中国李种质资源形态性状和农艺性状的遗传多样性分析

以国家果树种质熊岳李杏圃中保存的405份中国李和杂种李为材料,依据32个主要形态性状和农艺性状的评价数据,对这些主要性状进行了遗传多样性、相关性和主成分分析.结果表明,中国李表现出丰富的遗传多样性;从字符型形态和农艺性状数据看,叶形、果形、果皮彩色和果肉色泽等性状均表现出较为丰富的多样性;从数值型形态和农艺性状数据看.各性状的变异系数为47.09%～14.85%;其中单果重的变异系数最大,为47.09%,其变幅为4.50～107.90g.其次是维生素C含量,变异系数为40.44%,变幅为0.80～14.70mg/100g;相关性分析得出,节间长度与一年生枝条长度和可溶性糖含量呈正相关,果实发育期与可溶性固形物和可溶性糖含量也呈正相关,而与可滴定酸和维生素C含量呈负相关.     

Development and transportability across Prunus species of 42 polymorphic almond microsatellites

We report 47 new simple sequence repeats (SSRs) obtained from a CT/AG enriched genomic library of almond cv. Texas (syn. Mission). Forty‐two of them were polymorphic in a sample of eight almond cultivars and 31 of these were single‐locus. The average values of the number of alleles per locus (6.6), and mean observed (65%) and expected (76%) heterozygosities for these 31 SSRs indicated a high level of variability. All cultivars studied could be individually identified using any one of the five SSRs. Transportability to other Prunus species (peach, sweet cherry, Japanese plum and apricot) was also high (83–100%).     

中国李种质资源形态性状和农艺性状的遗传多样性分析

以国家果树种质熊岳李杏圃中保存的405份中国李和杂种李为材料,依据32个主要形态性状和农艺性状的评价数据,对这些主要性状进行了遗传多样性、相关性和主成分分析.结果表明,中国李表现出丰富的遗传多样性;从字符型形态和农艺性状数据看,叶形、果形、果皮彩色和果肉色泽等性状均表现出较为丰富的多样性;从数值型形态和农艺性状数据看....     

A new set of polymorphic simple sequence repeat (SSR) markers from a wild strawberry (Fragaria vesca) are transferable to other diploid Fragaria species and to Fragaria × ananassa

A set of 41 polymorphic microsatellite markers were developed using a CT/AG‐enriched genomic library of Fragaria vesca cv. Reine des Vallées. Thirty‐five of them were polymorphic in F. vesca and were tested in one accession each of six additional diploid Fragaria species and the octoploid Fragaria× ananassa. A mean of 5.3 alleles per locus and a low level of observed heterozygosity were generally detected in the 32 single‐locus simple sequence repeats of F. vesca. Most of these loci amplify in the other diploid species and in F. × ananassa.     

Regeneration of <Emphasis Type="Italic">Prunus salicina</Emphasis> Lindl (Japanese plum) from hypocotyls of mature seeds

Plant regeneration of Prunus salicina (Japanese plum) using mature seeds was studied and evaluated. Shoots were effectively induced from hypocotyl slices of mature seeds on media containing cytokinins. Among three plant growth regulators evaluated, thidiazuron (TDZ) was the most effective for shoot induction overall. Shoots were also induced using 6-benzylaminopurine (BA), but the effectiveness was reduced at low concentrations. Low regeneration was induced using kinetin. Three plum varieties were evaluated and the regeneration appeared to be genotype dependent. Induced shoots elongated, roots formed, and plantlets developed upon transfer of the shoots to the rooting medium. Primary shoots, when sub-cultured on fresh induction medium, produced multiple shoots, and such multiplication could continue for more cycles. The plantlets were transferred to soil, and the full plants were readily recovered in a greenhouse. The regeneration process was relatively fast as plants could be recovered in 4 to 5 mo. after the culture initiation.     

