A practical method for almond cultivar identification and parental analysis using simple sequence repeat markers

Early and accurate identification of almond [Prunus dulcis (Mill.) D.A. Webb] cultivars is critical to commercial growers and nurseries. Previously published simple sequence repeat loci were examined for their ability to distinguish commonly grown almond cultivars. Twelve highly polymorphic loci were selected for their ability to uniquely identify a set of 18 almond cultivars commonly grown in California, many of which are closely related. These markers also allow an accurate assessment of parent/progeny relationships among cultivars. This system can reliably identify at an early stage of development all major California almond cultivars in current production.     

Mapping QTLs for pre-harvest sprouting traits in the spring wheat cross ‘RL4452/AC Domain’

Pre-harvest sprouting (PHS) in spring wheat (Triticum aestivum L.) is a major downgrading factors for grain producers and can significantly reduce end-use quality. PHS resistance is a complex trait influenced by genotype, environment and plant morphological factors. A population of 185 doubled haploid (DH) lines from the spring wheat cross ‘RL4452/AC Domain’ were used as the mapping population to detect quantitative trait loci (QTLs) associated with three PHS traits, germination index (GI), sprouting index (SI) and falling number (FN). Six major QTLs linked with PHS traits were mapped on bread wheat chromosomes 3A, 3D, 4A (2 loci), 4B and 7D. ‘AC Domain’ alleles contributed to PHS resistance on 3A, 4A (locus-2) and 4B, and ‘RL4452’ alleles contributed resistance on 3D, 4A (locus-1) and 7D. QTLs detected on chromosome 4B controlling FN (QFN.crc-4B), GI (QGI.crc-4B) and SI (QSI.crc-4B) were coincident, and explained the largest amount of phenotypic variation in FN (22%), GI (67%) and SI (26%), respectively.     

Different quantitative trait loci for <Emphasis Type="Italic">Fusarium</Emphasis> resistance in wheat seedlings and adult stage in the Wuhan/Nyubai wheat population

Fusarium head blight (FHB), caused primarily by Fusarium graminearum (Schwabe), is an important wheat disease. In addition to head blight, F. graminearum also causes Fusarium seedling blight (FSB) and produces the mycotoxin deoxynivalenol (DON) in the grain. The objectives of this study were: (1) to compare the relationship between resistance of wheat lines to F. graminearum in the seedlings and spikes and (2) to determine whether the quantitative trait loci (QTL) for FSB were the same as QTLs for FHB resistance and DON level reported for the same population previously (Somers et al. 2003). There was no relationship between FSB infection and FHB index or DON content across the population. A single QTL on chromosome 5B that controlled FSB resistance was identified in the population; the marker WMC75 explained 13.8% of the phenotypic variation for FSB. This value implies that there may be other QTL with minor effects present, but they were not detected in the analysis. Such a QTL on chromosome 5B was not reported previously among the QTLs associated with FHB resistance and DON level in this population. However, because of recombination, some lines in the present study have Fusarium resistance for both seedling and head blight simultaneously. For example, DH line HC 450 had the highest level of resistance to FSB and FHB and was among the ten lines with lowest DON content. This line is a good candidate to be used as a parent for future crosses in breeding for Fusarium seedling resistance, together with breeding for head blight resistance. This approach may be effective in increasing overall plant resistance to Fusarium.     

High levels of pollen dispersal detected through paternity analysis from a continuous Symphonia globulifera population in the Brazilian Amazon

In this study, six highly polymorphic microsatellite loci and a categorical paternity analysis approach were used to investigate the contemporary pollen gene flow in the neotropical tree species Symphonia globulifera. Data for this study were taken from a 500 ha experimental plot in a dense terra firme forest in the Eastern Brazilian Amazon and included the mapping and genotyping of 161 reproductive trees, representing more than 90% of all adult trees, and the collection of 748 open-pollinated seeds from 56 seed-trees over two field seasons (2002 and 2003). High levels of pollen immigration from outside of the study plot were detected in both sampled seed-years (≥49%) suggesting long distance pollen gene flow. Low levels of self-fertilization were also detected (≤2%). The analysis showed long distance pollen dispersal occurred within the study area in both 2002 (δ = 907 ± 652 m SD) and 2003 (δ = 963 ± 542 m SD). Patterns of pollen dispersal distance within the plot were also found to be shorter than the distances between potential male parents and seed-trees. This result indicates that the distance between trees does not explain the identified pollen dispersal pattern. Our results support the hypothesis that animal pollinated species occurring in low-density populations can disperse pollen in long distances, despite the very dense nature of the forest.     

