Genetic diversity and relationship between wild and cultivated cowpea [Vigna unguiculata (L.) Walp.] as assessed by allozyme markers

In Cameroon, cowpea plays an important role in traditional agroecosystems. Genetic variation in wild and cultivated cowpea in Cameroon has not yet been documented. Allozyme markers because of their codominance and polymorphism are useful tools for studying genetic variation and disparity in plant species. The present study was undertaken to elucidate the relationship between wild and cultivated cowpea from Cameroon. Ten enzyme systems encoding nineteen isozyme loci were used on 62 cowpea germplasm (45 wild and 17 cultivated). A total of thirty-two alleles were found. One allele was only found in cultivated samples (Enp98 ). Eight alleles were specific only to wild plant (Amp2 98 , Amp3a 103 , Amp4 96 , Fdh104 , Idh2 95 , Pgi3 92 , Pgm2 95 and Sdh95 ). Twenty-three alleles were common to both wild and cultivated accessions. Amp2 10 2 (z = −4.633, p < 0.001) and Fle3 96 (z = −2.858, p < 0.010) were significantly more represented in cultivated compared to wild cowpea forms. The mean number of alleles per locus in wild (1.632 alleles/locus) cowpea were significantly higher (t = 2.805, p < 0.010) compared to cultivated (1.263 alleles/locus) cowpea. Also, the proportion of polymorphic loci (P = 52.63%) and average Nei’s genetic diversity (He = 0.126) were important in wild, compared to the cultivated plants: P = 26.31% and He = 0.063, respectively. The low level of diversity found in domesticated accessions compared to wild can be attributed to a major genetic bottleneck that probably happened during the domestication process. Cluster analysis revealed by UPGMA dendrogram separated the 62 accessions into three clusters. Although an admixture of both wild and cultivated accessions within the same cluster were found, the dendogram, however, highlighted a visible separation between wild and cultivated cowpea. Wild cowpea with many more private alleles indicates an untouched resource available for future breeding.

The consensus rye microsatellite map with EST-SSRs transferred from wheat

Microsatellite (SSR) markers with known precise intrachromosomal locations are widely used for mapping genes in rye and for the investigation of wheat-rye translocation lines and triticale highly demanded for mapping economically important genes and QTL-analysis. One of the sources of novel SSR markers in rye are microsatellites transferable from the wheat genome. Broadening the list of available SSRs in rye mapped to chromosomes is still needed, since some rye chromosome maps still have just a few microsatellite loci mapped. The goal of the current study was to integrate wheat EST-SSRs into the existing rye genetic maps and to construct a consensus rye microsatellite map. Four rye mapping populations (P87/P105, N6/N2, N7/N2 and N7/N6) were tested with CFE (EST-SSRs) primers. A total of 23 Xcfe loci were mapped on rye chromosomes: Xcfe023, -136 and -266 on chromosome 1R, Xcfe006, -067, -175 and -187 on 2R, Xcfe029 and -282 on 3R, Xcfe004, -100, -152, -224 and -260 on 4R, Xcfe037, -208 and -270 on 5R, Xcfe124, -159 and -277 on 6R, Xcfe010, -143 and -228 on 7R. With the exception of Xcfe159 and Xcfe224, all the Xcfe loci mapped were found in orthologous positions considering multiple evolutionary translocations in the rye genome relative to those of common wheat. The consensus map was constructed using mapping data from the four bi-parental populations. It contains a total of 123 microsatellites, 12 SNPs, 118 RFLPs and 2 isozyme loci.

