Genetic diversity in Ethiopian barley in relation to altitude

Summary A representative sample of the Ethiopian barley collection, maintained at the Ethiopian Plant Genetic Resources Centre (PGRC/E), was studied for its phenotypic diversity for some agronomic characters, i.e. kernel row number, spike density, spikelets per spike, caryopsis type, kernel colour, thousand grain weight, days to maturity and plant height. The diversity was estimated by using the Shannon-Weaver diversity index (H) for each of the characters to examine overall genetic divergence between accessions on the basis of administrative regions, ecogeographical zones as well as altitudinal ranges within Ethiopia. Most of the variation was due to differences among characters and only a relatively small fraction due to differences between regions. However, almost all characters are considerably influenced by altitude within the regions. The mean diversity index for all characters increases with altitude, reaches a maximum between 2,400 and 2,800 m, and decreases beyond that altitude.     

Phenotypic diversity of Ethiopian grass pea (Lathyrus sativus L.) in relation to geographical regions and altitudinal range

Fifty grass pea (Lathyrus sativus L.) populations collected from different administrative regions and altitude classes in Ethiopia, were evaluated for variations of five morphological traits. Shannon-Weaver diversity index was calculated for traits, populations and altitude classes. Monomorphism was recorded in flower color (blue) for most of the populations. Olive seed colour was dominantly distributed in all regions with mean frequency of 50% while black seed colour is rare with mean frequency of 4% in Ethiopia. Much variability was observed within populations. High diversity values for pattern of testa colour and leaflet size were recorded in populations of highland origin (>2550 m.a.s.l.). Shannon's diversity index is highest in Gondar (H = 0.65) followed by Tigray region (H = 0.64) even though there was no significant variation in H values between regions. These regions with high diversity are recommended for immediate in situ and ex situ conservation.     

Geographical, altitude and agro-ecological differentiation of isozyme and hordein genotypes of landrace barleys from Ethiopia: implications to germplasm conservation

An analysis of the variability of genes encoding six isozyme systems (15 loci) and two storage proteins (2 loci) in landrace barley from Ethiopia is reported. The materials consisted of populations collected from sites as low as 1650 and as high as 3750 meters, covering a wide range of agro-ecological conditions and geographical areas. Of the 17 loci 7 were polymorphic and 10 monomorphic when the 95% criterion of polymorphism was applied. Despite the disproportionate monomorphic loci, polymorphism was detected in all populations when this criterion is used. The populations were found to possess fairly low mean number of alleles per locus (A = 1.5), low mean value of expected heterozygosity (H = 0.134) and a fairly high mean percentage of polymorphic loci (P = 35.3%). The mean F_ST= 0.474 for the populations is typical of inbreeding species. The result indicated that allelic richness is concentrated in altitude class 3 (2500–3000 m) followed by altitude class 1 (<2000 m). Altitude class 2 (2000–2500) holds an intermediate place though it is the highest in terms of expected heterozygosity (H = 0.245). Higher genetic diversity is concentrated in some geographical regions such as Shewa, Arsi, Bale compared to others (Welo, Gamu Gofa, Gojam). Genetic differentiation among the agro-ecological zones was more profound than both among the altitudes and among regions. Correlation analysis between phenotypic diversity (Shannon-Weaver diversity index) and expected heterozygosity (H) for isozyme/hordein loci revealed non significant associations except with respect to agro-ecological zones. In general, it was detected that sites in highland areas in central and northern regions may be more desirable for in situ conservation than sites in peripheral regions in terms of isozyme/hordein diversity and current rate of varietal replacement.     

The third glume phenotype is associated with rachilla branching in the spikes of tetraploid wheat (<Emphasis Type="Italic">Triticum</Emphasis> L.)

