The use of microsatellite polymorphisms to characterise and compare genetic variability in Avena strigosa and A. barbata

Microsatellite (SSR) polymorphism was assessed across 90 diploid Avena strigosa Schreb. and tetraploid Avena barbata Pott ex Link accessions obtained from the USDA-ARS National Small Grains Collection using 105 genomic SSRs. Eleven polymorphic SSRs that detected 69 different alleles were identified and used to genotype the 90 accessions, which were chosen from a larger set of 385 accessions based on geographical source-diversity and variable reaction responses to five Australian pathotypes of the crown rust pathogen Puccinia coronata Corda f. sp. avenae Eriks. Eight diploid and eight tetraploid clades were identified among the 90 accessions. Diploid accessions displayed the lowest genetic diversity, with all accessions being at least 86 % similar, and included accessions from countries in the Americas such as Canada, USA, Argentina, Uruguay and Brazil, and European accessions from France, Romania and Poland. Although both species formed distinct clusters in the dendrogram, a few instances of diploids showing high similarity with tetraploids and vice versa were observed. An AMOVA analysis revealed 86 % of the total genetic variation to be distributed within the two oat species, while between-species differences accounted for only 14 %. Heterozygosity (H) index values of 0.32 and 0.40 were obtained for diploids and tetraploids respectively. Our study effectively differentiated A. strigosa and A. barbata, and identified 11 SSRs suitable for future characterisation of accessions of the two species.     

Geographical pattern and ploidy levels of the weed Solanum elaeagnifolium (Solanaceae) from Argentina

A total of 106 samples taken from natural Argentinean populations of the weedy Solanum elaeagnifolium (subgenus Leptostemonum) were studied cytologically to understand the impact of the different ploidy levels in its distribution and origin. Classical Feulgen staining was employed to determine mitotic chromosome numbers in all samples. 2C nuclear DNA content was determined by means of PI flow cytometry in eight samples of different ploidy levels. Principal component analysis and GIS tools were employed to compare altitude, annual precipitation and annual mean temperature among accessions. Three cytotypes were found: diploid (2n?=?24) which is widespread, tetraploid (2n?=?48) centered in western and southern Argentina, and hexaploid (2n?=?72) which predominates in central Argentina extending as well to the east. The annual precipitation is significantly different between tetraploids and hexaploids. Cx-values ranged from 1.231 to 1.275?pg, with statistical differences (of about 24.5–50.9?Mbp, p?≤?0.05) among accessions. Diploids are the most widespread cytotype and have adapted to a number of very different habitats. Tetraploids live in arid or semi-arid regions with a mean annual rainfall less than 500?mm. Hexaploids are successful in colonizing wetter areas, where no tetraploids were found. Thus, the distribution of cytotypes may be associated with habitat differences, particularly soil moisture. The observed cytotype pattern and the differences in DNA content suggest multiple places of origin for the polyploidy of S. elaeagnifolium in Argentina.     

Collection and morphological characterization of Panicum coloratum L. in Argentina

Panicum coloratum (Poaceae) is a perennial grass native to South Africa, distributed all over the world, but poorly adopted by ranchers in Argentina. Adapted to a wide range of soil and climatic conditions, it constitutes a good forage resource for zones with edaphic and climatic restrictions, where cattle rising activities are here displaced. The high polymorphism in the species has made it difficult to delineate sub specific taxonomic categories. It has been classified in botanical varieties, types and/or cultivars. In order to document the morphological variability in P. coloratum and to investigate the differences between var. makarikariense and var. coloratum, a collection was gathered in INTA Rafaela composed by fourteen accessions from different provinces of Argentina: six accessions of var. makarikariense and eight from var. coloratum. The evaluation of 152 individuals gives evidence of a wide morphological variation in the collection in traits related to forage and caryopses production; seven out of nine traits showed significant differences between var. makarikariense and var. coloratum. Based on the study of local type specimens, a morphological key to distinguish between P. coloratum varieties is provided. These results report new information about the diversity in P. coloratum in Argentina and provide valuable insights for future use of the collection as the base material of a breeding program.     

