Assessment of genetic diversity in cultivars and wild accessions of Luohanguo (<Emphasis Type="Italic">Siraitia grosvenorii</Emphasis> [Swingle] A. M. Lu et Z. Y. Zhang), a species with edible and medicinal sweet fruits endemic to southern China,using RAPD and AFLP markers

Genetic variation of wild populations and cultivars of Luohanguo (Siraitia grosvenorii), a plant species endemic to southern China, was assessed using random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers. Based on the results for 130 individuals from seven populations, a high level of genetic diversity of Luohanguo was observed at the species level. The percentage of polymorphic loci (P) was 89.4%, Nei’s gene diversity (H _e) was 0.239, and Shannon’s information index (H _o) was 0.373 based on the combined AFLP and RAPD data. There was a high degree of genetic differentiation, with 45.1% of the genetic variation attributed to differences between the populations. The genetic diversity of the Luohanguo cultivars is much lower than that of wild populations (P = 41.8%, H _e = 0.141, H _o = 0.211), and a distinct genetic differentiation is observed between the cultivars and wild accessions. The pool of genetic variation in the wild populations provides an excellent gene resource for Luohanguo breeding.     

Genetic diversity and structure of Ethiopian,Yemen and Brazilian C<Emphasis Type="Italic">offea arabica</Emphasis> L. accessions using microsatellites markers

Genetic diversity among 115 coffee accessions from the Coffea Germplasm Collection of IAC was assessed using SSR markers. The germplasm represents 73 accessions of Coffea arabica derived from spontaneous and subspontaneous plants in Ethiopia and Eritrea, species center of origin and diversity, 13 commercial cultivars of C. arabica developed by the Breeding Program of IAC, 1 accession of C. arabica cv. ‘Geisha’, 13 accessions of C. arabica from Yemen, 5 accessions of C. eugenioides, 4 accessions of C. racemosa and 6 accessions of C. canephora. Genetic analysis was performed using average number of alleles per locus (A), proportion of polymorphic loci (P), Shannon’s genetic index (H′ and G′_ST) and clustering analysis. All evaluated species were distinguished by a cluster analysis based on Jaccard’s coefficient. Differentiation between the cultivated plants of C. arabica and accessions derived from spontaneous and subspontaneous plants was observed. Spontaneous and subspontaneous accessions from Ethiopia were separated according to the geographical origin: east and west of the Great Rift Valley. Cultivated plants showed a low genetic diversity with a division in two groups: accessions from Yemen (H′=0,028) and Brazilian commercial cultivars (H′=0,030). The results agreed with previously reported narrow genetic basis of cultivated plants of C. arabica and supported the hypotheses about domestication of the species. This study also showed a significant genetic diversity among accessions from Ethiopia and Eritrea present in the Germplasm Collection of IAC. This diversity is specially observed in accessions from Sidamo (H′=0,143), Kaffa (H′=0,142) and Illubabor (H′=0,147) indicating their importance as source of genetic variability for coffee breeding programs.     

Genetic Variation of Ethiopian Mustard (Brassica carinata A. Braun) Germplasm in Western Canada

Information on genetic diversity and genetic relationships among genotypes of Brassica carinata is currently limited. The objectives of this study were to evaluate patterns and levels of genetic diversity in B. carinata based on amplified fragment length polymorphisms (AFLP) as compared with Brassica juncea and Brassica nigra, and to evaluate agronomic and seed quality data for plants grown in the field in western Canada. A total of 296 AFLP bands were generated from four primer pair combinations and scored for presence/absence in 66, 20 and 7 accessions of B. carinata, B. juncea and B. nigra, respectively. B. carinata was less genetically diverse than the other two species. Differences in diversity were evident in the proportion of polymorphic loci within each species: 23, 35 and 50% for B. carinata, B. nigra and B. juncea, respectively. Pair-wise similarity measures based on the Jaccard coefficient were highest among accessions of B. carinata and showed the narrowest range: 0.911 (0.810–0.981) compared to B. nigra: 0.569 (0.438–0.660) and B. juncea: 0.715 (0.345–0.951). AFLP-based genetic distance information can be used by plant breeders to select diverse genotypes. AFLPs are also useful for fingerprinting cultivars and two primer pair combinations were sufficient to uniquely identify all the accessions of B. carinata. More variation among accessions was identified in the agronomic trial than had previously been described in studies of B. carinata in western Canada, but the data were too limited to draw conclusions regarding specific accessions. Overall, the findings were in agreement with other published work describing the favourable agronomic potential of this species.     