We investigated the new inflorescence architectural character “three glumes” and a new status of ramification in tetraploid wheat. Using 9 tetraploid accessions with “turgidum type of branching”, the segregation of branched spike and the third glume indicated the complete linkage of genes for both phenotypes. The rachilla were elongated and bore florets at basal nodes while bearing spikelets at the apical nodes in T. durum Desf. TRI 9644 and T. turgidum L. PI 67339. The phenotype was different from “sham-ramification” in Triticum jakubzineri Udacz. et Schachm., with florets at basal and apical nodes of elongated spikelet rachilla. We confirmed a new status of ramification, “false-true ramification”. It was considered that the “false-true ramification” was determined by the shr2 gene in the long arm of chromosome 2A because the ramification of PI 67339 and TRI 9644 was supposed to be allelic. The segregation of “sham-ramification” and the third glume also indicated the complete linkage of genes for both phenotypes. Thus we concluded that the presence of third glume phenotype is associated with rachis and rachilla branching in the spikes of tetraploid wheat. The present study confirmed the existence of three distinct types of spike ramification, whose classification is not entirely unified: (a) “true ramification”—“branched spike”—“genuine branching”—“turgidum type of branching”, (b) “false ramification”—“pseudo-branched spike”—“sham ramification”—“vavilovii type of branching” and (c) “false-true ramification”.     

Multivariate Analysis of Diversity of Tetraploid Wheat Germplasm from Ethiopia

The variability of 2420 plants of tetraploid (2n = 4x = 28, AABB genome) wheat germplasm representing 121 accessions from Ethiopia were evaluated for 23 agro-morphological traits at Debre Zeit Agricultural Research Center area, Akaki substation, during the 2003 main season using multivariate methods. This enabled to assess the extent and pattern of variation of the germplasm with respect to regions, altitude classes and species and to identify the major traits contributing to the diversity. The first three and two principal components explained about 83 and 80% of the total variance among regions and altitudinal class, respectively. In the first principal component plant height, days to heading, the length and density of the spike, and kernel color were the most important traits contributing to variation that explained about 50% of regional variance. Cluster analysis grouped the accessions into 15 clusters, with 9 accessions remaining ungrouped. Based on the observed patterns of variation, it is concluded that there exists great variation in the germplasm, which provides opportunities to be utilized for genetic improvement.     

Genetic diversity of <Emphasis Type="Italic">Guizotia abyssinica</Emphasis> (L. f.) Cass. (Asteraceae) from Ethiopia as revealed by random amplified polymorphic DNA (RAPD)

Genetic diversity of 70 populations of niger (Guizotia abyssinica) representing all its growing regions in Ethiopia was investigated using random amplified polymorphic DNA (RAPD) to reveal the extent of its populations genetic diversity. Ninety-seven percent of the loci studied was revealed to be polymorphic for the whole data set. The within population diversity estimated by Shannon diversity index and Nei gene diversity estimates was revealed to be 0.395 and 0.158, respectively. The extent of genetic variation of populations from major niger producing regions was significantly lower than that of populations from other regions; however, it is distributed regardless of altitude of growth. Genetic differentiation between populations was estimated with Shannon index as G^′ _ST (0.432), Nei’s G _ST (0.242) and AMOVA based F _ST (0.350) and appears to be equivalent to the average values calculated from various RAPD based studies on outcrossing species. Higher proportion of the variation detected by AMOVA resided within populations (64.58%) relative to the amount of variation among populations (35.42%). UPGMA cluster analysis showed that most of the populations were clustered according to their region of origin. However, some populations were genetically distant from the majority and seem to have unique genetic properties. It is concluded that the crop has a wide genetic basis that may be used for the improvement of the species through conventional breeding and/or marker assisted selection. Collection of germplasm from areas not yet covered and/or underrepresented is the opportunity to broaden the genetic basis of genebank collection.     