不同种源槜李的RAPD分析及主要农艺性状比较

运用RAPD标记方法对18个槜李(Prunus salicina Lindl. )种源及3个外类群的总基因组DNA进行了PCR扩增,在此基础上采用聚类分析方法对不同种源的遗传关系进行了分析,此外对18个槜李种源果实的主要农艺性状也进行了比较分析.RAPD分析结果表明,用从70条随机引物中筛选出的14条随机引物共扩增出71条带,其中多态性条带29条,多态性条带百分率达40.8%.聚类分析结果表明,在欧氏平方距离0.060处可将18个槜李种源和3个外类群分为7组,其中3个外类群分别单独成组,18个槜李种源可分为4组;姚学明和洪魏3这2个种源分别独立成组,洪魏2、王施、洪彭1、凤表1和凤表2等5个种源聚为一组,其他11个种源为一组.18个槜李种源果皮均为红色,其中深红色和暗红色各占50%;根据果实的成熟期可将18个槜李种源大致分为早熟型和晚熟型,成熟期分别为6月中下旬和7月上中旬;比较而言,早熟型的槜李种源具有单果质量较大、可溶性固形物含量较低、花期早3～4 d等特征.RAPD标记和农艺性状的综合分析结果显示,嘉兴地区的这些槜李种源在栽培过程中产生了突变和分化;姚学明这一种源与大多数槜李种源关系密切,并具有一定的优良特性,可能是1个优良种源,值得进行深入研究.     

A high‐throughput transformation system allows the regeneration of marker‐free plum plants (Prunus domestica)

A high‐throughput transformation system previously developed in our laboratory was used for the regeneration of transgenic plum plants without the use of antibiotic selection. The system was first tested with two experimental constructs, pGA482GGi and pCAMBIAgfp94(35S) that contain selective marker and reporter genes. Transformation was monitored by GUS detection, and estimated transformation efficiencies were 5.7% and 17.7% for pGA482GGi and pCAMBIAgfp94(35S), respectively. Subsequently, an intron‐hairpin‐RNA (ihpRNA) construct, carrying the Plum Pox Virus coat protein (ppv‐cp) gene, without selectable or reporter marker genes was designed. Five transgenic lines were regenerated as confirmed by DNA blot analysis. We believe that this is the first report on the production of marker‐free plants transformed with a potential agronomically important trait in a Prunus species.     

Simple Sequence Repeat Analysis of Genetic Diversity in Primary Core Collection of Peach （Prunus persica）

In this study, the genetic diversity of 51 cultivars in the primary core collection of peach （Prunus persica （L.） Batsch） was evaluated by using simple sequence repeats （SSRs）. The phylogenetic relationships and the evolutionary history among different cultivars were determined on the basis of SSR data. Twenty-two polymorphic SSR primer pairs were selected, and a total of 111 alleles were identified in the 51 cultivars, with an average of 5 alleles per locus. According to traditional Chinese classification of peach cultivars, the 51 cultivars in the peach primary core collection belong to six variety groups. The SSR analysis revealed that the levels of the genetic diversity within each variety group were ranked as Sweet peach 〉 Crisp peach 〉 Flat peach 〉 Nectarine 〉 Honey Peach 〉 Yellow fleshed peach. The genetic diversity among the Chinese cultivars was higher than that among the introduced cultivars. Cluster analysis by the unweighted pair group method with arithmetic averaging （UPGMA） placed the 51 cultivars into five linkage clusters. Cultivar members from the same variety group were distributed in different UPGMA clusters and some members from different variety groups were placed under the same cluster. Different variety groups could not be differentiated in accordance with SSR markers. The SSR analysis revealed rich genetic diversity in the peach primary core collection, representative of genetic resources of peach.     

Characterization and compilation of polymorphic simple sequence repeat (SSR) markers of peanut from public database

ABSTRACT: BACKGROUND: There are several reports describing thousands of SSR markers in the peanut (Arachis hypogaea L.) genome. There is a need to integrate various research reports of peanut DNA polymorphism into a single platform. Further, because of lack of uniformity in the labeling of these markers across the publications, there is some confusion on the identities of many markers. We describe below an effort to develop a central comprehensive database of polymorphic SSR markers in peanut. FINDINGS: We compiled 1,343 SSR markers as detecting polymorphism (14.5%) within a total of 9,274 markers. Amongst all polymorphic SSRs examined, we found that AG motif (36.5%) was the most abundant followed by AAG (12.1%), AAT (10.9%), and AT (10.3%).The mean length of SSR repeats in dinucleotide SSRs was significantly longer than that in trinucleotide SSRs. Dinucleotide SSRs showed higher polymorphism frequency for genomic SSRs when compared to trinucleotide SSRs, while for EST-SSRs, the frequency of polymorphic SSRs was higher in trinucleotide SSRs than in dinucleotide SSRs. The correlation of the length of SSR and the frequency of polymorphism revealed that the frequency of polymorphism was decreased as motif repeat number increased. CONCLUSIONS: The assembled polymorphic SSRs would enhance the density of the existing genetic maps of peanut, which could also be a useful source of DNA markers suitable for high-throughput QTL mapping and marker-assisted selection in peanut improvement and thus would be of value to breeders. KEYWORDS: SSR, motif, polymorphism, cultivated peanut.     

