我国12个地区草莓叶螨种类分子鉴定及遗传多样性

为明确草莓上的叶螨种类及其遗传多样性,以便准确有效地指导草莓叶螨防治。本研究选取我国12个代表性的地区,采集草莓上的叶螨。采样范围覆盖了我国华北、华中、华东和西南的草莓产区。扩增和测定线粒体cox1基因部分序列,将所获得的序列通过BLAST与GenBank数据库中的序列进行比对,确定叶螨种类,并对cox1基因序列的多样性进行分析。测序获得了长度为632bp的cox1基因片段。BLAST比对结果和系统发育分析表明,来自我国12个地区的91个样品均为二斑叶螨Tetranychus urticae。遗传多样性分析发现我国草莓上二斑叶螨的cox1基因有2种单倍型,其中11个地区仅存在1种单倍型,北京昌平检测到2种单倍型。两种单倍型之间有1个核苷酸的同义突变。本研究表明,二斑叶螨为这些地区草莓上唯一的叶螨种类,种群内遗传多样性非常低。研究结果对于制定草莓上叶螨的防治策略具有指导意义。     

Estimates of Breed Average Direct,Maternal and Heterosis Effects for Some Pre-weaning Traits of Zebu Breeds and Their Crosses in Southeastern Mexico

Information on 936 birth weights (BW), adjusted weaning weights (AWW) and average daily gains (ADG) from Brahman (B), Indubrazil (I), Gyr (G) and commercial Zebu (C) cattle and their crosses were obtained from the records of a farm in the State of Yucatan, Mexico. Two statistical models were used to analyse the data: the first included the effects of year and season of birth, sex of the calf, cow's parity number and breed group. The other model included the same environmental effects as the previous model and the genetic components of breed group (breed additive, breed maternal and heterosis effects). Additive and maternal effects were expressed as deviations from those for the B breed. The means of BW, AWW and ADG for the B breed were 33.3 ± 0.64 kg, 204.0 ± 4.9 kg and 760.06 ± 19.24 g/day, respectively. Both models gave similar results in terms of the variance explained. Additive effects were significant (p < 0.05) for AWW and ADG but not for BW. The minor additive effect was for the C breed (−10.75 kg and −40.77 g for WW and ADG, respectively). Maternal and heterosis effects were not significant (p > 0.05) for any of the traits. The correlation between the breed group means and the means estimated by the prediction equation was r = 0.88. Finally, there was no significant genetic effect on pre-weaning calf performance among the genotypes evaluated. The genetic model can be used to predict the genotype means with a high degree of accuracy. This revised version was published online in July 2006 with corrections to the Cover Date.     

拟南芥霜霉病抗性分子机制研究进展

随着近年分子生物学技术的发展与应用,植物霜霉病抗性的研究有了长足的进展。本文就拟南芥抗霜霉病基因的克隆与结构分析,抗病信号传导,防卫反应和系统获得抗性,以及寄主-寄生菌共进化冲突方面进行了综述,并就今后的研究进行了展望。     

Genetic characterization by fluorescent AFLP of Pseudomonas savastanoi pv. savastanoi strains isolated from different host species

The genetic diversity of 71 Pseudomonas savastanoi pv. savastanoi strains isolated from different host species and from diverse geographical regions was determined by fluorescent amplified fragment length polymorphism (f-AFLP) analysis. The study was carried out using three different selective primer combinations. Strains of P. syringae pv. syringae , P. syringae pv. phaseolicola , P. syringae pv. glycinea , P. syringae pv. tagetis and P. amygdali were also included as outgroups. Based on cluster analysis of f-AFLP data, all P. savastanoi pv. savastanoi strains showed a high degree of similarity, grouping in a cluster and forming a taxon clearly separate from outgroup strains. AFLP analyses failed to support placing strains of P. savastanoi pv. savastanoi , P. syringae pv. phaseolicola and P. syringae pv. glycinea in the same species. Strains of P. savastanoi pv. savastanoi formed subclusters that correlated with the host species. Strains identified within these subclusters were related to the geographical region where the strains were isolated. Strains of P. savastanoi pv. savastanoi from olive were divided into two subclusters. Strains from oleander were differentiated from those from ash and were divided into two additional subclusters, distinct from olive strains. Three strains isolated from jasmine showed a high level of similarity among them but, at a lower Dice similarity coefficient, were linked to a subcluster including olive strains. Finally, two strains isolated from privet were similar to strains from olive and were included in the same subcluster.     

Pythium yorkensis sp. nov., a potential soybean pathogen from southeastern Pennsylvania,USA

Biodiversity surveys of natural as well as agricultural ecosystems commonly reveal novel isolates. A new species, Pythium yorkensis sp. nov., is reported here, isolated from field soil during a survey of oomycete diversity in symptomless soybean across southeastern Pennsylvania. Molecular data from both mitochondrial and nuclear loci support a unique phylogenetic position for the isolates collected, and morphological features distinguish this new species from close relatives in Pythium clade J. Pathogenicity assays suggest that this new species may be a potential agricultural pathogen, as isolates were mildly aggressive on soybean. This study highlights the continued need for culture‐based surveys in collaboration with high‐throughput sequence‐based approaches for environmental sampling.     

