Qualitative and quantitative characterization of RAPD variation among snap bean (Phaseolus vulgaris) genotypes

Ten snap bean (Phaseolus vulgaris) genotypes were screened for polymorphism with 400 RAPD (random amplified polymorphic DNA) primers. Polymorphic RAPDs were scored and classified into three categories based on ethidium bromide staining intensity. An average of 5.19 RAPD bands were scored per primer for the 364 primers that gave scorable amplification products. An average of 2.15 polymorphic RAPDs were detected per primer. The results show that primer screening may reduce the number of RAPD reactions required for the analysis of genetic relationships among snap-bean genotypes by over 60%. Based on the analysis of the distribution of RAPD amplification, the same number of polymorphic RAPDs were amplified from different genotypes for all RAPD band intensity levels. A comparison of RAPD band amplification frequency among genotypes for the three categories of bands classified by amplification strength revealed a measurable difference in the frequencies of RAPDs classified as faint (weakly amplifying) compared to RAPD bands classified as bold (strongly amplifying) indicating a possible scoring error due to the underscoring of faint bands. Correlation analysis showed that RAPD bands amplified by the same primer are not more closely correlated then RAPD bands amplified by different primers but are more highly correlated then expected by chance. Pairwise comparisons of RAPD bands indicate that the distribution of RAPD amplification among genotypes will be a useful criterion for establishing RAPD band identity. For the average pairwise comparison of genotypes, 50% of primers tested and 15.8% of all scored RAPDs detected polymorphism. Based on RAPD data Nei's average gene diversity at a locus was 0.158 based on all scorable RAPD bands and 0.388 if only polymorphic RAPD loci were considered. RAPD-derived 1 relationships among genotypes are reported for the ten genotypes included in this study. The data presented here demonstrate that many informative, polymorphic RAPDs can be found among snap bean cultivars. These RAPDs may be useful for the unique identification of bean varieties, the organization of bean germplasm, and applications of molecular markers to bean breeding.     

Impact of intercropping aphid-resistant wheat cultivars withoilseed rape on wheat aphid (Sitobion avenae) and its natural enemies

The effects of intercropping of wheat cultivars and oilseed rape on the densities of wheat aphid, Sitobion avenae, and their arthropod natural enemies were evaluated. Three winter wheat cultivars with different resistant levels to S. avenae were used: ‘KOK’ (high resistance), ‘Xiaobaidongmai’ (low resistance) and ‘Hongmanghong’ (susceptible). The results showed that the densities of S. avenae were significantly higher on the monoculture pattern than on either the 8-2 intercropping pattern (eight rows of wheat with two rows of oilseed rape) or the 8-4 intercropping pattern (eight rows of wheat with four rows of oilseed rape). The mean number of predators and the mummy rates of S. avenae were significantly higher in two intercropping patterns than those in the monoculture pattern. The densities of S. avenae, ladybeetles, and mummy rate of S. avenae were significantly different among different wheat cultivars. The highest densities of S. avenae and ladybeetles were found on wheat cultivar Hongmanghong. The lowest densities of S. avenae associated with high mummy rate of S. avenae were found on wheat cultivar Xiaobaidongmai. The results showed that wheat-oilseed rape intercropping conserved more predators and parasitoids than in wheat monoculture fields, and partial resistance of wheat cultivar Xiaobaidongmai had complementary or even synergistic effects on parasitoid of S. avenae.     

Inheritance of oilseed rape (Brassica napus) RAPD markers in a backcross progeny with Brassica campestris

Different cultivars/transgenic lines of oilseed rape (Brassica napus) were crossed (as females) with different cultivars/populations of Brassica campestris. All cross combinations produced seed, with an average seed set per pollination of 9.8. Backcrossing of selected interspecific hybrids (as females) to B. campestris resulted in a much lower seed set, average 0.7 seed per pollination. In the single backcross progeny where a large enough population (92 plants) was obtained for analysis, 33 B. napus specific RAPD markers were investigated to determine the extent of transfer of oilseed rape genetic material into this population. Markers were transferred to the backcross generation with frequencies ranging from 26% to 91%. Almost all of the markers (30/33) were transferred in a frequency not significantly different from 50%. Analysis of the pairwise segregation of markers revealed that 23 markers could be assigned to six linkage groups, most probably reflecting six B. napus C-chromosomes. The presence of backcross plants with recombinant genotypes suggests that complex genetic processes can take place during interspecific hybridisation and backcrossing in these Brassica species. The implications of our results for the possible choice of integration sites of transgenes in oilseed rape are discussed.     