Effects of foliar sprays containing calcium, magnesium and titanium on plum (Prunus domestica L.) fruit quality

An experiment was performed in which Ti⁴⁺-ascorbate was sprayed onto plum trees in several combinations with other commercial compounds containing Ca²⁺ and Mg²⁺ to study the effects on the commercial quality of fruits, with special focus on improving their resistance against postharvest handling damage.

All the treatments containing titanium increased the tree performance (branch elongation, flowering and fruit setting intensities) and fruit size. At harvest fruits from the Ti-treated trees showed improved resistance to compression and penetration, as well as a decrease in weight-loss during postharvest storage. A similar response was obtained for the external colour, though all the treatments seemed to delay somewhat the apparent ripening status. Nevertheless, the fruits from Ti-treated trees showed a better behaviour in the evolution of the colour parameters during storage than did the control fruits.

Titanium application significantly increased the calcium, iron, copper and zinc concentrations in peel and flesh. This improvement in the calcium absorption is explained as a consequence of the beneficial effect of titanium on the absorption, translocation and assimilation processes.     

Development of simple sequence repeat (SSR) markers for the assessment of gene flow between sea beet (Beta vulgaris ssp. maritima) populations

Molecular markers can be used to estimate gene flow indirectly by monitoring the relative frequency of alleles in adjacent populations. Sea beet (Beta vulgaris ssp. maritima) is a wild plant species found along the coastlines of many European countries and is closely related to cultivated beets. A set of six simple sequence repeat (SSR) markers that are polymorphic in UK populations have been developed for sea beet to assess the problems of indirect measurement of gene flow in these populations.     

Genetic linkage map of peach [Prunus persica (L.) Batsch] using morphological and molecular markers

A genetic linkage map of peach [Prunus persica (L.) Batch] was constructed in order to identify molecular markers linked to economically important agronomic traits that would be particularly useful for long-lived perennial species. An intraspecific F₂ population was generated from self-pollinating a single F₁ plant from a cross between a flat non-acid peach, ‘Ferjalou Jalousia^®’ and an acid round nectarine ‘Fantasia’. Mendelian segregations were observed for 270 markers including four agronomic characters (peach/nectarine, flat/round fruit, acid/non-acid fruit, and pollen sterility) and 1 isoenzyme, 50 RFLP, 92 RAPD, 8 inter-microsatellite amplification (IMA), and 115 amplified fragment length polymorphism (AFLP) markers. Two hundred and forty-nine markers were mapped to 11 linkage groups covering 712 centiMorgans (cM). The average density between pairs of markers is 4.5?cM. For the four agronomic characters studied, molecular markers were identified. This map will be used for the detection of QTL controlling fruit quality in peach and, particularly, the acid and sugar content.     

RAPD and SCAR markers linked to the Ma1 root-knot nematode resistance gene in Myrobalan plum (Prunus cerasifera Ehr.)

 The Myrobalan plum (Prunus cerasifera) is a self-incompatible species in which the clones P.2175, P.1079 and P.2980 are highly resistant to all root-knot nematodes (RKN), Meloidogyne spp. Each clone bears a single major dominant gene, designated Ma1, Ma2 and Ma3 respectively, that controls a high and wide-spectrum resistance. Bulked segregant analysis (BSA) and random amplified polymorphic DNA (RAPD) analysis were both performed to detect markers linked to the Ma1 gene using three segregating progenies from P.2175 (Ma1 ma1) crossed by three host parents (ma1 ma1). Four dominant coupling-phase markers were identified from a total of 660 10-base primers tested. The resulting linkage map spans 14.7 cM and comprises three markers located on the same side of Ma1 and one marker located on the other side. The nearest markers (OPAL19₇₂₀ and OPA16₁₄₀₀) are located at 3.7 and 6.7 cM, respectively, on each side of the gene. Among the three markers that could be successfully converted into sequence characterized amplified region (SCAR) markers, two of them (SCAL19₆₉₀ and SCAN12₆₂₀) were scored as dominant markers whereas the third (SCAO19₇₇₀) failed to produce any polymorphism. SCAL19, and to a lesser extent SCAN12, can be used reliably in the marker-assisted selection of Prunus rootstocks. These markers are adequate to identify the Ma1 RKN resistance gene in intraspecific segregating progenies and will be suitable for the creation of interspecific rootstocks involving Myrobalan plum. Some of the RAPD and SCAR markers for Ma1 were also recovered in clones P.1079 and P.2980, but not in additional host clones, suggesting that Ma1, Ma2 and Ma3 are either allelic or at least closely linked. Received: 22 September 1998 / Accepted: 19 December 1998     