Analysis of genetic diversity in oilseed brassica germplasm through ISSR markers and isozyme profiling

Eleven Brassica germplasm were characterized through the application of 12 oligonucleotide Inter Simple Sequence Repeat (ISSR) primers. A total 1248 bands were amplified through polymorphic chain reaction and were visualized by agarose gel electrophoresis. Among the amplified marker bands 71.47% were polymorphic in nature and 352 bands were found to be monomorphic. The polymorphic bands of the amplified DNAs mostly ranged between 110 bp and 3 kb. Genetic distance among the germplasm ranged between 0.0468 and 0.7189. Moreover, three isozyme systems such as esterase, acid phosphatase and peroxidase were analyzed for allozyme variability that detected distinct 93 isozyme loci of which nearly 61.9% were polymorphic. Two dendrograms were constructed based on the ISSR profiling and isozyme data obtained through electrophoresis to find out the relatedness and phylogenetic relationship among the investigating Brassica germplasm. The clusters of the phylogenetic tree revealed 4 distinct groups of Brassica based upon their ISSR banding patterns and isozyme analysis. Nei’s genetic distance analysis provided strong information about the existence of variability among the germplasm of Brassica. All the germplasm was found to be clustered according to their respective species. Brassica carinata (Ethiopian mustard) showed individuality from all the germplasm studied and made a different branch in the phylogenetic tree suggesting its diverse origin. From the clustering pattern and genetic relationship obtained with ISSR markers and isozyme analysis, breeders can successfully identify the diverse germplasm from different cluster and use them in their future breeding program.

Genetic studies revealed differences between European and North American populations of Calypogeia azurea

Calypogeia azurea, a widespread, subboreal-montane liverwort species, is one of a few representatives of the Calypogeia genus that are characterized by the occurrence of blue oil bodies. The aim of the study was to investigate the genetic variation and population structure of C. azurea originating from different parts of its distribution range (Europe and North America). Plants of C. azurea were compared with C. peruviana, another Calypogeia species with blue oil bodies. In general, 339 gametophytes from 15 populations of C. azurea were examined. Total gene diversity (HT) estimated on the basis of nine isozyme loci of C. azurea at the species level was 0.201. The mean Nei’s genetic distance between European populations was equal to 0.083, whereas the mean genetic distance between populations originating from Europe and North America was 0.413. The analysis of molecular variance (AMOVA) showed that 69% of C. azurea genetic variation was distributed among regions (Europe and North America), 15% - among populations within regions, and 16% - within populations. Our study revealed that C. azurea showed genetic diversity within its geographic distribution. All examined samples classified as C. azurea differed in respect of isozyme patterns from C. peruviana.

DIVERSITY AND GENETIC STRUCTURE OF NATURAL POPULATIONS OF ARAÇÁ (Psidium guineense Sw.)

ABSTRAT: Psidium guineense Sw, popularly known as araçá, is a fruit tree there is widely distributed in Brazil and belongs to the Myrtaceae family. In northeastern Brazil, araçá occurs along coast and in the Zona da Mata; its fruit looks like guava but is more acidic and has a stronger smell. There is a little information about this species, which increases the difficulty of conserving its genetic resources and exploiting araçá as an economic resource. The objective of this research was the evaluation of the genetic diversity and genetic structure of P. guineense from Pernambuco's Zona da Mata. One hundred and fourteen individuals and 18 isozyme loci were evaluated, showing 28 alleles. The percentage of polymorphic loci () and the average number of alleles per locus () were 0.5 and 1.5, respectively, in this population. The expected heterozygosity, which corresponds to the genetic diversity, ranged from 0.22 to 0.23, a high value when considering that isozymes mark access from the functional genome. The differentiation index among the population was () = 0.015; therefore, the populations were not different among the sampled places. The inbreeding values () ranged from -0.549 to -0.794, indicating an absence of inbreeding and a greater-than-expected heterozygosity in all the studied populations. The estimated gene flow (Nm) for a pair of this population ranged from 3.23 to 20.77, sufficient to avoid genetic differentiation among the population and in accordance with the values of genetic divergence found in this study.