Assessment of genetic variation within Indian mustard (Brassica juncea) germplasm using random amplified polymorphic DNA markers

Genetic diversity among 45 Indian mustard (Brassica Juncea L.) genotypes comprising 37 germplasm collections, five advance breeding lines and three improved cultivars was investigated at the DNA level using the random amplified polymorphic DNA (RAPD) technique. Fifteen primers used generated a total of 92 RAPD fragments, of which 81 (88%) were polymorphic. Of these, 13 were unique to accession 'Pak85559'. Each primer produced four to nine amplified products with an average of 6.13 bands per primer. Based on pairwise comparisons of RAPD amplification products, Nei and Li's similarity coefficients were calculated to evaluate the relationships among the accessions. Pairwise similarity indices were higher among the oilseed accessions and cultivars showing narrow ranges of 0.77-0.99. An unweighted pair-group method with arithmetic averages cluster analysis based on these genetic similarities placed most of the collections and oilseed cultivars close to each other, showing a low level of polymorphism between the accessions used. However, the clusters formed by oilseed collections and cultivars were comparatively distinct from that of advanced breeding lines. Genetically, all of the accessions were classified into a few major groups and a number of individual accessions. Advanced breeding lines were relatively divergent from the rest of the accessions and formed independent clusters. Clustering of the accessions did not show any pattern of association between the RAPD markers and the collection sites. A low level of genetic variability of oilseed mustard was attributed to the selection for similar traits and horticultural uses. Perhaps close parentage of these accessions further contributed towards their little diversity. The study demonstrated that RAPD is a simple and fast technique to compare the genetic relationship and pattern of variation among the gene pool of this crop.     

西藏白菜型油菜遗传多样性的RAPD分析

通过利用22个10bp随机引物对来自西藏高原地区107份白菜型油菜种质资源材料的PAPD分析,探讨了西藏白菜型油菜品种之间的遗传分化关系,结果表明：（1）供试的107份材料共产生236条谱带,其中210条谱带有多态性,占88．98％,说明白菜型油菜在西藏高原地区具有较丰富的遗传多样性;（2）根据引物扩增出的DNA指纹图谱,运用UPGMA分析法,在遗传距离为0．078处,可将供试的107份白菜型油菜划分为11个类群,发现来自于同一地区或气候相似区的品种往往聚在一起,表明西藏高原白菜型油菜品种的相似性与其原产地的地理,气候背景密切相关,并在此基础上,结合西藏高原农业发展历史,气候背景以及地形地貌特点和植物地理学,植物区系学,植物进化论等方面的综合分析,提出西藏高原是世界白菜型油菜起源地的观点。     

Estimation of genetic distance based on RAPDs between 11 cotton accessions varying in heat tolerance

The genetic distance of 11 cotton genotypes varying in heat tolerance was studied using RAPD markers. Fifty-three random decamer primers were used for the estimation of genetic distance. Among the 53 RAPD primers, which were custom synthesized by GeneLink Inc., UK, 32 were polymorphic and 21 were monomorphic. The 32 polymorphic primers produced 273 fragments, with a mean of 8.3 fragments per primer. The number of polymorphic bands produced in the 11 cotton accessions ranged from 1 to 31. Primer GLC-20 produced 31 polymorphic bands, while two primers, GLB-5 and GLC-12, produced one polymorphic band each. A range of 88.89 to 42.48% genetic similarity was observed among the 11 cotton accessions. The highest genetic similarity was observed between FH-945 and BH-160 (88.89%), whereas the lowest value was found between NIAB-801/2 and FH-945 (42.48%). Unique amplification profiles were produced by most of the cultivars; the differences were sufficient to distinguish them from other genotypes. This confirms the efficacy of RAPD markers for the identification of plant genotypes. An accumulative analysis of amplified products generated by RAPDs was sufficient to assess the genetic diversity among the genotypes. This information should be helpful for formulating breeding and genome mapping programs.     