Geographical variation of solanidane aglycone glycoalkaloids in the wild potato species Solanum chacoense Bitter

The Colorado Potato Beetle is a serious pest of the cultivated potato. Natural resistance has been found in a few wild species, including Solanum chacoense Bitter, in which the resistance is attributed to the presence of leptine glycoalkaloids. Production and accumulation of these compounds within S. chacoense varies widely and appears to be inherited in a quantitative fashion, but high leptine-producing clones occur rarely. In the present study, 15 different accessions from various locations and altitudes of origin within central to northern Argentina and Paraguay were analyzed for foliar glycoalkaloid (leptine, leptinine, solanine, chaconine) content. The objective was to infer the frequency of leptine production in ecogeographically distinct S. chacoense accessions, and to ascertain any possible association between leptine levels/concentrations and ecogeographical location. Leptines were detected in 8 of the 15 accessions, and the amounts within each accession varied widely. Most of the leptine-containing accessions originated from western Argentina except two in province Córdoba in central Argentina. There was no relationship between elevational level and leptine, but there was a negative trend with total glycoalkaloids (TGA) and elevation, due to solanine and chaconine levels which decreased with increasing elevation. In addition, nine unidentified, putative glycoalkaloids were detected, in very high proportions in some individuals and accessions. This study raises interesting questions about glycoalkaloid distribution, helps provide direction for new avenues of leptine and glycoalkaloid research, and proposes a systematic, ecogeographically based method for bioprospecting genes controlling rare plant secondary compounds.     

Phaseolin diversity in wild Lima bean (Phaseolus lunatus L.) in American centres of origin

Summary Phaseolin variability was analyzed in 86 wild Phaseolus lunatus accessions, representing a wide geographical distribution from Mexico to Argentina, to determine geographical patterns of variability. The collection can be divided into two major groups. One group consists of accessions from Mexico, Central America, Cuba, Columbia, Argentina showing two Mesoamerican (M) phaseolin pattern types, already described in cultivated materials, as well as a variety of additional banding patterns. This suggests that at least two genotypes in the Mesoamerican gene pool were involved in a domestication process and spread throughout the world. The other group, consisting of wild Andean (A) forms from Northern Peru and belonging to the Andean gene pool, showed, among others, two A pattern types comparable to those found in cultivated large-seeded accessions.     

Genetic diversity and population structure of Capsicum baccatum genetic resources

Capsicum baccatum is one of five domesticated pepper species which, despite its morphological and ecological variability, has been underexploited for germplasm improvement. Utilizing a broad spectrum of domesticated and wild C. baccatum germplasm, we utilize AFLP markers to describe the species’ molecular diversity and population structure in the South American gene pool. Analysis of molecular variance (AMOVA) revealed greater genetic diversity in the wild form of C. baccatum (C. baccatum var. baccatum) than in the domesticated form of the species (C. baccatum var. pendulum). Both Bayesian and distance based clustering analysis, as well as principal coordinates analysis (PCA), concordantly demonstrated admixture/shared ancestry between wild and cultivated C. baccatum botanical varieties. Two principal genetic groups were identified in the domesticated C. baccatum accessions largely based on their geographic distribution in South America. One group was predominated by accessions from the western territories of the species’ distribution (Peru, Colombia, Ecuador, Bolivia, Chile and northwestern Argentina) and the second by accessions from the eastern regions, Paraguay and eastern Argentina). The two genetic groups overlapped in the geographic location of present-day Bolivia. The grouping pattern suggested that C. baccatum was domesticated in multiple sites and that its evolution took two lineages followed by lineage differentiation. The wild accessions most closely related to the cultigens were found in the highlands of Peru and Bolivia, which support the early hypothesis that this region is one of the domestication sites of this species. A Bayesian assignment analysis demonstrated that Brazilian wild forms of C. baccatum were genetically distant to all other accessions and made little to no contribution to the domesticated genepool. Moreover, results of clustering analysis suggested that C. baccatum likely originated from present day Paraguay. Analysis of inter-specific relationships across selected Capsicum species supported independent lineages for the two crossability groups within Capsicum, the baccatum species-complex (including C. baccatum) and the annuum species-complex (including C. annuum, C. chinense and C. frutescens). However, the results did not support taxonomic distinction of C. baccatum var. umbilicatum from C. baccatum var. pendulum. The present study provides new insights into the domestication of C. baccatum. The results will be useful for identifying accessions for crop improvement and guiding the development of in situ and ex situ conservation programs.     

Geographic variation for isozymes in cherimoya (<Emphasis Type="Italic">Annona cherimola</Emphasis> Mill.)

