Genome discrimination by in situ hybridization in Icelandic species of Elymus and Elytrigia (Poaceae: Triticeae).

The genome constitution of Icelandic Elymus caninus, E. alaskanus, and Elytrigia repens was examined by fluorescence in situ hybridization using genomic DNA and selected cloned sequences as probes. Genomic in situ hybridization (GISH) of Hordeum brachyantherum ssp. californicum (diploid, H genome) probe confirmed the presence of an H genome in the two tetraploid Elymus species and identified its presence in the hexaploid Elytrigia repens. The H chromosomes were painted uniformly except for some chromosomes of Elytrigia repens which showed extended unlabelled pericentromeric and subterminal regions. A mixture of genomic DNA from H. marinum ssp. marinum (diploid, Xa genome) and H. murinum ssp. leporinum (tetraploid, Xu genome) did not hybridize to chromosomes of the Elymus species or Elytrigia repens, confirming that these genomes were different from the H genome. The St genomic probe from Pseudoroegneria spicata (diploid) did not discriminate between the genomes of the Elymus species, whereas it produced dispersed and spotty hybridization signals most likely on the two St genomes of Elytrigia repens. Chromosomes of the two genera Elymus and Elytrigia showed different patterns of hybridization with clones pTa71 and pAes41, while clones pTa1 and pSc119.2 hybridized only to Elytrigia chromosomes. Based on FISH with these genomic and cloned probes, the two Elymus species are genomically similar, but they are evidently different from Elytrigia repens. Therefore the genomes of Icelandic Elymus caninus and E. alaskanus remain as StH, whereas the genomes of Elytrigia repens are proposed as XXH.     

垂穗披碱草与达乌里披碱草基因组细胞遗传学比较

采用顺序FISH-GISH技术,12个重复序列探针,包括9个三核苷酸简单重复序列、2个卫星DNA重复序列pSc119.2和pAs1以及5S rDNA,通过重复序列的物理定位对达乌里披碱草和垂穗披碱草基因组中部分重复序列的分布特征进行了比较分析,为进一步研究垂穗披碱草和达乌里披碱草的物种形成及演化提供新的分子细胞遗传学证据。结果表明:(1)所有的序列在这2个物种的染色体上都能产生可检测的杂交信号,且在2个物种中(AAC)_(10)、(ACT)_(10)、(CAT)_(10)都表现为共分布,(AAG)_(10)与(AGG)_(10)表现为近似共分布;2个物种的H基因组除5S rDNA序列外,其他序列都产生强烈且丰富的杂交位点,St与Y基因组不同重复序列探针的荧光位点数目有所差别,表现为5S rDNA、pSc119.2、(AAC)_(10)、(CAT)_(10)、(ACT)_(10)、(CAC)_(10)探针的信号位点较少或无信号,其余的探针信号位点稍多。(2)达乌里披碱草的第2对染色体上具有(AAC)_(10)、(CAT)_(10)、(ACT)_(10)的杂交位点、第6对染色体上具有(CAC)_(10)的杂交位点,而在垂穗披碱草的St基因组中未观察到上述序列杂交位点;达乌里披碱草St基因组仅有第4对染色体的端部具有pSc119.2杂交位点,而在垂穗披碱草St基因组中的pSc119.2杂交位点位于第5对染色体长臂的间隔区;相对于达乌里披碱草,垂穗披碱草St和Y基因组染色体含有更多的重复序列杂交位点。(3)达乌里披碱草的H/Y基因组间易位在不同材料间是稳定存在的,达乌里披碱草基因组相对稳定,不同材料间H基因组重复序列杂交信号多态性高于St和Y基因组;垂穗披碱草基因组的变异较大,不同材料间St和Y基因组重复序列杂交信号多态性高于H基因组。研究认为,垂穗披碱草和达乌里披碱草的H基因组均起源于布顿大麦,St基因组可能起源于不同的拟鹅观草属物种;与达乌里披碱草相比垂穗披碱草St与Y基因组可能具有更高的染色体结构变异性,而垂穗披碱草St与Y基因组变异较大的原因可能是与同区域分布的含StY基因组的物种发生了种间渗透杂交。     

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。     

The use of double fluorescence in situ hybridization to physically map the positions of 5S rDNA genes in relation to the chromosomal location of 18S-5.8S-26S rDNA and a C genome specific DNA sequence in the genus Avena.