Performance of cabbage stem flea beetle larvae (Psylliodes chrysocephala) in brassicaceous plants and the effect of glucosinolate profiles

The cabbage stem flea beetle (CSFB), Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae), is one of the most important pests in European winter oilseed rape production. Adult beetles feed on young leaves whereas larvae mine within the petioles and stems. Larval infestation can cause significant crop damage. In this study, the host quality for CSFB of four oilseed rape (Brassica napus L.) cultivars and seven other brassicaceous species with different glucosinolate (GSL) profiles was assessed under controlled conditions. Larval instar weights and mortality were measured after 14 and 21 days of feeding in the petioles of test plants. To study the impact of GSL on the performance of larvae, the GSL contents in petioles from non-infested and infested plants were analysed before, and 21 days after, the start of larval infestation. Larval performance was not significantly different between the four cultivars of oilseed rape, but differed considerably among the other brassicaceous species tested. In comparison to the weight of larvae in the standard B. napus cv. Robust, the larval weight was higher in turnip rape (Brassica rapa L. var. silvestris) and significantly reduced in white mustard (Sinapis alba L.), oil radish (Raphanus sativa L. var. oleiformis), and cabbage (Brassica oleracea L. convar. capitata var. alba). The duration of larval development increased in white mustard and oilseed radish. The GSL profiles of the petioles showed little difference between non-infested and infested plants of oilseed rape whereas the content of aliphatic GSL increased in the infested turnip rape plants. In contrast, the aliphatic and benzenic GSL decreased in infested Indian rape (B. rapa subsp. dichotoma Roxb.). Larval weight was not correlated with the total GSL content of plants, neither before infestation nor 21 days after. Larval weight was positively correlated with progoitrin and 4-hydroxyglucobrassicin. White mustard, which provides inferior host quality for larval development, has the potential to introduce insect resistance into high-yielding oilseed rape cultivars in breeding programmes.     

Extending the rapeseed gene pool with resynthesized <Emphasis Type="Italic">Brassica napus</Emphasis> II: Heterosis

Hybrid breeding relies on the combination of parents from two differing heterotic groups. However, the genetic diversity in adapted oilseed rape breeding material is rather limited. Therefore, the use of resynthesized Brassica napus as a distant gene pool was investigated. Hybrids were derived from crosses between 44 resynthesized lines with a diverse genetic background and two male sterile winter oilseed rape tester lines. The hybrids were evaluated together with their parents and check cultivars in 2 years and five locations in Germany. Yield, plant height, seed oil, and protein content were monitored, and genetic distances were estimated with molecular markers (127 polymorphic RFLP fragments). Resynthesized lines varied in yield between 40.9 dt/ha and 21.5 dt/ha, or between 85.1 and 44.6% of check cultivar yields. Relative to check cultivars, hybrids varied from 91.6 to 116.6% in yield and from 94.5 to 103.3% in seed oil content. Mid-parent heterosis varied from −3.5 to 47.2% for yield. The genetic distance of parental lines was not significantly correlated with heterosis or hybrid yield. Although resynthesized lines do not meet the elite rapeseed standards, they are a valuable source for hybrid breeding due to their large distance from present breeding material and their high heterosis when combined with European winter oilseed rape.     

Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

红掌品种亲缘关系SRAP分析

利用相关序列扩增多态性（SRAP）分子标记,从100对引物组合中筛选出 26对多态性高、条带清晰的SRAP引物,对33个红掌品种进行遗传多样性和亲缘关系分析。结果如下：（1）26对引物共扩增出366条条带,其中有314条多态性条带,多态性比率为85.79%。引物组合产生的条带数在9～23之间,平均每对引物组合扩增出14.1条和12.1条多态性条带。（2）根据SRAP扩增结果,利用UPGMA法进行聚类分析,33份材料的遗传相似系数在0.55～0.94之间,在遗传相似系数0.786处可将33个红掌品种分为5个类群。结果表明,供试品种遗传多样性丰富,本研究为品种鉴定和杂交育种提供了参考信息。     

Genetic manipulation in cultivars of oilseed rape (Brassica napus) using Agrobacterium

Summary The response of oilseed rape cultivars to infection with Agrobacterium tumefaciens and A. rhizogenes and the possibility of regenerating genetically transformed oilseed rape plants were examined. The frequency at which Agrobacterium induced galls or hairy-roots on in vitro cultured plants ranged from 10% to 70%, depending on the cultivar. From galls induced by the tumorigenic strain T37, known to be strongly shoot inducing on tobacco, roots developed frequently. Occasionally, shoots formed and some of these produced tumour cell specific nopaline. Attempts to grow the transformed shoots into plants have so far been unsuccessful. Whole plants transformed with Ri-T-DNA, however, were regenerated. These had crinkled leaves and abundant, frequently branching roots that showed reduced geotropism, similar to previously isolated Ri T-DNA transformed tobacco and potato plants. The transformed oilseed rape plants flowered, but failed to form seeds.     

