SSR分子标记鉴定山葡萄和河岸葡萄种间杂种

利用SSR分子标记技术,对山葡萄和河岸葡萄种间杂交后代的真伪性进行鉴别。从12对多态性SSR引物中筛选出能扩增出父本特异性条带的7对引物,作为杂种鉴定的标记。用这7对引物对239株山葡萄和河岸葡萄的杂交后代进行鉴定。结果表明,有161株后代具有父本的特异性条带,结合田间形态学分析,确认为真杂种。另外,后代中还出现了新的条带,表明杂交后代产生了丰富的变异。因此,SSR标记可以有效地对葡萄属种间杂交后代进行真实性鉴定,可作为葡萄种质创新的有效辅助手段。     

不同居群龙须草RAPD分析及其分类研究

利用RAPD分子标记和形态特征观察,分析研究了中国12个龙须草居群的遗传差异,16个寡聚核苷酸引物扩增共得到124条带,其中110条为多态性带,占88.7%.Shannon多样性指数(I)为0.359 0,物种水平N e i s基因多样性(H)为0.224 1.12个龙须草居群的遗传相似系数在0.48~0.99之间.聚类结果结合形态学特征分析,12个龙须草居群可划分为4类,其中河南、湖北、陕西山阳的9个居群聚为1类,陕西洋县居群、广东星子山居群、广西百色居群各代表1类.     

基于SSR分子标记的延胡索遗传多样性研究

采用SSR分子标记分析延胡索的遗传多样性,筛选出多态性高、稳定性好的12对引物,对19个居群360份延胡索样品进行了群体遗传分析。结果表明:(1)12对SSR引物共扩增出多态性位点227个,检测到4~9个等位基因,平均等位基因数目为5.25个,表现出丰富的多态性;延胡索居群具有较高的遗传多样性(Na=5.25,I=1.192 6,H=0.387 9),物种间遗传分化程度高(Fst=0.388 3),基因流较弱(Nm=0.393 8)。(2)UPGMA聚类分析和贝叶斯距离分析结果表明,19个居群明显聚为4大支;Mantle Test结果(r=0.326,P=0.01)表明,地理位置相近的种群亲缘关系更近。研究认为,延胡索的遗传结构是该物种自交为主的繁育系统、克隆生长、地理隔离以及居群间有限的基因流共同作用的结果,故对该物种的保护应以就地保护为主。     

基于磁珠富集法的绣线菊SSR分子标记分离与筛选

微卫星序列（SSR）具有多态性高、共显性遗传等特点,是一种极具价值的分子遗传标记。采用磁珠富集法从高山绣线菊基因组DNA中分离和筛选SSR标记。高山绣线菊基因组经限制性内切酶Mse I酶切后与接头连接,并与生物素标记SSR探针（AC）15和（AG）15杂交,然后通过链霉亲和素磁珠富集、洗脱、PCR扩增、克隆,完成微卫星文库构建。利用载体通用引物和探针序列引物进行PCR扩增,筛选重组克隆并测序,获得112条序列。随机挑选其中60条序列设计的引物,经初期筛选获得多态性引物16对。用所得16对引物对4个居群92个个体的蒙古绣线菊和高山绣线菊进行PCR扩增。统计分析PCR产物的毛细管电泳结果,发现4个居群的平均等位基因数、平均期望杂合度及平均观测杂合度都比较高。64个数据系列（4个居群×16个位点）中的26个显著偏离HardyWeinberg平衡,推测可能由于无效等位基因的存在所引起。分析显示研究开发的16对多态性SSR引物可以用于后续遗传多样性、物种进化与亲缘关系等方面研究,丰富了绣线菊遗传多样性研究的分子标记。     

利用荧光标记SSR鉴别21个茶花新品种

利用杜鹃红山茶(Camellia azalea)转录组数据和前人研究中获得的12个高多态性的SSR位点, 采用荧光毛细管电泳分析了21个茶花杂交新品种的基因型。结果显示, 12对SSR引物都能获得稳定清晰的扩增产物, 且上述12个SSR位点的基因型能够完全区分上述21个茶花新品种。其中, 来自同一杂交组合后代的多个品种, 基因型间有差异的位点数为2-10个, 来自不同杂交组合后代的品种间, 其基因型有差异的位点数为5-12个。研究结果表明, 上述21个茶花新品种均获得了独特的基因型标记, 能准确地进行品种身份鉴定, 这对以扦插或嫁接扩大生产的茶花品种的鉴定和品种权保护具有重要意义。     

