Molecular typing of rose cultivars using RAPDs

Summary

A rapid molecular typing method is described in this work. RAPD amplification products are very dependent upon various factors such as source of taq DNA polymerase, thermocycling programmes and DNA concentrations. This issue has been consequently been examined to establish a suitable experimental protocol. Subsequently, genomic DNA from 25 cultivars of rose were amplified using RAPD techniques with twenty 10-mer primers (Operon Kit A). The data obtained reveal no variability within cultivars and a high degree of variation between cultivars. With the patterns obtained with two of the primers (OPA-11 and OPA-17) all the rose cultivars were unequivocally identified. The results suggest that RAPD profiles provide a simple and efficient way to identify rose cultivars.     

Genetic diversity of ash gourd [Benincasa hispida (Thunb.) Cogn.] inbred lines based on RAPD and ISSR markers and their hybrid performance

Ten inbred lines of ash gourd [Benincasa hispida (Thunb.) Cogn.] were crossed to produce 45 F₁ hybrids (without reciprocal) which were evaluated along with the parents for 20 growth- and yield-related traits, in a replicated field trial. High level of heterosis was observed among the hybrids for most of the traits examined, including yield. These inbred lines were analysed by using 42 RAPD primers those produced 282 DNA marker bands. A total of 130 RAPD markers were obtained with a mean of 3.1 per primer, which in combination discriminated all the inbreds from each other. Pair-wise genetic distance measurements ranged from 0.07 to 0.31, suggesting a wide genetic diversity for these inbreds. These inberds were also analysed with five ISSR primers of which four were informative. Twenty-six ISSR marker bands were generated of which 11 were polymorphic with an average of 2.80 per primers. The percentage of polymorphic bands produced were higher in ISSR markers (>80%) than generated through RAPD markers (46%). Although the results indicated significant positive correlations of genetic distance with hybrid performance and heterosis, the RAPD based genetic distance measures and use of limited ISSR markers in this present study could not effectively predict hybrid performance in this crop. The genetic variation among ash gourd inbred lines examined, herein, defined a marker array (combined ISSR and RAPD) for the development of a standard reference for further genetic analyses, and the selection of potential parents for predicting hybrid performance and heterosis.     

DNA fingerprinting and genetic diversity analysis of late-bolting radish cultivars with RAPD,ISSR and SRAP markers

Three molecular marker systems, RAPD (random amplified polymorphic DNA), ISSR (inter-simple sequence repeat) and SRAP (sequence-related amplified polymorphism), were employed for identification and genetic diversity analysis of 35 elite late-bolting radish cultivars. Detected by 35 RAPD primers, 22 ISSR primers and 17 SRAP primer combinations, the proportions of polymorphic bands were 85.44%, 85.2% and 85.41%, respectively, and the mean genetic similarity coefficients between pairs of genotypes were 0.781, 0.787 and 0.764, respectively. Each of the three molecular marker systems can identify all the cultivars. Five sets of three-RAPD primers, 3 sets of three-ISSR primers and 16 sets of three-SRAP primer combinations were able to distinguish all the cultivars. A linear relationship was observed between Resolving power (Rp) of a primer and its ability to distinguish genotypes. The 35 cultivars were clustered into three major groups based on the RAPD, ISSR and marker combination data with UPGMA, which are in high accordance with their own origins and main characteristics. The results demonstrated that these three marker systems could be useful for identification and genetic diversity analysis of radish cultivars.     

Assessment of genetic purity of tomato (Lycopersicon esculentum L.) hybrid using molecular markers

Three DNA molecular marker systems, RAPD, ISSR and SSR, were used to test seed genetic purity of two commercial hybrid tomato (Lycopersicon esculentum L.) cultivars ‘Hezuo 903’ and ‘Sufen No. 8’. Genomic DNA from the two F₁ hybrid cultivars and their corresponding parental lines was screened with 218 RAPD decamer primers, 54 ISSR primers and 49 SSR primers. Among the 321 primers, 4 primers for ‘Hezuo 903’ and 3 for ‘Sufen No. 8’, which could produce both female and male parent-specific markers, were selected for testing the genetic purity. A total of 210 hybrid individuals of each cultivar were analyzed using the identified primers. The combined results of the marker analysis showed that eight of the 210 F₁ plants in ‘Hezuo 903’ and 13 of 210 in ‘Sufen No. 8’ were false hybrids, and the overall genetic purity of the two F₁ hybrid seed lots was 96.2 and 93.8%, respectively. This study showed that RAPD and SSR markers could provide a practical and efficient tool in quality control of the tomato commercial hybrid seeds.     