Polymorphism for interspecific hybridisation within a population of wild radish (Raphanus raphanistrum) pollinated by oilseed rape (Brassica napus)

The within-population polymorphism of wild radish (Raphanus raphanistrum) for interspecific hybridisation with two cultivars of oilseed rape (Brassica napus) was investigated by hand crossing experiments and fluorescence microscopy. Wide variability among plants was observed in the ability of oilseed rape pollen to germinate on the wild radish stigma; the frequency of pistils showing pollen tubes ranged from 0 to 1, depending on the female plant. The ratio of fertilised ovules to the total number of ovules in ovaries where pollen tubes arrived ranged from 0.02 to 0.51. Overall, the results provide evidence for the presence of different phenotypes. In 40% of the plants, pistils had no or very few pollen tubes and few fertilised ovules. In 23%, the foreign pollen tubes grew through the style towards the ovary, but had low ovule fertilisation efficiency. The remaining 37% showed a large number of pollen tubes in the style and frequent ovule fertilisation, and two plants showed no difference between foreign and conspecific pollen. With regard to post-zygotic barriers, pollen germination and ovule fertilisation represent minor barriers to interspecific hybridisation between oilseed rape and wild radish. It is suggested that the effectiveness of these barriers could be improved through plant breeding; this could reduce the risk of gene flow from transgenic oilseed rape to populations of wild relatives. Received: 15 April 2001 / Accepted: 24 May 2001     

Association of gene-linked SSR markers to seed glucosinolate content in oilseed rape (Brassica napus ssp. napus)

Breeding of oilseed rape (Brassica napus ssp. napus) has evoked a strong bottleneck selection towards double-low (00) seed quality with zero erucic acid and low seed glucosinolate content. The resulting reduction of genetic variability in elite 00-quality oilseed rape is particularly relevant with regard to the development of genetically diverse heterotic pools for hybrid breeding. In contrast, B. napus genotypes containing high levels of erucic acid and seed glucosinolates (++ quality) represent a comparatively genetically divergent source of germplasm. Seed glucosinolate content is a complex quantitative trait, however, meaning that the introgression of novel germplasm from this gene pool requires recurrent backcrossing to avoid linkage drag for high glucosinolate content. Molecular markers for key low-glucosinolate alleles could potentially improve the selection process. The aim of this study was to identify potentially gene-linked markers for important seed glucosinolate loci via structure-based allele-trait association studies in genetically diverse B. napus genotypes. The analyses included a set of new simple-sequence repeat (SSR) markers whose orthologs in Arabidopsis thaliana are physically closely linked to promising candidate genes for glucosinolate biosynthesis. We found evidence that four genes involved in the biosynthesis of indole, aliphatic and aromatic glucosinolates might be associated with known quantitative trait loci for total seed glucosinolate content in B. napus. Markers linked to homoeologous loci of these genes in the paleopolyploid B. napus genome were found to be associated with a significant effect on the seed glucosinolate content. This example shows the potential of Arabidopsis-Brassica comparative genome analysis for synteny-based identification of gene-linked SSR markers that can potentially be used in marker-assisted selection for an important trait in oilseed rape. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Direct comparison of levels of genetic variation in tomato detected by a GACA-containing microsatellite probe and by random amplified polymorphic DNA.

In this study, a direct comparison was made of the ability of four selected random amplified polymorphic DNA (RAPD) primers and a GACA-containing microsatellite probe to detect genetic variation in Lycopersicon. Of the 89 RAPD primers initially tested, 85 showed differences between a representative of Lycopersicon pennellii and L. esculentum, but only 4 distinguished among three L. esculentum cultivars. These four primers were subsequently tested on representatives of six Lycopersicon species. In pairwise comparisons of species, all or 14 of the 15 combinations could be distinguished by single primers. When the primers were tested on 15 L. esculentum cultivars, 90 of the 105 combinations could be distinguished by the four primers together. Finally, none of 118 tested primers showed reproducible differences among calli or progeny of régénérants from tissue culture, although some of the plants had inherited morphological mutations. The probe pWVA16, which detects GACA-containing microsatellites, could distinguish in TaqI-digested DNA the representatives of Lycopersicon species as well as all the L. esculentum cultivars tested. The probe was unable to detect polymorphisms among calli and the progeny of regenerants from tissue culture. An analysis of the results showed that the four selected RAPD primers were able to detect polymorphic bands among species at a frequency of 80%, and among cultivars at a frequency of 44%. In contrast, the microsatellite probe detected polymorphic bands at a frequency of 100 and 95%, respectively. The GACA-containing probe did not detect any common bands among the representatives of the six species, while band sharing with RAPDs was 48%. These results indicate that the two methods detect two types of DNA that differ in their degree of variability.     