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.     

Comparative analysis of genetic diversity using molecular and morphometric markers in Andrographis paniculata (Burm. f.) Nees

Andrographis paniculata is a medicinal plant of immense therapeutic value. The present study was aimed to elucidate its genetic diversity based on morphochemical and RAPD markers from 53 accessions belonging to 5 eco-geographic regions. Analysis of variance and D ² statistics revealed significant differences in all the metric traits and sufficient inter-cluster distances indicating considerable diversity among the accessions. The complementary approach of RAPD was used to evaluate the genetic dissimilarities among all the accessions using 6 highly polymorphic primers. The average proportion of polymorphic loci across primers was 96.28%. The molecular genetic diversity based on Shannon index per primer averaged 5.585 with values ranging from 3.08 to 8.70 indicating towards wide genetic base. RAPD based UPGMA and D ² cluster analysis also revealed that various accessions available in different eco-geographic regions might have originated from native places of wild abundance. Similarity matrices were generated for molecular markers and morphometric data to determine the degree of congruence between the two. A highly significant but low correlation (r = 0.547, P < 0.001) was obtained thus implying the correspondence between the two. The species is hermaphroditic and a habitual inbreeder. The present study yielded a typical triangular congruence between its breeding system, morphometric traits and RAPD markers thus elucidating the usefulness of complementary approaches to make diversity analysis more explanatory and purposeful for optimum genetic amelioration and effective conservation of its genotypic variability.     

Preliminary study of genetic diversity in Swedish flax (Linum usitatissimum)

To investigate the genetic diversity of Linum usitatissimumL. in Sweden, 18 accessions, including 13 cultivars and five landraces, were analysed. This study was based on genetic variation in three enzyme systems (i.e., PGD, GPI and MDH) by using horizontal starch gel electrophoresis. The total genetic diversity of the studied flax material was very high (H _T= 0.62). Even though the highest genetic diversity lies within the accessions (G _ST= 0.07), a clear differentiation between fibre and oil flax was found with respect to three polymorphic loci (Pgd-1, Gpi-2 and Mdh-1). A phenogram, based on Nei's genetic distances between the accessions studied, showed five clearly defined groups but with low variation within the groups. The unexpected high genetic diversity found within accessions in the studied flax material may indicate that flax is more outbreeding than earlier believed.     

Comparison of the genetic structure of populations of wild emmer wheat, <Emphasis Type="Italic">Triticum turgidum</Emphasis> ssp. <Emphasis Type="Italic">dicoccoides</Emphasis>, from Israel and Turkey revealed by AFLP analysis

The aim of the present study was to assess the genetic variation in several Israeli and Turkish populations of wild emmer wheat, Triticum turgidum ssp. dicoccoides, the progenitor of most domesticated wheat. Single spikes were collected in 2002 from 60 plants that grew in six different habitats in Ammiad, northeastern Israel (8–12 plants from each habitat), and in 1998 from 56 plants that grew in seven different habitats in Diyarbakir, southeastern Turkey (8 plants from each habitat). Seeds were planted in a nursery and DNA was extracted from every plant and analyzed by the fluorescent-based amplified fragment length polymorphism (AFLP) method. Seven primer combinations produced 788 discernible loci of which 48.6% were polymorphic in Israel and 40.5% in Turkey. The genetic diversity estimates P (frequency of polymorphic loci) and He (gene diversity) were higher in Ammiad than in Diyarbakir (means of P = 0.34 and He = 0.13 in Ammiad vs. P = 0.20 and He = 0.08 in Diyarbakir). Ammiad populations contained more unique alleles than Diyarbakir populations. The relative genetic diversity estimates (θ) values were 0.188 in Ammiad and 0.407 in Diyarbakir, suggesting better differentiation of the populations in Turkey. Genetic distance was larger between Israeli and Turkish populations than between populations of each country. The data indicate that the Israeli and Turkish populations are considerably diverged and that the Israeli populations are more polymorphic than the Turkish ones, having a larger within-populations genetic variation than among-populations one. The significance of the results in relation to the differentiation pattern of wild emmer in the Near East is discussed.     

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.     