A PCR-based assessment of genetic diversity,and parentage analysis among commercial mango cultivars and hybrids

Summary

Three different PCR methods [Random Amplified Polymorphic DNA (RAPD), Inter-Simple Sequence Repeats (ISSR), and Directed Amplification of Minisatellite DNA (DAMD)] were used to analyse genetic diversity and parentage among 20 mango cultivars, including 18 landraces and two hybrids (‘Amrapali’ and ‘Mallika’). These hybrids together with a third hybrid (‘Ratna’), and an out-group species (Mangifera sylvatica) were also analysed for parentage. Fifteen, seven and four primers were used to amplify a total of 158, 69 and 59 distinct DNA fragments by RAPD, ISSR and DAMD, respectively. Of these, approx. 85%, 64% and 90% were polymorphic, respectively. Genetic distances between pairs of mango cultivars were measured separately by each method and depicted graphically as a Neighbor Joining (NJ) tree. The three methods revealed different groupings of cultivars and hybrids. A NJ tree based on the cumulative data from all methods correlated well with the parentage of the mango hybrids, and the grouping of cultivars on a regional basis. Genetic markers likely to be associated with important agronomic traits were identified by further analysing the hybrids, with their respective parents, using all three methods. On the basis of the highest number of polymorphic bands observed (90%), DAMD was judged to be the best method with which to analyse mango germplasm.     

豆瓣菜种质资源遗传多样性的RAPD和ISSR分析

以8个豆瓣菜的品种为试材，用筛选出的79个RAPD引物和34个ISSR引物对这8个品种的基因组DNA进行扩增，分别扩增出361条和179条谱带，每个引物扩增出的带在3～10条之间，平均每个引物扩增出约5条带。根据所得的条带进行聚类分析，两种标记产生的聚类图存在一些差异，但它们都可以较好地将8个品种按亲缘关系的远近划分为3个不同的类群。Mantel测试得出相关系数r=0．58155，表明RAPD和ISSR两种分子标记技术的相关度很低。     

Analysis of genetic diversity among Indian short-day onion (Allium cepa L.) cultivars using RAPD markers.

Summary

Randomly amplified polymorphic DNA (RAPD) markers were used to estimate genetic diversity among 24 cultivars of short-day onions. Total genomic DNA was extracted and subjected to RAPD analysis using 90 arbitrary 10-mer primers. Of these, 15 primers were selected which yielded 137 bands, 91.24% of which were polymorphic. None of the primers produced a unique banding pattern for each cultivar. RAPD data were used to calculate a Squared-Euclidian Distance matrix which revealed a minimum genetic distance between cultivars ‘AFLR-722’ and ‘PBR-140’, and a maximum genetic distance between cultivars ‘PBR-139’ and ‘A.Kalyan’, and ‘MS-48’ and ‘A.Kalyan’. Based on the distance matrix, cluster analysis was done using a minimum variance algorithm.The dendrogram thus generated, based on Ward’s method, grouped the 24 onion cultivars into two major clusters. The first cluster consisted of cultivars from the northern region, and the second of cultivars from the southern region of India. The present study shows that there is high diversity among the onion cultivars selected and indicates the potential of RAPD markers for identification and maintenance of onion germplasm for crop improvement purposes.     

Genetic structure of Buxus sinica var. parvifolia, a rare and endangered plant

Buxus sinica var. parvifolia, a rare and endangered tree species in some semitropics alpine areas of China, plays an important role in the maintenance of the landscape and ecosystem. In this study, RAPD and ISSR markers were used to investigate the genetic diversity and structure of five natural populations and one tamed population of B. sinica var. parvifolia. 21 RAPD primers amplified 209 bands with 167 (79.90%) polymorphic and 21 ISSR primers amplified 518 bands with 467 (90.15%) polymorphic. The genetic diversity, estimated by Shannon’ index, was 0.4343 (by RAPDs) and 0.3661 (by ISSRs). Both RAPD and ISSR analyses revealed a high level of genetic diversity in natural populations of B. sinica var. parvifolia. Furthermore, analysis of molecular variance (AMOVA) was used to apportion the variation within and between populations. The proportion of variation attributable to within-population differences was very high (69.2% by RAPDs; 84.51% by ISSRs). Moderate differentiation was detected among populations using RAPDs (30.80%), while only a small amount of variation (15.49%) was detected among populations using ISSRs. We suggest that the present genetic structure is due to high levels of environmental variability and gene flow, which still need further study to confirm. Conservation measures are suggested, including in situ and ex situ strategies, based on the observed population genetic information.     

