The hybridization of tetraploid wheat with the octoploid wheat-wild rye amphiploid Elytricum fertile and the chromosome behavior in meiotic MI

The hybridization and chromosome behaviour regularities at meiotic MI of reciprocal F1 hybrids of tetraploid wheats T. durum and T. turgidum with 56-chromosome incomplete wheat-Elymus amphiploid (IWEA) Elytricum fertile, were investigated. Variation of main indices of the hybridization has been revealed to be determined by variance of such factors as cross direction, genotype peculiarities of wheat strains and their interaction. Elymus sibiricus genome, contained in IWEA karyotype, carries several genes, that can suppress wheat diploidization system. Reduction of homologous chromosome synapsis is not determined by these genes, but is connected with influence of other Elymus sibiricus chromosome factors.     

Elymus sibiricus, E. nutans 和 E. burchan-buddae 的形态学鉴定及其染色体组亲缘关系的研究

为了进一步研究Elymus sibiricus L.、E．nutans Griseb．和E．burchan-buddae(Neuski)Tzelev [＝Roegneria nutans(Keng)Keng]的外部形态差异及其系统学关系,本文对这三种植物的6个穗部形 态性状进行了观测和比较,并对这三个Elymus种进行了种间杂交及杂种F1的减数分裂染色体配对行 为的分析研究。结果表明：这三个Elymus种的穗长及颖长等性状均变异很大,而内稃的长、宽则变异 不大并具有明显的种间差异。E. nutans×E．barchan-buddae及E.nutans×E．sibiricus的杂种F1均完 全不育,减数分裂不规则。E．nutans×E．burchan-buddae杂种F1的减数分裂构型为：7.70I+13.40 Ⅱ+0.06Ⅲ+O.08 Ⅳ,而E．sibiricus×E．nutans杂种F1的构型为11.98 Ⅰ+9.61Ⅱ+O.64Ⅲ+0.39 Ⅳ+0.01V。由本实验的形态学和细胞学的研究结果得出以下结论：1．利用内稃形态性状结合穗部 其它性状的差异能对这三个物种进行较准确的鉴定;2．E．nutans与E.burchan-buddae的亲缘关系较 近,而E．nutans与E．sibiricus的亲缘关系则较远;3. E,burchan-buddae×E．nutans的杂种Fl中存在着染色体配对控制因子。     

Origin of the H genome in StH-genomic Elymus species based on the single-copy nuclear gene DMC1

Previous studies have suggested that the H haplome in Elymus could originate from different diploid Hordeum species, however, which diploid species best represent the parental species remains unanswered. The focus of this study seeks to pinpoint the origin of the H genome in Elymus. Allopolyploid Elymus species that contain the StH genome were analyzed together with diploid Hordeum species and a broad sample of diploid genera in the tribe Triticeae using DMC1 sequences. Both parsimony and maximum likelihood analyses well separated the American Hordeum species, except Hordeum brachyantherum subsp. californicum, from the H genome of polyploid Elymus species. The Elymus H-genomic sequences were formed into different groups. Our data suggested that the American Horedeum species, except H. brachyantherum subsp. californicum, are not the H-genomic donor to the Elymus species. Hordeum brevisubulatum subsp. violaceum was the progenitor species to Elymus virescens, Elymus confusus, Elymus lanceolatus, Elymus wawawaiensis, and Elymus caninus. Furthermore, North American H. brachyantherum subsp. californicum was a progenitor of the H genome to Elymus hystrix and Elymus cordilleranus. The H genomes in Elymus canadensis, Elymus sibiricus, and Elymus multisetus were highly differentiated from the H genome in Hordeum and other Elymus species. The H genome in both North American and Eurasian Elymus species was contributed by different Hordeum species.     

Morphological Identification of Elymus sibiricus,E. nutans,and E. burchan-buddae,and Their Genomic Relationships

In order to investigate morphological variations of Elymus sibiricus L., E. nutans Griseb., and E. burchan-buddae (Nevski) Tzvelev ［=Roegneria nutans (Keng) Keng］, and to explore their systematic relationships, six morphological characters were measured and compared between the Elymus species. Interspecific hybridizations between E. nutans and E. sibiricus, and E. burchan-buddae were carried out with the aid of embryo rescue. Chromosome pairing behaviour was also analysed at metaphase- I of meiosis in pollen mother cells of F₁ hybrids. Morphologic characters, such as length of spikes and length of glumes varied considerably between different individuals of each species, whereas length and width of paleas were quite stable and different between species. The interspecific hybrids were completely sterile and their meioses were irregular. Meiotic configuration of E. nutans × E. burchan-buddae was 7.70I +13.40Ⅱ+0.06Ⅲ+0.08 IV, whereas that of E. sibircus×E. nutans was 11.98I+9.61Ⅱ+0.64Ⅲ+0.39Ⅳ+0.01V. It is concluded from the morphological and cytological study that (1) it is possible to identify the three Elymus species using the palea character, in addition to other traditionally applied characters; (2) Elymus nutans and E. burchan-buddae have a comparatively high genomie relationship, while E. nutans and E. sibircus have a relatively low genomic affinity to one another; and (3) a certain chromosome pairing regulator was presented in the hybrid between E. burchan-buddae andE. nutans.     