基于新一代高通量测序技术开发巨人半边莲Lobelia deckenii的SSR标记

为了开发东非半边莲属特有植物的微卫星分子标记(SSR),本研究基于Illumina-HiSeq 2000测序平台对巨人半边莲Lobelia deckenii的基因组进行高通量测序。利用MISA软件对获得的基因组数据库进行搜索与分析,共鉴别出58 966个SSR位点,并利用Primer软件成功设计出3558对特异性的SSR引物。利用L.deckenii 3个居群的6个样品对随机挑选的40对SSR引物进行扩增效率检验,发现有32对重复性好且可扩增出清晰条带。利用筛选出的32对SSR引物对来自肯尼亚山居群的24株个体进行PCR扩增并采用荧光分型技术检测多态性,结果显示有14对可扩增出稳定的多态性条带,共有86个等位基因,各SSR位点的等位基因数(NA)为4~9个,观测杂合度(Ho)和期望杂合度(He)分别为0.000~1.000和0.625~0.854。本研究结果表明,通过高通量测序技术开发东非特有植物巨人半边莲的SSR标记是一种简单而高效的途径,这些新的SSR分子标记为巨人半边莲的居群遗传多样性、遗传结构以及对其开展保护生物学研究提供了工具。     

利用电子PCR分析草菇基因组SSR标记多态性

【目的】利用电子PCR分析草菇基因组SSR标记多态性,并通过PCR验证分析结果的可靠性。【方法】利用MISA程序定位草菇基因组SSR位点并结合Primer3.0程序设计SSR分子标记引物,运用电子PCR进行SSR分子标记多态性分析,基于分析结果进行PCR验证。【结果】随机选取658对SSR引物在草菇同核体菌株V23-1和PD19中进行真实PCR检测,结果表明28.6%的SSR引物具有多态性。数据分析表明,如果SSR标记来源于电子PCR产物长度没有差异的类型,仅4.8%的SSR引物在真实PCR中表现出多态性;如果SSR标记来源于电子PCR产物长度差异大于或者等于3 bp的类型,其中至少48.3%的SSR引物在真实PCR中表现出多态性。【结论】PCR验证结果表明利用电子PCR可以提高SSR多态性引物的筛选效率。     

椭圆叶花锚简化基因组的SSR信息分析及SSR引物开发

基于RAD-seq简化基因组测序技术获得椭圆叶花锚（Halenia ellipitica D.Don）简化基因组水平上的序列信息并开发SSR分子标记。利用SR search软件检测而得到双端各有至少100 bp的五种类型的SSR（二、三、四、五、六核苷酸）位点共6 201个,并成功设计其中3 865个SSR引物。在能成功设计引物的SSR位点中,三核苷酸SSR位点最多;重复序列长度包括17种（12~36 bp）;重复序列的基序共达316种,其中五核苷酸基序种类最多（91种）。从中挑选65对可对应五种SSR类型的引物,经梯度PCR检验后,利用椭圆叶花锚的4个居群32个个对可扩增的引物进行PCR和聚丙烯酰氨凝胶电泳检测,其中14对引物能在绝大多数个体中扩增,且13对具多态性。13个多态性位点的等位基因数量均值为5.462,多态性较高且不连锁（P<0.05）;其中10个位点在多数居群中偏离哈迪温伯格平衡（P<0.01）且存在较高的纯合子数量（观测杂合度H_o均值0.226）;近交系数在-0.443~1,均值为0.656;基因流N_m为0.474。     