Differential response of oilseed rape (Brassica napus L.) cultivars to low boron supply

Three experiments were carried out on an alluvial sandy loam (Udifluvent) at Tonglu, Zhejiang Province, P.R. China from 1992 to 1995, to determine the genotypic range in boron (B) efficiency of 16 oilseed rape (Brassica napus L.) cultivars, to identify the B-efficient cultivars and to identify specific responses which can be utilised for selection in a breeding program. The 16 cultivars which included high-quality and conventional types differed significantly in survival, plant height, leaf area, shoot dry weight and seed yield; however, the ranking of the cultivars for their seed yield or other plant traits differed with B treatment. With severe B deficiency (CaCl2 extractable B < 0.26 mg/kg) and no boron applied, none of the cultivars exhibited significant B efficiency, with seed yield <300 kg/ha. With moderate B deficiency (CaCl2 extractable B 0.34 mg/kg or 0.17 kg B/ha applied), seed yield varied significantly among the cultivars from 397 to 1889 kg/ha in year 1 and from 616 to 1260 kg/ha in year 3. Zhongyou 821 and 92-13 were the most B-efficient and Wanyou 324, Huashuang 2 and Su 2051 were the most B-inefficient cultivars under moderate B deficiency. Significant differences were found among the cultivars in leaf B concentration; however, there was no close relationship between leaf B concentration and seed yield responses to B of oilseed cultivars. Of all the growth parameters measured, leaf area was the early indicator best correlated with subsequent seed yield and may be useful for evaluating the response of cultivars to low B supply. Contrary to current opinion, it was also found that high-quality oilseed rape cultivars were not all sensitive to low B supply nor were all conventional cultivars B-efficient.     

Comparison of RAPD and RFLP genetic markers in determining genetic similarity among Brassica oleracea L. genotypes

Genetic similarity among 45 Brassica Oleracea genotypes was compared using two molecular markers, random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLPs). The genotypes included 37 broccolis (var. italica), five cauliflowers (var. botrytis) and three cabbages (var. capitata) which represented a wide range of commercially-available germplasm, and included open-pollinated cultivars, commercial hybrids, and inbred parents of hybrid cultivars. Fifty-six polymorphic RFLP bands and 181 polymorphic RAPD bands were generated using 15 random cDNA probes and 62 10-mer primers, respectively. The objectives were to compare RFLP and RAPD markers with regard to their (1) sampling variance, (2) rank correlations of genetic distance among sub-samples, and (3) inheritance. A bootstrap procedure was used to generate 200 random samples of size n (n=2,3,5,... 55) independently from the RAPD and RFLP data sets. The coefficient of variance (CV) was estimated for each sample. Pooled regressions of the coefficient of variance on bootstrap sample size indicated that the rate of decrease in CV with increasing sample size was the same for RFLPs and RAPDs. The rank correlation between the Nei-Li genetic similarity values for all pairs of genotypes (990) based on RFLP and RAPD data was 0.745. Differences were observed between the RFLP and RAPD dendrograms of the 45 genotypes. Overlap in the distributions of rank correlations between independent sub-samples from the RAPD data set, compared to correlations between RFLP and RAPD sub-samples, suggest that observed differences in estimation of genetic similarity between RAPDs and RFLPs is largely due to sampling error rather than due to DNA-based differences in how RAPDs and RFLPs reveal polymorphisms. A crossing algorithm was used to generate hypothetical banding patterns of hybrids based on the genotypes of the parents. The results of this study indicate that RAPDs provide a level of resolution equivalent to RFLPs for detemination of the genetic relationships among genotypes.     

Impact of intercropping aphid-resistant wheat cultivars withoilseed rape on wheat aphid (Sitobion avenae) and its natural enemies

The effects of intercropping of wheat cultivars and oilseed rape on the densities of wheat aphid, Sitobion avenae, and their arthropod natural enemies were evaluated. Three winter wheat cultivars with different resistant levels to S. avenae were used: ‘KOK’ (high resistance), ‘Xiaobaidongmai’ (low resistance) and ‘Hongmanghong’ (susceptible). The results showed that the densities of S. avenae were significantly higher on the monoculture pattern than on either the 8-2 intercropping pattern (eight rows of wheat with two rows of oilseed rape) or the 8-4 intercropping pattern (eight rows of wheat with four rows of oilseed rape). The mean number of predators and the mummy rates of S. avenae were significantly higher in two intercropping patterns than those in the monoculture pattern. The densities of S. avenae, ladybeetles, and mummy rate of S. avenae were significantly different among different wheat cultivars. The highest densities of S. avenae and ladybeetles were found on wheat cultivar Hongmanghong. The lowest densities of S. avenae associated with high mummy rate of S. avenae were found on wheat cultivar Xiaobaidongmai. The results showed that wheat-oilseed rape intercropping conserved more predators and parasitoids than in wheat monoculture fields, and partial resistance of wheat cultivar Xiaobaidongmai had complementary or even synergistic effects on parasitoid of S. avenae.     