The origin of a "zebra" chromosome in wheat suggests nonhomologous recombination as a novel mechanism for new chromosome evolution and step changes in chromosome number

An alloplasmic wheat line, TA5536, with the "zebra" chromosome z5A was isolated from an Elymus trachycaulus/Triticum aestivum backcross derivative. This chromosome was named "zebra" because of its striped genomic in situ hybridization pattern. Its origin was traced to nonhomologous chromosome 5A of wheat and 1H(t) of Elymus; four chromatin segments were derived from chromosome 1H(t) and five chromatin segments including the centromere from 5A. In this study, our objective was to determine the mechanism of origin of chromosome z5A, whether by nonhomologous recombination or by multiple translocation events. Different crossing schemes were used to recover recombinants containing various Elymus chromatin segments of the z5A chromosome. In addition, one z5AL telocentric chromosome and three z5AL isochromosomes were recovered. The dissection of the Elymus segments into different stocks allowed us to determine the chromosomal origin of the different chromosome fragments on the basis of the order of the RFLP markers employed and suggested that the zebra chromosome originated from nonhomologous recombination. We present a model of possible mechanism(s) of chromosome evolution and step changes in chromosome number applicable to a wide range of organisms.     

A molecular genetic linkage map identifying the St and H subgenomes of Elymus (Poaceae: Triticeae) wheatgrass

Elymus L. is the largest and most complex genus in the Triticeae tribe of grasses with approximately 150 polyploid perennial species occurring worldwide. We report here the first genetic linkage map for Elymus. Backcross mapping populations were created by crossing caespitose Elymus wawawaiensis (EW) (Snake River wheatgrass) and rhizomatous Elymus lanceolatus (EL) (thickspike wheatgrass) to produce F(1) interspecific hybrids that were then backcrossed to the same EL male to generate progeny with segregating phenotypes. EW and EL are both allotetraploid species (n = 14) containing the St (Pseudoroegneria) and H (Hordeum) genomes. A total of 387 backcross progeny from four populations were genotyped using 399 AFLP and 116 EST-based SSR and STS markers. The resulting consensus map was 2574 cM in length apportioned among the expected number of 14 linkage groups. EST-based SSR and STS markers with homology to rice genome sequences were used to identify Elymus linkage groups homoeologous to chromosomes 1-7 of wheat. The frequency of St-derived genome markers on each linkage group was used to assign genome designations to all linkage groups, resulting in the identification of the seven St and seven H linkage groups of Elymus. This map also confirms the alloploidy and disomic chromosome pairing and segregation of Elymus and will be useful in identifying QTLs controlling perennial grass traits in this genus.     

Physical mapping of repetitive sequences and genome analysis in six Elymus species by in situ hybridization

Genome constitution and genetic relationships between six Elymus species were assessed by physical mapping of different repetitive sequences using a technique of sequential fluorescence in situ hybridization and genomic in situ hybridization.The six Elymus species are all naturally growing species in northwest China,namely,E.sibiricus,E.nutans,E.barystachyus,E.xiningensis,E.excelsus,and E.dahuricus.An StStHH genome constitution was revealed for E.sibiricus and StStHHYY for the remainder species.Each chromosome could be clearly characterized by physical mapping with 18S-26S rDNA,5S rDNA,Afa-family,and AAG repeats,and be allocated to a certain genome by genomic in situ hybridization.Two 5S rDNA sites,each in the H and St genomes,and three 18S-26S rDNA sites,two in the St genome and one in the Y genome,were uncovered in most of the species.The strong Afa-family hybridization signals discriminated the H genome from the St and Y genomes.The H and Y genome carried more AAG repeats than St.A common non-Robertsonian reciprocal translocation between the H and Y genomes was revealed in E.barystachyus,E.xiningensis,E.excelsus and E.dahuricus.Comparison of molecular karyotypes strongly suggests that they can be classified into three groups,namely,E.sibiricus,E.nutans,and others.     

