Characterization of Some Italian Common Bean (<Emphasis Type="Italic">Phaseolus Vulgaris</Emphasis> L.) Landraces by RAPD,Semi-random and ISSR Molecular Markers

Randomly amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR) and a semi-random PCR system were used to analyze the genetic diversity of 16 Italian common bean landraces and their relationship to four commercial cultivars. Of the primers tested, 8 ISSR, 6 RAPD and 7 semi-random primers produced polymorphic and reproducible DNA fragments. A higher proportion of polymorphic bands were observed using ISSR (85%) and semi-random (90%) primers than RAPD (69%) method. The combination of any two semi-random markers allowed the identification of all 20 bean genotypes. In contrast ISSR (except for primer (CAC)₃GC) and RAPD markers appeared to be less informative as more than two markers were necessary to achieve the same diagnostic level. Moreover, 7 ISSR, 2 RAPD and 8 semi-random exclusive bands were identified as putative population-specific markers. Semi-random and ISSR derived dendrograms showed similar tendencies in terms of genetic relatedness, whereas clustering of genotypes within groups was not similar when compared with the RAPD technique. Despite the different ability to resolve genetic variation among the investigated landraces, two major clusters with less than 60% (ISSR) and 40% (RAPD and semi-random) genetic similarity were formed with all three marker systems. The two groups were correlated with the phaseolin patterns and seed size of the landraces. The analysis showed that the cultivar ȁ8Lingua di Fuocoȁ9 and most of the landraces (13 out of 16) collected in Italy belong to the Andean gene pool, whereas only the three populations from Pratomagno belong to the Middle American gene pool.     

Genetic diversity assessment of <Emphasis Type="Italic">Gymnema sylvestre</Emphasis> (Retz.) R. Br. ex Sm. populations from Western Ghats of Maharashtra,India

Gymnema sylvestre (Retz.) R. Br. ex Sm., a rich source with gymnemic acid, has been used to treat diabetes since past 2000 years. In the current investigation, nomenclature, geographical distribution as well as morphological and genetic diversity of 22 G. sylvestre populations spread across of Western Ghats of Maharashtra has been reported. The genetic variability has been assessed using RAPD and ISSR molecular markers. The populations recorded high level of gene differentiation (G_ST = 0.41 based on ISSR) and gene flow (Nm = 0.92 based on RAPD). The high level of gene differentiation among the populations attributed to entomophilous pollination, wind seed dispersal, out crossing and anthropogenic activities.     

RAPD and ISSR fingerprinting in cultivated chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) and its wild progenitor <Emphasis Type="Italic">Cicer reticulatum</Emphasis> Ladizinsky

Detection of genetic relationships between 19 chickpea cultivars and five accessions of its wild progenitor Cicer reticulatum Ladizinsky were investigated by using RAPD and ISSR markers. On an average, six bands per primer were observed in RAPD analysis and 11 bands per primer in ISSR analysis. In RAPD, the wild accessions shared 77.8% polymorphic bands with chickpea cultivars, whereas they shared 79.6% polymorphic bands in ISSR analysis. In RAPD analysis 51.7% and 50.5% polymorphic bands were observed among wild accessions and chickpea cultivars, respectively. Similarly, 65.63% and 56.25% polymorphic bands were found in ISSR analysis. The dendrogram developed by pooling the data of RAPD and ISSR analysis revealed that the wild accessions and the ICCV lines showed similar pattern with the dendrogram of RAPD analysis. The ISSR analysis clearly indicated that even with six polymorphic primers, reliable estimation of genetic diversity could be obtained, while nearly 30 primers are required for RAPD. Moreover, RAPD can cause genotyping errors due to competition in the amplification of all RAPD fragments. The markers generated by ISSR and RAPD assays can provide practical information for the management of genetic resources. For the selection of good parental material in breeding programs the genetic data produced through ISSR can be used to correlate with the relationship measures based on pedigree data and morphological traits to minimize the individual inaccuracies in chickpea.     

