Development of Chromosome Segment Substitution Lines Derived from Backcross between Two Sequenced Rice Cultivars, <Emphasis Type="Italic">Indica</Emphasis> Recipient 93-11 and <Emphasis Type="Italic">Japonica</Emphasis> Donor Nipponbare

Chromosome segment substitution lines (CSSLs) are powerful tools for detecting and precisely mapping quantitative trait loci (QTLs) and evaluating gene action as a single factor. In this study, 103 CSSLs were produced using two sequenced rice cultivars: 93-11, an elite restorer indica cultivar as recipient, and Nipponbare, a japonica cultivar, as donor. Each CSSL carried a single chromosome substituted segment. The total length of the substituted segments in the CSSLs was 2,590.6 cM, which was 1.7 times of the rice genome. To evaluate the potential application of these CSSLs for QTL detection, phenotypic variations of seed shattering, grain length and grain width in 10 CSSLs were observed. Two QTLs for seed shattering and three for grain length and grain width were identified and mapped on rice chromosomes. The results demonstrate that CSSLs are excellent genetic materials for dissecting complex traits into a set of monogenic loci. These CSSLs are of great potential value for QTL mapping and plant marker-assisted breeding (MAB).     

四川当归属六种植物的核型

从居群水平对四川当归属(AngelicaL.)6种植物的核型进行了研究,其中管鞘当归核型为首次报道。6个种的染色体均为2n=2x=22,多为中部和近中部着丝粒染色体,核型多为2A型,仅疏叶当归石灰窑居群为1A型;峨眉当归核型为2n=22=10m 2sm 10st,茂汶当归核型为2n=22=16m 4sm 2sm(SAT),当归核型为2n=22=14m 8sm,阿坝当归核型为2n=22=14m 8sm,管鞘当归核型为2n=22=12m 8sm 2sm(SAT),而疏叶当归不同居群的核型或多或少发生了不同程度的变异。参照Stebbins的观点,峨眉当归以核型不对称系数最高而在6个种中显示一定的核型进化性,疏叶当归不对称系数较低,且出现1A型核型因而体现出一定的原始性。但是,综合形态解剖、花粉性状以及核型特征可以看出,四川当归属植物各性状间具有进化的不同步性,这也表明,作为当归属分布频度中心之一的四川地区,同时也是当归属的分化中心之一。     

三种榉属植物染色体数目及核型分析

报道了我国3种榉属(Zelkova)植物核型。结果如下:大叶榉(Z.schneideriana Hand.-Mazz.)2n=2x=28=14m 14sm;光叶榉(Z.serrata(Thunb.)Makino)的核型公式为2n=2x=28=26m 2sm,1、2、3对染色体的短臂上有次缢痕存在;大果榉(Z.sinica Schneid)的核型公式为2n=2x=28=20m 8sm。     

Testing the association of phenotypes with polyploidy: An example using herbaceous and woody eudicots

Although numerous studies have surveyed the frequency with which different plant characters are associated with polyploidy, few statistical tools are available to identify the factors that potentially facilitate polyploidy. We describe a new probabilistic model, BiChroM, designed to associate the frequency of polyploidy and chromosomal change with a binary phenotypic character in a phylogeny. BiChroM provides a robust statistical framework for testing differences in rates of polyploidy associated with phenotypic characters along a phylogeny while simultaneously allowing for evolutionary transitions between character states. We used BiChroM to test whether polyploidy is more frequent in woody or herbaceous plants, based on tree with 4711 eudicot species. Although polyploidy occurs in woody species, rates of chromosome doubling were over six times higher in herbaceous species. Rates of single chromosome increases or decreases were also far higher in herbaceous than woody species. Simulation experiments indicate that BiChroM performs well with little to no bias and relatively little variance at a wide range of tree depths when trees have at least 500 taxa. Thus, BiChroM provides a first step toward a rigorous statistical framework for assessing the traits that facilitate polyploidy.     

Karyomorphology of Turkish species in Centaurea sections Centaurea and Phalolepis (Asteraceae) and implications for taxonomy

In this paper, 31 mostly endemic and locally distributed Turkish Centaurea taxa belonging to Centaurea and Phalolepis sections were examined in terms of their karyomorphology. The basic chromosome number for all of the studied species was concurringly determined as 9(x = 9) for both sections, excluding C. hierapolitana. We also determined tetraploid and hexaploid species in spite of many species having diploid chromosome numbers. Twelve chromosome counts are reported for the first time and most of the karyotyping analyses are described for the first time via the KAMERAM program. The karyotypes had a predominance of metacentric (m) chromosomes. However, in the karyotyping of six taxa, submetacentric (sm) chromosomes were dominant. Five quantitative asymmetric indices were used to evaluate karyological features of the species. A meaningful dendrogram was carried out to assess the karyotype-symmetry conditions and describe the karyotyping relationships between different taxa.     