小麦族披碱草属、鹅观草属和猬草属模式种的C带研究

采用改良的Giemsa C带技术,分析了小麦族披碱草属、鹅观草属和猬草属模式种的染色体C带带型。Elymus sibiricus、Roegneria caucasica和Hysrix patula的染色体在Giemsa C带带型上存在明显的差异,显示了这3个属模式种的物种特异性。3个模式种的Giemsa C带核型表明,C带带纹主要分布在染色体的末端和着丝粒附近,而中间带相对较少。对E.sibiricus、R.caucasica和H.patula的St、H、Y染色体组C带带型与其它物种的St、H、Y染色体组C带带型的差异进行了讨论。     

加拿大披碱草、老芒麦及其杂种F1代的RAPD分析

加拿大披碱草和老芒麦是披碱草属地理性远缘的2个种。采用RAPD技术,筛选了16个随机引物对这2个种及其F1代进行遗传多态性检测。在获得的186个位点中,114个为多念性位点,占61．29％。从种群内的遗传多态性来看,加拿大披碱草的多态性位点百分率最高(242．04%),其次是老芒麦(9．14%),杂种F1(1．61％)。从种群间的遗传关系来看,加拿大披碱草和老芒麦的遗传距离为0．4979,杂种F1与母本加拿大披碱草的遗传距离(0．2720)较近,而与父本老芒麦的遗传距离(0.4074)相对较远。     

Identification of highly conserved hydrophobic amino acid motif in deduced amino acid sequence of Elymus sibiricus L. mitochondrial S13 ribosomal protein

The nucleotide sequence of mitochondrial ribosomal protein rps13 gene from wild perennial grass Elymus sibiricus is presented. It was determined by the method of PCR amplification with specific oligonucleotide primers and the direct sequencing of the amplification product. The sequence of E. sibiricus mitochondrial gene for S13 predicts a hydrophobic ribosomal protein of 116 amino acids that shows strong similarity to those of wheat (99.7% identity) and maize (98%). The deduced amino acid sequence of S13 protein from E. sibiricus and homologous plant's (Zea mays, Daucus carota, Nicotiana tabacum, Marchantia polymorpha) and nonplant's (Escherichia coli) proteins shows the presence of hydrophobic amino acids' motif -L-X10-L-X10-M-X10-L-X10-L-. Slightly modified it can be found in many other ribosomal proteins. This conserved motif is presumed to be particularly important for association of the ribosomal S13 protein with other proteins in the small subunit of the mitochondrial ribosome.     

披碱草属与大麦属系统关系的研究

禾本科中,披碱草属Elymus L.为多倍体属,约含150余种;大麦属Hordeum L.具二倍体和多倍体,约有40余种,该两属均广泛地分布于全球温带地区。该两属,尤其是披碱草属的系统分类较为困难。基于形态学的传统研究认为这两个属的系统关系较远,而细胞学研究的资料却表明,披碱草属的H染色体组起源于大麦属。笔者对来源不同的披碱草属和大麦属的物种进行了远缘杂交,并对其属间杂种F1的减数分裂中期I染色体配对行为进行了分析。结果表明,若以披碱草属作母本,该两属有相对较高的杂交亲合力,通过对杂种幼胚进行分割和离体培养,也能获得杂种F1植株。属间杂种植株的形态介于双亲之间,但更接近于披碱草属,杂种的生殖器官发育不健全,而且所有的杂种F1均完全不育。细胞学的观察结果表明,这两个属间的杂种F1通常具有较低的减数分裂中期I染色体配对数,但有较大的变异。通过笔者的工作及掌握的形态学和细胞学的资料分析认为：披碱草属和大麦属的亲缘关系较为复杂,不能一概而论。含H染色体组的披碱草属和大麦属物种有着较近的亲缘关系,但这两个属中所含的H染色体组已产生了程度不同的分化;不含H染色体组的披碱草属及大麦属的物种具有较远的亲缘关系。     

Genomic constitutions of four Chinese endemic Elymus species: E. brevipes, E. yangii, E. anthosachnoides, and E. altissimus (Triticeae, Poaceae).