Relationships among different geographical groups,agro-morphology,fatty acid composition and RAPD marker diversity in Safflower (<Emphasis Type="Italic">Carthamus tinctorius</Emphasis>)

Patterns of geographical diversity, and the relationship between agro-morphological traits and fatty acid composition were assessed for 193 safflower (Carthamus tinctorius) accessions representing forty countries. Accessions were assigned to eight groups based on geographical proximity. Cluster and Principal Component analyses were performed to assess patterns of diversity among the accessions and to select the most distant accessions from each of eight groups for analysis of randomly amplified polymorphic DNA (RAPD) markers. There was a large amount of diversity for agro-morphological traits, fatty acid composition, and RAPD markers. Most correlations among different traits were rather low. Plant height showed a positive correlation with days to flowering (r = 0.63**). Palmitic acid was positively correlated with stearic acid and oleic acid values, and negatively correlated with linoleic acid (P < 0.01). Oleic acid and linoleic acid showed a strong negative correlation (r = −0.89**). The first three principal components together explained 59% of the variation, however, neither principal component analysis (PCA) nor marker analysis revealed a clear relationship between diversity pattern and geographical origin. Accessions from some geographical regions tended to group together, such as accessions from South Western Asia, Central Western Europe, and the Mediterranean region. The correlation between the morphological matrix and the genetic matrix based on RAPD markers was not significant (r = 0.027). Wide diversity in safflower germplasm indicates a considerable potential for improving this crop for both agronomic and quality traits.     

RAPD and ISSR molecular markers in <Emphasis Type="Italic">Olea europaea</Emphasis> L.: Genetic variability and molecular cultivar identification

Thirty Portuguese and eight foreign olive (Olea europaea L.) cultivars were screened using Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Repeat (ISSR) markers. Twenty RAPD primers amplified 301 reproducible bands of which 262 were polymorphic; and 17 ISSR primers amplified 204 bands of which 180 were polymorphic. The percentage of polymorphic bands detected by ISSR and RAPD was similar (88 and 87%, respectively). The genetic variability observed was similar in the Portuguese and foreign olive cultivars. Seven ISSR and 12 RAPD primers were able to distinguish individually all 38 olive cultivars. Twenty specific molecular markers are now available to be converted into Sequence Characterised Amplified Region (SCAR) markers. Relationships among Portuguese and foreign cultivars is discussed.     

Microsatellites based marker molecular analysis of Ghanaian bambara groundnut (Vigna subterranea (L.) Verdc.) landraces alongside morphological characterization

Bambara groundnut an indigenous crop of African origin is drought tolerant and the third most important leguminous crop in Ghana and Sub-Saharan Africa. In order to assess the level of genetic diversity within a small collection of Ghanaian landraces, molecular analysis was performed using microsatellite markers alongside characterization of morphological features. Genetic distance based on Jaccard’s similarity coefficient from the SSR marker analysis ranged from 0.48 to 0.9 among the landraces. 80 individual genotypes were clustered into 17 units with substantial levels of inter- and intra-landrace polymorphism. The analyses of variance from the morphological characterization for all quantitative traits were statistically significant (p < 0.05) except for terminal leaflet width. The first 4 principal components accounted for 41.97, 20.15, 13.39 and 9.81 % respectively of the morphological variations among the landraces. Qualitative traits however accounted for less of these variations. The results of the present study support the availability of high level of polymorphism within the collection of bambara groundnut analysed. This report is useful to crop improvement and germplasm conservation of bambara groundnut in Ghana.     

Genetic diversity of Cucurbita maxima assessed using morphological characteristics and random-amplified polymorphic DNA markers in China

Cucurbita maxima is one of the most widely cultivated Cucurbitaceae in Heilongjiang province, China. The objectives of this study were to clarify the genetic diversity of 44 accessions from different geographical origins using morphological and molecular characteristics and to compare the consistency of these morphological and molecular characteristics. Morphological characteristics showed a large qualitative variability primarily according to fruit-related traits. Twenty-eight random-amplified polymorphic DNA (RAPD) markers produced 128 bands. Both morphological characteristics and RAPD markers grouped 44 accessions of C. maxima into four clusters, and the similarity coefficients ranged from 0.70 to 0.91 and from 0.40 to 0.98, respectively. DNA polymorphisms were highly consistent with phenotypic traits on rootstock C. maxima. The relationships between C. maxima from different origins were not clearly defined via morphological characteristics and RAPD analysis, suggesting some traits of C. maxima were specific to geographical location had disappeared or were weak in Heilongjiang province, which would not facilitate pumpkin breeding. Hybrid generations and their parent plants or sister lines were grouped into sub-clusters and showed little genetic distance according to both evaluation methods. Overall, morphological characteristics and RAPD markers were consistent and revealed high genetic diversity between C. maxima landraces from different origins.     