19个枇杷杂交新品种(系)的SSR鉴定和指纹图谱构建

为探究枇杷(Eriobotryajaponica)杂交品种真实性和DNA指纹图谱,对新育成的19个枇杷杂交品种(系)进行SSR标记鉴定分析。结果表明,从已发表的89对SSR引物中筛选出扩增条带清晰稳定的多态性引物19对,在24份枇杷材料中共扩增到83条带,每对引物平均扩增4.37条,PIC值为0.234～0.983,平均为0.764。经12对具有父本特征带多态性引物鉴定, 19个杂交新品种(系)全部为真杂种,真杂种率为100%。UPGMA聚类分析表明,19个杂交新品种(系)的遗传相似系数为0.728～0.969,与杂交亲本‘新白2号’和‘贵妃’聚为同一个大类,并可细分为4个亚类,红肉与白肉的枇杷品种(系)间无明显划分。同时利用8对多态性SSR引物组合,构建了19个枇杷杂交新品种(系)的分子指纹图谱。这为枇杷品种鉴定、新品种权保护和杂交育种提供重要参考依据。     

32个柿主栽品种SSR图谱构建及遗传变异分析

以32份柿主栽品种为试验材料,利用SSR标记技术构建其指纹图谱并进行遗传多样性分析。从78对候选引物中筛选出20对多态性高、稳定性好的引物作为核心引物,构建柿主栽品种SSR指纹图谱。结果显示:(1)20对引物在32份材料中共扩增出183条多态性条带,每对引物扩增出3～20条不等,平均每对引物扩增出9.15条,多态性比率为81.3%。各个位点的杂合度在0.410 3～0.914 3之间,平均为0.702 7。(2)8对引物在12个品种上具有特征带型,采用5对引物进行组合鉴定即可将32个柿品种完全区分开。(3)依据SSR带型特征,对每对引物生成的不同带型直接编号,简化柿SSR带型记录方法,并利用每个品种的带型编号,建立其DNA指纹图谱,结果表明,核心引物组合法比特征谱带法更适用于构建中国柿主栽品种DNA指纹图谱。(4)根据系统聚类分析将32个柿主栽品种分为两大类,品种间的亲缘关系与地理来源具有一定的相关性。     

Amplification of DNA markers from evolutionarily diverse genomes using single primers of simple-sequence repeats

The abundance and scattered distribution of simple-sequence repeats (SSR) in eukaryotic genomes prompted us to explore the use of SSR-based oligonucleotide primers in single primer amplification reactions. In a pilot experiment, 23 primers were used across a panel of evolutionarily diverse eukaryotic genomes, including grapes, lettuce, tomato, pine, maize, salmon, chicken, Holstein cows and humans. The primers were 16–20 bases in length and represented SSRs of di-, tri-, tetra-, and pentanucleotide repeats. The results showed that tetranucleotide repeat primers were most effective in amplifying polymorphic patterns. Of 11 such primers tested, 70% produced polymorphic patterns from the DNA of one or more species. Primers representing a combination of two tetranucleotide repeats, or compound microsatellites, were equally effective. The polymorphisms contained in such fingerprints were able to identify individuals of vertebrate species as well as lines or varieties of plants. Inheritance of the polymorphic bands was studied in a maize recombinant inbred population, DE811 x B73. Thirty-two polymorphic bands, derived from two amplification patterns, were mapped as dominant markers on an existing RFLP map of the same population. The bands were distributed across nine of the ten chromosomes.     

Rapid microsatellite marker isolation for the Pink Stem Borer,Sesamia inferens (Lepidopetera: Noctuidae), through 454 GS-FLX Titanium pyrosequencing of enriched DNA libraries and cross amplification in related taxa

Next-generation Roche 454 pyrosequencing was used to rapidly identify polymorphic microsatellites from enriched DNA libraries for the pink stem borer, Sesamia inferens (Walker). A total of 1,459 simple sequence repeats (SSRs) were isolated from the microsatellite-enriched library using 454 sequencing. Thirty-nine microsatellite markers were selected to synthesize for further optimization, and 12 loci exhibited reliable amplification of a single product of expected size. The forward primer of 12 primer pairs was end labeled with a fluorescent dye. All of the 12 microsatellite loci were polymorphic, with 5–13 alleles per locus and observed heterozygosities ranging from 0.097 to 0.957. Here, we also tested these 12 SSRs for cross-species amplification in Chilo suppressalis (Walker), Tryporyza incertulas (Walker) and Cnaphalocrocis medinalis (Guenée). These polymorphic markers will be a valuable tool for analyses of population connectivity and genetic structure in this rice pest.     

