小麦与彭梯卡偃麦草杂种及其衍生后代的细胞遗传学研究──Ⅱ．来自小麦和彭梯卡（长穗）偃麦草及中间偃麦草杂种后代11个八倍体小偃麦的比较研究

利用染色体配对分析和酯酶及种子醇溶蛋白电泳分析研究了我国育成的１１个八倍体小偃麦,结果表明：（ａ）来源于小麦和中间偃麦草杂交后代的６个部分双二倍体中,中１和中２的偃麦草染色体组不同于中３、中４、中５和小偃７８８２９的偃麦草染色体组;（ｂ）来源于小麦和长穗偃麦草杂交后代的５个部分双二倍体中,小偃７８４的偃麦草染色体组不同于小偃６９３和小偃７６３１中的偃麦草染色体组,表明在长穗偃麦草中有两个互不相同又不同于小麦的染色体组Ｅ和Ｆ,而小偃７４３０和小偃６８中的偃麦草染色体组很可能是Ｅ和Ｆ染色体组的重组体;（ｃ）小偃７８４中的长穗偃麦草染色体组和中５及小偃７８８２９中的中间偃麦草染色体组基本相同,而中２的中间偃麦草染色体组不同于小偃６９３和小偃７６３１中的长穗偃麦草染色体组Ｆ,这意味着在长穗偃麦草和中间偃麦草中可能只有一个共同的染色体组Ｅ。部分双二倍体中酯酶及醇溶蛋白偃麦草染色体特征带的存在和发现,为这些染色体或其片段导入小麦后的鉴定提供了方便。     

一个多抗小麦—中间偃麦草新种质的选育和细胞分子生物学鉴定

经过多年田间和温室接种抗病性鉴定,从(77-5433×中5)杂交组合花药培养后代中选育出一个兼抗大麦黄矮病、条锈、叶锈和秆锈4种小麦主要病害的新种质遗4212。遗4212的体细胞染色体数为42,在减数分裂中期Ⅰ,在几乎所有的花粉母细胞中都可以观察到21个二价体,这说明遗4212是一个在遗传上业已稳定的整倍体材料。对(遗4212×77-5433)F_1代花粉母细胞的观察表明,遗4212可能是含1对外源中间偃麦草染色体的代换系或具较大中间偃麦草染色体片段的易位系。用基因组原位杂交(genomic in situ hybridization,GISH)对遗4212的有丝分裂中期相、减数分裂后期Ⅰ相和(遗4212×77-5433)F_1代花粉母细胞减数分裂中期Ⅰ、后期Ⅰ进行了检测,确证遗4212含1对外源中间偃麦草染色体。这些结果表明,遗4212是一个小麦一中间偃麦草代换系,其抗病性来自其携带的1对中间偃麦草。     

硬粒小麦 长穗偃麦草2E和4E附加系及E染色体传递

为探讨长穗偃麦草E染色体在硬粒小麦背景中的传递特点,利用染色体特异分子标记、基因组原位杂交(GISH)、非变性荧光原位杂交(ND FISH)等方法,对小偃麦8801(AABBEE)与硬粒小麦(AABB)杂交后代中选育的株系Du_No.2和Du_No.4进行了分析。结果表明：(1)分子标记检测株系Du_No.2及Du_No.4分别能扩增出长穗偃麦草2E、4E染色体特异条带。(2)GISH和ND FISH分析显示,株系Du_No.2和Du_No.4分别附加了1条2E和4E染色体,表明株系Du_No.2 和Du_No.4分别为硬粒小麦 长穗偃麦草2E和4E单体附加系。(3)2个株系的减数分裂过程观察发现,后期Ⅰ、Ⅱ和末期Ⅱ都有E染色体分离异常现象,且株系Du_No.2和 Du_No.4的异常率分别为22.24%和36.18%。(4)2个株系分别与硬粒小麦进行正反杂交的后代PCR分析表明, 2E和4E染色体经雄配子的传递率分别为4.41%和2.17%,而通过雌配子的传递率都为零,表明2E和4E染色体在硬粒小麦背景中能通过雄配子传递,但不通过雌配子的传递。该研究为创建全套硬粒小麦 长穗偃麦草双体附加系及代换系提供基础。     

Physical localization of the 18S-5.8S-26S rDNA and sequence analysis of ITS regions in Thinopyrum ponticum (Poaceae: Triticeae): implications for concerted evolution

