Identification of QTLs related to sugar and organic acid composition in melon using near-isogenic lines

The soluble sugar and organic acid composition of melon (Cucumis melo L.) fruit flesh has become a major focus of plant breeding worldwide in an attempt to improve taste. Thus, sugar and organic acid profiles were characterized using near-isogenic lines (NILs) derived from the Spanish cultivar Piel de Sapo (PS) and the exotic Korean accession Shongwan Charmi (PI 161375). Fruits were cultivated in only one environment. These data were used to map 60 quantitative trait loci (QTLs): 18 for individual sugars, eight for sucrose equivalents, five for the glucose-to-fructose ratio, seven for the total sugar content and 21 for organic acids. Within the QTLs that were associated with the sugar profile, 27 defined the sugar content: eight for fructose, six for glucose, four for sucrose, and nine for sucrose equivalents. Although increased sweetness of selected NILs compared with the parental PS was achieved by an increased glucose or fructose content, only glucose heritability was above 0.5. A total of 21 QTLs (two with positive effects and nineteen with detrimental effects compared with the PS levels) controlled the organic acid profile: l-glutamic, ascorbic and succinic acids (the principal ones) and fumaric, citric, oxalacetic, and isocitric acids. The levels of sugars imparted by the PI 161375 introgression frequently decreased the score grades given to NILs by consumers. Within the 32 QTLs mapped for sensory traits, 27 were associated with lower scores in taste (nine QTLs), sweetness (eight QTLs) or global quality appreciation (nine QTLs); two with increased fruit sourness or sweetness and three with increased fruit bitterness. The QTLs defined herein may assist breeders to understand the overall organoleptic balance (sweetness, sourness, and umami taste) in melon fruit, particularly those located within linkage groups III, V, VI, and VIII to XI.     

野生大豆回交导入系蛋白质含量性状的QTL分析

以野生型大豆ZYD00006（供体亲本）与黑龙江省主栽品种绥农14（轮回亲本）所构建的回交导入系（1204株）为研究材料,利用WinQTL2.5的复合区间作图法(CIM)在9个连锁群定位了16个与蛋白质含量相关的QTL（14个正效应,2个负效应）;导入系群体经过严格的蛋白质含量筛选鉴定,得到10个蛋白质含量性状明显大于轮回亲本的导入系株行。利用这10个高蛋白含量株行（选择群体）结合随机对照群体,通过基于遗传搭车原理的卡方分析,检测到分布于10个连锁群上的17个与大豆蛋白质含量相关的标记位点,对蛋白质含量表现为正效应。两种方法共同检测到7个QTL。这些材料和位点将为高蛋白含量相关基因克隆及分子辅助育种提供重要的材料基础和标记信息。     

基于近等基因导入系发掘玉米抗甘蔗花叶病毒主效基因

利用玉米自交系掖478与中自01构建近等基因导入系群体(BC4F2),通过田间人工接种甘蔗花叶病毒鉴定获得抗病植株。采用38个SSR标记分析抗病株基因型,通过连锁不平衡分析,在玉米第3和6染色体上发掘3个主效抗病QTL。第3染色体上的QTL置信区间为26.1cM-phi053-5cM;第6染色体上的QTL置信区间分别为1.2cM-bnlg161和5.3cM-bnlg1538-7cM。建立了基于近等基因导入系发掘玉米抗甘蔗花叶病毒主效QTL技术,获得了一批含有抗病毒QTL的近等基因导入系,为抗病育种提供了信息和材料。     

Improving Drought Tolerance of Rice by Designed QTL Pyramiding

Drought is the most important factor limiting rice yields in the rainfed areas of Asia. To overcome the problem, we developed a new strategy ＇designed QTL pyramiding＇ to more efficiently develop drought tolerant （DT） rice cultivars. In the first phase of this strategy, we developed large numbers of introgression lines （ILs） in elite backgrounds using backcross （BC） breeding, each of which carries multiple genomic segments for improved DT from a known donor. Then, we genotyped all ILs with SSR markers to track the genomewide pattern of introgression in the DT ILs of 16 BC populations derived from crosses between 2 recipients （IR64 and Teqing） and four different donors. X^2 tests and linkage disequilibrium analyses of introgression in the DT ILs revealed significant frequency shifts at many loci across the genome and non-random associations at the multilocus level as a result of selection for DT in the ILs, which led us to the discovery of putative genetic networks underlying DT in the ILs. The networks each containing all DT loci detected in ILs from a BC population showed some interesting features.     

