A Bayesian analysis of gene flow from crops to their wild relatives: cultivated (Lactuca sativa L.) and prickly lettuce (L. serriola L.) and the recent expansion of L. serriola in Europe

Interspecific gene flow can lead to the formation of hybrid populations that have a competitive advantage over the parental populations, even for hybrids from a cross between crops and wild relatives. Wild prickly lettuce (Lactuca serriola) has recently expanded in Europe and hybridization with the related crop species (cultivated lettuce, L. sativa) has been hypothesized as one of the mechanisms behind this expansion. In a basically selfing species, such as lettuce, assessing hybridization in natural populations may not be straightforward. Therefore, we analysed a uniquely large data set of plants genotyped with SSR (simple sequence repeat) markers with two programs for Bayesian population genetic analysis, STRUCTURE and NewHybrids. The data set comprised 7738 plants, including a complete genebank collection, which provided a wide coverage of cultivated germplasm and a fair coverage of wild accessions, and a set of wild populations recently sampled across Europe. STRUCTURE analysis inferred the occurrence of hybrids at a level of 7% across Europe. NewHybrids indicated these hybrids to be advanced selfed generations of a hybridization event or of one backcross after such an event, which is according to expectations for a basically selfing species. These advanced selfed generations could not be detected effectively with crop‐specific alleles. In the northern part of Europe, where the expansion of L. serriola took place, the fewest putative hybrids were found. Therefore, we conclude that other mechanisms than crop/wild gene flow, such as an increase in disturbed habitats and/or climate warming, are more likely explanations for this expansion.     

谷子(Setaria italica(L.) P. Beauv.)作为功能基因组研究模式植物的发展现状及趋势

模式植物对遗传学和分子生物学前沿理论探索和实践研究至关重要。玉米、拟南芥和水稻等主要的模式植物,在植物遗传学发展的不同时期发挥了不可替代的作用,但随着研究的深入和细化,迫切需要更多别具特色的物种成为模式植物。谷子(Setaria italia)及其野生种青狗尾草(S.viridis)因具备C_4光合途径和特殊的抗旱耐逆性备受关注,谷子也因其较小的二倍体基因组、自花授粉、高繁殖系数、较小的株高和易于操作的栽培方法,以及生育周期短、易于快速繁殖等特点,非常适合作为分子遗传学研究的模式植物,近年来作为C4和抗旱耐逆研究的模式系统越来越受到国际植物遗传学界的关注。谷子是起源于中国的古老农作物,我国拥有最丰富的遗传资源,并在遗传育种研究上处于领先。现简述我国谷子的研究基础,综述近年来谷子和青狗尾草作为模式作物的研究进展,讨论相关研究存在的问题,并对谷子遗传研究的发展趋势进行展望。     

Testing the enemy release hypothesis: a comparison of foliar insect herbivory of the exotic Norway maple (Acer platanoides L.) and the native sugar maple (A. saccharum L.)

Norway maple (Acer platanoides) is a Eurasian introduced tree species which has invaded the North American range of its native congener, sugar maple (A. saccharum). One hypothesis used to explain the success of an invasive species is the enemy release hypothesis (ERH), which states that invasive species are often particularly successful in their new range because they lack the enemies of their native range. In this study, we hypothesized that Norway maple would have less insect damage than sugar maple due to such enemy release. Autumn 2005 and summer 2006 leaves of Norway and sugar maple were collected from six sites in New Jersey and Pennsylvania to compare percent leaf area loss, gall damage, fungal damage, and specific leaf area (cm²/g). Although both species had low overall mean levels of leaf damage (0.4–2.5%), in both years/seasons Norway maple had significantly less leaf damage than sugar maple. Insects were also collected to compare insect assemblies present on each tree species. The numbers of insect taxa and individuals found on each species were nearly equivalent. Overall, the results of this study are consistent with the enemy release hypothesis for Norway maple. In addition, sugar maples when surrounded by Norway maples tended to show reduced herbivory. This suggests that the spread of Norway maple in North America, by reducing amounts of insect herbivory, may have further ecosystem-wide impacts.     