A study of genetic diversity of sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) in Vietnam and Cambodia estimated by RAPD markers

Sesame (Sesamum indicum L.) is a traditional oil crop cultivated throughout South East Asia. To estimate the genetic diversity of this crop in parts at the region, 22 sesame accessions collected in Vietnam and Cambodia were analyzed using 10 RAPD markers. The 10 primers generated 107 amplification products of which 88 were polymorphic fragments (83%). Genetic diversity of all populations was H_t = 0.34 when estimated by Nei’s genetic diversity and species diversity was H′_sp = 0.513 when estimated by Shannon diversity index. Genetic distance ranged from 0.03 to 0.43, with a mean genetic distance of 0.23. The unweighted pair group method with arithmetic averages (UPGMA) cluster analysis for the 22 accessions divided the material in four groups. The dendrogram revealed a clear division among the sesame accessions based on their geographical region. Interestingly, some geographically distant accessions clustered in the same group, which might indicate the human factor involved in the spreading of sesame varieties. The high level of polymorphism shown suggests that RAPD techniques can also be useful for the selection of parents in sesame (Sesamum indicum L.) breeding program and for cultivar differentiation.     

Analysis of genetic diversity among European and Asian fig varieties (<Emphasis Type="Italic">Ficus carica</Emphasis> L.) using ISSR,RAPD, and SSR markers

Nineteen fig varieties and lines from Europe and Asia have been fingerprinted by ISSR, RAPD, and SSR markers, respectively, using 13, 19, and 13 primer combinations. All primers produced 258 loci, with the highest number of loci (119) generated by RAPD (R _p: 48.42). Clustering analysis was applied to the three marker datasets to elucidate the genetic structure and relationships among these varieties. Mean genetic similarities were 0.787, 0.717, and 0.749, respectively, as determined using ISSR, RAPD, and SSR. Each marker system produced incompletely separated clusters, although a weak binding group based on race type appeared in the combined dataset. Comparisons of coefficients revealed no correlation between different similarity matrices; congruence was observed between similarity matrices and co-phenetic matrices in all markers. Analysis of molecular variance (AMOVA) showed that most of the total polymorphism was attributable to within-group variance (ISSRs + RAPDs, 97.41%; SSRs, 90.18%). These results suggest that the genetic diversity of this fig population is low and that multiple marker utilization is critical to estimate the relatedness of figs at the variety level. Additionally, it was presumed that ‘Houraihi’, the oldest variety in Japan, was disseminated independently of other foreign varieties in the 17th century or before then.     

The genetic characterization of Turkish watermelon (<Emphasis Type="Italic">Citrullus lanatus</Emphasis>) accessions using RAPD markers

Genetic diversity of the Turkish watermelon genetic resources was evaluated using different Citrullus species, wild relatives, foreign landraces, open pollinated (OP) and commercial hybrid cultivars by RAPD markers. The germplasm was consisted of 303 accessions collected from various geographical regions. Twenty-two of 35 RAPD primers generated a total of 241 reproducible bands, 146 (60.6%) of which were polymorphic. Based on the RAPD data the genetic similarity coefficients were calculated and the dendrogram was constructed using UPGMA (Unweighted pair-group method with arithmetic average). Cluster analysis of the 303 accessions employing RAPD data resulted in a multi-branched dendrogram indicating that most of the Turkish accessions belonging to var. lanatus of Citrullus lanatus (Thunb.) Matsum et Nakai were grouped together. Accessions of different Citrullus species and Praecitrullus fistulosus (Stocks) Pangalo formed distant clusters from C. lanatus var. lanatus. Among 303 accessions, a subset of 56 accessions was selected representing different groups and a second dendrogram was constructed. The genetic similarity coefficients (GS) within the Turkish accessions were ranged from 0.76 to 1.00 with 0.94 average indicating that they are closely related. Taken together, our results indicated that low genetic variability exist among the watermelon genetic resources collected from Turkey contrary to their remarkable phenotypic diversity.     