Genetic and ecological differences between two Utah endemics: US federally threatened Townsendia aprica and its close congener, T. jonesii var. lutea (Asteraceae)

We used genetic data from isozymes, along with soil analysis and ecological niche models to characterize two rare, morphologically similar Utah endemic Townsendias (Asteraceae). Townsendia aprica Welsh & Reveal and Townsendia jonesii (Beaman) Reveal var. lutea S.L. Welsh are herbaceous perennials endemic to adjacent areas of the Colorado Plateau region in southern Utah. Both are rare (T. aprica is listed as threatened under the Endangered Species Act, USA), and the validity of recognizing them as separate has been questioned. Populations of both taxa were scored for nine informative isozyme loci. High levels of genetic variation were found in each, with little variation among populations within taxa and low but significant divergence estimated between the taxa (FST = 0.119). Neighbor-joining analysis revealed two moderately supported clusters of populations corresponding to the two taxa. Characteristics of the soils on which the two taxa occur differed significantly in percentage sand (higher for T. aprica), percentage clay, and CaCO3 (both higher for T. jonesii var. lutea). Furthermore, ecological niche modeling using 19 climatic variables suggests that the two taxa occupy distinct niches. Taken together, these results support recognition of the two taxa as distinct, and suggest that they are equally imperiled based on their genetic and ecological features.

PCR-based molecular markers for identification of taxa from the Calypogeia fissa complex (Jungermanniopsida, Calypogeiaceae)

Within Calypogeia fissa, two subspecies connected with geographic distribution are formally recognized: C. fissa subsp.fissa in Europe and C. fissa subsp.neogea in North America. Isoenzyme studies have shown that the European subspecies is genetically differentiated and composed of three genetically distinct groups PS, PB and G. The PS group has the most distinctive morphological features, but no morphological diagnostic traits have been found for groups PB and G. The sequence characterized amplified region (SCAR) markers developed on the basis of ISSR markers, applied in the study, allowed the delimitation of all groups distinguished in Europe within the C. fissa complex (PS, PB and G). The markers also revealed genetic differences between the European and American subspecies. Five primer pairs (Cal01, Cal03-Cal06) of the six pairs studied are useful as the diagnostic tool for the identification of particular groups from the C.fissa complex. The examined SCAR markers showed that the PS group of C.fissa subsp.fissa was the most distinct; it differed from both groups PB and G as well as from C.fissa subsp.neogea. All plants determined on the basis of diagnostic isozyme loci as the PS group amplified a longer product (380 bp) of the Cal04 primer pair than the rest of studied groups and yielded no amplification products in Cal03, Cal05 and Cal06 primers. The primer pair Cal03 distinguished the plants of the PB group from the remaining groups, since only the PB group generated a PCR product of about 290 bp. The genetic differences between all four studied groups of the C.fissa complex were supported by DNA sequences of the SCAR marker Cal04.

Flavonoid-Deficient Mutants in Grass Pea (Lathyrus sativusL.): Genetic Control, Linkage Relationships, and Mapping with Aconitase and S-Nitrosoglutathione Reductase Isozyme Loci

Two flavonoid-deficient mutants, designated asfldL-1andfldL-2, were isolated in EMS-mutagenized (0.15%, 10 h) M2progeny of grass pea (Lathyrus sativusL.). Both the mutants contained total leaf flavonoid content only 20% of their mother varieties. Genetic analysis revealed monogenic recessive inheritance of the trait, controlled by two different nonallelic loci. The two mutants differed significantly in banding patterns of leaf aconitase (ACO) and S-nitrosoglutathione reductase (GSNOR) isozymes, possessing unique bands inAco 1, Aco 2,andGsnor 2loci. Isozyme loci inherited monogenically showing codominant expression in F2(1 : 2 : 1) and backcross (1 : 1) segregations. Linkage studies and primary trisomic analysis mappedAco 1andfld 1loci on extra chromosome of trisomic-I andAco 2,fld 2,andGsnor 2on extra chromosome of trisomic-IV in linked associations.