Geographic Pattern of Genetic Diversity Among 43 Ethiopian Mustard(Brassica carinata A. Braun) Accessions as Revealed by RAPD Analysis

As an oilseed crop, the cultivation of Ethiopian mustard (Brassica carinata) is restricted only to Ethiopia. Even though geographic diversity is a potent source of allelic diversity, the extent of genetic diversity among germplasm material of Ethiopian mustard from different countries has not been assessed. Forty-three accessions, comprising 29 accessions from eight different geographic regions of Ethiopia and 14 exotic accessions from Australia, Pakistan, Spain, and Zambia were analysed for their genetic diversity using random amplified polymorphic DNA (RAPD) technique. A set of 50 primers yielded a total of 275 polymorphic bands allowing an unequivocal separation of every Ethiopian mustard accession. The usefulness of the 50 RAPD primers in measuring heterozygousity and distinguishing accessions was variable such that polymorphic information content (PIC) varied from 0.05 to 0.40, band informativeness (BI) from 0.05 to 0.65 and primer resolving power (RP) from 0.15 to 6.83. Jaccard's similarity coefficients ranged from 0.44 to 0.87 indicating the presence of a high level of genetic diversity. On the average, Australian and Ethiopian accessions were the most similar while, Spanish and Zambian accessions were the most distant ones. Cluster analysis grouped the 43 accessions into four groups, which has quite a high fit (r = 0.80) to the original similarity matrix. With no prior molecular information, the RAPD technique detected large genetic diversity among the 43 accessions from five different countries and their grouping by dendrogram and principal coordinate analysis (PCoA) was inclined towards geographic differentiation of RAPD markers. Conversely, RAPD differentiation along geographic origin was not apparent within the Ethiopian accessions.     

Genetic diversity in grasspea (Lathyrus sativus L.)

Genetic diversity was investigated in 348 accessions and subaccessions of grasspea (Lathyrus sativus L.) from 10 geographical regions. Polymorphism for 20 isozymes of 13 enzyme systems was studied to estimate the genetic diversity. The Near East and North Africa regions included the most variability for these isozyme systems, suggesting that the center of diversity (center of origin) for grasspea is in this general area. The lowest variability was found in accessions and subaccessions from South America, followed by those from Sudan–Ethiopia. Diversity was measured for individual loci over regions and EST-1 and SKDH had the highest genetic diversity. The closest genetic diversity was observed for LAP-2, followed by AAT-1 and PGM. The closest genetic distance existed between populations from the Near East and North Africa. Populations from South Asia and Sudan–Ethiopia, though geographically widely separated, exhibited a closer genetic distance from each other than from other regions.     

Abundant genetic diversity in cultivated <Emphasis Type="Italic">Codonopsis pilosula</Emphasis> populations revealed by RAPD polymorphisms

Genetic diversity of seven cultivated populations of Codonopsis pilosula Nannf. from Longxi County, Gansu Province of China was estimated using randomly amplified polymorphic DNA (RAPD) markers. The 17 selected RAPD primers amplified 205 polymorphic bands out of a total of 235 (87.2%). Nei’s gene-diversity statistics and population differentiation parameters based on AMOVA analysis indicated that the cultivated C. pilosula populations remained a high level of genetic diversity with Hs = 0.299 and I = 0.450. A greater proportion of genetic diversity was found within (77%) rather than among (23%) the populations. In addition, we also detected that populations from different altitudes had a considerable genetic differentiation after 40 years of cultivation at the same site. Populations from higher altitude had lower genetic diversity than those from lower altitude. Our results suggested that irregular and sparse cultivation practices, i.e., random collecting, preserving, and planting seeds of the medicinal species without deliberate selection, might be an efficient way to conserve genetic resources of medicinal plants, in addition to their effective uses.     

Comparative genetic diversity of <Emphasis Type="Italic">Triticum aestivum–Triticum polonicum</Emphasis> introgression lines with long glume and <Emphasis Type="Italic">Triticum petropavlovskyi</Emphasis> by AFLP-based assessment