Fluorescence in situ hybridization was used in Thinopyrum ponticum, a decaploid species, and its related diploid species, to investigate the distribution of the 18S-5.8S-26S rDNA. The distribution of rDNA was similar in all three diploid species (Th. bessarabicum, Th. elongatum and Pseudoroegneria stipifolia). Two pairs of loci were observed in each somatic cell at metaphase and interphase. One pair was located near the terminal end and the other in the interstitial regions of the short arms of one pair of chromosomes. However, all of the major loci in Th. ponticum were located on the terminal end of the short arms of chromosomes, and one chromosome had only one major locus. The maximum number of major loci detected on metaphase spreads was 20, which was the sum of that of its progenitors. The interstitial loci that exist in the possible diploid genome donor species were probably 'lost' during the evolutionary process of the decaploid species. A number of minor loci were also detected on whole regions of two pairs of homologous chromosomes. These results suggested that the position of rDNA loci in the Triticeae might be changeable rather than fixed. Positional changes of 18S-5.8S-26S rDNA loci between Th. ponticum and its candidate genome donors indicate that it is almost impossible to find a genome in the polyploid species that is completely identical to that of its diploid donors. The possible evolutionary significance of the distribution of the rDNA is also discussed. Internal transcribed spacer (ITS) regions of nuclear DNA in Th. ponticum were investigated by PCR amplification and sequencing. The sequence data from five positive clones selected at random, together with restriction site analysis, indicated that the ITS repeated units are nearly homogeneous in this autoallodecapolypoid species. Combined with in situ hybridization results, the data led to the conclusion that the ITS region has experienced interlocus as well as intralocus concerted evolution. Phylogenetic analyses showed that the sequences from Th. ponticum have concerted to the E genome repeat type.     

Spatial and temporal patterns in the occurrence of peritrich ciliates as epibionts on calanoid copepods in the Chesapeake Bay, USA

We investigated temporal and spatial patterns of distribution in two peritrich ciliates (i.e. Zoothamnium intermedium and Epistylis sp.) living as epibionts on calanoid copepods (i.e. Acartia tonsa and Eurytemora affinis) in Chesapeake Bay. Net tow samples collected along the main axis of the Bay were analyzed to estimate the occurrence of epibionts on copepods and to explore relationships among infestation prevalence, host abundance, and environmental variables. Zoothamnium intermedium and Epistylis sp. colonized populations of A. tonsa during spring and summer months, while only Z. intermedium colonized E. affinis during spring. Occurrence of epibionts on copepods showed high interannual variation, marked seasonality, and geographic heterogeneity. Extensive statistical analyses rejected simple scenarios of interactions between epibiosis, environmental variables, and host density, suggesting a more complex dynamics for the system. Analyses of epibiont colonies and zooids per host area (i.e. the sum of width and length of the body including antennae and swimming legs calculated assuming a cylindrical shape) were also performed. Overall, epibiont infestation prevalence (i.e. colonies/host area) and load (i.e. zooids/host area) were higher on copepodites than on adults for both host species, suggesting a preferential attachment to juveniles, or a higher predation pressure on adult stages. Infestation density and loads of both epibiont species were higher on the cephalothorax and abdomen of A. tonsa and E. affinis in comparison to the antennae and swimming legs, suggesting that ciliates can more easily colonize less active parts of the host.     

兼抗白粉、条锈病小偃麦渗入系CH7124抗性遗传及细胞学鉴定

CH7124是通过八倍体小偃麦TAI8335与感病小麦杂交、回交育成的兼抗白粉病、条锈病的小偃麦种质系。利用抗性接种鉴定、细胞学和基因组原位杂交(GISH)技术相结合的方法,对CH7124的抗性来源、遗传方式及细胞学特征进行了分析和鉴定。结果表明,CH7124在苗期和成株期对条锈菌系CYR29、CYR31、CYR32、CYR33和白粉菌系E09、E20、E21、E26表现为免疫或近免疫,其抗性来自中间偃麦草,受1对显性核基因控制;CH7124的根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期I(PMC MI)绝大多数细胞内可观察到21个二价体,平均配对构型为2n=0.30 I+20.79 II+0.04 III;与普通小麦中国春、绵阳11的杂种F1中,有80%以上的花粉母细胞可观察到2n=21Ⅱ的染色体构型,其平均配对构型均为2n=21II。说明CH7124具有与普通小麦相似的染色体结构和规则的配对构型。由于利用以中间偃麦草总DNA为标记探针的原位杂交未观察到可见的外源DNA杂交信号,进一步证明CH7124是一个小麦-中间偃麦草的隐形异源渗入系。     