Unraveling the efficiency of RAPD and SSR markers in diversity analysis and population structure estimation in common bean

Increase in food production viz-a-viz quality of food is important to feed the growing human population to attain food as well as nutritional security. The availability of diverse germplasm of any crop is an important genetic resource to mine the genes that may assist in attaining food as well as nutritional security. Here we used 15 RAPD and 23 SSR markers to elucidate diversity among 51 common bean genotypes mostly landraces collected from the Himalayan region of Jammu and Kashmir, India. We observed that both the markers are highly polymorphic. The discriminatory power of these markers was determined using various parameters like; percent polymorphism, PIC, resolving power and marker index. 15 RAPDs produced 171 polymorphic bands, while 23 SSRs produced 268 polymorphic bands. SSRs showed a higher PIC value (0.300) compared to RAPDs (0.243). Further the resolving power of SSRs was 5.241 compared to 3.86 for RAPDs. However, RAPDs showed a higher marker index (2.69) compared to SSRs (1.279) that may be attributed to their higher multiplex ratio. The dendrograms generated with hierarchical UPGMA cluster analysis grouped genotypes into two main clusters with various degrees of sub clustering within the cluster. Here we observed that both the marker systems showed comparable accuracy in grouping genotypes of common bean according to their area of cultivation. The model based STRUCTURE analysis using 15 RAPD and 23 SSR markers identified a population with 3 sub-populations which corresponds to distance based groupings. High level of genetic diversity was observed within the population. These findings have further implications in common bean breeding as well as conservation programs.     

PCR analysis of oilseed rape cultivars (Brassica napus L. ssp. oleifera) using 5′ -anchored simple sequence repeat (SSR) primers

Primers complementary to simple sequence repeats (SSRs) and with variable three-base anchors at their 5 end, were used in PCR analyses to compare pooled DNA samples from various Brassica napus and B. rapa cultivars. Amplification products were resolved on polyacrylamide gels and detected by silver-nitrate staining. The resulting banding patterns were highly repeatable between replicate PCRs. Two of the primers produced polymorphisms at 33 and 23 band positions, respectively, and could each discriminate 16 of the 20 cultivars studied. Combined use of both primers allowed all 20 cultivars to be distinguished. The UPGMA dendrogram, based on the cultivar banding profiles, demonstrated clustering on the basis of winter/spring growth habit, high/low glucosinolate content, and cultivar origin (i.e. the breeder involved). Intracultivar polymorphism was investigated using a minimum of ten individuals for each cultivar and was found to vary considerably between cultivars. It is concluded that anchored SSR-PCR analysis is a highly informative and reproducible method for fingerprinting oilseed rape populations, but that intra-cultivar variation should be investigated before using banding profiles from pooled samples for the identification of individuals.     

牛鞭草品种EST-SSR指纹图谱构建及遗传多样性分析

为探讨牛鞭草(Hemarthria spp.)品种间的遗传多样性,从86对EST-SSR引物中筛选出8对引物对牛鞭草属6个品种进行指纹图谱的构建及遗传多样性分析。结果表明,8对EST-SSR引物对牛鞭草属6个品种共扩增出193条清晰条带,多态性条带161条,多态性比例为83.4%。每条引物的多态信息含量(PIC)为0.480~0.695,平均为0.602。UPGMA聚类分析表明,牛鞭草属6个品种在相似系数为0.652处可分为两大类群。8对EST-SSR引物均能将6个品种完全区分开,以3对EST-SSR引物扩增的电泳图谱为基础,建立了牛鞭草属6个品种的指纹图谱标准模式图,每个品种都有唯一的指纹图谱。牛鞭草属6个品种的平均Nei’s基因多样性指数为0.333,平均Shannon信息指数为0.496,品种间的相似系数介于0.399~0.782之间。可见,牛鞭草属植物品种的遗传多样性较丰富,种间差异明显。