应用白僵菌(Beauveria bassiana(Bals.) Vuill.)防治大豆食心虫(Grapholitha glycinivorella Mats.)的初步研究

1.白僵菌(Beauveria bassiana(Bals.)Vuill.)是大豆食心虫幼虫的寄生性真菌。自然寄生率5—10％,有时可达30％以上,是造成大豆食心虫幼虫自然死亡的有力因素之一。 2.白僵菌的发育及孢子发芽温度是18—28℃,其中以25—28℃最为适宜。适宜的发芽湿度要在99％以上。在土壤中如果温度适宜(25—28℃)土壤含水量10％以上就可以引起幼虫显著寄生。 3.幼虫体沾着一定数量的病菌孢子可以引起大量死亡,如果幼虫体上沾着孢子数4944个以上则可致100％寄生,不足此数的,寄生率成比例地降低。菌粉在太阳光照射下6天后寄生力受到影啊,30天以后寄生作用已极小。病菌对于带菌的幼虫虽可同样寄生,但寄生能力要比直接使幼虫接触孢子要小得多。 在室温下的菌粉中,病菌的生活力(致病力)可以保持一年左右。 4.利用白僵菌防治大豆食心虫的效果是:室内不论菌粉浓度及用量多少,寄生率均达100％。小区试验可致幼虫寄生70.19—100％,田间防治可以提高幼虫寄生30.15—36.11％,降低成虫羽化49.83—69.8％。 5.作者认为:利用白僵菌防治大豆食心虫是有希望的。今后是对于大量繁殖病菌的方法,施用药剂时期及与农药混用以提高效果有进一步研究之必要。     

Microsatellite mapping of genes that determine supernumerary spikelets in wheat (T. aestivum) and rye (S. cereale)

The wheat and rye spike normally bears one spikelet per rachis node, and the appearance of supernumerary spikelets is rare. The loci responsible for the ‘multirow spike’ or MRS trait in wheat, and the ‘monstrosum spike’ trait in rye were mapped by genotyping F₂ populations with microsatellite markers. Both MRS and the ‘monstrosum’ trait are under the control of a recessive allele at a single locus. The Mrs1 locus is located on chromosome 2DS, co-segregating with the microsatellite locus Xwmc453. The placement of flanking microsatellite loci into chromosome deletion bin 2DS-5 (FL 0.47–1.0) delimited the physical location of Mrs1 to the distal half of chromosome arm 2DS, within the gene rich region 2S0.8. The Mo1 locus maps about 10 cM from the centromere on chromosome arm 2RS. The similar effect on phenotype of mo1 and mrs1, together with their presence in regions of conserved synteny, suggest that they may well be members of an orthologous set of Triticeae genes governing spike branching. The practical importance of the MRS spike is that it produces more spikelets per spike, and thereby enhances the sink capacity of wheat, which is believed to limit the yield potential of the crop.     

The interplay of hybridization and clonal reproduction in the evolution of willows – Experiments with hybrids of S. eriocephala[R] & S. exigua[X] and S. eriocephala & S. petiolaris[P].

Clonal reproduction may contribute to plant evolution either by affecting population biology or by allowing partially sterile individuals (e.g., hybrids) repeated opportunities to reproduce sexually. The interplay of hybridization and clonal reproduction was first proposed by Stebbins (1950), but previously has not been tested experimentally. Alternative models for the effects of hybridization include speciation, introgression, and swamping. Salix spp. were chosen to test comparatively these hypotheses because they are easily hybridized and cloned. Over 500 separate crosses and backcrosses were made and over 6000 separate plants were measured in field experiments and statistically compared for significance to both evolutionary theory and plant breeding for biomass production. The F₁ hybrids in this study always equalled, and in the case of the hybrid PR, outperformed their parents in vegetative parameters. It seems likely that even without reproducing sexually, these F₁ hybrids could exist as successful individuals (sensu Stebbins 1950). However, it also seems likely that they would sexually reproduce: three of four F₁ hybrids studied (RX, RP, and PR) equalled or surpassed their parents in sexual parameters when crossing with at least one other accession. Of the alternative models, experimental data suggest that introgression would be the most likely outcome of a hybridization event. The hybrid XR, however, was partially sterile and performed poorly when crossing with all other accessions in its group except S. exigua (pistillate parent). Thus, this hybrid may fit Stebbins' model of a partially sterile yet vegetatively vigorous plant that can exist as a successful individual and make some contribution to interspecific gene flow over time. This is the first experimental study to confirm the evolutionary importance of clonal reproduction coupled with hybridization. However, distinguishing any of these evolutionary pathways would be difficult in nature using morphological techniques, as interspecific hybrids tend to resemble their pistillate parents in terms of leaf shape.     

假俭草(Eremochloa ophiuroides (Munro.)Hack.)种质资源改良研究进展

假俭草(Eremochloa ophiuroides (Munro.)Hack.)是主产于中国的世界著名的暖季型草坪草。全面系统地研究假俭草在遗传多样性和抗性生理等各方面的变异变化规律对于开发利用假俭草种质资源具有十分重要的意义。在综述假俭草种质资源的收集、整理和初步评价的基础上,重点介绍了近年来国内外在其遗传多样性(包括形态水平、细胞水平和分子水平)、抗性生理、育种进程和栽培管理措施等方面的研究进展。     

假俭草(Eremochloa ophiuroides(Munro.)Hack.)种质资源改良研究进展

假俭草(Eremochloa ophiuroides(Munro.)Hack.)是主产于中国的世界著名的暖季型草坪草.全面系统地研究假俭草在遗传多样性和抗性生理等各方面的变异变化规律对于开发利用假俭草种质资源具有十分重要的意义.在综述假俭草种质资源的收集、整理和初步评价的基础上,重点介绍了近年来国内外在其遗传多样性(包括形态水平、细胞水平和分子水平)、抗性生理、育种进程和栽培管理措施等方面的研究进展.     

