A FISH karyotype to study chromosome polymorphisms for the Elytrigia elongata E genome

Elytrigia elongata (Host) Nevski(= Agropyron elongatum, Thinopyrum elongatum, 2n = 2x = 14, EE) has long been used as a source of various types of resistance for wheat improvement, and numerous transfers have been made. However, despite heavy use, no high-resolution karyotype exists. We characterized the E. elongata karyotype of several accessions applying highly repetitive DNA sequences as mcFISH probes for chromosome identification. The complete E. elongata disomic chromosome addition series and 11 ditelosomic addition lines in Chinese Spring wheat were exposed to sequential GISH-mcFISH. Based on the mcFISH results, each complete chromosome and each telocentric studied was unambiguously identified. The validation of the karyotype in 4 E. elongata accessions with different geographical origins showed extensive variations in the probe hybridization patterns, but this did not prevent chromosome identification. The established karyotype will be useful for the rapid identification of potential donor chromosomes in wheat improvement programs, allowing appropriate alien transfer.     

RAPD and ISSR-assisted identification and development of three new SCAR markers specific for the Thinopyrum elongatum E (Poaceae) genome

Diploid Thinopyrum elongatum, a wild relative of wheat, contains many agronomically desirable traits and has potential for increasing genetic variability and introducing desirable characters in this crop. Few molecular markers are available for rapid screening of T. elongatum genome segments in the wheat genetic background. We used 36 RAPD primers and 33 ISSR primers to screen for polymorphisms in the common wheat variety Chinese Spring and in T. elongatum. Two RAPD markers and one ISSR marker, designated OPF03(1407), LW10(1487) and UBC841(701), were identified and were specific for the T. elongatum E genome. Three pairs of primers flanking these specific sequences were designed to produce SCAR markers. All three SCAR markers were T. elongatum E genome-specific. Two of these SCAR markers, SCAR(807) and SCAR(577), were present in all seven T. elongatum chromosomes, while SCAR(839) was specific for T. elongatum chromosomes 2E and 3E. These newly developed SCAR markers should be useful for detecting alien genome chromatin or chromosome segments in the genetic background of common wheat.     

Molecular cytogenetic characterization of wheat--Thinopyrum elongatum addition, substitution and translocation lines with a novel source of resistance to wheat Fusarium Head Blight

Thinopyrum elongatum(2n = 2x = 14,EE),a wild relative of wheat,has been suggested as a potentially novel source of resistance to several major wheat diseases including Fusarium Head Blight(FHB).In this study,a series of wheat(cv.Chinese Spring,CS) substitution and ditelosomic lines,including Th.elongatum additions,were assessed for TypeⅡresistance to FHB.Results indicated that the lines containing chromosome 7E of Th.elongatum gave a high level of resistance to FHB,wherein the infection did not spread beyond the inoculated floret.Furthermore,it was determined that the novel resistance gene(s) of 7E was located on the short-arm(7ES) based on sharp difference in FHB resistance between the two 7E ditelosomic lines for each arm.On the other hand,Th.elongatum chromosomes 5E and 6E likely contain gene(s) for susceptibility to FHB because the disease spreads rapidly within the inoculated spikes of these lines. Genomic in situ hybridization(GISH) analysis revealed that the alien chromosomes in the addition and substitution lines were intact,and the lines did not contain discernible genomic aberrations.GISH and multicolor-GISH analyses were further performed on three translocation lines that also showed high levels of resistance to FHB.Lines TA3499 and TA3695 were shown to contain one pair of wheat-Th. elongatum translocated chromosomes involving fragments of 7D plus a segment of the 7E,while line TA3493 was found to contain one pair of wheat-Th.elongatum translocated chromosomes involving the D- and A-genome chromosomes of wheat.Thus,this study has established that the short-arm of chromosome 7E of Th.elongatum harbors gene(s) highly resistant to the spreading of FHB,and chromatin of 7E introgressed into wheat chromosomes largely retained the resistance,implicating the feasibility of using these lines as novel material for breeding FHB-resistant wheat cultivars.     

Genetic variation for waterlogging tolerance in the Triticeae and the chromosomal location of genes conferring waterlogging tolerance in Thinopyrum elongatum.