A physical map of the locations of the 5S rDNA genes and their relative positions with respect to 18S-5.8S-26S rDNA genes and a C genome specific repetitive DNA sequence was produced for the chromosomes of diploid, tetraploid, and hexaploid oat species using in situ hybridization. The A genome diploid species showed two pairs of rDNA loci and two pairs of 5S loci located on both arms of one pair of satellited chromosomes. The C genome diploid species showed two major pairs and one minor pair of rDNA loci. One pair of subtelocentric chromosomes carried rDNA and 5S loci physically separated on the long arm. The tetraploid species (AACC genomes) arising from these diploid ancestors showed two pairs of rDNA loci and three pairs of 5S loci. Two pairs of rDNA loci and 2 pairs of 5S loci were arranged as in the A genome diploid species. The third pair of 5S loci was located on one pair of A-C translocated chromosomes using simultaneous in situ hybridization with 5S rDNA genes and a C genome specific repetitive DNA sequence. The hexaploid species (AACCDD genomes) showed three pairs of rDNA loci and six pairs of 5S loci. One pair of 5S loci was located on each of two pairs of C-A/D translocated chromosomes. Comparative studies of the physical arrangement of rDNA and 5S loci in polyploid oats and the putative A and C genome progenitor species suggests that A genome diploid species could be the donor of both A and D genomes of polyploid oats. Key words : oats, 5S rDNA genes, 18S-5.8S-26S rDNA genes, C genome specific repetitive DNA sequence, in situ hybridization, genome evolution.     

Phylogenetic relationships in Elymus (Poaceae: Triticeae) based on the nuclear ribosomal internal transcribed spacer and chloroplast trnL-F sequences

To estimate the phylogenetic relationship of polyploid Elymus in Triticeae, nuclear ribosomal internal transcribed spacer (ITS) and chloroplast trnL-F sequences of 45 Elymus accessions containing various genomes were analysed with those of five Pseudoroegneria (St), two Hordeum (H), three Agropyron (P) and two Australopyrum (W) accessions. The ITS sequences revealed a close phylogenetic relationship between the polyploid Elymus and species from the other genera. The ITS and trnL-F trees indicated considerable differentiation of the StY genome species. The trnL-F sequences revealed an especially close relationship of Pseudoroegneria to all Elymus species included. Both the ITS and trnL-F trees suggested multiple origins and recurrent hybridization of Elymus species. The results suggested that: the St, H, P, and W genomes in polyploid Elymus were donated by Pseudoroegneria, Hordeum, Agropyron and Australopyrum, respectively, and the St and Y genomes may have originated from the same ancestor; Pseudoroegneria was the maternal donor of the polyploid Elymus; and some Elymus species showed multiple origin and experienced recurrent hybridization.     

Molecular phylogeny of RPB2 gene reveals multiple origin, geographic differentiation of H genome, and the relationship of the Y genome to other genomes in Elymus species

It has been hypothesized from isozymic and cytological studies of Elymus species that the Old and New World taxa may be of separate origin of the H genome in the StH genome species. To test this hypothesis, and estimate the phylogenetic relationships of polyploid Elymus species within the Triticeae, the second largest subunit of RNA polymerase II (RPB2) sequence of 36 Elymus accessions containing StH or StY genomes was analyzed with those of Pseudoroegneria (St), Hordeum (H), Agropyron (P), Australopyrum (W), Lophopyrum(Ee), Thinopyrum(Eb) and Dasypyrum (V). Our data indicated that the H genome in Elymus species is differentiated in accordance with geographical origin, and that the Eurasian and American StH genome species have independent alloploid origins with different H-genome donors. Phylogenetic analysis of Y genome sequences with other genome donors (St, H, P, W) of Elymus revealed that W and P genomes are sister to Y genome with a 87% bootstrap support, and that StY and StH species group might have acquired their RPB2 St sequences from distinct Pseudoroegneria gene pools. Our data did not support the suggestion that the St and Y genomes have the same origin as put forward in a previous study using ITS data. Our result provides some insight on the origin of Y genome and its relationship to other genomes in Elymus.     