The objectives of this study were to determine the genomic constitution and to explore the genomic variation within four Chinese endemic Elymus species, i.e., E. brevipes (Keng) L?ve (2n = 4x = 28) and E. yangii B.R. Lu (2n = 4x = 28), E. anthosachnoides (Keng) L?ve (2n = 4x = 28), and E. altissimus (Keng) L?ve (2n = 4x = 28). Intraspecific crosses between different populations of the four Elymus species, as well as interspecific hybridizations among the four target species, and with six analyzer species containing well-known genomes, i.e., E. caninus (L.) L. (2n = 4x = 28, SH), E. sibiricus L. (2n = 4x = 28, SH), E. semicostatus (Lees ex Steud.) Melderis (2n = 4x = 28, SY), E. parviglumis (Keng) L?ve (2n = 4x = 28, SY), E. tsukushiensis Honda (2n = 6x = 42, SHY), and E. himalayanus (Nevski) Tzvelev (2n = 6x = 42, SHY), were achieved through the aid of embryo rescue. Chromosome pairing behaviors were studied in the parental species and their hybrids. Numerical analysis on chromosome pairing was made on the interspecific hybrids. With one exception, each meiotic configuration at metaphase I in the hybrids involving the target taxa and the analyzer species containing the "SH" genomes fit a 2:1:1 model with x-values ranging between 0.91 and 1.00; chromosome pairing in the hybrids involving analyzer parents with the "SY" genomes match a 2:2 model, with x-values between 0.97 and 0.99. All pentaploid hybrids with a genomic formula "SSYYH," except for two crosses having unexpected low c-values, had pairing patterns fitting the 2:2:1 model with x-values varying between 0.96 and 1.00. It is concluded based on hybridization, fertility, and chromosome pairing data that (i) the four target Elymus species are strictly allotetraploid taxa, (ii) they are closely related species, all comprised of the "SY" genomes, (iii) minor genomic structural rearrangements have occurred within the four Elymus species, and (iv) meiotic pairing regulator(s) exists in some of the Elymus taxa studied.     

老芒麦(Elymus sibiricus)种群地上生物量空间分布格局研究

采用分形几何学的方法对老芒麦（Elymus sibiricus)种群地上生物量空间分布格局进行了研究,结果表明：1）在某一时刻老芒麦不同植株地上生物量的空间分布格局具有相似性,7月6日的分形维数最大,为1.5054;6月16日、7月31日以及8月10日的分形维数较小,分别为0.7001、0.4675和0.3428。2）虽然在整个生长季内,老芒麦地上生物量与株高的对数值之间存在线性关系,但仍然存在许多细节问题,3）老芒麦株高在20-59cm尺度范围内,双对数半方差图存在明显的2个线性区域,反映出生物量空间分布格局的异质性。4）高度间隔为4cm以下的分形维数为1.63465,高度间隔大于4cm时的分形维数为1.0407。     

老芒麦遗传多样性及育种研究进展

摘要 老芒麦(Elymus sibiricus)的研究对我国北方草原及青藏高原高寒草甸的退化草地改良、发展草地畜牧业具有重要意义。 本文综述了老芒麦在形态学、细胞学、蛋白质和DNA分子水平上的遗传多样性研究概况, 并总结了国内老芒麦的育种研究进展。目前国内外专门针对不同老芒麦种质材料(accession)或居群(populations)遗传多样性的研究鲜见报道, 相关研究主要集中在与披碱草属(Elymus)及其近缘小麦族物种的系统进化研究方面; 其次, 我国仅有6个老芒麦国家审定品种, 且育种手段较单一、落后, 育成品种优势集中在产量和适应性上, 缺乏对抗逆性种质的筛选培育。     

Meiotic analysis of the interspecific and intergeneric hybrids between Hystrix patula Moench and H. duthiei ssp. longearistata, Pseudoroegneria, Elymus, Roegneria, and Psathyrostachys species (Poaceae, Triticeae)

Interspecific and intergeneric hybridizations were carried out in an investigation of genome homology between Hystrix patula and other species of Hystrix , as well as the generic relationships between H. patula and its related species. Meiotic pairing in the hybrids H. patula  ×  H. duthiei ssp. longearistata (Ns–), H. patula  ×  Pseudoroegneria spicata (St), H. patula  ×  Pse. libanotica (St), Elymus sibiricus (StH) ×  H. patula , H. patula  ×  E. wawawaiensis (StH), Roegneria ciliaris (StY) ×  H. patula , H. patula  ×  R. grandis (StY), and H. patula  ×  Psathyrostachys huashanica (Ns^h) averaged 1.32, 6.53, 5.62, 10.08, 12.83, 3.57, 3.98, and 0.29 bivalents per cell, respectively. The results indicate that: (1) H. patula has no genome homology with H. duthiei ssp. longearistata or the Ns genome from Psathyrostachys ; (2) H. patula contains the same StH genomes as the Elymus species, and the St genome is homologous to the genome of Pse. spicata and Pse. libanotica ; and (3) H. patula has a low genome affinity with the StY genomes of Roegneria . Therefore, it is reasonable to treat H. patula Moench as E. hystrix L.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 213–219.     