Genetic diversity of a set of introgression lines of Triticum aestivum L./T. polonicum L. with long glume and T. petropavlovskyi Udacz. et Migusch. were analyzed by Amplified Fragments Length Polymorphism (AFLP). Small-scale bulk breeding method was applied throughout until F₆ generation to develop the introgression lines. Thirty-eight hexapolid F₇ plants with long glume phenotype and their parents were subjected to AFLP analysis by four primer combinations. A total of 47 polymorphic loci were detected between the parents, 15 of them were introgressed across the 38 lines. It was hypothesized that approximately 50% of A or B genomes associated polymorphic loci were introgressed. The variation of introgression lines was limited within the diversity between their parents, T. aestivum L. cv. Novosibirskaya 67 (N67) and T. polonicum L. cv. IC12196. N67 was closer to 38 introgression lines than that of IC12196. The UPGMA cluster and principal coordinate analysis (PCO) grouping showed 0.84 to 0.98 similarity values between N67 and the introgression lines. Eleven T. petropavlovskyi accessions were distinguished from introgression lines with UPGMA clusters and PCO groupings, and T. petropavlovskyi was located between the introgressions lines and IC12196. Several introgression lines resembled with T. petropavlovskyi for awning and glume length. The genetic variation among 38 introgression lines was much wider than that of T. petropavlovskyi. We concluded that T. petropavlovskyi was established by intensive selection of hybrid between T. aestivum/T. polonicum.     

Genetic variation of Ethiopian and Eritrean sorghum (Sorghum bicolor (L.) Moench) germplasm assessed by random amplified polymorphic DNA (RAPD)

The extent and patterns of distribution of genetic variation among 80 sorghum (Sorghum bicolor (L.) Moench) germplasm accessions from Ethiopia and Eritrea were investigated using RAPD with 20 oligonucleotide primers. The primers generated a total of 147 polymorphic bands across the 80 accessions with a mean of 7.35 bands per primer. Estimation of the extent of variation by the Shannon-Weaver diversity index revealed an intermediate level of overall variation (H = 53), although the levels varied among regions of origin of the accessions. Partitioning of the total variation revealed considerable variation (77%) within the region of origin of the accessions and the remainder (23%) among regions of origin. Similarly, a large portion (94%) of the total variation was found within the adaptation zones compared to among the adaptation zones (6%). The results suggest a weak differentiation of the sorghum material both on regional and agro-ecological bases, which could be ascribed to the high rate of outcrossing in cultivated sorghum and its free natural hybridization with its wild and weedy relatives, as well as to seed movement by humans. The average genetic dissimilarity was found to be 36% among the 80 accessions and 13% among the 15 regions of origin. Cluster analysis failed to group accessions of the same region or the same adaptation zone, which further confirmed the weak differentiation of the material studied. The clustering pattern of the regions of origin was broadly concordant with previous clustering patterns obtained using morphological characters, in which regions with broad agro-climatic conditions were grouped together.     

Sunflower ( Helianthus annuus L.) Seeding Rate Additions to Forage Oat-Legume Mixtures in Newfoundland

Lingonberry (Vaccinium vitis‐idaea L.) cvs “Sussi”; and “Sanna”; were cultivated on mineral soil with four different soil surface treatments (Sphagnum peat mulch, sand mulch, plastic mulch and herbicide 3‐syclohexyl‐5, 6‐trimethylenurasil (lenasil)). Amount of annual weeds, plant coverage and yield were observed over five years. Weeds were most abundant in the first two observation years. Sand mulch was the least efficient for the control of annual weeds for both cultivars, whereas lenasil was the most efficient for “Sussi”;, and peat mulch for “Sanna”;. The plant coverage increased steadily throughout the years in the “Sussi”; plots, especially in plots mulched with peat. The spreading of “Sanna”; was slower in all treatments. It was best in plots mulched with peat or sand. Overall, “Sanna”; was more productive, with the highest yield on sand mulch and the lowest on lenasil‐treated plots. “Sussi”;, instead, yielded best on lenasil plots and poorest on sand.     