Patterns of phenotypic diversity for phenologic and qualitative traits in Ethiopian tetraploid wheat germplasm

A total of 4,840 entries of tetraploid wheat germplasm collections representing 121 accessions from Ethiopia were evaluated for phenologic and qualitative trait diversity. The objectives were to assess the diversity patterns of the germplasm with respect to regions, species and altitudinal class. High values of Shannon–Weaver Diversity Index (H′) were recorded for most traits in each region, altitudinal classes, and species. Monomorphism was also high at accession levels. Both H′ and Nei’s gene diversity value for the entire data set (total gene diversity H _T = 0.572; the within accessions gene diversity H _S = 0.112; and gene diversity among accessions D _ST = 0.460) showed the variation for the trait is mainly among accessions/populations rather than within accessions/population. The least mean H′ value over all the traits used for the study was obtained from released varieties (among the origin groups) and Triticum dicoccon (among species). Triticum durum exhibit the highest H′ for a number of traits. Accessions collected from altitudinal class III (2401–2800 m a.s.l.) and class II (2001–2400 m a.s.l.) showed the highest H′ values for a valuable number of traits. Thus classifications using various phenology and qualitative traits enable to identify adaptation of a genotype and would improve the evaluation of genotype for potential adaptation.     

Phenotypic diversity in wild barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L. ssp. <Emphasis Type="Italic">spontaneum</Emphasis> (C. Koch) Thell.) accessions collected in Jordan

Wild barley, Hordeum vulgare L. ssp. spontaneum (C. Koch) Thell., is the progenitor of cultivated barley. Almost unanimously the center of diversity is considered to be in the Fertile Crescent of the Near East, where wild barley grows under a wide range of environmental and climatic conditions. Jordanian wild barley is expected to harbor genes useful for the improvement of cultivated barley, particularly those associated with tolerance to drought. This study evaluated 103 wild barley accessions collected from different areas of Jordan along with 29 cultivated barley genotypes for several morphological and agronomical traits. The Hordeum vulgare ssp. spontaneum C. Koch accessions were grouped into six populations according to the longitude, latitude, altitude, and rainfall zone of the collection site, and the cultivated barley in one population. The evaluation was conducted during the 2004–2005 growing season under field conditions in three locations in Jordan; namely, Khanasri, Ramtha, and Maru with 123.0, 222.9, and 429.2 mm annual rainfall, respectively. We used an unreplicated design with two systematic checks (the cultivars Rum and Mu’ta) each repeated 15 times. The results showed the existence of high variability among the Hordeum vulgare ssp. spontaneum C. Koch accessions for most of the traits, especially for plant height, tiller number, days to heading, days to anthesis, peduncle length, and peduncle extrusion. Plant height, earliness, peduncle length, and peduncle extrusion were found to be adaptive traits under drought conditions and several superior genotypes for each trait were identified. Genetic variation within population was much higher than between populations. Clustering of populations was according to their ecological geographical pattern.     

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (<Emphasis Type="Italic">Triticum dicoccoides</Emphasis>) and their ecological associations

Using the 8 specific primer pairs based on the conserved motifs of plant resistance genes, the plant disease resistance gene analog polymorphisms (RGAPs) in 15 wild emmer wheat (Triticum dicoccoides) populations from Israel had been detected. High genetic variations at the RGAP loci were observed in T. dicoccoides populations. A total of 254 discernible bands were obtained among 115 accessions, and 192 bands (75.6%) were polymorphic. Each genotype had a unique banding profile, and the genetic similarity coefficient ranged from 0.094 to 0.862. In T. dicoccoides, the proportion of polymorphic loci (P), the genetic diversity (He) and Shannon’s information index were 0.756, 0.362 and 0.541, respectively. The proportion of polymorphic loci (P) per population averaged 0.732 (range: 0.515–0.932); genetic diversity (He) averaged 0.271 (range: 0.212–0.338); and Shannon’s information index averaged 0.404 (range: 0.310–0.493). The coefficients of genetic distance (D) among populations averaged 0.107 (range: 0.043–0.178), and the results of Mantel test (r = 0.168, P = 0.091) showed that the estimates of genetic distance were geographically independent. Neighbor-joining cluster analysis suggested that the genetic relationships of T. dicoccoides populations were associated with their ecogeographic distribution. The hierarchical analysis of molecular variance (AMOVA) and the coefficient of gene differentiation (G _ST ) values revealed that most of the variations were presented within populations, although significant differences among populations and regions were also detected. The values of P and Shannon’s information index were negatively correlated with the two factors: Tdd (day–night temperature difference) and Ev (mean annual evaporation), whereas they were positively correlated with one water factor: Rn (mean annual rainfall). The correlation matrix between He in the RGAPs and geographic variables contained 20 significant (P < 0.05) correlations. The present study established that T. dicoccoides in Israel had a considerable amount of genetic variations at RGAP loci at least partly correlated with ecological factors.     

