Genetic Diversity in Domestic and Introduced Wheats

A set of 33 wheat EST-SSR markers was designed and 18 from them were polymorphic and used for assessment of genetic diversity within 36 introduced genotypes of hexaploid bread wheat. Altogether 105 alleles were detected, in average 3.18 alleles per locus. Maximum number of alleles 14 was detected at the locus TDI389708. Five the most polymorphic markers were used for the evaluation and comparison of genetic variation within 46 domestic (Slovak) wheat genotypes and 36 introduced (foreign) wheat genotypes. The number of alleles per used primer pair within domestic genotypes varied from 7 to 19, with an average of 13.2 alleles, an average gene diversity 0.846 and PIC 0.980 per locus. The number of alleles per primer within introduced genotypes varied from 7 to 14, with an average of 10.8 alleles, an average gene diversity 0.780 and PIC 0.958 per locus. The level of polymorphism in EST- SSRs was sufficient for discrimination between genotypes and variation within domestic genotypes was slightly higher than in introduced genotypes. Variation revealed by 5 selected EST-SSR markers clustered genotypes according to origin. Domestic and introduced wheats were grouped distinctly into two separate groups.

Development of Microsatellite Markers from Crape Myrtle (Lagerstroemia L.)

Lagerstroemia L. (crape myrtle) is an economically important woody plant genus with several deciduous flowering ornamental species. A wide range of flower colors, long flowering periods, growth habits ranging from miniature to tree sizes, and exfoliating bark characteristics provide horticulturists and nursery growers with a great deal of interest in the breeding and genetics of this genus. We report microsatellite marker development from a GT-enriched genomic library of the interspecific hybrid ‘Natchez’ (L. indica L. × L. fauriei Koehne). Twelve of 43 novel microsatellite loci were characterized on a collection of 33 Lagerstroemia cultivars and accessions. Four to eight alleles per locus (mean = 5.6 alleles) were detected. Allelic richness ranged from 3.9 to 7.2 with a mean of 5.3. The level of polymorphism detected (average gene diversity of 0.68) indicates moderately high genetic diversity within the selections of crape myrtle cultivars and accessions. The examined markers also exhibited high cross-species transferability to L. fauriei, L. limii Merr., and L. subcostata Koehne.

Highly polymorphic microsatellite markers in Chamaecyparis obtusa

Nine microsatellite loci in hinoki, Chamaecyparis obtusa (Sieb. et Zucc.) Endl., were identified and characterized. A genomic library, developed using enrichment with magnetic beads, was screened to identify microsatellite repeats (CT/AG). The microsatellite loci, where the alleles were segregated, displayed codominant Mendelian inheritance. Genetic analysis of 16 plus trees and two unrelated individuals of Chamaecyparis obtusa revealed that all loci were highly polymorphic, with an average of 10.3 alleles per locus, and an average gene diversity of 0.77. The applicability of these microsatellite loci was also tested in other species of the Cupressaceae and in Cryptomeria japonica (L.f.) D. Don (Taxodiaceae, a family closely related to Cupressaceae). Polymerase chain reaction (PCR) amplification was successful for about half of the loci of the species in the genus Chamaecyparis. However, the PCR amplification patterns of the 11 species of Cupressaceae showed no clear correlations with their molecular phylogeny. The highly polymorphic microsatellite loci in Chamaecyparis obtusa, identified here, will be useful in studies of hinoki breeding and population genetics.

Genetic diversity between Italian and Greek buffalo populations

SummaryThe present study is a first step of a global project aiming at the estimation of the genetic distances and relationships among buffalo breeds and sub-populations and the investigation of the production potential and adaptability of different buffalo genotypes in various environments.Genetic diversity of Italian and Greek buffalo populations was estimated on the basis of allele frequencies at nine polymorphic microsatellite loci: CSSM43, CSSM38, DRB3, D21S4, CYP21, CSSM47, CSSM60, CSSM36 and CSSM33. The number of detected alleles per locus varied from two (D21S4) to thirteen (CSSM47). Allele frequency distribution was similar in the two populations, which have the same alleles at the highest frequency at all loci, except loci CSSM47 and CSSM60. Average gene diversity over all loci was 0.60. Across-loci average gene diversity increased with the number of alleles. Observed average heterozygosity was 0.167 and 0.177 in the Italian and Greek populations, respectively. The degree of differentiation between Italian and Greek buffalo was moderate and estimated at 0.021 ± 0.009.

Randomly Amplified Polymorphic DNA (RAPD) Variation among and within Artichoke (Cynara scolymus L.) Cultivars and Breeding Populations

The magnitude of genetic differences among and heterogeneity within globe artichoke cultivars is unknown. Variation among individual heads (capitula) from three artichoke cultivars and two breeding populations were evaluated using RAPD markers. One vegetatively propagated cultivar (`Green Globe'), two seed-propagated cultivars (`Imperial Star' and `Big Heart') and two breeding populations were examined. Two to thirteen polymorphic bands were observed for 27 RAPD primers, which resulted in 178 scored bands. Variation was found within and among all cultivars, and breeding populations indicating that all five groups represent heterogeneous populations with respect to RAPD markers. The genetic relationships among individual genotypes were estimated using the ratio of discordant bands to total bands scored. Multidimensional scaling of the relationship matrix showed five independent clusters corresponding to the three cultivars and two breeding populations. The integrity of the five clusters was confirmed using pooled chi-squares for fragment homogeneity. Average gene diversity (Hs) was calculated for each population sample, and a one-way analysis of variance showed significant differences among populations. `Big Heart' had an Hs value equivalent to the two breeding populations, while clonally propagated `Green Globe' and seed propagated `Imperial Star' had the lowest Hs values. The RAPD heterogeneity observed within clonally propagated `Green Globe' is consistent with phenotypic variability observed for this cultivar. Overall, the results demonstrate the utility of the RAPD technique for evaluating genetic relationships and contrasting levels of genetic diversity among populations of artichoke genotypes.

Assessment of inter- and intra-inbred line variability in sunflower (Helianthus annuus) by RFLPs

The restriction fragment length polymorphism (RFLP) between 26 sunflower inbred lines was evaluated with 81 probe–enzyme combinations involving 51 cDNA clones and 4 restriction enzymes (HindIII, EcoRI, EcoRV, and BglII). An average of 4.6 fragments and 4.9 profiles was detected per probe–enzyme combination, across all inbred lines. The RFLPs revealed were characterized by a high percentage (>70%) of multifragment profiles. Nei's average gene diversity was calculated to measure the genetic variability within cultivated sunflower; the average gene diversity computed with 81 probe–enzyme combinations was 0.59. The relationships between the 26 sunflower inbred lines were analysed by estimates of Nei's F index, which ranged from 0.50 to 0.91, as well as Nei's genetic distance, d, which varied from 0.05 to 0.41. A UPGMA (unweighted pair-group arithmetic average clustering) dendrogram was constructed using the genetic distance matrix; likewise, a principal component analysis was performed using the F matrix. The results obtained from the two clustering analyses allowed the separation of maintainer lines (females) from restorer lines (males). After partitioning the 26 lines into a pool of maintainer lines and a pool of restorer lines, the estimation of gene differentiations showed that the absolute difference (Dm) between females and males was only about 5%. Intraline variability was also examined in 4 sunflower inbred lines, using 30 probe–enzyme combinations. Heterogeneity at varying levels was detected in 3 of the 4 lines studied. The RFLPs detected by this set of selected clones in the 26 inbred lines suggests that RFLPs could be very useful descriptors for sunflower inbred line and variety studies.Key words: RFLPs, sunflower, inbred lines, genetic diversity.