Sexual reproduction development in apomictic Eulaliopsis binata (Poaceae)

Apomixis is a particular mode of reproduction that allows progeny formation without meiosis and fertilization. Eulaliopsis binata, a tetraploid apomictic species, is widely used for making paper, rope and mats. There is great potential for fixation of heterosis in E. binata due to autonomous endosperm formation in this species. Although most of its embryo sac originates from nucellus cells, termed apospory, we observed sexual reproduction initiation in 86.8 to 96.8% of the ovules, evidenced by callose deposition on the walls of cells undergoing megasporogenesis. However, only 2-3% mature polygonum-type sexual embryo sacs were confirmed by embryological investigation. Callose was not detected on aposporous initial cell walls. The aposporous initial cells differentiated during pre- and post-meiosis of the megaspore mother cell, while the sexual embryo sac degenerated at the megaspore stage. DNA content ratio of embryo and endosperm in some individuals was 2C:3C, based on flow cytometry screening of seed, similar to that of normal sexual seed. These results confirm that apomictic E. binata has conserved sexual reproduction to a certain degree, which may contribute to maintaining genetic diversity. The finding of sexual reproduction in apomictic E. binata could be useful for research on genetic mechanism of apomixis in E. binata.     

Development and characterization of nine new microsatellite markers in Taraxacum (Asteraceae)

This study aims at developing and characterizing new microsatellite primer pairs in Taraxacum officinale auct. to produce polymorphic markers for genetical and evolutionary studies on apomixis in this sexual‐apomictic complex. A total of 24 diploid plants were tested for allelic polymorphism and heterozygosity. Out of nine loci three deviated significantly from the Hardy–Weinberg equilibrium expectations, probably due to the presence of null‐alleles. Successful cross‐species amplification was obtained for all markers in 29 Taraxacum microspecies from five sections.     

In silico mining and characterization of simple sequence repeats from gilthead sea bream (Sparus aurata) expressed sequence tags (EST-SSRs); PCR amplification, polymorphism evaluation and multiplexing and cross-species assays

We screened for simple sequence repeats (SSRs) found in ESTs derived from an EST-database development project ('Marine Genomics Europe' Network of Excellence). Different motifs of di-, tri-, tetra-, penta- and hexanucleotide SSRs were evaluated for variation in length and position in the expressed sequences, relative abundance and distribution in gilthead sea bream (Sparus aurata). We found 899 ESTs that harbor 997 SSRs (4.94%). On average, one SSR was found per 2.95 kb of EST sequence and the dinucleotide SSRs are the most abundant accounting for 47.6% of the total number. EST-SSRs were used as template for primer design. 664 primer pairs could be successfully identified and a subset of 206 pairs of primers was synthesized, PCR-tested and visualized on ethidium bromide stained agarose gels. The main objective was to further assess the potential of EST-SSRs as informative markers and investigate their cross-species amplification in sixteen teleost fish species: seven sparid species and nine other species from different families. Approximately 78% of the primer pairs gave PCR products of expected size in gilthead sea bream, and as expected, the rate of successful amplification of sea bream EST-SSRs was higher in sparids, lower in other perciforms and even lower in species of the Clupeiform and Gadiform orders. We finally determined the polymorphism and the heterozygosity of 63 markers in a wild gilthead sea bream population; fifty-eight loci were found to be polymorphic with the expected heterozygosity and the number of alleles ranging from 0.089 to 0.946 and from 2 to 27, respectively. These tools and markers are expected to enhance the available genetic linkage map in gilthead sea bream, to assist comparative mapping and genome analyses for this species and further with other model fish species and finally to help advance genetic analysis for cultivated and wild populations and accelerate breeding programs.     