Prevalence of Bovine Dermatophilosis in a Tropical Highland Region of Ethiopia

A study was made of bovine dermatophilosis on 540 animals at a high altitude (2400–2500 m above sea level) in Ethiopia. Eighty-two (15.4%) of the animals were affected by the disease which was more prevalent in local animals than was previously assumed. There was a significant (p<0.05) difference in the prevalence among different age groups. However, the difference in the prevalence of the disease between males and females was not significant (p>0.05). Associated risk factors included the relatively high average annual rainfall and humidity, tick infestation (76%) and management, related to the mixed crop-livestock production system. The possible impact of the disease on Ethiopian agriculture is indicated.     

高效实用型黄瓜嫁接技术——生长点斜插法

为了提升黄瓜嫁接苗对设施栽培连作障碍的耐受能力,提高幼苗的抗病性与抗逆性,同时确保嫁接成活率,增加产品产量及品质,在传统的黄瓜嫁接方法基础上,改进出高效实用的生长点斜插嫁接法,为此创新出了专用嫁接工具——β形铝合金嫁接签,并申报了实用新型专利（专利号： 201811595026.X）;为了提高嫁接苗的成活率,在对砧穗进行特定处理的同时,还探索出了嫁接苗生长最佳环境的保障装置——育苗钢架。通过育苗基质的营养控制、省略嫁接夹具的插接方法及保温保湿的育苗钢架等系列配套技术的使用,使得生长点斜插嫁接技术具备了突出的实用性与高效性,十分适合在实际生产中推广使用。     

祁连山中段退化高寒草地土壤细菌群落分布特征

为探究祁连山中段不同退化高寒草地土壤细菌群落分布特征,采用Illumina HiSeq PE250高通量测序平台对轻度、中度和重度退化草地土壤细菌群落变化特征进行研究,并对土壤细菌群落与土壤酶活性、土壤理化因子间关系进行分析。结果表明:随着退化程度加剧,植被盖度、高度、地上生物量和多样性指数均明显降低(P<0.05);土壤理化性质和酶活性变化各异且差异显著(P<0.05)。高通量测序共得到257971条有效序列,219017条优质序列和2004个OTUs。细菌群落丰富度指数依次为轻度>中度>重度,多样性指数为轻度>重度>中度,Beta多样性分析表明各样地间差异为轻度>重度>中度。其中,放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)、酸杆菌门(Acidobacteria)和变形菌门(Proteobacteria)为3种退化草地土壤的优势菌门,在轻度、中度和重度退化草地土壤中分别占77.25%、84.27%和78.66%;乳球菌属为3种退化草地土壤的优势菌属,在轻度、中度和重度退化草地土壤中分别占14.29%、38.84%和7.39%。冗余分析表明:土壤酶活性和土壤理化性质均对细菌群落的组成具有影响,其中土壤pH是影响土壤细菌群落分布的主要驱动因子。祁连山中段不同退化高寒草地土壤细菌群落的变化主要受土壤理化性质和酶活性的影响。     

基于线粒体基因cyt b和COI的莺科部分鸟类系统发育

雀形目(Passeriformes)莺科(Sylviidae)鸟类广泛分布于旧大陆,该科许多种类的系统发育关系一直存在争议.本研究采用分子系统学方法,对莺科11属37种鸟类的cyt b全基因序列和COI部分基因序列进行系统发育分析,构建TML和Bayesian系统发育树.结果显示,柳莺属(Phylloscopus)并非单系发生,(鹟)莺属(Seicercus)可能是其同类或其属下的一个类群;在柳莺属内,乌嘴柳莺(P.magnirostris)与极北柳莺(P. borealis)亲缘关系较近;黄腰柳莺(P.proregulus)、云南柳莺(P.yunnanensis)、橙斑翅柳莺(P. pulcher)及灰喉柳莺(P. maculipennis)亲缘关系较近;黄腹柳莺(P.occisinensis)、巨嘴柳莺(P.schwarzi)、棕眉柳莺(P. armandii)、叽喳柳莺(P. collybita)及褐柳莺(P.fuscatus)亲缘关系较近;树莺属(Cettia)并非单系发生,与拟鹅莺属(Abroscopus)和地莺属(Tesia)聚在一起;大苇莺属(Acrocephalus)为单性系;此外,林莺属(Sylvia)与绣眼鸟属(Zosterops)的亲缘关系、以及鹪莺属(Prinia)、缝叶莺属(Orthotomus)及扇尾莺属(Cisticola)三者间的亲缘关系也被支持.     

甘肃黄鸡早期生长发育规律的分析

为探讨甘肃黄鸡的育效果及其利用价值，对甘肃黄鸡早期生长发育规律进行了系统测定。结果表明，甘肃黄鸡体重达２．０kg的日龄平均为８７．５d（公鸡７７d，母鸡９８d)，全期饲料转化比为２．９３，成活率较高达９４．０％，甘肃黄鸡９周龄时体重接近１．５kg,有一定的市场意义，可以考虑及早上市；对甘肃黄鸡体重进行选择时，应同时注意对胫长的适当控制。