两种施肥环境下冬小麦京411及其衍生系产量和生理性状的遗传分析

明确高产广适性与肥料高效利用相关性状的遗传特性对培育优良新品种具有重要意义。本研究以京411及其衍生后代共15个品种(系)为材料,在4个正常施肥和1个常年不施肥环境下研究品种(系)的产量构成因素和生理性状,结合90K SNP芯片,解析骨干亲本携带的产量和生理性状等位基因信息,探讨优异基因对高产品种的贡献。结果表明,正常施肥环境下,京411衍生后代的产量和收获指数均随世代增加呈逐渐上升趋势,其中收获指数增加较为显著(P0.05)。冠层温度对籽粒产量有重要贡献(P0.05),而叶面积指数和光合速率对收获指数有显著贡献(P0.05)。两种施肥条件下中麦175具有较高且稳定的产量和生物学产量,主要与其较高的肥料吸收效率有关。控制产量和生理性状的遗传区段主要分布在A和B基因组上,2B、3A和5A染色体分别携带控制穗粒数、叶面积指数和光合速率的位点。京411携带31个对产量和生理性状为正向效应的等位基因,衍生品种CA0958和中麦175携带的正向效应区段最多,分别占正向效应位点总数的53.85%和51.35%。中麦175的高产潜力和广适应性可能与其携带较多有利等位基因有关。     

中国88个马铃薯审定品种SSR指纹图谱构建与遗传多样性分析

为对马铃薯品种鉴别、优良杂交组合选配提供分子水平上的依据,利用SSR标记构建了中国2000-2007年审定的88个马铃薯品种的指纹图谱并进行了遗传多样性分析。以138对SSR引物对16份遗传差异较大的马铃薯材料的基因组DNA进行了扩增,筛选出10对多态性高、谱带清晰的引物。利用10对SSR引物对全部供试材料进行扩增及电泳检测,共检测到135个等位位点,其中133个为多态性位点,多态性比率达98.52%。每对SSR引物扩增出的等位位点数7~22个,平均13.5个,多态性信息量变化范围为0.7604~0.9375,平均0.8501。通过对电泳检测结果的统计分析,利用S180、S25、S7、S151、S184及S192等6对引物构建了88份供试材料的SSR指纹图谱。聚类分析表明,在相似系数0.620处,所有供试材料被被聚为一类,在相似系数0.652处,81.8%的材料仍然聚在一起,从分子水平上表明供试材料遗传基础非常狭窄。聚类分析结果与供试材料系谱来源有较好一致性,同一栽培区域育成的品种在不同程度上聚在一类。     

Recent advances in molecular genetics of forest trees

The use of molecular markers has greatly enhanced our understanding of the genome structure of forest trees. Conifers, in particular, have a relatively large genome, containing a very high proportion of repeated DNA, consisting of tandemly repetitive and dispersed repetitive DNA sequences. The nature of highly conserved tandemly repetitive rRNA genes has been investigated in a number of tree species, and their sites mapped on specific chromosomes by fluorescent in situ hybridization (FISH). Different families of retrotransposons (IFG, and TPE1) have been isolated and characterized from the dispersed repetitive DNA of pines. Genome maps have been constructed in a number of forest tree genera: Pinus, Picea, Pseudotsuga, Cryptomeria, Taxus, Populus, and Eucalyptus. EST databases have been established from cDNA clones of pines and poplars. The structure and maternal or paternal modes of inheritance of organelle genomes have been investigated in forest trees. Comparative mapping in conifers has shown that gene families are conserved across genera. Due to lack of polyploidy in conifers, the evolution of this group of trees may have occurred primarily by duplication and dispersal of genes, probably by retrotranspositions, to form complex gene families. The evolution of angiosperm tree species has presumably involved both gene duplication as well as genome duplication (polyploidy). Application of genetic engineering has shown that genes from phylogenetically unrelated organisms can be introduced and expressed in trees, thus offering prospects of genetic improvement of forest trees. This revised version was published online in August 2006 with corrections to the Cover Date.     