苹果蠹蛾Cydia pomonella(L.)

<正>苹果蠹蛾Cydia pomonella(L.)是世界重要的苹果害虫,原产于欧洲中南部,现在已经入侵世界5大洲71个国家。该入侵昆虫1953年首次报道在中国新疆发现,目前已入侵新疆、甘肃、宁夏、内蒙古、黑龙     

云南栘(木衣)(Docynia delavayi(Franch.)Schneid.)黄酮成分研究

本文首次对采自云南西双版纳的栘(木衣)树皮的主要成分进行了研究,从其乙醚提取物中分离出四种黄酮类化合物,通过NMR、MS和IR等波谱手段,鉴定出它们分别为:白杨素(Chrysin,Ⅰ),柚皮素(Naringenin,Ⅱ),槲皮素(Quercetin,Ⅲ)和广寄生甙(Avicularin,Ⅳ)     

ПРИСПОСОБЛЕНИЯ К ПЛАНИРОВАНИЮ ПЕРЕДНИХ КОНЕЧНОСТЕЙ У ЛЕТЯГИ(Pteromys volans L.)

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Cytological differentiation between the two subgenomes of the tetraploid Emilia fosbergii Nicolson and its relationship with E. sonchifolia (L.) DC. (Asteraceae)

The diploid Emila sonchifolia (2n = 10) and the tetraploid E. fosbergii (2n = 20) species are widely distributed throughout tropical and subtropical America, and are the only two Emilia species occurring in Brazil. Emilia fosbergii displays two sets of ten chromosomes, one slightly larger than the other. The smaller chromosome set is similar to the chromosome complement of the diploid, which agrees with the suggested participation of E. sonchifolia in the formation of E. fosbergii. To elucidate this hypothesis, the relationship between the genomes of the two species was investigated using chromomycin A3 (CMA)/4’,6-diamidino-2-phenylindole (DAPI) double staining, distribution of 5S and 45S rDNA sites by fluorescence in situ hybridization (FISH) and whole genome comparison by genomic in situ hybridization (GISH). CMA/DAPI staining and FISH revealed the occurrence of one pair of CMA bands in E. sonchifolia and three pairs in E. fosbergii, all of them co-localized with 45S rDNA sites. Additionally, E. fosbergii displayed a fourth, small 45S rDNA site in its larger subgenome which was not detected as CMA band. Surprisingly, the euchromatin of the smaller subgenome of E. fosbergii stained less intensely with CMA than the larger one. The GISH procedure demonstrated the similarity between the genome of E. sonchifolia and the smaller chromosome set of E. fosbergii. GISH and CMA staining clearly demonstrate that E. fosbergii is an allotetraploid species and suggest E. sonchifolia as one of its ancestors. The maintenance of at least one pair of 5S and 45S rDNA sites per subgenome of E. fosbergii and the differentiation between its subgenomes by CMA staining seem to indicate that post-polyploidization changes are still incipient, probably because the polyploidization event and the origin of E. fosbergii were relatively recent.     

山东湖北海棠(Malus hupehensis (Pamp.) Rehd.)两新变种

记载了分布于山东省的两个湖北海棠的地理变种,泰山海棠与原变种区别于叶缘锯齿较钝较小,果实紫红色,直径约0.6 cm,花较小,直径不足2 cm;平邑甜茶与原变种区别于叶片较大,平展,锯齿大而钝,叶脉较多,较直行, 花萼齿披针形,长于萼筒。     

水稻(Oryza sativa L.)×狼尾草(Pennisetum sp.)胚胎发育的细胞学观察

1.狼尾草花粉可以在水稻柱头上萌发并能长入胚囊,但受精过程缓慢而且不正常,单受精现象经常出现。2.胚胎发育滞缓,长时间停留在球状胚阶段,很难进一步分化,而且不时败育,只在传粉后16—24天的一些胚囊中看到有简单分化的胚胎。3.胚乳发育异常,由游离核形成细胞的时间推迟到传粉后第八天。整个胚乳组织由形状及功能上均有很大差异的细胞团块组成。其中一部分细胞缺乏合成淀粉的能力,胚乳在发育过程中不时出现解体现象。4.在反足细胞附近的一些珠心细胞中出现多量淀粉积累,反映因杂交而出现的胚囊代谢上的某些变化。讨论了胚和胚乳发育困难的原因和得到杂种种子的可能性。     