Genetic diversity and differentiation in Ethiopian populations of Phytolacca dodecandra as revealed by AFLP and RAPD analyses

Amplified fragment length polymorphism (AFLP) and random amplified polymorphic DNA (RAPD) analyses were performed on six populations (a total of 89 individuals) of Phytolacca dodecandra (endod) collected in Ethiopia. The populations were selected based on our previous investigation to represent two altitude groups: lowland/central-highland (1600–2500 m) and highland (2501–3000 m). A total of 197 AFLP and 68 RAPD markers were scored from 5 primer pairs and 12 random primers, respectively. The overall patterns obtained for AFLPs and RAPDs from diversity, cluster and principal component analyses were very comparable. However, the moderate correlation (r = 0.56) between AFLP and RAPD similarity matrices as well as the discrepancies in diversity estimates between the two techniques in some populations and in the lowland/central-highland plants could be due to differences in sensitivity of reaction conditions, bias in scoring of bands, number of markers used for analyses, and/or parts of the genome surveyed. For both AFLP and RAPD, the lowland/central-highland populations showed higher polymorphism and Shannon information measure (H) than the highlands. Cluster and principal component analyses performed for both marker types have also clearly demonstrated the differentiation of all the lowland/central highland plants from those of the highlands, in agreement with our previous conclusion. Markers scored from any of the five AFLP primer pairs were sufficient to clearly distinguish the two altitude groups; with RAPD, selection of about 8 informative markers produced by seven random primers was needed for the same purpose.     

Sorghum genotype differences to leaf “red‐speckling”; induced by phosphorus 1

Sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solutions, sand, and soil under greenhouse or growth chamber conditions developed a lower leaf “red‐speckling”; which was induced by phosphorus (P). As P in solution increased, the intensity of the “red‐speckling”; increased. Although the severity of “red‐speckling”; was not directly related to leaf P concentration, leaves with more severe symptoms had higher P concentrations. KS35, ‘Martin’, and ‘Plainsman’ developed severe symptoms, CK60‐Korgi, SC369–3‐1JB, and TX415 developed intermediate symptoms, and NB9040 developed no symptoms when grown at relatively low levels of P (10 to 20 umol per plant). Organic sources of P induced more severe “red‐speckling”; than inorganic sources. The severity of “red‐speckling”; induced by P compounds followed the sequence of gyceryl > ethyl ammonium = phenyl > potassium dihydrogen > calcium meta > calcium dibasic > calcium tribasic > ferric > calcium pyro = ferrous = aluminum phosphates. “Red‐speckling”; on young sorghum leaves may be caused by excess P. This excess or toxic P “red‐speckling”; occurred at P levels lower than had normally been considered or expected.     

Genetic diversity of ICARDA’s worldwide barley landrace collection

Twenty genic- and genomic SSR markers were used to study genetic diversity and geographical differentiation of barley from 29 countries through analysis of a worldwide collection of 304 ICARDA’s barley landraces. Of these, 19 loci were highly polymorphic in the material studied. Based on Nei-distance matrix, Principal Component Analysis (PCoA) and cluster analysis using UPGMA associated with AMOVA the data revealed countries’ grouping within regions. Three distinct germplasm pools were identified in the landraces. The first of these was from Eastern Africa (Eritrea and Ethiopia) and South America (Ecuador, Peru and Chile) suggesting that barley introduced to South America might have originated specifically from East Africa or that they share a common genetic basis for adaptation. The second was the Caucasus (Armenia and Georgia) and the third included the remaining regions of Central Asia, Near East, Northern Africa and Eastern Asia. Genetic diversity of barley subspecies (Six-rowed barley, Two-rowed barley, H. spontaneum C. Koch and H. agriocrithon Åberg) also discriminates them into three groups: cultivated barleys (Six-rowed barley and Two-rowed barley), wild barley H. spontaneum and subspecies H. agriocrithon. These results associated with parsimony analysis demonstrate that H. agriocrithon and H. spontaneum might be distinct and do not support a hybrid origin for H. agriocrithon suggesting further investigation of the basis of more intense sampling of the two subspecies H. spontaneum and H. agriocrithon.     

