Genetic structure of Mycosphaerella fijiensis populations from Australia, Papua New Guinea and the Pacific Islands

Single-copy restriction fragment length polymorphism (RFLP) markers were used to determine the genetic structure of Mycosphaerella fijiensis , the cause of black leaf streak (black Sigatoka) disease of banana and plantain, in the Torres Strait, Papua New Guinea (PNG), and the Pacific Islands. A moderate level of genetic variation was observed in all populations with genotypic diversity values of 60–78% of the theoretical maximum, and gene diversity ( H ) values between 0·269 and 0·336. All populations were at gametic equilibrium, and with the high level of genotypic diversity observed this indicated that sexual reproduction has a major role in the genetic structure of the M. fijiensis populations examined. Population differentiation was tested on several hierarchical scales. No evidence of population differentiation was observed between sites on Mer Island. A moderate level of population differentiation was observed within the Torres Strait, between Badu and Mer Islands ( F _ST = 0·097). On a regional scale, the greatest differentiation was found between the populations of the Torres Strait and the Pacific. Populations from these regions were more closely related to the PNG population than to each other, suggesting they were founded in separate events from the same population.     

Nuclear genome constitution and other characteristics of somatic hybrids between dihaploid Solanum acaule and tetraploid S. tuberosum

Eleven somatic hybrids (2n = 68 to 74) obtained between S. tuberosum ssp. tuberosum cv. Dejima (2n = 48) and ATDH-1 (2n = 24), an anther-culture-derived dihaploid of S. acaule (Yamada et al., 1997), were characterized by nuclear RFLP markers using 49 single-copy DNA probes distributed throughout the potato genome (2 to 6 probes per chromosome). One of the somatic hybrids, DA8-2, had 72 chromosomes and all the Dejima- and ATDH-1-specific markers (124 and 103 bands, respectively), suggesting the presence of a whole set of both parental chromosomes. The other somatic hybrids lost varying numbers of markers up to seventeen. The pattern of the loss of markers indicated the elimination of five chromosomes among four somatic hybrids. A nucleolar organizer region of chromosome 2 was often eliminated in the somatic hybrids. The somatic hybrids studied here had higher frequencies of multivalent formation than the S. tuberosum parent. They had reasonably good seed set when pollinated with S. tuberosum pollen. Hence, homoeologous recombination between S. acaule and S. tuberosum chromosomes is possible and useful traits from S. acaule may be transferred to the S. tuberosum gene pool. This revised version was published online in July 2006 with corrections to the Cover Date.     

RFLP variability in apricot (Prunus armeniaca L.)

The level of polymorphism of the restriction fragment length polymorphisms (RFLPs) detected by 33 almond genomic and cDNA probes was studied in a set of 52 European and North-American apricot cultivars. Eighteen of these probes were polymorphic and yielded a total of 48 scorable bands, allowing the identification of 45 different phenotypes. Most cultivars (43) had an individually distinguishable RFLP phenotype, and three of the five clusters with the same phenotype contained cultivars that were likely to be synonymous. The group of Spanish cultivars (25) had a lower level of polymorphism than the others, suggesting that bottlenecks may have occurred in the recent history of the apricot that have eroded its genetic variability.     

籼、粳、中间型水稻杂种F1的生物优势、经济优势与RFLP的关系研究

对典型灿、粳稻南京１１、金南凤突变体和中间型品种Ｂｅｌｌｅｍｏｎｔ相互杂交形成的三各上杂种优势及三者之间的ＲＦＬＰ进行了系统分析,结果表明：Ｆ１杂种生物学优势存在着籼／粳〉籼／中间型〉粳／中间型趋势,经济优势则为籼／中间型〉粳／中间型〉籼／粳。而多态性是籼／粳〉籼／中间型〉粳／中间型,并且各珠１２条染色体我态性程度也有差异,因此,多态性与生物优势趋于一致,但经济优势却与多态性及亲和性基因有关。     

RFLP标记揭示的1RS/1BL易位系对小麦农艺性状的影响

以含1RS／1BL易位染色体的多小穗小麦新种质10-A和普通小穗小麦品系88-1463,及其与非1RS／1BL易位系小麦川育12构成的重组系为供试材料,选用4个RFLP标记和1个醇溶蛋白标记Gld1B3分析了1RS／1BL易位系对小麦农艺性状的影响。结果表明,1RS／1BL易位系的每穗小穗数目和株高均显著或极显著地高于非易位系,其千粒重略高于非易位系(p＜0.1),而每小穗结实粒数却显著低于非易位系。抽穗期、穗粒数和穗粒重几个性状间差异不显著。1RS／1BL易位染色体在增加每穗小穗数目的同时还具有降低每小穗结实粒数的作用,这可能是导致易位系和非易位系间穗粒数差异不显著的直接原因。     