Assessment of genetic relatedness among mango cultivars of India using RAPD markers

Summary

DNA-based RAPD (Random Amplification of Polymorphic DNA) markers have been used extensively to study genetic relationships in a number of fruit crops. A wide genetic diversity exists in the mango fruit in India. Present day commercial cultivars originated mainly from this subcontinent. In this study, 18 commercial mango cultivars, traditionally grown in western, southern, northern and eastern parts of India, were selected to assess genetic relatedness. Total genomic DNA was extracted and subjected to RAPD analysis using 30 arbitrary 10-mer primers. Of these, 27 primers amplified mango genomic DNA. None of these primers produced unique band pattern for each cultivar. RAPD data were used to calculate a squared Euclidean distance matrix, and based on this cluster analysis was done using a minimum variance algorithm. Cluster analysis clearly showed two groups—the first consisting of western, northern and eastern mango cultivars and the second group consisting of southern cultivars. From the analysis of results, it appears the majority of mango cultivars originated from a local mango genepool and were domesticated later.     

Genetic similarities among cocoyam cultivars based on randomly amplified polymorphic DNA (RAPD) analysis

Eighteen cultivars of cocoyam (Xanthosoma spp.) and two cultivars of taro (Colocasia esculenta (L.) Schott) from the USDA/ARS germplasm collection were evaluated for genetic relatedness using RAPD data. Seven random primers generated 40 RAPD loci. Of the 18 cultivars screened, 11 (61%) were identical at all RAPD loci evaluated. A similarity matrix was constructed on the basis of the presence or absence of bands. Among cocoyam cultivars the genetic similarity ranged from 0.86 to 0.97 with a mean of 0.91. Cluster analysis identified two main clusters with some unexpected groupings. These data indicate that very little genetic variation exists within the accessions used in this study and that this Xanthosoma spp. collection is of limited value as a genetic resource.     

山楂（Crataegus pinnatifida Bge.)遗传多样性的RAPD和ISSR标记分析

 利用RAPD和ISSR标记对35份山楂（Crataegus pinnatifida Bge.）资源进行了DNA多态性分析。12个RAPD引物共扩增出110条清晰的谱带,其中89条显示多态性,平均每个引物扩增出7.4条多态性谱带。13个ISSR引物共扩增出110条清晰的谱带,其中94条显示多态性,平均每个引物扩增出7.2条多态性谱带。基于RAPD和ISSR标记,利用UPGMA分别构建了35份山楂资源的聚类树状图。距离系数分别为0～0.62（RAPD）和0～0.64（ISSR）,表明山楂具有较高的遗传多样性。     

Cultivar identification and genetic diversity analysis of broccoli and its related species with RAPD and ISSR markers

A total of 18 genotypes of broccoli were subjected to random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) marker analysis. Seventy-four RAPD and eight ISSR primers generated 344 and 67 polymorphic bands, respectively. All broccoli genotypes could be distinguished with two-primer combinations, indicating that RAPD and ISSR markers can be used to efficiently identify broccoli cultivars. These 18 broccoli genotypes could be separated into two major sub-groups. The first major sub-group (A) included 13 genotypes and the second major sub-group (B) was comprised of five genotypes belonging to early-maturating cultivars. Genetic diversity analysis was performed on the 18 broccoli genotypes, one radish genotype, and six related Brassica accessions. All accessions could be clustered into two groups (radish and Brassica) based on the unweighted pair group of arithmetic average (UPGMA) cluster analysis. The UPGMA analysis indicated that broccoli is most closely related to cauliflower, than to cabbage and Chinese cabbage.     

RAPD技术在石榴品种分类上的应用

以55个石榴栽培品种为试验材料,利用15条多态性好的随机引物进行RAPD分析,共扩增出125条带,其中多态性条带92条,多态性百分率73.6%,说明品种间有变异。应用TFPGA软件计算55个石榴品种间的Nei’s遗传距离,并用UPGMA法构建聚类图,将55个石榴品种分为4个类群,从DNA水平上揭示了石榴品种之间的亲缘关系。结果表明,采用UPGMA法聚类的结果与形态上的分类存在着一定的差异,即与根据花色和果味进行的分类没有相关性而与瓣型进行的分类有一定的相关性。     

Assessment of clonal genetic variability in Olea europaea L. ‘Cobrançosa’ by molecular markers

Olive tree is mainly vegetatively propagated; therefore a small level of polymorphism is expected among clones of the same cultivar. In order to access the level of intra-varietal genetic variability within a collection of 120 clones of the Portuguese olive ‘Cobrançosa’ DNA fingerprinting was performed. Ten random amplified polymorphism DNA (RAPD) primers amplified 150 fragments, of which 75 were polymorphic, while 10 inter-simple sequence repeats (ISSR) primers amplified 179 fragments of which 98 were polymorphic. ‘Cobrançosa’ clones were compared and analysed using Jaccard's coefficient with unweighted pair group mathematical averages, using the RAPD data, the ISSR data and both markers simultaneously. The data indicates a wide intra-varietal genetic variability among the clones. It was possible to cluster some clones according to geographical provenance. Analysis of molecular variance revealed greater variation within clones than among different geographical origins. Significant genetic diversity among the ‘Cobrançosa’ olive cultivar, even though the clones came from a limited geographical area, was also detected.     