Morphological and isozyme variation in genebank accessionsof Aegilops umbellulata Zhuk., a wild relative of wheat

Morphological variation and genetic variation at 15 enzyme lociwere studied in genebank accessions of Aegilopsumbellulata Zhuk., the diploid genome donor to all thepolyploid species of the section Aegilops ofAegilops. Accessions from the Greek Islands hadshorter spikes with smaller number of spikelets and smaller number ofawns on the empty glume. The number of alleles per locus (A= 2.01) and the proportion of polymorphic loci (P= 0.627) were similar to those of the other species ofAegilops so far reported. Genetic distancescalculated from isozyme variations among five regions revealed thataccessions from the Greek Islands are more distantly related to theother four continental regions, Iran and Iraq, Southeast Turkey,Central Turkey and South and West Turkey. The present resultsindicated the importance of collection covering the whole range ofgeographical distribution to capture the genetic variation present inAe. umbellulata.     

Genetic relationships within Vigna unguiculata (L.) Walp. based on isozyme analyses

Summary Isozyme analyses of genetic diversity in Vigna unguiculata were performed to determine genetic relationships and level of genetic diversity between wild and cultivated cowpea. Thirty-four cultivated accessions of V. unguiculata, 56 wild accessions of V. unguiculata, and six accessions representing five related wild Vigna species were analyzed. Ten enzyme systems were polymorphic within Vigna unguiculata: AAT, ACO, G6PDH, DIAP, LAP, MUE, ME MDH, PRX, and SOD. Fourteen of 24 putative loci (58%) were polymorphic within wild V. unguiculata, but only one locus (4%) was polymorphic within cultivated cowpea; when five related Vigna species were examined, 21 of the 24 bands of activity showed polymorphisms (88%) adding 33 alleles to the 48 identified within V. unguiculata. In one F₂ population of 68 plants (UCDVg 36 × UCDVg 21) a loose linkage was indicated between Diap-2 and G6pd-1 (² = 15.39; p = 0.004) with an estimated distance of 36.0 cM ± 5.02 (recombination (r) = 0.31). Also in another F₂ population of 38 plants (CB 88 × UCDVg 21) a loose linkage was indicated between Lap-1 and Prx (\gC² = 9.62; p = 0.047) with an estimated distance of 39.8 cM ± 7.0 (r = 0.33). Total genetic diversity (H_T) was 0.085 over all of the accessions including the one classified as V. nervosa. Within accession diversity (H_s) approached zero and between accession diversity (D_si) was responsible for all of the genetic diversity present. Therefore the coefficient of gene differentiation (G_ST = D_STII_T) approached 1. Absolute gene differentiation (D_m) was 0.087. Two of the nine segregations in this study were skewed. In general, results of this study concurred with the taxonomic classification within V. unguiculata and provided a strong indication that a severe genetic bottleneck occurred during the domestication process of cowpea.Abbreviations AAT aspartate amino-transferase - ACO aconitase - ALD aldolase - AUS Australia - BDI Burundi - BWA Botswana - CHN China - CMR Cameroon - DIAP diaphorase - DZA Algeria - ETH Ethiopia - G6PDH glucose-6-phosphate dehydrogenase - GDH glutamate dehydrogenase - GHA Ghana - GUY Guyana - IDH isocitrate dehydrogenase - IND India - KEN Kenya - LAO Laos - LAP leucine aminopeptidase - MDH malate dehydrogenase - ME malic enzyme - MEX Mexico - MOZ Mozambique - MUE methylumelliferyl-esterase - MWI Malawi - MYS Malaysia - NER Niger - NGA Nigeria - PRX peroxidase - RBSC ribulose-bisphosphate carboxylase - SEN Senegal - SLE Sierra Leone - SOD superoxide dismutase - TGO Togo - TZA Tanzania - USA United States of America - XDH xanthine dehydrogenase - ZAF South Africa - ZAR Zaire - ZIM Zimbabwe - ZMB Zambia     

Analyses of genetic diversity and population structure of anchote (Coccinia abyssinica (Lam.) Cogn.) using newly developed EST-SSR markers