Total phenolic content,RAPDs, AFLPs and morphological traits for the analysis of variability in <Emphasis Type="Italic">Smallanthus sonchifolius</Emphasis>

Smallanthus sonchifolius is a periennal herb originally cultivated in South America and now grown in several other countries. Recently, greater attention has been focused on this plant due to its agronomical, nutritional and pharmacological characteristics. In this paper the application of RAPDs and AFLPs for the analysis of genetic diversity in a group of 5 Smallanthus sonchifolius landraces is presented. Both methods proceed through the direct analysis of DNA, and their results were compared with the total phenolic content of each landrace and its morphological traits. Using 61 RAPD primers, 85 informative bands were identified, corresponding to 28.7% of polymorphism. In comparison, only six selected AFLP primer pairs produced 84 informative bands, with a similar percentage of polymorphism (23.4%). RAPD and AFLP markers were analyzed separately. Total phenolic content varied twofold among the five landraces analysed, ranging from 3,494 to 6,849 mg/g. Each type of molecular marker resolved two main groups that included the same genotypes, but with different within-group relationships among genotypes. The two groups are consistent with some phenotypic characters but they do not reflect faithfully their geographical origin. Most notably, the two groups comprise landraces with higher and lower total phenolic content, respectively. Dendrograms based on the two molecular data sets graphically depicted the ability of both methods to differentiate all the cultivars studied. Data obtained suggest that the two molecular markers applied are useful to investigate intra-specific genetic variability in Smallanthus sonchifolius, and predict well the total phenolic content of each landrace.     

Analysis of genetic diversity in Piper nigrum L. using RAPD markers

RAPD analysis was conducted in 22 cultivars of P. nigrum(black pepper) from South India and one accession each of P. longum and P. colubrinum. Twenty-four primers generated 372 RAPD markers of which 367 were polymorphic. Jaccard's similarity between pairs of accessions ranged between 0.11 and 0.66 with a mean of 0.38. Among P. nigrum cultivars, the similarity ranged between 0.20 and 0.66 and the mean was 0.42. The existence of wide genetic diversity as revealed in the present study is supported by earlier reports of extensive inter- and intrapopulation morphological variability in pepper cultivars from South India. UPGMA dendrogram and PCO plot revealed P. colubrinum to be most distant of the three species. Genetic proximity among P. nigrum cultivars could be related to their phenotypic similarities or geographical distribution. Greater divergence was observed among landraces than among advanced cultivars. Landraces grown in southern parts of coastal India and those grown in more northern parts were grouped in separate clusters of the dendrogram.     

Genetic diversity and differentiation in Chinese sour cherry <Emphasis Type="Italic">Prunus pseudocerasus</Emphasis> Lindl., and its implications for conservation

In this study, the genetic diversity and differentiation of 10 natural Prunus pseudocerasus Lindl. populations were investigated using inter-simple sequence repeat (ISSR) markers. Totally, 18 selected primers generated 150 loci, with an average of 8.33 bands per primer. The results showed that the percentage of polymorphic bands (PPB) was pretty low at the population level (PPB = 1.13–32%), but relatively high at the species level (PPB = 84%). Besides, a high level of genetic differentiation among populations was detected based on the gene differentiation coefficient (G _ST = 0.7118) and the hierarchical analysis of molecular variance (AMOVA) (Φ _ST = 64.53%, P < 0.001), in line with the low inter-population gene flow (N _m = 0.2025). Moreover, Mantel test revealed a significant correlation between genetic and geographic distances among the populations (r = 0.5272, P < 0.005). The high level of intraspecific genetic diversity was probably related with its life history traits, while its small population size and the resultant high levels of genetic drift and inbreeding might explain the low genetic diversity within populations. The relatively high inter-population genetic differentiation was largely attributed to its small population size, habitat fragmentation, the mode of pollen and seed dispersal, and geographic isolation. Based on the present study, conservation strategies were proposed to preserve this valuable natural germplasm resource.     