老芒麦遗传多样性及育种研究进展

老芒麦（Elymus sibiricus）的研究对我国北方草原及青藏高原高寒草甸的退化草地改良、发展草地畜牧业具有重要意义。本文综述了老芒麦在形态学、细胞学、蛋白质和DNA分子水平上的遗传多样性研究概况,并总结了国内老芒麦的育种研究进展。目前国内外专门针对不同老芒麦种质材料（accession）或居群（populations）遗传多样性的研究鲜见报道,相关研究主要集中在与披碱草属（Elymus）及其近缘小麦族物种的系统进化研究方面;其次,我国仅有6个老芒麦国家审定品种,且育种手段较单一、落后,育成品种优势集中在产量和适应性上,缺乏对抗逆性种质的筛选培育。     

根据形态和叶片微形态特征讨论无芒披碱草的归并

通过形态学观测和叶片解剖特征分析,比较了无芒披碱草、短芒披碱草及老芒麦3个近缘种的主要性状差异,以探讨无芒披碱草的系统分类归属.结果表明,在外部形态上无芒披碱草与短芒披碱草差异甚小,难以进行区分,但与老芒麦差异明显,是典型的种间关系;在叶片解剖上,无芒披碱草的绝大多数特征与短芒披碱草的一致或类同,可与老芒麦的却存在明显间断.故研究认为:无芒披碱草与短芒披碱草是同一个种,无芒披碱草应作为短芒披碱草的异名.     

利用RAPD分析披碱草属、鹅观草属和猬草属模式种的亲缘关系

利用随机扩增多态性DNA（RAPD）技术对小麦族披碱草属、鹅观草属和猬草属3个属的模式种进行了基因组DNA多态性分析。42个引物产物的290条谱带中,257条（88.62%)表现出多态性,说明披碱草属、鹅观草属和猬草属3个属的模式种间具有丰富的遗传多样性。利用290个RAPD标记,计算材料间Nei氏遗传相似性系和遗传距离,在NTSYS程序中利用UPGMA进行聚类。结果表明,Elymus sibiricus种不同居群间的遗传差异较小,遗传距离在0.097-0.180之间。E.sibiricus,Roegneria caucasica和Hystrix patula的种间遗传差异明显,遗传距离在0.458-0.605之间。H.patula与E.sibiricus的亲缘关系较近。R.caucasica与E.sibiricus的亲缘关系较远。     

利用SSR标记对垂穗披碱草和老芒麦进行物种鉴定和遗传变异分析

垂穗披碱草(Elymus nutans)和老芒麦(Elymus sibiricus)皆为花序下垂类披碱草属物种,高海拔地区的E.sibiricus的部分变异类型也具有小穗紧密排列等特征,与E.nutans在形态学性状上具有较多的交叉,造成野外种质资源采集时进行直接的田间鉴定存在困难。本研究利用12对小麦族SSR引物对8份垂穗披碱草和10份老芒麦种质进行遗传变异和物种鉴定分析,UPGMA聚类分析表明供试材料明显可依据物种差异划分成两大类,主向量分析(PCo A)与聚类分析的结果保持一致。种质间遗传相似系数分析和分子方差分析(AMOVA)也表明种间变异远高于种内。另外,本研究筛选出3对引物,ESGS79和ESGS155能够在垂穗披碱草材料中扩增出特异性条带,Xgwm311能够在老芒麦材料中扩增出特异性条带,这3对引物能够作为区分垂穗披碱草和老芒麦的依据,为野外种质资源的收集以及田间育种工作提供指导。     

Terminal regions of wheat chromosomes select their pairing partners in meiosis

Many plant species, including important crops like wheat, are polyploids that carry more than two sets of genetically related chromosomes capable of meiotic pairing. To safeguard a diploid-like behavior at meiosis, many polyploids evolved genetic loci that suppress incorrect pairing and recombination of homeologues. The Ph1 locus in wheat was proposed to ensure homologous pairing by controlling the specificity of centromere associations that precede chromosome pairing. Using wheat chromosomes that carry rye centromeres, we show that the centromere associations in early meiosis are not based on homology and that the Ph1 locus has no effect on such associations. Although centromeres indeed undergo a switch from nonhomologous to homologous associations in meiosis, this process is driven by the terminally initiated synapsis. The centromere has no effect on metaphase I chiasmate chromosome associations: homologs with identical or different centromeres, in the presence and absence of Ph1, pair the same. A FISH analysis of the behavior of centromeres and distal chromomeres in telocentric and bi-armed chromosomes demonstrates that it is not the centromeric, but rather the subtelomeric, regions that are involved in the correct partner recognition and selection.