 10?1 and the modulus of elasticity decreased from 84 to 15 MPa × 10?1, when the moisture content increased from 9.5 to 17%. In silty loam, the penetration resistance decreased from 3.6 to 1.7 MPa × 10?1, the shear resistance decreased from 0.6 to 0.4 MPa × 10?1 and the modulus of elasticity decreased from 58 to 11 MPa × 10?1 when the moisture content increased from 17.5 to 22%. 相似文献
40.
Haixia ZhangDouglas J.H. Olson Dang VanRandy W. Purves Mark A. Smith 《Industrial Crops and Products》2012,37(1):186-194
Triacylglycerol-estolides are components of the storage oil of certain plant and fungal species and are generally associated with the presence of fatty acids containing hydroxyl groups. These unusual acyl-glycerols can easily go undetected when oils are analyzed by gas chromatography of fatty acid methyl esters, or by thin layer chromatography if the TAG-estolides and TAG have similar polarity. We describe the detection of TAG-estolides in intact seeds of Lesquerella lyrata and whole sclerotia of the ergot fungus Claviceps purpurea using 1H MAS-NMR for nondestructive analysis. We also conducted analysis of small amounts of oil by MALDI-TOF MS to clearly show the presence of TAG-estolides and to rapidly characterize their acyl composition. The matrix used in this work was 2,4,6-trihydroxyacetophenone (THAP) made up in sodium chloride-saturated solvent. We were able to confirm the presence of TAG-estolides with no free hydroxyl groups in the fungal oil, and TAG-estolides with free hydroxyl groups in the oil of L. lyrata. The development of a technique for the rapid identification of TAG-estolides in oil samples will simplify the detection of these novel lipids in plant and fungal species. 相似文献