Multiple methods for the identification of polymorphic simple sequence repeats (SSRs) in sorghum [Sorghum bicolor (L.) Moench]

Simple sequence repeats (SSRs), also known as microsatellites, are highly variable DNA sequences that can be used as markers for the genetic analysis of plants. Three approaches were followed for the development of PCR primers for the amplification of DNA fragments containing SSRs from sorghum [Sorghum bicolor (L.) Moench]: a search for sorghum SSRs in public DNA databases; the use of SSR-specific primers developed in the Poaceae species maize (Zea mays L.) and seashore paspalum grass (Paspalum vaginatum Swartz); and the screening of sorghum genomic libraries by hybridization with SSR oligonucleotides. A total of 49 sorghum SSR-specific PCR primer pairs (two designed from GenBank SSR-containing sequences and 47 from the sequences of genomic clones) were screened on a panel of 17 sorghum and one maize accession. Ten primer pairs from paspalum and 90 from maize were also screened for polymorphism in sorghum. Length polymorphisms among amplification products were detected with 15 of these primer pairs, yielding diversity values ranging from 0.2 to 0.8 with an average diversity of 0.56. These primer pairs are now available for use as markers in crop improvement and conservation efforts.     

基于陆地棉茎尖转录组序列的genic-SSR标记的开发与评价

利用软件MISA和SSR Locator 对陆地棉（Gossypium hirsutum L.）Coker312茎尖转录组测序得到的73515条Unigene序列进行分析,查找到4507个SSR位点,分布于4039条转录本序列中,SSR出现频率为5.5%,非编码区的SSR位点要显著高于编码区（2853/1654）。SSR重复基元中,三核苷酸重复基元占主导地位（51.03%）,且AAG/CTT （20.08%）类型最多;其次是二核苷酸重复基元（28.76%）,主要为AG/CT（55.47%）。利用引物批量设计软件共开发1569对SSR引物,在陆地棉TM-1、海岛棉3-79 (G. barbadense L.)、阿非利加棉(G. herbaceum L.)、雷蒙德氏棉(G. raimondii Ulbrich.)四个棉种中进行初步评价,其中1117对引物能在四个棉种间扩增出稳定的条带,扩增率为71.2%。选择650对能稳定扩增出条带的引物,在涉及5个棉种（增加了亚洲棉（G. arboreum L.））的13份材料中进一步筛选,83对引物能在13份材料中扩增出特异性条带, PIC变幅在0.121～0.648之间,平均值为0.422,其中80对引物能在7份陆地棉材料中扩增出特异性条带,平均PIC值为0.336;挑选5对在本实验室作图亲本鲁棉研22和鲁原343间有明显多态的引物进行连锁分析,其中4对成功连锁到本实验室构建的遗传图谱上。本研究丰富了棉属genic-SSR的数量,为棉属遗传作图、性状关联分析提供了更多引物选择。     

Identification and genetic mapping of highly polymorphic microsatellite loci from an EST database of the septoria tritici blotch pathogen Mycosphaerella graminicola

A database of 30,137 EST sequences from Mycosphaerella graminicola, the septoria tritici blotch fungus of wheat, was scanned with a custom software pipeline for di- and trinucleotide units repeated tandemly six or more times. The bioinformatics analysis identified 109 putative SSR loci, and for 99 of them, flanking primers were developed successfully and tested for amplification and polymorphism by PCR on five field isolates of diverse origin, including the parents of the standard M. graminicola mapping population. Seventy-seven of the 99 primer pairs generated an easily scored banding pattern and 51 were polymorphic, with up to four alleles per locus, among the isolates tested. Among these 51 loci, 23 were polymorphic between the parents of the mapping population. Twenty-one of these as well as two previously published microsatellite loci were positioned on the existing genetic linkage map of M. graminicola on 13 of the 24 linkage groups. Most (66%) of the primer pairs also amplified bands in the closely related barley pathogen Septoria passerinii, but only six were polymorphic among four isolates tested. A subset of the primer pairs also revealed polymorphisms when tested with DNA from the related banana black leaf streak (Black Sigatoka) pathogen, M. fijiensis. The EST database provided an excellent source of new, highly polymorphic microsatellite markers that can be multiplexed for high-throughput genetic analyses of M. graminicola and related species.