A number of Triticeae species were tested for tiller production, shoot dry matter production, and root penetration in waterlogged soil, and Thinopyrum elongatum and Elytrigia repens were shown to have better tolerance than wheat using these criteria. Tests of a number of wheat-alien amphiploids showed that there was at least partial expression of this exotic genetic variation in a wheat genetic background. The presence of chromosomes 2E and 4E of Th. elongatum was associated with a positive effect on root growth in waterlogged conditions. The positive effect of the 4E chromosome addition was mimicked by tetrasomic lines carrying extra doses of wheat homoeologues 4B and 4D, and it was concluded that the beneficial effect contributed by the presence of 4E was probably due to an increased dosage of group 4 chromosomes. However, the positive effect of adding chromosome 2E to wheat could not be reproduced by added doses of chromosomes 2A, 2B, or 2D, suggesting that this alien chromosome carries gene(s) for tolerance not present on its wheat homoeologues. This gene(s) was further located to the long arm of chromosome 2E by testing ditelosomic addition lines.     

长穗偃麦草基因组中与耐低磷营养胁迫有关的基因的染色体定位

以中国春－长穗偃麦草二体异附加系和二体异代换系为材料，对其耐低磷营养胁迫特性进行鉴定和遗传分析，结果表明（１）长穗偃麦草的４Ｅ一＾ 色体携有耐低营养胁迫的基因，且其效应远远超过背景亲本中国春。     

一种小麦蓝粒标记单体代换系4E（3D）的创制

以中国春3D单体和小麦-长穗偃麦草4E二体异附加系为材料,通过杂交、回交结合染色体鉴定等方法,培育出了一种具有蓝粒标记的小麦4E(3D)单体代换系.该小麦4E(3D)单体代换系籽粒为浅蓝色,能够正常生长,自交结实率为36.1%,其自交后代可分离出深蓝籽粒小麦4E(3D)二体代换系、浅蓝籽粒小麦4E(3D)单体代换系和白粒小麦3D缺体.结果表明,长穗偃麦草4E染色体对小麦3D染色体缺失有一定的补偿功能,对以染色体定向代换方式快速创制蓝粒标记小麦单体系统具有一定的参考价值.     

簇毛麦基因组特异性PCR标记的建立和应用

以普通小麦中国春、簇毛麦、中国春－簇毛麦二体附加系和代换系为材料进行RAPD分析,筛选出一个簇毛麦基因组特异性RAPD片段OPFO2757,该片段分布于簇毛麦所有染色体上。在对OPFO2757进行克隆、测序的基础上,设计一对PCR引物,建立了簇毛麦基因组特异性PCR标记。用这对PCR引物对不同普通小麦品种、不同硬粒小麦品种、不同居群的簇毛麦、中国春－簇毛麦二体附加系、中国春－簇毛麦二体代换系、普通小麦－簇毛麦双二倍体、硬粒小麦－簇毛麦双二倍体等材料进行扩增,凡具有簇毛麦染色体的材料都能扩增出一条长为677bp的DNA片段,而不具簇毛麦染色体的材料包括大麦、黑麦、长穗偃麦草、中间偃麦草等不能扩增出该片段。所以,该特异性PCR标记可用于快速跟踪检测小麦背景中的簇毛麦染色体。     

长穗偃麦草优异基因的染色体定位及应用

长穗偃麦草比较公认的有2个种,即二倍体长穗偃麦草(Thinopyrum elongatum,2n=2X)和十倍体长穗偃麦草(Thinopyrum ponticum,2n=10X),是重要的小麦近缘种,具有抗病、抗寒、抗旱、耐盐碱等优良性状。因其基因组中蕴含许多对小麦品种改良极为有用的基因,且易与小麦杂交等优势,多年来长穗偃麦草一直作为小麦遗传改良的优良种质资源而备受关注。本文对长穗偃麦草的基因组研究及其在小麦的抗逆、抗病和提高光合能力、产量及高分子量谷蛋白(HMW-GS)含量等方面的应用做了综述,为其基因组中优异基因的进一步开发和利用提供了理论依据。     

Does tolerance of wheat to salinity and hypoxia correlate with root dehydrogenase activities or aerenchyma formation?