棉花抗黄萎病基因的QTL定位

以高感黄萎病的陆地棉品种"邯郸208"与高抗黄萎病海岛棉品种"Pima90"的136个F2单株为作图群体,构建了一个包括17个连锁群、标记间平均间距18.61cM、全长1842.8cM的陆海种间分子标记遗传连锁图,该图约覆盖棉花基因组的36.8%。单因子方差分析和复合区间作图检测到与黄萎病抗性相关的3个QTL,分别位于第四连锁群和第七连锁群上,分别解释表型变异方差的15.39%、54.11%和57.18%。初步认为海岛棉"Pima90"对陆地棉"邯郸208"的黄萎病抗性由两个主效QTL和一个微效QTL共同控制。     

棉花表型性状基因的SSR标记定位

本文以两个陆地棉多标记基因系T582和T586,以及杂交获得的F_1、F_2及F_3代作为试验材料,利用11对SSR引物对F_2群体的120个单株的DNA样品进行多态性分析,并利用F_2和F_3群体对F_2群体对应单株的13个表型性状进行基因型的判定,结果得到了3个与表型性状基因连锁的SSR标记,分别是红茎基因(R_1)与J178连锁、遗传距离为24.9cM,簇生铃基因(CL_1)与J236连锁,遗传距离为46.0cM,茸毛基因(T_1)与J252连锁,遗传距离为28.5cM,其中R_1、CL_1、J178和J236在同一连锁群上。红茎和植株茸毛是具有抗虫性能的形态性状,用SSR标记这些性状将有助于提高育种家的育种效率。     

Classification of cassava into ‘bitter’ and ‘cool’ in Malawi: From farmers' perception to characterisation by molecular markers

Cassava roots, a major food in Africa, contain cyanogenic glucosides that may cause toxic effects. Malawian women farmers considered fields of seemingly similar cassava plants to be mixes of both ‘cool’ and ‘bitter’ cultivars. They regard roots from ‘cool’ cultivars as non-toxic. Roots of ‘bitter’ were considered to require extensive traditional processing done by women to be safe for consumption. But curiously, these women farmers preferred ‘bitter’ cultivars since toxicity confers protection against theft, which was a serious threat to the food security of their families. We studied how well these farmers comprehend the effects of genetic variations in cassava when dealing with cyanogenesis in this complex system. Using molecular markers we show that most plants farmers identified as belonging to a particular named cultivar had a genotype typical of that cultivar. Farmers' ethno-classification into ‘cool’ and ‘bitter’ cultivars corresponded to a genetic sub-division of the typical genotypes of the most common cultivars, with four-fold higher cyanogenic glucoside levels in the bitter cultivars. Examining morphology, farmers distinguished genotypes better than did the investigators when using a standard botanical key. Undoubtedly, these women farmers grasp sufficiently the genetic diversity of cassava with regard to cyanogenesis to simultaneously benefit from it and avoid its dangers. Consequently, acyanogenic cassava – the breeding of which is an announced good of some cassava genetic improvement programmes – is not a priority to these farmers. Advances in molecular genetics can help improve food supply in Africa by rapid micropropagation, marker assisted breeding and introduction of transgenic varieties, but can also help to elucidate tropical small-scale farmers' needs and skills. This revised version was published online in August 2006 with corrections to the Cover Date.     

Assessment of EST- and genomic microsatellite markers for variety discrimination and genetic diversity studies in wheat

It is likely that in the near future sequence information from sequencing programmes and EST libraries will generate an abundance of genic microsatellite markers. This study is focused on the assessment of their likely impact and performance vis-à-vis their genomic counterparts. Microsatellites from two sources were used to assess the genetic diversity in 56 old and new varieties of bread wheat on the UK Recommended List. A set of 12 microsatellite markers generated from genomic libraries and 20 expressed sequence tag (EST)-derived microsatellites were used in the study, and the performance of both marker sets assessed. The EST-derived or genic microsatellites delivered fingerprints of superior quality, amplifying clear products with few stutter bands. Diversity levels as revealed bygenic microsatellites are similar to the few published results. The PIC values for the genic markers were generally lower than those calculated for the genomic microsatellites, though advantages of both marker classes for variety identification applications are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Isozyme studies of genetic diversity and evolution in Hippophae

Summary To provide information on the genetic variation, differentiation and evolution in Hippophae seed samples of 25 populations from China, Finland and Russia were electrophoretically analyzed. Of six loci investigated, four were good genetic markers for identifying species and subspecies. The percentages of polymorphic loci per population were 40.3% and 62.5% at 0.95 and 0.99 polymorphic criteria respectively. The mean number of alleles per locus per population was 2.1. Total genetic diversity in the material was 0.4614. Genetic diversity partitioning showed that there was a large amount of diversity residing within geographical populations (0.1354), between subspecies within species (0.1046) and between species (0.2566) but not between geographical populations (0.0114). There were nearly twice as many negative fixation indices as positive ones in Hippophae populations. The phylogenetic tree agreed very well with botanic classifications of the species and subspecies and their geographical distributions, and quantitatively presented the genetic relationships of 25 populations. A detailed view of the evolutionary stages in Hippophae showed clearly a general decline of similarity as evolutionary divergence continued, which further explained the evolution process in Hippophae.     