Characterization of Tunisian pomegranate (Punica granatum L.) cultivars using amplified fragment length polymorphism analysis

The amplified fragment length polymorphism (AFLP) analysis of DNA was used to characterize 34 pomegranate cultivars. By using a combination of six primers, a total of 327 markers were scored with a mean of 57.5. The high percentage of polymorphic bands (ppb) of 94.7 and the resolving power (R_p) collective rate value of 129.14 were scored. Data proved that the tested primers were informative to discriminate among cultivars and to survey the genetic diversity in this fruit crop. It has been assumed that the local pomegranate germplasm is characterized by a typically continuous genetic diversity. The derived dendrogram proved that cultivars are clustered independently from their geographical origin and their denomination. In addition, AFLP permitted the generation of a nearly unlimited number of molecular markers that are reliable in differentiating the cultivars and/or the polyclonal varieties.     

不同山楂品种亲缘关系的RAPD分析

为探讨山楂品种间的亲缘关系,采用RAPD技术对20个不同品种的山楂材料进行了基因组DNA多态性分析。从120个引物中筛选出15个10bp的随机引物对所选山楂品种的DNA样品进行PCR扩增,共得到216条谱带,177条表现多态性,多态性比率达81.9%,其中包含27条特异性谱带,揭示了山楂植物丰富的遗传多样性。且利用NTSYS软件和UPGMA法对扩增结果进行了品种间相似系数的计算及聚类分析,结果表明相似系数在0.71～0.87,实生楂与其他山楂品种亲缘关系较远。     

Characterization of white sapote (Casimiroa edulis Llave & Lex.) germplasm using floral morphology,RAPD and AFLP markers

Floral morphology, random amplified polymorphic DNA (RAPD), and amplified fragment length polymorphism (AFLP) were used to characterize and verify genetic diversity within a white sapote cultivar collection and to develop molecular markers for germplasm identification. On the basis of floral morphology, the cultivars were classified into three types: type I included 23 cultivars with large ovaries and small anthers; type II included 13 cultivars with small ovaries and large anthers; and type III included one cultivar, named ‘Maltby’, with a large ovary and large anthers. DNA was isolated from 39 cultivars of white sapote and subjected to RAPD and AFLP analysis using 24 and 7 primers, respectively. One hundred and sixty-eight RAPD and 286 AFLP bands were used to assess genetic characterization among white sapote. Sixty percent of the RAPD and 77% of the AFLP amplification products were polymorphic among accessions. RAPD or AFLP markers differentiated all white sapote cultivars effectively. Moreover, each flower type was characterized as specially associated with two RAPD bands. UPGMA dendrograms based on RAPD and AFLP data, showed the majority of the cultivars from flower type I and flower type II clustering together. Finally 101 RAPD markers and 220 AFLP markers were used to construct a neighbor-joining dendrogram. This showed that the 37 cultivars could be classified into six distinct clusters, between which the similarity coefficient was as low as 0.00–0.55, even though the cultivars were morphologically very similar. The remaining two cultivars namely ‘Smathers’ and ‘Maltby’ were found genetically very distant from the other cultivars in RAPD, AFLP or combined RAPD and AFLP based dendrograms. The results suggested that the level of genetic variation among white sapote cultivars is diverse and the morphological and molecular data may lead to representation of the cultivar relationships as well as flower type discrimination.     

Identification of persimmon (Diospyros kaki) cultivars and phenetic relationships between Diospyros species by more effective RAPD analysis

Randomly amplified polymorphic DNA (RAPD) markers were used to identify cultivars of persimmon (Diospyros kaki Thunb.) and to estimate the phenetic relationships between Diospyros species. Long random primers (15 and 20 bases) were used to increase the effectiveness of recognizing polymorphism. Twenty-five of 34 (74%) long random primers amplified polymorphic bands of 25 persimmon cultivars, indicating that the effectiveness improved compared with RAPD analysis using 10-base primers. The 25 primers amplified a total of 444 polymorphic bands, which distinguished all 25 cultivars. RAPD markers (133) clarified the phenetic relationship between the six species and subspecies of Diospyros: D. lotus, D. lotus subsp. glabbra and D. taitoensis formed one group (lotus group), and persimmon was related in order of closeness to the lotus group, D. oleifera, and D. rhombifolia.