基于远缘杂交的黄瓜种质资源的创新与利用研究

未来作物改良的最大希望在于有用外源基因的导入，远缘杂交是导入外源有用基因的主要途径之一。基于笔者近年来在甜瓜属（Cucumis）种间杂交所取得的进展，本文综述了甜瓜属种间杂交双二倍体、异源三倍体、单体异附加系和异源易位系的合成、鉴定和定性研究，以及对外源有用基因，包括抗病、抗逆性的转导利用情况，并展望了这些特异种质资源在甜瓜属作物的遗传和品种改良上的理论和实践价值。     

冀豆12遗传背景导入系蛋白、脂肪含量分布特征

以高蛋白品种冀豆12为受体亲本,不同来源、不同蛋白脂肪含量的大豆种质资源为供体亲本,构建了28个组合BC2F1后代群体,分析冀豆12遗传背景导入系后代蛋白、脂肪含量分布特征。结果表明,28个后代群体均有蛋白含量超高亲个体,超高亲个体比例介于4.0%～68.2%之间,超高亲比例≥40%的组合有18个,占64.3%,BC2F1后代群体蛋白含量以超高亲和偏高亲类型组合为主。而脂肪含量分布特征恰相反,BC2F1后代群体脂肪含量以超低亲和偏低亲类型组合为主,超高亲个体比例介于0～67.4%,超高亲个体比例≥40%的组合有7个,占25.0%,9个组合无超高亲后代。表明以冀豆12为遗传背景通过有限回交易选育高蛋白含量品种,而不易选育高脂肪含量品种。本研究结果为利用冀豆12培育高蛋白品种提供了依据。     

Interspecific hybridisation between alien and native plant species in Germany and its consequences for native biodiversity

We explored the extent of interspecific hybridisation between alien and native plant species in Germany with a special focus on the potential threat for native biodiversity. In total we listed 134 hybrids which are interpreted as products of hybridisation between 81 alien and 109 native plant species (including 13 archeophytes) that occur in Germany. Seventy-five of these hybrids have been recorded in Germany, while the remaining 59 hybrids have not been detected in Germany yet, although both parental species currently occur in Germany. Interspecific hybridisation between abundant alien and rare native species can threaten populations of the native species through outbreeding depression and/or through high rates of gene flow swamping native populations. We identified 37 threatened native plant species which hybridise with aliens. Seventeen of these threatened plant species may suffer from outbreeding depression when hybridising with a more abundant alien invader (minority disadvantage). Using hybrid abundance as an indicator of hybrid fitness we argue that introgression of alien genes may affect the gene pool of eight threatened native plant species. Consequently, hybridisation with aliens has to be considered as an additional risk potentially leading to a loss of biodiversity and should be included in the repertoire of causes for rare species extinction in German Red Lists of threatened plant species.     

Hatchery introgression blurs ancient hybridization between brown trout (Salmo trutta) lineages as indicated by complementary allozymes and mtDNA markers

Populations living on the periphery of a species range are subjected to intense habitat pressures that stress their vulnerability to threats. South Iberian brown trout (Salmo trutta) populations are located on the southwestern boundary of the species range in Europe. This region has been described as a contact zone between Atlantic and Mediterranean populations in other fish species, and allozyme data detected natural hybridization between native Atlantic and Mediterranean brown trout in this area. Nevertheless, native pattern of populations relationships are threatened by hybridization with exogenous hatchery fish. Allozyme data and complete mtDNA control region sequences were used to analyse the ongoing processes of human mediated hybridization between native and hatchery brown trout in this region. Estimates of the persistence of hatchery genes detected a high level of introgression in some of the sampled locations (hatchery ancestry more than 25% in GF-1, GF-2 and GF-3), but results differed from both kinds of markers. The low intrapopulation diversity (H_s = 0.051) indicated that genetic drift could explain discrepancies between markers. At individual level, the complementary use of both markers detected more hatchery origin fish than those detected by the use of a single technique. Based on these results, the importance of considering a large number of genetic markers to evaluate introgression accurately is emphasized. The ability of the current management policies to the protection and conservation of marginal populations that retain complex and special evolutionary histories such as those studied is also questioned.     

利用基础导入系群体定位氮胁迫下水稻产量性状QTL

水稻产量性状的遗传机制复杂,在低氮胁迫下进行QTL定位,可为产量性状遗传机制的解释、基因的精细定位和克隆提供参考价值,也可为筛选耐低氮水稻材料提供有价值的参考.本研究以66个水稻籼粳交片段导入系群体[粳稻(Oryza sativa ssp,japonica)楚粳12是供体亲本,籼稻(O.sativa ssp,indica)蜀恢527是受体亲本,采用回交和分子标记辅助选择相结合的方法构建]为定位群体,利用单标记作图法,对正常与低氮胁迫条件下水稻有效穗、单株产量、株高和生物学产量等性状进行QTL定位.共检测到24个QTLs,20个为新检测出的QTL,而qph-1、qpn-1、qby-2、qby-4与前人研究结果相似,另外,qph-1a和qph-1b为在不同处理下均能影响株高的位点;生物学产量的QTL仅在低氮处理下被检测到;qpn-2b与qyd-2具有共同的连锁标记RM521;qpn-1b、qpn-2a、qpn-2b等加性效应值都小于1.结果表明,低氮胁迫明显影响单株有效穗、单株产量和生物学产量,且导入系群体检测微效QTL的能力较强.