Isolation and characterization of highly polymorphic microsatellite markers in Hypochaeris radicata (Asteraceae)

We developed five highly polymorphic dinucleotide microsatellite loci for the grassland species Hypochaeris radicata (Asteraceae). Polymorphism of these markers was examined in six populations in the Netherlands. All loci were polymorphic in all populations. The number of alleles per locus varied between 18 and 43. Expected heterozygosity was between 0.86 and 0.91. Cross‐species amplification was tested in six Hypochaeris species and was successful for three different loci in four species. These microsatellites are a useful tool in population genetic, dispersal and metapopulation studies or in testing levels of inbreeding.     

Development and characterisation of simple sequence repeat (SSR) markers for white clover (Trifolium repens L.)

Highly informative molecular markers, such as simple sequence repeats (SSRs), can greatly accelerate breeding programs. The aim of this study was to develop and characterise a comprehensive set of SSR markers for white clover (Trifolium repens L.), which can be used to tag genes and quantitative trait loci controlling traits of agronomic interest. Sequence analysis of 1123 clones from genomic libraries enriched for (CA) _n repeats yielded 793 clones containing SSR loci. The majority of SSRs consisted of perfect dinucleotide repeats, only 7% being trinucleotide repeats. After exclusion of redundant sequences and SSR loci with less than 25 bp of flanking sequence, 397 potentially useful SSRs remained. Primer pairs were designed for 117 SSR loci and PCR products in the expected size range were amplified from 101 loci. These markers were highly polymorphic, 88% detecting polymorphism across seven white clover genotypes with an average allele number of 4.8. Four primer pairs were tested in an F₂ population revealing Mendelian segregation. Successful cross-species amplification was achieved in at least one out of eight legume species for 46 of 54 primer pairs. The rate of successful amplification was significantly higher for Trifolium species when compared to species of other genera. The markers developed in this study not only provide valuable tools for molecular breeding of white clover but may also have applications in related taxa. Received: 3 April 2000 / Accepted: 12 May 2000     

Development and characterisation of simple sequence repeat (SSR) markers for perennial ryegrass (Lolium perenne L.)

Enrichment methods were optimised in order to isolate large numbers of simple sequence repeat (SSR) markers for perennial ryegrass (Lolium perenne L.), with the aim of developing a comprehensive set of loci for trait mapping and cultivar identification. Two libraries were constructed showing greater than 50% enrichment for a variety of SSR-motif types. Sequence characterisation of 1853 clones identified 859 SSR-containing clones, of which 718 were unique. Truncation of flanking sequences limited potential primer design to 366 clones. One-hundred selected SSR primer pairs were evaluated for amplification and genetic polymorphism across a panel of diverse genotypes. The efficiency of amplification was 81%. A relatively high level of SSR polymorphism was detected (67%), with a range of 2–7 alleles per locus. Mendelian segregation of alleles detected by selected SSR-locus primer pairs was demonstrated in the F₁ progeny of a pair cross. Cross-species amplification was detected in a number of related pasture and turfgrass species, with high levels of transfer to other Lolium species and members of the related genus Festuca. The identity of putative SSR ortholoci in these related species was confirmed by DNA sequence analysis. These loci constitute a valuable resource of ideal markers for the molecular breeding of ryegrasses and fescues. Received: 8 May 2000 / Accepted: 13 June 2000     

Characterization and PCR multiplexing of polymorphic microsatellite loci in cashew (Anacardium occidentale L.) and their cross‐species utilization

Cashew (Anacardium occidentale L.) is the most economically important tropical nut crop in the world, and yet there are no sequence tagged site (STS) markers available for its study. Here we use an automated, high‐throughput system to isolate cashew microsatellites from a non‐enriched genomic library blotted onto membranes at high density for screening. Sixty‐five sequences contained a microsatellite array, of which 21 proved polymorphic among a closely related seed garden population of 49 genotypes. Twelve markers were suitable for multiplex analysis. Of these, 10 amplified in all three related tropical tree species tested: Anacardium microcarpum, Anacardium pumilum and Anacardium nanum.