红花(Corthamus tinotorius L.)和党参(Codonopsis pilosula Nannf.)的核型研究

本试验采用常规压片技术,对两种应用较广的中药材——红花和党参的染色体核型进行了分析,其结果报道如下: 1.红花(图1):淋细胞染色体数为2n=24,有10对染色体具中部着丝点,1对具随体(表1),2对染色体为亚中部着丝点。核型公式为:2n=24=20m(2SAT)+4sm。染色体绝对长度介于1.990μm-3.483μm之间,相对长度变动幅度为3.663—4.649。     

Two new records of ascomycetes from Japan,Pyrenopeziza protrusa and P. nervicola (Helotiales,Dermateaceae sensu lato)

Two Pyrenopeziza species, P. protrusa and P. nervicola known to have similar morphology, were newly reported from Japan. This study clarified that P. protrusa morphologically differs from P. nervicola in (1) more protruded outermost cells in ectal excipulum, (2) smaller ascospores, and (3) longer and thinner asci. Pyrenopeziza protrusa produces chlamydospore-like brown cells under culture while P. nervicola forms more complex, brown bulbils. These species formed distinct clades based on ITS-5.8S rDNA in the phylogenetic analysis. The two species did not share the same host.     

基于ISSR数据探讨卷叶凤尾藓(Fissidens dubius P.Beauv.)遗传多样性

卷叶凤尾藓(Fissidens dubius P.Beauv.)是凤尾藓科凤尾藓属植物,该种分布广泛,形态变异强烈。为了解其遗传多样性及种群遗传结构特点,本研究利用ISSR分子标记对采集于浙江、福建、广西、四川、辽宁5个省区的卷叶凤尾藓14个自然种群的遗传多样性进行了评价。结果显示:筛选出的12对引物共扩增出259条清晰、重复性高的条带,其中多态性位点有248个,多态位点百分率为95.75%;种群总的Nei's基因多样性指数为0.2327,Shannon's信息指数为0.3701,说明卷叶凤尾藓遗传多样性水平较高;14个种群的遗传分化系数(Gst)为0.7078,种群间的基因流(Nm)为0.1864,表明大部分遗传变异(72.01%)存在于种群间,27.99%的遗传变异存在于种群内,即卷叶凤尾藓种群间遗传分化明显。基于ISSR数据的聚类分析表明,在遗传距离50为分组阈值处,14个种群可被分为6组(G1~G6):G1为来自于浙江省不同采集地点的8个种群(JHBS除外);G2由浙江金华北山种群(JHBS)组成;G3包括福建武夷山(WYS)和天宝岩种群(TBY);G4、G5、G6分别由广西龙胜县花坪种群(GX)、四川龙池种群(LC)、辽宁白石砬子保护区种群(BSLZ)组成,表明卷叶凤尾藓种群间的遗传分化主要由地理距离造成,种群内的遗传分化可能与其生境的异质性有关。     

黑竹冲河小裳蜉(Leptophlebia sp.)和蜉蝣(Ephemera sp.)周年生产量

大型底栖动物在河流生态系统中发挥着重要作用。2003年6月至2004年6月间对汉江流域2级河流--黑竹冲河大型底栖动物群落优势种类的生产力进行了为期一周年的调查研究。结果表明,主要优势种小裳蜉(Leptophlebia sp.)和蜉蝣(Ephemera sp.)的生活史均为一年两代,蜉蝣的两个代之间界限比较明显;小裳蜉成虫羽化主要发生在秋季和冬季,而蜉蝣成虫羽化主要发生在夏季和冬季。小裳蜉和蜉蝣种群的生物量和多度均出现两次峰值。采用体长频率法(size-frequencymethod)测算的周年生产量分别为:小裳蜉,38.0362g·m^-2·a^-1,P/B为11.4;蜉蝣,76.0318g·m^-2·a^-1,P/B为11.8。     

甘薯蚁象Cylas formicarlus(F.)

<正>甘薯蚁象隶属于鞘翅目Coleoptera锥象科Brenthidae,是危害甘薯的重要害虫,成虫和幼虫均危害甘薯,而以幼虫在薯块内取食危害最为严重,常造成甘薯产量损失达20%以上。成虫体长5~8 mm,体形类似蚂蚁,所以也叫甘薯蚁象。前胸、触角末节和足桔红色,身体其余部门为蓝黑色有金属光泽。头部延伸成喙,触角10节;前胸长为宽的2倍,基部1/3处缢缩成颈状;腹部长卵形,鞘翅隆