鸡微卫星DNA标记与其生长性状的相关分析

测定了固始鸡与安卡鸡杂交后自交F2代500多个个体的0,2,4,6,8,10,12周龄体重,检测10个微卫星DNA标记,对标记基因型生长性状值进行方差分析和多重比较。结果表明:对于2,8,12周龄体重,MCW166各基因型间有显著差异(P<0.05);6周龄体重,MCW166各基因型间有极显著差异(P<0.01);对于2周龄体重,ADL169各基因型间有极显著差异(P<0.01),4,6,8周龄体重,ADL169各基因型间有显著差异(P<0.05)。     

猪不同基因组DNA模板来源和浓度与微卫星位点扩增效果的比较研究

[目的]探讨全部使用猪毛发作为试验材料进行遗传多样性研究的可行性。[方法]以贵州黔北黑猪中的3头成年母猪为试材,分别拔取100、200根毛发和抽取5 ml全血进行DNA提取。以微卫星引物S0225和S0227为引物,设置1.0、2.5、5.0 ng/μl 3种模板浓度进行PCR扩增。[结果]采用2.5、5.0 ng/μl的模板浓度均可获得较好的PCR产物,用于聚丙烯酰胺凝胶电泳对扩增基因有较好的分辨效果。毛发DNA和血样DNA的PCR产物数量和质量均无明显差异。毛发数量与所提取DNA的浓度无直接关系。利用21个全毛样PCR产物进行变性聚丙烯酰胺凝胶电泳,均可观察到清晰的条带。[结论]该研究进一步证明全毛样DNA可作为猪遗传多样性研究的材料。     

应用微卫星DNA技术研究中华蜜蜂群内工蜂监督效果

【目的】研究不同中华蜜蜂（Apis cerana cerana）群内的工蜂繁殖现象,探讨蜂群的工蜂监督效果。【方法】以中华蜜蜂为试验材料,对处女蜂王分别进行单雄和双雄人工授精,并以蜂王自然交尾的蜂群作为对照。蜂王成功繁殖后7周,利用蜜蜂微卫星DNA技术检测蜂群内的雄蜂是由蜂王产的未受精卵发育而成,还是由工蜂产的未受精卵发育而成。【结果】所有蜂群中的雄蜂都是由蜂王产的未受精卵发育而成。【结论】在人工授精和自然交尾蜂群中都明显存在工蜂监督行为。     

小滨麦易位系山农0096抗条锈基因的微卫星标记和染色体定位

从普通小麦品种烟农15与八倍体小滨麦杂交后代中选育的小滨麦种质系山农0096,综合性状优良,高抗条锈病,经鉴定为导入了滨麦草染色体的小片段易位系.通过抗性接种鉴定和遗传分析,推测山农0096的条锈病抗性由显性单基因控制,抗条锈病基因来源于滨麦草,暂将其表示为YrSn0096.利用F2分离群体分组法(BSA)对山农0096中的抗条锈病基因进行了微卫星标记分析,从1 261对SSR引物中筛选出引物BARC236-4A能在滨麦草、八倍体小滨麦和山农0096中扩增出特异性DNA片段Xbarc236-4A255bp;利用该标记检测山农0096x辉县红F2群体的单株DNA,根据扩增带型,利用软件MAPMAKER3.0确定标记Xbarc236-4A与滨麦草抗条锈基因的遗传距离为5.0 cM,并将该抗条锈病基因定位在4A染色体上.     

Development and validation of microsatellite markers linked to the rice blast resistance gene <Emphasis Type="Italic">Pi-z</Emphasis> of Fukunishiki and Zenith

Rice blast resistance gene ‘Pi-z’ present in rice genotypes, Zenith and Fukunishiki, represents a potential source of blast resistance for the north-western Himalayan region of India. We tested the reliability of microsatellite markers linked to Pi-z for assessing blast resistance phenotype in crosses of commercial importance. A new set of microsatellite markers linked to Pi-z was also developed by exploiting the publicly available marker and genomic resources of rice. Of the three previously reported markers for Pi-z, only MRG5836 was suitable for the marker assisted selection of Pi-z. Among the 17 microsatellites selected from the putative region of Pi-z locus, two, RM8225 and RM8226 cosegregated with MRG5836 and were located at distance of 1.2–4.5 cM from the gene. A new microsatellite marker ‘SSR236’ was developed from the (CT)₁₆ repeat of PAC clone P0502B12, which exhibited closer linkage (0.6–1.2 cM) to Pi-z. Survey of the allelic diversity at the loci of the Pi-z linked microsatellite markers revealed that the Fukunishiki and Zenith type alleles were not present in majority of the local indica rice genotypes. As these markers are polymorphic between the Pi-z donors and a great majority of local indica rices tested, they can be used as a selection tool in rice breeding programs aimed at improving the blast resistance of local rices.     

一张含有227个SSR标记的大豆遗传连锁图

利用由大豆主栽种晋豆23和农家种灰布支(ZDD2315)杂交培育的F10代大豆重组自交系群体Jinf,共474个家系作为作图群体。依据1999年Cregan等发表的大豆“公共图谱”,选用441对SSR引物,建成了含有227个SSR座位的大豆SSR连锁图,该图覆盖大豆基因组1900cM,两个相邻标记的平均间距为8．3cM,归属于20个大豆连锁群,与Song等2004年发表的公共图谱相比,所有标记都被定位于相同的连锁群,且排列顺序大致相同,具有很好的线性关系。