Genetic diversity in bambara groundnut (Vigna subterranea (L.) Verdc) landraces assessed by Random Amplified Polymorphic DNA (RAPD) markers

Genetic diversity in 12 landraces of bambara groundnut (Vigna subterranea), an indigenous African legume, was evaluated using Random Amplified Polymorphic DNA (RAPD) markers. DNA from individuals of each landrace was also analysed to determine the level of heterogeneity within landraces. RAPDs revealed high levels of polymorphism among landraces. The percentage polymorphism ranged from 63.2% to 88.2% with an average of 73.1% for the 16 RAPD primers evaluated. The construction of genetic relationships using cluster analysis groups the 12 landraces in two clusters. RAPDs are useful for the genetic diversity studies in V. subterranea and can identify variation within landraces.     

RAPD Polymorphism of the White-Flowered Gourd (Lagenaria siceraria (Molina) Standl. Landraces and its Wild Relatives in Kenya

The present study was performed to investigate genetic diversity of Kenyan landraces of the white-flowered gourd (Lagenaria siceraria), which exhibits tremendous morphological variation. RAPD analyses were performed on 53 landraces of the cultivated species L. siceraria and 42 accessions of three wild species (40 L. sphaerica, 1 L. abyssinica, and 1 L. breviflora). A total of 432 polymorphic bands were detected using 54 primers. The four species were clearly differentiated from one another. Intra-specific variations were investigated with L. siceraria and its wild relative L. sphaerica. Landraces of the cultivated species collected from different ethnic communities or regions were differentiated. Morphological variations were not associated with RAPD variations. Bitter landraces collected in Maasai communities showed two specific RAPD bands. In the wild species, accessions collected from the eastern and western sides of the Great Rift Valley were genetically differentiated from each other. In both species, genetic and geographical distance matrices computed among all pairs of accessions were significantly correlated, implying that the observed geographical variation can be explained by the 'Isolation by distance model'. Progeny plants derived from a common mother in L. siceraria showed a low level of segregation in RAPD pattern, suggesting that collected landraces are cultivated, maintaining their inherent traits although they are monoecious and insect-pollinated, whereas the wild relative L. sphaerica showed a higher level of segregation. The morphological diversity observed among landraces of L. siceraria is the result of human selection and their genetic identities are maintained by inbreeding probably resulting from frequent self-pollination.     

Genetic erosion and in situ conservation of Lima bean (Phaseolus lunatus L.) landraces in its Mesoamerican diversity center

Lima bean (Phaseolus lunatus L.) is an important crop in traditional Mayan agriculture of the Yucatan Peninsula, Mexico, its Mesoamerican center of diversity. Genetic erosion in this species is currently a threat in this region out of 3 of 21 landraces dominate 71.24% of the cultivated area, and 12 are rare landraces grown only in 6.29%. Using 90 ISSR loci, we estimated the diversity and genetic relationships for 21 landraces to analyzing their risk of genetic erosion, and generate data for their in situ conservation. Total genetic diversity was high (h = 0.29), however it was lower than wild gene pool reported (h = 0.69). The abundant landraces had genetic diversity values lower (h = 0.13, I = 0.17) than the common (h = 0.26, I = 0.33) and rare landraces (h = 0.24, I = 0.27). However, the rare landraces are in a higher risk of genetic erosion due to local extinction. The cluster analysis showed no groups corresponding to morpho-phenological characteristics, geographic origin or traditional classification, which resulted from high inter-landraces gene flow levels. The molecular data confirmed that the domesticated Lima bean pool of the Yucatan Peninsula has a high risk of genetic erosion. If current tendencies in landrace cultivation continue, many will no longer be planted within two to three generations, with a consequent loss of their alleles. Programs urgently need to be established for in situ conservation of Lima bean landraces in this region.     