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     

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 of <Emphasis Type="Italic">Nelumbo</Emphasis> accessions revealed by RAPD

Total 65 lotus accessions in genus Nelumbo mainly collected from China, were subjected to random amplified polymorphic DNA (RAPD) markers to estimate the genetic diversity and to test the genetic basis of the relationships between morphotypes and molecular markers. Seventeen primers generated a total of 195 highly reproducible and discernible loci, among which 173 were polymorphic. Percent polymorphism varied from 66.7 to 100 with an average of 88.72, and five primers out of them, OPC05, OPG10, OPN20, OPP09 and OPS17, showed 100% polymorphism. A relatively high genetic diversity was detected among all the samples with the similarity coefficient values ranging from 0.45 to 0.85, and Nei’s gene diversity (h) 0.30, and Shannon index (I) 0.46. The UPGMA dendrogram clustered 65 accessions in four clusters and the clustering pattern showed two groups, N. nucifera ssp. nucifera and those accessions related to the American lotus, and some special cultivars, landraces, hybrids and the American lotus. Principal Coordinate Analysis (PCA) further indicated that the genetic diversity of Nelumbo accessions was not evenly distributed, instead, was presented by a clustered distribution pattern. Similar to the results revealed by the dendrogram, two main groups representing the two subspecies of N. nucifera, as well as some special landraces, cultivars of Chinese lotus, the Japanese lotus and hybrids out of the two groups were obtained. Neither the UPGMA dendrogram nor the PCA analysis exhibited strict relationship with geographic distribution and morphotypes among the accessions.     

Worldwide genotyping of castor bean germplasm (<Emphasis Type="Italic">Ricinus communis</Emphasis> L.) using AFLPs and SSRs

Worldwide genetic diversity in 200 individuals comprising 41 castor bean accessions was assessed using amplified fragment polymorphisms (AFLPs) and simple sequence repeats (SSRs). We found that, despite surveying five continents and 35 countries, genetic diversity in castor bean germplasm is relatively low (overall H _e = 0.126 for AFLPs and 0.188 for SSRs) compared to estimates of genetic diversity in other plant species. Our data also show no geographic structuring of genotypes across continents or countries within continents. An assessment of the congruence between AFLP and SSRs indicates a low correlation (R ² = 0.19) between the two data sets, but each marker class nonetheless shows similar patterns of low-genetic diversity and a lack of geographic structure. Our data do suggest that SSRs yield a higher percentage of polymorphic loci, higher heterozyosity and a greater range of genetic distances, and are therefore more informative than are AFLPs on a locus-by-locus basis. Based on comparisons with numerous other plant species, we suggest that the lower genetic variation in this worldwide collection may be due to one or more factors including: sampling strategies that have not captured the full extent of genetic variation in the species; artifactual variation due to long-term germplasm storage and seed regeneration; or intense selection followed by domestic cultivation of a limited number of castor bean genotypes, which are widely propagated for their horticultural and agro-economic value.     

Characterisation of germplasm accessions of Napier grass (pennisetum purpureum and P. purpureum×P. glaucum Hybrids) and comparison with farm clones using RAPD

Fifty six germplasm accessions of the important East African fodder crop Napier grass, Pennisetum purpureum, and its hybrids with P. glaucum, were characterised using 67 random amplified polymorphic DNA (RAPD) fragments. No or very low intra-accession variation was found for 49 of the accessions examined, confirming field observations that this species is predominantly clonally propagated. Comparison of intra and inter-accession variation identified several groups of identical/similar accessions that could be targeted if the collection is to be rationalised, and also highlighted two misplantings of germplasm material during transfer to a field trial site. A neighbour joining dendrogram of Jaccard's similarity estimates, clearly separated 50 accessions of P. purpureum from three P. glaucum individuals, and placed six hybrid accessions in an intermediate position. These groupings were well supported by a nested AMOVA (P<0.001; 29.5% of total variance due to taxonomic delineation). The main group of P. purpureum individuals could be further differentiated into five sub-groups (designated East Africa, Southern Africa, USA1, USA2 and Miscellaneous, to reflect the majority membership of sub-groups) and examination of the within P. purpureum component of the nested AMOVA, found them to be significantly different (P<0.001; 18.8% of variance). Genetic diversity across all accessions was found to be fairly high (Shannon's diversity index 0.306) and thus the collection probably represents a wide genetic base for this species. In addition to germplasm accessions, 25 Kenyan farm clones were also analysed. A principal coordinate analysis found that all but one of the clones clustered with the main P. purpureum group of accessions, indicating that the majority are probably not interspecific hybrids. The origin and pedigree of clones is discussed based on genetic similarity amongst clones and to germplasm accessions.     