The effects of NaCl salinity (100 or 150 mol m^-3) and hypoxia on seedlings of several wheat varieties (Lyallpur-90, SARC-1, Pato, Tchere, Pb-85, Siete Cerros, Chinese Spring and a Chinese Spring × Thinopyrum elongatum amphidiploid) were studied in solution culture. In vivo studies of activities of different enzymes (alcohol dehydrogenase (ADH), lactate dehydrogenase (LDH) and cytochrome oxidase (COase)) extracted from Pato and Pb-85 included the effect of salinity with and without hypoxia, while during in vitro studies, NaCl, glycinebetaine and proline were added to the assay mixture. The extent of aerenchyma formation was also determined in Pato, Chinese Spring and a Chinese Spring × Thinopyrum elongatum amphidiploid. Imposition of hypoxia greatly induced ADH and LDH activity in roots of wheat seedlings after a week-long exposure. However, exposure of roots to salinity also slightly increased LDH and ADH activity compared with the non-saline control. On a relative basis, Pato had higher ADH activity under hypoxic (21×) or saline-hypoxic stress (20×) than in aerated conditions. Hypoxia alone or in the presence of salts decreased COase activity in both Pato and Pb-85. The in vitro studies revealed that NaCl (on an equimolar basis at up to 500 mol m^-3) is more disruptive than glycinebetaine or proline. LDH was more sensitive to NaCl than ADH. Aerenchyma development was higher near the root-shoot interface compared to near the root tip. Salinity under hypoxic conditions significantly reduced aerenchyma development near the root tip and root-shoot interface compared to hypoxia alone. Neither enzyme activity nor aerenchyma formation could account for varietal differences in tolerance to hypoxia alone or in combination with salinity.     

Evolutionary origin of a periodical mass‐flowering plant

The evolutionary origin of periodical mass‐flowering plants (shortly periodical plants), exhibiting periodical mass flowering and death immediately after flowering, has not been demonstrated. Within the genus Strobilanthes (Acanthaceae), which includes more than 50 periodical species, Strobilanthes flexicaulis on Okinawa Island, Japan, flowers gregariously every 6 years. We investigated the life history of S. flexicaulis in other regions and that of closely related species together with their molecular phylogeny to reveal the evolutionary origin of periodical mass flowering. S. flexicaulis on Taiwan Island was found to be a polycarpic perennial with no mass flowering and, in the Yaeyama Islands, Japan, a monocarpic perennial with no mass flowering. Molecular phylogenetic analyses indicated that a polycarpic perennial was the ancestral state in this whole group including S. flexicaulis and the closely related species. No distinctive genetic differentiation was found in S. flexicaulis among all three life histories (polycarpic perennial, monocarpic perennial, and periodical plant). These results suggest that among S. flexicaulis, the periodical mass flowering on Okinawa Island had evolved from the polycarpic perennial on Taiwan Island via the monocarpic perennial in the Yaeyama Islands. Thus, the evolution of life histories could have taken at the level of local populations within a species.     

Survivorship after flowering and flowering synchronicity of three cultivated Strobilanthes flexicaulis individuals from Iriomote Island,Japan

Strobilanthes flexicaulis in Iriomote Island, Japan, is a monocarpic perennial plant, which is thought to be an intermediate evolutionary state from a polycarpic perennial plant to a periodical mass-flowering plant. It remains unclear whether the intermediate reproductive traits are altered by cutting propagation or disbudding treatment (flower bud removal). To evaluate whether these traits are affected by such treatments, three individuals of S. flexicaulis from Iriomote Island were cultivated, and their flowering patterns and survivorship were observed. The monocarpic trait seemed to have been altered into a polycarpic trait by cultivation. The disbudding treatment was not related to the survivorship. The initiation of flowering was synchronized, but the termination of the second flowering period was variable among the three individuals and between the treatments. S. flexicaulis on Iriomote Island seemed to have individual variation in reproductive traits. This variation may result in their intermediate evolutionary state.     

四倍体小麦背景中长穗偃麦草E染色体传递特征

通过细胞学方法和染色体特异分子标记鉴定六倍体小偃麦(AABBEE)与硬粒小麦(AABB)杂交的自交后代F₂和F₃植株,探讨长穗偃麦草染色体在硬粒小麦背景中世代间的传递特征,并筛选硬粒小麦-长穗偃麦草E染色体附加系。对218个F₂单株染色体数检测表明,2n=28植株占41.7%,2n=29植株占18.3%,其余40.0%植株的染色体数在2n=31~42范围内。分子标记鉴定表明,在F₂代2n=29单体附加植株中,不同的长穗偃麦草染色体传递率之间存在明显差异,1E传递率最高,3E和6E传递率最低。在F₂代2n=30单株中,1E、4E、7E和5E染色体相互组合产生的双单体多,6E参与组合较少,未检测到2E或3E与其他染色体的组合单株。在1E~7E单体附加株自交后代F₃中,E染色体传递率变化范围为9.1%~27.5%,1E传递率最高,6E传递率最低,与F₂的传递率一致。从F₃代中选育出1E~7E单体附加及少数二体附加,所有单体附加均可育。这些附加E染色体材料将对小麦代换系和易位系的创制提供有益的中间材料。     

An analysis of life history evolution in terms of the density-dependent Lefkovitch matrix model.