Anchote (Coccinia abyssinica (Lam.) Cogn.) is a perennial root crop belonging to Cucurbitaceae family. It is endemic to Ethiopia and distributed over wide range of agro-ecologies. For further improvement and efficient conservation of this crop, characterization of its genetic diversity and its pattern of distribution is a vitally important step. Expressed sequence tags-simple sequence repeats (EST-SSRs) markers were developed from publicly available watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] ESTs in the GenBank database. Among those novel markers, eight were polymorphic and subsequently used for genetic diversity and population structure analyses of 30 anchote accessions collected from western Ethiopia. A total of 24 alleles were obtained across the eight polymorphic loci and 30 accessions that revealed moderate level of genetic diversity in this minor crop. Among the eight loci, locus CA_06 was the most informative with six alleles and polymorphic information content (PIC) of 0.76. The accessions showed about threefold variation in terms of genetic diversity, with expected heterozygosity (He) ranging from 0.15 (accession An) to 0.44 (accession Dg). Other accessions with higher genetic diversity include Ar and Gu (He?=?0.43 and 0.41, respectively). Analysis of molecular variance (AMOVA) revealed that the variation within accessions and among accessions accounted for 84.7% and 15.3% of the total variation, respectively. The study revealed low but significant population differentiation in this crop with no clear pattern of population structure. The EST-SSR markers developed in this study are the first of their kind for anchote and can be used for characterization of its wider genetic resources for conservation and breeding purposes.

     

Analysis of genetic diversity in the endangered tropical tree species <Emphasis Type="Italic">Hagenia abyssinica</Emphasis> using ISSR markers

Genetic diversity within and among 12 populations of the dioecious tropical tree species Hagenia abyssinica (Bruce) J.F. Gmel. in Ethiopia was examined with eight inter simple sequence repeat (ISSR) primers. A total of 104 clearly scorable bands were generated, among which 84 (81%) were polymorphic. Jaccard similarity coefficient was calculated for pairwise comparisons among all 120 individuals and ranged from 0.30 to 0.88 while average within-population similarity ranged from 0.53 to 0.66. Within-population variability was estimated as percentage polymorphic loci (ranging from 52% to 87%), Shannon’s information index (0.30–0.50) and Nei’s genetic diversity (0.21–0.35). The highest variability values were obtained for one recently planted population and for one wild population growing in an undisturbed primary forest area. Significant overall differentiation among populations was detected by both Shannon’s information index (0.26) and G _ST (0.25). Relatedness among samples was estimated with a principal coordinate analysis, and relatedness among populations was estimated with a cluster analysis (UPGMA). A Mantel test indicated a significant association between genetic and geographic distances, and an autocorrelation analysis showed significant evidence of gene flow over distances up to 30 km. This study is the first of its kind for H. abyssinica, which has decreased recently in Ethiopia and now must be regarded as an endangered species. Both within-population and between-population diversity estimates are typical of outcrossing, longlived and late successional species, suggesting that recent anthropogenic disturbances have not yet had much impact on population genetic parameters. DNA marker data can, however, be used to identify the most suitable sites for in situ conservation and for collection of material for establishment of genebanks and plant improvement programs.     

Genetic variation in barley landraces from Bhutan

Summary In Bhutan, barley is usually grown in mountainous regions over 2,000 m elevation. The barleys investigated were six-rowed naked, and classified into three groups by spike and awn characters; lax spike and long awn, dense spike and long awn, and dense spike and elevated hood. They also varied in spike color; yellow, purple and black. For isozymes, there was no variation at Aat2 and Aat3 loci for aspartate aminotransferase in the Bhutanese barley.However, allelic variations at Est1, Est2 and Est4 loci for esterase were detected, and three genotypes consisting of their allelic combinations were found. Most of the collections were heterogeneous for these features. Combinations between spike-awn types and esterase genotypes were not at random, indicating that genetic diversities resulted from mechanical mixtures of different types. These types were distributed with geographical regularity in Bhutan. In comparing the spike-awn type and esterase genotype in barley collections from other regions of the Himalayas, the Bhutanese barleys were s-imilar to the Tibetan ones, but were much different from the Nepalese barleys. This suggests that the Bhutanese barleys had been introduced from Tibet.