A study of 28 Elymus species using repetitive DNA sequences.

Four repetitive DNA sequences cloned from the barley (Hordeum vulgare) genome and common for different Triticeae species were used for a molecular study of phylogenetic relationships among 28 Elymus species. Two wild Hordeum species (H genome), two Pseudoroegneria species (S genome), Agropyron cristatum (P genome), and Australopyrum velutinum (W genome) were included as genomic representatives for the genomes that supposedly were involved in the evolution of the genus Elymus. Our results are essentially congruent with the genomic classification system. This study demonstrates that Elymus is not a monophyletic genus. Based on an analysis of Southern blot hybridization we could discriminate between SY and SH species owing to the strong specific hybridization pattern of the H genome. Hexaploid SYH species gave a hybridization pattern similar to SH species for the same reason. The results support the genomic composition of Elymus batalinii as SYP and also indicated the presence of at least one H genome in Elymus enysii with a hitherto unknown genomic constitution. Elymus erianthus had a hybridization pattern distinctly different from all other species in the investigation. Key words : Elymus, RFLP, phylogeny, repetitive DNA.     

我国11种披碱草的核型研究

本文报道了中国产的11种披碱草属植物的核型,其中9种为首次报道。结果如下:老芒麦2n=4x=28=24m+4sm(2SAT);披碱草2n=6x=42=36m(2SAT)+6sm(4SAT);青紫披碱草2n=6x=42=32m+10sm(4SAT);垂穗披碱草2n=6x=42=34m+8sm(2SAT);圆柱披碱草2n=6x=42=32m+10sm(2SAT);短芒披碱草2n=6x=42=30m+12sm(4SAT);黑紫披碱草2n=6x=42=36m(6SAT)_1+6sm;毛披碱草2n=6x=42=30m+12sm(6SAT);紫芒披碱草2n=6x=42=22m=12sm(2SAT)+8st(4SAT);肥披碱草2n=6x=42=34m(2SAT)+6sm(4SAT)+2st;麦(?)草2n=6x=42=30m(4SAT)+12sm(2SAT)。     

Discovery of the genus Pseudoroegneria (Triticeae,Poaceae) in the Western Mediterranean on exploring the generic boundaries of Elymus

In this study, we review the classification of two species, Elymus hispanicus and E. marginatus, which are restricted to highly valuable and sensitive Mediterranean ecosystems. The genomic composition of the two species is analysed by in situ hybridization. In addition, lodicule morphology and foliar anatomy of both species are compared with those of E. caninus, E. repens, E. sibiricus (i.e., the type species of Elymus s.s.) and Pseudoroegneria strigosa (i.e., the type species of Pseudoroegneria). The genomic formula 2n = 8x = 56; HStStSt is proposed for E. hispanicus and 2n = 4x = 28; StSt for E. marginatus. In this latter species, the absence of the ribosomal genes in one of the two St genomes suggests that diploidization may have occurred during the evolution the species. Regarding foliar anatomy, E. hispanicus, E. caninus, E. repens, and E. sibiricus shared several characteristics, but the leaf blades of E. marginatus proved anatomically more similar to those of Ps. strigosa. The data compiled support the contention that: (1) E. hispanicus belongs to Elymus s.s.; (2) E. marginatus should be transferred to Pseudoroegneria; and (3) the morphology of the lodicules should be carefully reconsidered for appropriately describing the boundaries between Elymus s.s. and Pseudoroegneria. The new combination Ps. marginata is proposed and a detailed iconography of the plant is provided.     