Phenotypic Variation and Relationships in Landraces and Improved Varieties of Rye (Secale cereale L.) from Northern Europe

Phenotypic diversity for agronomic characteristics was determined in an experiment with 29 landraces and 14 improved varieties of rye from the Nordic area, Germany and Poland. The accessions were scored for 12 characters. Effects of the location, year, type, and country of origin for landraces were investigated with analysis of variance. Phenotypic variations for the traits were estimated using the Shannon–Weaver diversity index. The genetic variation was high, with an average of H ₀ = 0.566. The landraces from Norway, Sweden and Finland showed the highest variation, whereas the improved varieties had the lowest. The German material also had low variation but the status of this material is uncertain. The genetic diversity showed that 70% of the variation was found within the accessions. A cluster analysis was carried out to identify the relationship between the accessions. The material grouped into eight clusters, where clusters I to V included landraces from Sweden, Finland and Norway, except for cluster III, which included one improved variety from Denmark. Cluster VI comprised a single Swedish landrace from Gotland. Most of the improved varieties were in cluster VII and the last cluster contained accessions from Germany and Sweden.     

Genetic and Phenotypic Diversity in Downy-mildew-resistant Sorghum (Sorghum bicolor (L.) Moench) Germplasm

Genetic and phenotypic diversity among randomly selected 36 downy-mildew-resistant sorghum accessions were assessed, the former using 10 simple sequence repeat (SSR) marker loci and the latter using 20 phenotypic traits. The number of alleles (a _j ) at individual loci varied from five to 14 with an average of 8.8 alleles per locus. Nei's gene diversity (H _j ) varied from 0.59 to 0.92 with an average of 0.81 per locus. High gene diversity and allelic richness were observed in races durra caudatum (H _j = 0.76, a _j = 4.3) and guinea caudatum (H _j = 0.76, a _j = 3.8) and in east Africa (H _j = 0.78, a _j = 7.2). The regions were genetically more differentiated than the races as indicated by Wright's F _st. The pattern of SSR-based clustering of accessions was more in accordance with their geographic proximity than with their racial likeness. This clustering pattern matched little with that obtained from phenotypic traits. The inter-accession genetic distance varied from 0.30 to 1.00 with an average of 0.78. Inter-accession phenotypic distance varied from 0.01 to 0.55 with an average of 0.33. Eleven accession-pairs had phenotypic distance of more than 0.50 and genetic distance of more than 0.70. These could be used as potential parents in a sorghum downy mildew resistance-breeding program.     

Patterns of diversity in pigeonpea (<Emphasis Type="Italic">Cajanus cajan</Emphasis> (L.) Millsp.) germplasm collected from different elevations in Kenya

Pigeonpea germplasm accessions collected from low (<500 m), medium (501–1000 m), high (1001–1500 m) and very high elevation zones (>1500 m) of Kenya were evaluated for 15 agronomic traits and seed protein content at ICRISAT, Patancheru, India. There were significant differences (P < 0.001) among elevation zones for the number of primary and secondary branches, days to 75% maturity, pod length, seeds per pod, 100-seed weight and seed yield. Mean values indicated that the accessions from low elevation zone were significantly different from those collected in higher elevation zones for early flowering and maturity, number of primary branches, pod length, number of pods per plant, seeds per pod, 100-seed weight, seed yield and harvest index. None of the accessions collected in Kenya belonged to extra early (<80 days to 50% flowering) and early (80–100 days to 50% flowering) maturity groups, as defined by time to flowering at Patancheru, India. Mean diversity index based on all characters indicated that accessions from the low elevation zone are more diverse than those from the higher elevation zones. Frequency distribution for trait extremes indicated that the accessions from the low elevation zone were early to flower and mature, short statured, produced more primary and secondary branches with high pod bearing length, long pods, more pods per plant, more seeds per pod, a high seed yield and harvest index. Accessions from the very high elevation zone were late flowering, with a large number of tertiary branches, large seeds and a high shelling percentage and could be a source for cold tolerance and the breeding of vegetable types. Results suggest that the elevation of collection sites is therefore a very important determinant of variation patterns of pigeonpea in Kenya.