The evolution of demographic characteristics is considered in terms of the density-dependent Lefkovitch matrix model, which describes a species' population dynamics with a stage-specific pattern of reproduction and mortality. We obtain the invadability condition of a mutant-type into the wild-type population at the equilibrium state. The condition depends on the left and right eigenvectors at the equilibrium state. The condition depends on the left and right eigenvectors at the equilibrium state and the difference, between wild-type and mutant-type populations, of the values of elements in the Lefkovitch matrix at the equilibrium state. It is also shown that if elements of the density-dependent Lefkovitch matrix are decreasing functions of population density, then the equilibrium population density increases in the process of natural selection; that is, K-selection acts even on the stage-structured population. The evolution of life history in perennial plants is discussed through two models as an application of the above results. The evolution of perennial plants with no vegetative reproduction is analyzed in the first example. It is shown that whether monocarpic perennials (which reproduce once and die) or polycarpic perennial plants (which reproduce more than once) are favored depends on the cost of a produced seed. The second example concerns perennial plants that reproduce vegetatively. It is shown that whether monocarpic or polycarpic perennial plants are favored depends on the cost of a seed and that where vegetative reproduction is common, polycarpic perennials with no seed reproduction are favored.     

长穗偃麦草酸性磷酸酶与碱性磷酸酶编码基因的染色体定位

以一套中国春-长穗偃麦草二体异附加系与二体异代换系为材料,用等电聚焦(IEF)研究长穗偃麦草基因组中酸性磷酸酶(AcPh)与碱性磷酸酶(APH)编码基因的染色体定位。结果表明,AcPh大多聚焦于pH5～7范围内,其编码基因位于3E染色体,而APH编码基因则位于4E染色体。由于5E染色体的附加,AcPh活性带强度显著减弱。     

Utilization of blue-grained character in wheat breeding derived from Thinopyrum poticum

The blue grain trait in common wheat （Triticum aestivum L., 2n = 6x = 42, AABBDD）, which is caused by blue pigments in the aleurone layer, was originally derived from the tall wheatgrass （Thinopyrum ponticum Liu ＆ Wang = Agropyron elongatum, 2n = 10x = 70, StStStStEeEeEbEbEXEx） during chromosome engineering research. Over the last few decades, there have been continued interests in the genetic mechanism of this blue coloration and the practical utilization of the blue aleurone character as a phenotypic marker. This article reviews the research history and the recent progress of the studies on blue-grained wheat, with emphases on genetic and biochemical analysis and practical applications of blue-grained wheat.     

抗白粉病小偃麦异代换系的细胞学和RAPD鉴定

利用细胞学和RAPD方法,对从长穗偃麦草与普通小麦复合杂交后代中选育的抗白粉病小麦种质系山农87074－526和山农87074－551进行了鉴定。结果表明,两种质系的根尖细胞染色体数目均为2n=42,花粉母细胞减数分裂中期I（PMC MI）染色体构型为2n=21Ⅱ;二者杂交F1 PMC MI染色体构型亦为2n=21Ⅱ,两种质系分别与小麦中国春的杂种F1 PMC MI染色体构型均为2n=20Ⅱ 2I,说明两种质系为相同的双体异代系。在苗期和成株期两种质系对白粉病15号菌种均表现免疫,其白粉病抗性为显性,并且来自长穗偃麦草,抗白粉病基因位于它们所含的偃麦草染色体上。从80个随机引物中,筛选出2个引物OPE13和OPH15能在两种质系中稳定地扩增出长穗偃麦草亲本的特异DNA片段。     

Identification of Blue-grained Wheat Translocation Lines Using Fluorescence in Situ Hybridization