Karyotypes of Elymus scabrifolius (Poaceae: Triticeae) from South America studied by banding techniques and in situ hybridization

Karyotypes of 4 accessions of Elymus scabrifolius (2n = 4x = 28) were investigated by Giemsa C- and N-banding, GAA-banding (one accession), AgNO3-staining and in situ hybridization with the rDNA probe pTa71. Two additional accessions were studied in less detail. The chromosomes were large (9-14 microns). The complements included 11 pairs of metacentrics, one with conspicuous satellites on the short arms, and 3 pairs of submetacentrics. Two of 4 accessions from Eastern Argentina and Uruguay had minute or small satellites on a submetacentric pair. No such satellites were observed in the other two accessions. In two accessions from the Cordoba province, a non-homologous submetacentric pair had very long satellites. AgNO3-staining established the presence of 4 nucleoli, two larger and two small ones, in 5 accessions. The C-banding patterns comprised from one to 12 conspicuous bands per chromosome at no preferential positions. The amount of constitutive heterochromatin (19-21%) was the highest hitherto established in the Triticeae. Similarities in banding patterns and chromosome morphology identified homologous and discriminated between non-homologous chromosomes within and, except for two chromosomes, between plants. Heteromorphic chromosome pairs were identified in satellite-carrying chromosomes only. N-banding produced conspicuous bands overall at the same positions as C-banding. GAA-banding patterns were similar to N-banding patterns. The rDNA probe hybridized to chromosome segments at nucleolar constrictions only. The production of C- and N-banding patterns in both genomes of E. scabrifolius suggests the presence of two H genomes and the absence of the pivotal St genome of Elymus. On account of the uncertain identity of one genome, and the overall similar gross morphology of E. scabrifolius and other tetraploid South American species referred to Elymus, E. scabrifolius is retained in Elymus.     

Genome constitution of Elymus tangutorum (Poaceae: Triticeae) inferred from meiotic pairing behavior and genomic in situ hybridization

Elymus tangutorum (Nevski) Hand.-Mazz (2n = 6x = 42) is a perennial species in the tribe Triticeae, which distributes in Nepal and north and northwest China. However, the genome constitution of E. tangutorum is controversial and its taxonomic status is not clear. Hybridizations of E. tangutorum were carried out with E. wawawaiensis J. R. Carlson & Barkworth (StH), Roegneria grandis Keng (StY), and E. dahuricus Turcz. ex Griseb. (StYH). Meiotic pairing in the hybrids E. tangutorum × E. wawawaiensis (StH), E. tangutorum × R. grandis (StY), and E. tangutorum × E. dahuricus (StYH) averaged 10.48, 11.12, and 20.92 bivalents per cell, respectively. The results suggested that E. tangutorum is an allohexaploid and contains the StYH genomes. Results of genomic in situ hybridization analysis strongly supported the chromosome pairing data. Therefore, E. tangutorum should be treated as Campeiostachys dahurica var. tangutorum (Nevski) B. R. Baum, J. L. Yang & C. Yen. Intergenomic rearrangements of E. tangutorum may be affected by environmental factors.     

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.     

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。     

中间偃麦草(Thinopyrum intermedium)18S-5.8S-26S rDNA位点在染色体上的分布及对其核ITS序列异质性的分析(英文)

中间偃麦草(Thinopyrum intermedium(Host)Barkworth et Dewey)是禾本科小麦族植物中的一个异源六倍体物种,是重要的牧草植物,在小麦的抗病育种中发挥了重要作用。利用荧光原位杂交(FISH)技术,在体细胞中期染色体上,对18S-5.8S-26S rDNA位点进行了物理定位,发现该物种有3～4对染色体携带18S-5.8S-26S rDNA主位点。结合基因组原位杂交(GISH)分析,证明中间偃麦草的St基因组中有一对同源染色体短臂末端携带一个主位点,其余2～3对主位点位于E基因组染色体上。对不同来源的材料研究表明:18S-5.8S-26S rDNA位点的数目(包括主位点和小位点)、位置、拷贝数在不同收集材料之间的差异较大,甚至在同一个体的不同细胞中也存在差异。讨论了rDNA物理作图数据在分析系统发育问题中的局限性。结合中间偃麦草的三个可能的二倍体基因组供体(Th.bessarabicum、Th. elongatum和Pseudoroegneria stipifolia)rDNA位点分析的结果,对中间偃麦草进化过程中rDNA位点的变化进行了分析,同时,对其中一份材料的核ITS序列进行了克隆、测序和系统发育分析,发现在中间偃麦草中,ITS序列具有很高的异质性。     

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.     