水稻产量及其构成因子对大气CO2浓度升高响应的相关QTL初步分析

以粳稻Asominori与籼稻IR24所衍生的染色体片段置换系(CSSL)为材料,于2003年和2004年连续2年在FACE(free air CO2 enrichment,大气CO2浓度增加200μmol/mol)和正常大气CO2浓度(约370μmol/mol)下,分析了控制单株产量、有效分蘖数、每穗实粒数和千粒重的数量性状位点(QTL)。结果表明,2年共检测到36个控制产量性状的QTL,分布在除第5、10和11染色体的各条染色体上。其中,仅有位于第1染色体上靠近XNbp113标记的1个控制千粒重的QTL,在2年的FACE和对照下都被检测到,并且其加性效应均来自IR24,但其贡献率在各个年份和两CO2浓度下却表现不同。另外,36个QTL中,2个QTL(qTGW1-3QE和qFT3-3QE)被检测到具有显著的基因型×环境互作。     

Genotoxic effects of the pesticides Rubigan, Omite and Rovral in root-meristem cells of Crepis capillaris L.

Three pesticides have been studied for their genotoxicity by the use of assays in the plant Crepis capillaris, aimed at measuring chromosomal aberrations, micronuclei and sister chromosome exchange (SCE). The fungicides Rubigan 12 EC (fenarimol) and Rovral 25 Flo (iprodione) and the insecticide Omite 57 E (propargite) are all widely used nowadays. The aim of our study was to evaluate the genotoxic effects of these pesticides at concentrations corresponding to those applied in agricultural practice. In preliminary experiments we found that these concentrations do not influence cell proliferation and do not inhibit the growth of root meristems. In all experiments formulated commercial products were used. From the results we conclude that the three pesticides did not induce chromosomal aberrations as estimated by metaphase and anaphase analyses. They were also not capable to induce SCE. Rubigan did not induce micronucleus formation even at the highest concentration tested, but Omite and Rovral markedly increased micronucleus formation. The MN response depended on the sampling time and the concentration used, which showed a significant dose–response correlation (r = 0.978, P < 0.01 and r = 0.941, P < 0.01, respectively). A greater increase in micronucleus frequency was observed after Rovral treatment, where the highest concentration gave a response 8–10-fold above the negative control. Both pesticides induced high frequencies of lagging chromosomes, even after exposure to the lower test concentrations. The presence of lagging chromosomes is an indication of anti-microtubule activity of the pesticides tested. This effect was more strongly expressed after exposure to the two higher concentrations of Omite and Rovral. In this case a complete destruction of the mitotic spindle was observed, resulting in C-mitoses as well as in numerical aberrations—polyploidy and aneuploidy. The present findings suggest that Omite and Rovral at concentrations comparable to those used in practice can be regarded as potential aneugens.     

五种橐吾属植物的核型研究

首次报道了5种国产橐吾属植物的核型,结果如下：东俄洛橐吾(Ligularia tongolensis)核型为2n=58=32m 14sm 12st;侧茎橐吾(L.pleurocaulis)四川稻城居群核型为2n=58=24m 32sm 2st 3～5B,云南中甸居群核型为2n=58=36m 22sm;云南橐吾(L．yunnanensis)核型为2n=58=28m 30sm;叶状鞘橐吾(L．phyllocolea)核型为2n=58=30m 24sm 4st 1B;浅苞橐吾(L．cynthceps)核型为2n=58=24m 34sm。5种橐吾染色体数目都为58。在叶状鞘橐吾和四川稻城产侧茎橐吾中发现有B染色体存在,这在以前对橐吾属及近缘属植物的核型研究中未见报道。     

The peripheral chromosome scaffold, a novel structural component of mitotic chromosomes

Using an original high-salt extraction protocol, we observed a novel chromosome substructure, referred to as the peripheral chromosome scaffold. This chromosome domain contained the perichromosomal layer proteins pKi-67, B23/nucleophosmin and fibrillarin, but no DNA fragments (i.e., the loop domain bases were not associated with the peripheral scaffold). Modern models of chromosome organization do not predict the existence of a peripheral chromosome scaffold domain, and thus our observations have conceptual implications for understanding chromosome architecture.     

远缘杂交在转移有益基因创造小麦新种质中的潜力

本文概述了小麦远缘杂交技术的发展以及这些技术的应用对以染色体易位方式转移有益基因到普通小麦中的影响。通过对小麦远缘杂交技术的总结得出,普通小麦由于本身的多倍性,对导入的外源基因具有较强的调节能力,是适宜外源有益基因导入的良好受体。而以染色体易位方式转移有益基因是创造小麦新种质的有效方法之一,许多研究也表明以染色体易位导入的外源有益基因更利于表达。近几年,随着细胞遗传学以及其它生物技术的发展,对小麦族进化途径和染色体间的亲缘关系进一步明确,从而更便于进行易位导入的技术选择,也使得染色体易位鉴定方法更趋完善。现在已有更良好的外源导入的工具和方法,使多基因控制的外源优良性状导入成为可能。在小麦远缘杂交中染色体易位所具有的上述优势,在育种实践中逐步显示出来,为开拓小麦种质资源开创了一条新的途径。