The blue-grained wheat substitution line (blue 58) originated from wild hybridization between Triticum aestivum L. and Agropyron elongatum (Host) Beauv= Elytrigia elongatum (Host) Nevski= Thinopyrum ponticum (Host) Barkworth and Dewey (2n=10x=70) was irradiated and four translocation lines were screened by fluorescence in situ hybridization from the offsprings. The results obtained include the following: (1) both the two translocation lines, 9906 and 9902, have 42 chromosomes. The length of the translocated blue-grained segment was approximately one-third of the short-arm and one-half of the long-arm of the translocated wheat chromosome in 9906 and 9902, respectively, and the blue-grained translocated segment in 9902 was located on D genome; (2) both 9915 and 9904 have 44 chromosomes. One pair of chromosomes was translocated and two chromosomes from Th. ponticum were added in 9903, while two pairs of chromosomes were translocated in 9904 by blue-grained wheat segment. The location and application of blue-grained wheat translocation lines were discussed.     

蓝粒小麦易位系的荧光原位杂交鉴定

普通小麦（Triticum aestivum L.)和长穗偃麦草（Agropyron elongatum (Host)Beauv=Elytriga elongatum(Host)Nevski=Thinopyrum ponticum (Host)Barkworth and Dewey,2n=10x=70)杂交后选育出的蓝粒小麦异代换系（蓝５８）,２n=42其中９９０６中被易位蓝粒片段的相对长度约占易位小麦染色体短臂的１／３,而９９０２中被易位蓝粒片段的相对长度约占易位小麦染色体长臂的１／２,并将９９０２的蓝粒易位片段定位在小麦Ｄ组染色体上;（２）９９１５易位附加和９９０４易位－易位附加,其体细胞染色体数均为４４,其中９９１５的体细胞染色体只有一对发生了易位,另外队了两条长穗偃麦草染色体;而９９０４有两对染色体发生了易位,并易位系中控制蓝粒性状的长穗偃麦草染色体片段的定位和蓝粒小麦易位系的应用进行了讨论。     

Characterization of six wheat x Thinopyrum intermedium derivatives by GISH, RFLP, and multicolor GISH.

Restriction fragment length polymorphism (RFLP) analysis and multicolor genomic in situ hybridization (GISH) are useful tools to precisely characterize genetic stocks derived from crosses of wheat (Triticum aestivum) with Thinopyrum intermedium and Thinopyrum elongatum. The wheat x Th. intermedium derived stocks designated Z1, Z2, Z3, Z4, Z5, and Z6 were initially screened by multicolor GISH using Aegilops speltoides genomic DNA for blocking and various combinations of genomic DNA from Th. intermedium, Triticum urartu, and Aegilops tauschii for probes. The probing (GISH) results indicated that lines Z1 and Z3 were alien disomic addition lines with chromosome numbers of 2n = 44. Z2 was a substitution line in which chromosome 2D was substituted by a pair of Th. intermedium chromosomes; this was confirmed by RFLP and muticolour GISH. Z4 (2n = 44) contained two pairs of wheat--Th. intermedium translocated chromosomes; one pair involved A-genome chromosomes, the other involved D- and A- genome chromosomes. Z5 (2n = 44) contained one pair of wheat--Th. intermedium translocated chromosomes involving the D- and A-genome chromosomes of wheat. Z6 (2n = 44) contained one pair of chromosomes derived from Th. intermedium plus another pair of translocated chromosomes involving B-genome chromosomes of wheat Line Z2 was of special interest because it has some resistance to infection by Fusarium graminearum.     

Characterization of a Wheat- wheatgrass Translocation Line by FISH

The genomic DNA of wheatgrass (Agropyron intermedium (Host) P.B. = Elytrigia intermedia (Host) Nevski = Thinopyrum intermedium (Host) Barkworth and Dewey) was labelled with biotin-16-dUTP as a probe, and genomic DNA of common wheat ( Triticum aestivum L. ) "Chinese Spring" was used for blocking. Wheat-wheatgrass line 33 was examined by fluorescence in situ hybridization (FISH) technique. The terminal regions of a pair of chromosomes showed green fluorescent signals. It has been concluded that chromosome segrnents containing alien genes of wheatgrass are located at the terminal regions of wheat chromosomes in wheat-wheatgrass line 33, and the translocated segments were small. Wheat-wheatgrass line 33 has been proved to be a translocation line with chromosome segments of wheatgrass translocated to the terminal regions of wheat chromoSomes.