Genetic variation in the endangered Rutaceae species <Emphasis Type="Italic">Citrus hongheensis</Emphasis> based on ISSR fingerprinting

Citrus hongheensis is a critically endangered species endemic to the Honghe river region in southeastern Yunnan, China. Its genetic diversity and differentiation were investigated using Inter-Simple Sequence Repeat (ISSR) markers. One hundred primers were screened, and a total of 245 loci were amplified from seven natural populations by 13 informative and reliable primers. Of these 245 ISSR loci, 233 were polymorphic and the detected variations revealed a relatively high level of intraspecific genetic diversity. At the population level, the mean percentage of polymorphic loci (PPB) was 36.50%, while the average expected heterozygosity (He) and Shannon diversity index (Ho) were 0.1327 and 0.1972, respectively. At the species level (across all populations), PPB was 95.10%, while He and Ho were 0.3520 and 0.5195, respectively. A high Gst value (0.6247) indicated that there is significant differentiation among populations, which was confirmed by AMOVA analysis (Φst = 0.6420). Pairwise genetic identity (I) values among populations ranged from 0.6341 to 0.7675, with a mean of 0.7008. We propose that the high level of genetic differentiation may be the result of habitat fragmentation and limited gene flow (Nm = 0.1502). For effective in situ conservation and population restoration of C. hongheensis it will be important to maintain historical processes, including high outbreeding rates, sufficient gene flow, and large effective population sizes.     

Study of clonally propagated cassumunar ginger (<Emphasis Type="Italic">Zingiber montanum</Emphasis> (Koenig) Link ex Dietr.) and its relation of wild <Emphasis Type="Italic">Zingiber</Emphasis> species from Thailand revealed by RAPD markers

The genetic relatedness among 51 accessions, 14 species of the genus Zingiber and genetic variability of a clonally propagated species, Zingiber montanum (Koenig) Link ex Dietr., from Thailand were studied using random amplified polymorphic DNA (RAPD) profiles. Twenty-nine random primers gave reproducible amplification banding patterns of 607 polymorphic bands out of 611 scored bands accounting for 99.40% polymorphism across the genotypes. Jaccard’s coefficient of similarity varied from 0.119 to 0.970, indicative of distant genetic relatedness among the genotype studied. UPGMA clustering indicated eight distinct clusters of Zingiber, with a high cophenetic correlation (r = 1.00) value. Genetic variability in Z. montanum was exhibited by the collections from six regions of Thailand. High molecular variance (87%) within collection regions of Z. montanum accessions was displayed by AMOVA and also explained the significant divergence among the sample from six collection regions. Our results indicate that RAPD technique is useful for detecting the genetic relatedness within and among species of Zingiber and that high diversity exists in the clonally propagated species, Z. montanum.     

Inter Simple Sequence Repeat (ISSR) Analysis of Diploid Coffee Species and Cultivated Coffea arabica L. from Tanzania

Inter simple sequence repeat (ISSR) markers were used to evaluate levels of genetic similarity among Coffea arabica L. accessions from Tanzania and to estimate levels of genetic similarities in C. arabica and diploid coffee species. The six ISSR primers used generated a total of 82 fragments and the dissimilarity values ranged from 0.21 to 1. Mean dissimilarity values between provenances (0.56–0.85) were higher than within provenances (0.37–0.68). Cluster analysis based on Nei’s genetic distances showed C. arabica provenances grouping based on geographical origin. Two major clusters were formed that constituted of provenances from Kilimanjaro and Arusha in one sub-cluster; Tanga and Morogoro in the other; the second cluster had Mbeya provenances and diploid species, respectively. The implication is that Mbeya provenances are different from the rest of Tanzanian C. arabica. A principal coordinate analysis (PCA), whose first three coordinates explained 43% of the variation, showed similar groupings as in the cluster analysis. A separate cluster analysis of diploid species showed a distinct separation of the three species used. ISSR data gave results similar to previous findings from random amplified polymorphic DNA(RAPD) analysis. The results also confirm the limited diversity present in cultivated C. arabica in Tanzania