Agronomical,quality, and molecular characterization of twenty Italian emmer wheat (<Emphasis Type="Italic">Triticum dicoccon</Emphasis>) accessions

Emmer wheat (Triticum dicoccon Schrank, 2n = 4x = 28) consists in a hulled wheat; its cultivation has been drastically reduced during the last century as a consequence of its low yield. Recently, its agronomic and nutritive values, as well as the increase of popularity of organic agriculture, have led to a renewed interest making its cultivation economically viable in the marginal lands with an increase of the cultivated areas. In Italy, it mainly survives in few marginal lands of central and southern Italy, where local varieties, adapted to the natural environment from where they originate, are used; moreover, some selected lines have also been developed. In the present work, agro-morphological and qualitative traits, together with molecular analyses of 20 emmer accessions consisting of Italian landraces, breeding lines, and cultivars, were performed. The field experiments were conducted for two consecutive years (2001/2002–2002/2003) in two locations: Viterbo in central Italy, and Foggia in south Italy. The analyzed emmer wheat accessions showed a good amount of genetic variability for both evaluated agro-morphological and molecular traits. This study illustrates an increase in earliness, GY, TW, TKW, and YI going from landraces, breeding lines to cultivars, while the variability does not change proportionally.     

Nomenclature and genetic relationships of apples and pears from Terceira Island

Heritage apple (Malus domestica Borkh. hybrids) and pear (Pyrus communis L. hybrid) trees grow in villages throughout Terceira Island, Azores, Portugal. Some of these pears have different names but similar morphology. The objective of this study was to determine synonymy, homology, and phylogeny of apples and pears from Terceira and to examine potential relationships of the island pears with standard apples and pears of Portuguese or American descent. Nine apple microsatellite markers were used to determine genetic relationships. Distance- and parsimony-based cluster analysis grouped these genotypes into separate apple and pear clades. The Terceira apples were divided into two clades: the maçā and the reineta-reinette. Among the 17 heritage apple genotypes, seven unique accessions were identified and four groups of synonyms, or possibly clones, were detected including: ‘Reineta Agosto’ and ‘Reineta Verde’ from Altares; ‘Reineta Castanha’ and ‘Reineta Verde Miuda’; ‘Maçā Pêra,’ ‘Maçā Calhau’, ‘Pêro Branco’ from Salga and from Terra-Chā and ‘Maçā Marmelo’; and the five genotypes ‘Maçā Sao Joao’, ‘Malápio Rosa’, ‘Maçā Gaspar’, ‘Maçā Branca’ and ‘Maçā Pato’. In addition, two homonyms were detected. ‘Pêro Vermelho’ from Terra Chā was a separate genotype from a tree from Doze Ribeiras of the same name, but Pêro Branco from Terra Chā appears to be a clone that can be distinguished by an additional allele at CH1F07a from a tree with that name from Salga. One pair of apple clones, ‘Reineta Agosto’ and ‘Reineta Verde’ from Altares appear to be derived from an unreduced gamete of ‘Golden Delicious.’ Another apple genotype ‘Maçā Acida’ could be a sibling of the ‘Maçā Pêra’ clonal group. Other tested standard apples from the US genebank were unrelated to Terceira genotypes. Of the seven heritage pears, five unique genotypes and one pair of synonyms were detected. ‘Pêra Papo Pintassilgo’ from Raminho and ‘Pêra Vermelha’ from the nursery of Serviço de Desenvolvimento Agario da Terceira (SDAT) were synonyms. ‘Passans du Portugal’ was related to ‘Pêra Cabaca’ but other standard pears from the US genebank were unrelated to Terceira genotypes. Future studies will include additional apple and pear cultivars from other Islands of the Azores and continental Portugal, and wild Asian species to further explore genetic relationships.