小麦-中间偃麦草双体异附加系的选育和鉴定

在小麦-中间偃麦草59个杂交后代种质系中,筛选出6个小麦-中间偃麦草双体异附加系(line0605,line0607,line0609,line0610,line0611,line0625),并对其进行了形态学、白粉病抗性、细胞学和RAPD鉴定。形态学结果表明:6个双体异附加系农艺性状较好地结合了双亲的优良特点;细胞学结果表明:6个双体异附加系具有高度的细胞学稳定性,花粉母细胞减数分裂中期Ⅰ(PMCMI)的染色体构型为2n=22Ⅱ;RAPD分析表明:在供试的209个随机引物中有5个引物分别能在6个异附加系中稳定地扩增出不同的特异带型,可以作为各个异附加系所附加染色体的特异分子标记;白粉病抗性鉴定结果表明:line0605表现免疫,line0610和line0625表现高抗,line0607表现中抗,line0609和line0611表现中感。     

抗大麦黄矮病的小偃麦易位系的创制与鉴定

抗大麦黄矮病的小偃麦易位系的创制与鉴定@辛志勇$中国农业科学院作物育种载培研究所!北京100081@张增燕$中国农业科学院作物育种载培研究所!北京100081@陈孝$中国农业科学院作物育种载培研究所!北京100081@林志珊$中国农业科学院作物育种载培研究所!北京100081大麦;;小偃麦;;易位系     

中间偃麦草染色体2Ai-2特异PCR新标记的建立和St基因组特异序列的克隆

中间偃麦草麦、小麦和小麦－中间偃麦草2Ai－2附加系Z1、Z2、X6,代换系ZD28等进行RAPD分析,从320个RAPD引物中,鉴定出2Ai－2染色体特异的2个RAPD标记OPO05650和OPMO414000。利用这2个特异OPO05和OPM04,PCR扩增普通小麦CS（ABD）及其近缘植物中间偃麦草（E1E2St）、拟鹅冠草（St）,长穗偃麦草（E）、簇毛麦（V）、黑麦（R）、大麦（H）粗山羊草（D）等基因组DNA。结果表明,OPO05650和OPO41400均是2Ai－2染色体上St基因组区域的特异标记。将上棕2个特异片段分离回收、克隆、测序,根据测序结果重新设计、合成特异引物,成功地转换RAPD标记为SCAR（sequence characterizked amplifed region）标记SC－05和SC－M4。利用SCAR标记对不同材料进行分析的结果表明,凡含有2Ai－2染色体的抗黄矮病材料及拟鹅冠草均产生一条扩增带,不含2Ai－2染色体的材料,包括小麦、长穗麦草、簇毛麦、黑麦、在麦、粗山羊草以有含有其他他中间偃麦草染色休的附加系,均没有扩增产物,说明上棕2个SCAR标记是中间偃麦草2Ai－2染色体的特异性PCR标记,且是2Ai－2染色体上St基因组区域的特异性标记。克隆与鉴定中间偃麦草的2个SCAR扩增片段TiSCO5和TiSCM4。结果表明,克隆的中间偃麦草TiSCO5和TiSCM4特异片段,分别是St基因组特异性的寡拷贝序列有多拷贝重复序列,为St基因组遗传研究的新探针。     

A Thinopyrum ponticum and Triticum aestivum hybrid. Electrophoretic patterns of their endogenous phosphorylation, Diphosphonucleoside kinases, DNases and RNases

Endogenous protein phosphorylation, DNase and RNase electrophoretic patterns, and the detection of NDP-kinases by TLC (Thin Layer Chromatography) were performed in Thinopyrum ponticum (2n=10x=70), Triticum aestivum (2n=6x=42), and their hybrid seedlings in order to accomplish intergeneric hybridization. Octoploid intergeneric hybrids (2n=8x=56) were synthesized in less than 50% of the hybrids. The F₁ hybrid plants resembled Th. ponticum with regard to morphological features and were sterile. Hybrid seedlings revealed very low endogenous phosphorylation and very low NDP-kinase activity in comparison to their parents. In addition hybrid seedlings expressed a new nuclease. Received: 29 June 2000 / Accepted: 28 July 2000