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。     

Biosystematic study of hexaploids Elymus tschimganicus and E. glaucissimus. II. Interspecific hybridization and genomic relationship.

To investigate genomic relationships of Elymus tschimganicus (Drobov) Tzvelev (2n = 6x = 42, S1S2Y genomes) and E. glaucissimus (M. Pop.) Tzvelev (2n = 6x = 42, S1S2Y genomes), interspecific hybridizations of the two target species were carried out with 27 other Elymus species containing the SH, SY, SYH, SYP, SYW, and SH1H2 genomes, respectively, collected from different geographic regions. Chromosome pairing behavior was analyzed at metaphase I in 27 hybrids representing 23 hybrid combinations, and overall genomic relationships of the two target species with the other Elymus taxa were estimated. The study concluded that (i) interspecific hybridization was principally easy to perform between the Elymus species, but no general pattern of crossability was obtained, and all hybrids were completely sterile, (ii) the two species have a similar meiotic pattern in their hybrids with the other Elymus species, and (iii) species containing the SY, SYP, and SYH genomes have a generally higher level of genomic homology to the target species than those possessing the SH genomes, and the South American hexaploid with the SH1H2 genomes has the lowest level of genomic homology to the two target taxa.     

Ancestry of American polyploid Hordeum species with the I genome inferred from 5S and 18S-25S rDNA

* BACKGROUND AND AIMS: The genus Hordeum exists at three ploidy levels (2x, 4x and 6x) and presents excellent material for investigating the patterns of polyploid evolution in plants. Here the aim was to clarify the ancestry of American polyploid species with the I genome. * METHODS: Chromosomal locations of 5S and 18S-25S ribosomal RNA genes were determined by fluorescence in situ hybridization (FISH). In both polyploid and diploid species, variation in 18S-25S rDNA repeated sequences was analysed by the RFLP technique. * KEY RESULTS: Six American tetraploid species were divided into two types that differed in the number of rDNA sites and RFLP profiles. Four hexaploid species were similar in number and location of both types of rDNA sites, but the RFLP profiles of 18S-25S rDNA revealed one species, H. arizonicum, with a different ancestry. * CONCLUSIONS: Five American perennial tetraploid species appear to be alloploids having the genomes of an Asian diploid H. roshevitzii and an American diploid species. The North American annual tetraploid H. depressum is probably a segmental alloploid combining the two closely related genomes of American diploid species. A hexaploid species, H. arizonicum, involves a diploid species, H. pusillum, in its ancestry; both species share the annual growth habit and are distributed in North America. Polymorphisms of rDNA sites detected by FISH and RFLP analyses provide useful information to infer the phylogenetic relationships of I-genome Hordeum species because of their highly conserved nature during polyploid evolution.     

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.     

Genetic Relationships Among Five Basic Genomes St,E,A,B and D in Triticeae Revealed by Genomic Southern and in situ Hybridization

The St and E are two important basic genomes in the perennial tribe Triticeae (Poaceae). They exist in many perennialspecies and are very closely related to the A, B and D genomes of bread wheat (Triticum aestivum L.). Genomic Southernhybridization and genomic in situ hybridization (GISH) were used to analyze the genomic relationships between the twogenomes (St and E) and the three basic genomes (A, B and D) of T. aestivum. The semi-quantitative analysis of the Southernhybridization suggested that both St and E genomes are most closely related to the D genome, then the A genome, andrelatively distant to the B genome. GISH analysis using St and E genomic DNA as probes further confirmed the conclusion.St and E are the two basic genomes of Thinopyrum ponticum (StStE~eE~bE~x) and Th. intermedium (StE~eE~b), two perennialspecies successfully used in wheat improvement. Therefore, this paper provides a possible answer as to why most of thespontaneous wheat-Thinopyrum translocations and substitutions usually happen in the D genome, some in the A genomeand rarely in the B genome. This would develop further use of alien species for wheat improvement, especially thosecontaining St or E in their genome components.