应用RFLP图谱定位分析籼稻粒形数量性状基因座位

 用二个籼型杂交组合的F#-2群体，构建了二张分别具有89和93个标记位点的RFLP图谱。在此基础上，应用方差分析法和区间作图法对控制籼稻粒形性状的QTLs进行定位。在特三矮2号/CB1128群体中，定位了14个QTLs，其中5个控制粒长，2个主效基因（分别位于第5、第7染色体）和2个微效基因控制粒宽，1个主效基因和4个微效基因控制粒厚。在外引2号/CB1128群体中，共定位了13个QTLs，其中5个影响粒长，2个主效基因（分别位于第2、第5染色体）和3个微效基因控制粒宽，3个微效基因影响粒厚。此外，估算了每个QTL的贡献率、加性效应和显性效应值，分析某些染色体区间的多效现象，比较分析二群体QTLs定位结果的异同。     

稻属叶绿体DNA限制性片段长度多态性

 对稻属（Oryza）的14个种和李氏禾属（Leersia）的 2个种共 138份材料进行了叶绿体 DNA限制性片段长度多态性的分析。用内切酶EcoRⅠ酶切、4 个叶绿体 DNA探针杂交,共发现10种叶绿体 DNA变异类型。在稻属各个种内没有观察到叶绿体 DNA的变异,叶绿体 DNA变异类型基本上以稻属的染色体组型水平划分,因此认为稻属的叶绿体 DNA在进化过程中变异程度很低。推测 CCDD组的O. alta、O. grandiglumis和O. latifolia 及 CC组的 O.officinalis 和 O. eichingeri各有共同的原始祖先。遗传距离分析显示 CC、CCDD、BBCC组之间亲缘关系很近,这3个组与 EE组亲缘关系也较近。李氏禾属的 2个种 L. perrieri 和 L. tisseranti 与稻属的遗传距离很远。     

几种DNA分子标记技术及其在水产动物中的应用

本文介绍TRFLP、RAPD和AFLP分子标记技术的原理及其特点，并论述了三种DNA分子标记技术在水产动物种质资源和遗传育种研究中的应用。     

中华鳖体表和体内菌群多样性分析

采用16S rDNA分析方法,分别提取中华鳖体表和体内细菌总DNA,以之为模板进行PCR扩增获得细菌16S rDNA基因片段,并构建16S rDNA克隆文库.从2个文库中分别随机选取100个重组克隆子,抽提重组质粒,用Hae Ⅲ和MspⅠ限制性内切酶进行酶切,获得酶切指纹图谱,从每种图谱随机挑选克隆子测序,获得其16S rDNA部分序列,构建了系统进化树.在中华鳖体表和体内细菌克隆文库中分别包含13种和10种RFLP谱型,分别挑选了70个和60个克隆子进行测序.结果表明,中华鳖体表和体内文库克隆子分别归为15类和11类OTU,体表和体内菌群多样性较强,优势细菌类群分别为拟杆菌和变形菌,并在文库中检测到了几株益生菌和条件致病菌.     

长春地区绵羊和兔隐孢子虫分子流行病学调查

采用抗酸染色法分别对长春地区287份兔粪便样品和167份绵羊粪便样品进行隐孢子虫检查,确认阳性的样品用巢武PCR-RFLP方法扩增隐孢子虫Small-Subunit rRNA基因,选择限制性内切Ssp Ⅰ和Vsp Ⅰ分别对该目的片段单酶切,PCR产物测序后进行RFLP及系统发育分析.结果共检出97份兔粪便和45份羊粪便含有隐孢子虫卵囊,感染率为33.8%和26.9%.巢式PCR-RFLP检测发现由绵羊和兔粪便中分离的隐孢子虫分别是C.parvum和C.bovis,系统发育分析显示隐孢子虫虫种形成了2个群,一个群包括C.parvum,C.boris,C.baileyi,C.meleagridis,C.feti,和C.wrairi,另一个群包括C.andersoni,C.muris和C.serpentis.