Cherimoya (Anonna cherimola Mill.) is a fruit tree which originated in Peru and Ecuador and is now cultivated in several subtropical areas of the world. The characterization of cherimoya cultivars at allozyme level has been previously reported, but the geographic distribution and organization of this variation have not been fully characterized. In this study, we assessed the relationships among 206 cherimoya and four atemoya (A. cherimola ×A. squamosa) cultivars based on allozyme polymorphism. We have confirmed the genetic differences between atemoya and cherimoya cultivars, and showed that cherimoya accessions from Madeira, Bolivia and Spain form homogeneous groups of cultivars. Accessions from Chile and California form heterogeneous groups, probably due to their mixed origins. Cultivars from Peru and Ecuador showed a wide range of allelic variation, as is expected for accessions from the center of origin of this species.     

Genetic characterization of guava (Psidium guajava L.) germplasm in the United States using microsatellite markers

Genetic diversity of 35 Psidium guajava L. accessions and three related species (P. guineense Sw., P. sartorianum (O. Berg) Nied. and P. friedrichsthalianum (O. Berg) Nied.) maintained at the U.S. Department of Agriculture (USDA), National Plants Germplasm System, Hilo, HI, was characterized using 20 simple sequence repeat (SSR) markers. Diversity analysis detected a total of 178 alleles ranging from 4 to 16 alleles per locus. The observed mean heterozygosity (0.2) and inbreeding coefficient (0.8) indicated a high level of inbreeding among the accessions tested. Multi-locus DNA fingerprints based on the 20 SSR loci unambiguously differentiated all accessions and revealed the absence of duplicated samples. Ordination and cluster analyses suggested that the genetic relationships between majorities of the accessions could be explained by geographic origin, mainly including tropical America, Southeast Asia and Hawaii. A Bayesian cluster analysis partitioned the accessions into two groups and the partition was largely compatible with the result of ordination analyses. Distance-based cluster analyses further indicated that accessions from same geographical region or breeding programs grouped together in spite of the inter-regional exchange of germplasm. Accessions from Southeast Asia were dominantly white fleshed, whereas accessions from tropical America and Hawaii exhibited diverse flesh colors. The results also indicated that accessions from the same region were likely derived from a small number of common ancestors or progenitors. All 20 SSRs were transferable to P. guineense, P. sartorianum and P. friedrichsthalianum, indicating a close relationship between the cultigens and wild relatives. Application of SSR markers in the USDA/Agricultural Research Service germplasm collection provides new insight into the diversity of the guava germplasm, which will be valuable in future breeding endeavors and the conservation of guava genetic resources.     

Evolution of tetraploid wheat based on variations in 5′ UTR regions of Ppd-A1: evidence of gene flow between emmer and timopheevi wheat

Previous study showed that tetraploid wheat was divided into two groups (Type AI and Type AII) based on sequences around Ppd-A1 gene (Takenaka and Kawahara in Theor Appl Genet 125(5):999–1014, 2012). That study focused on domesticated emmer wheat and used only 19 wild emmer wheats, so could not be clear the evolutional relationship between Type AI and Type AII. Here, a total of 669 accessions comprising 65 einkorn wheats, 185 wild emmer wheats, 107 hulled emmer wheats, 204 free-threshing (FT) emmer wheats, and 108 timopheevii wheats were studied by PCR assay and DNA sequencing for Type AI/AII. Type AII was an older type than Type AI because all einkorn accessions had Type AII. In wild emmer, Type AI was distributed in the northeast regions of its distribution and Type AII was found to be centered on Israel. A total of 37.4 % of hulled emmer accessions were Type AI, while 92.2 % of FT emmer accessions were Type AI. Differences in the proportion of Type AI/AII in domesticated emmer suggested a strong bottle-neck effect. We also found two MITE-like sequence deletion patterns from a part of Type AII accessions (dic-del and ara-del). Dic-del was found from only Israeli wild emmer accessions and ara-del was found from almost all timopheevii wheat accessions. Only three timopheevii accessions did not have ara-del, and one wild emmer accession and ten hulled emmer accessions had ara-del. These accessions suggested gene flow between emmer and timopheevii wheat.     

Multiple domestications of the Mesoamerican gene pool of lima bean (Phaseolus lunatus L.): evidence from chloroplast DNA sequences

The Mesoamerican (MA) gene pool of lima bean (Phaseolus lunatus L.) is widely distributed from northern Mexico to northern Argentina in its wild forms and from the southern United States to the east coast of Brazil in its domesticated forms. This broad distribution and lack of wild accessions of the MA gene pool in many areas of its natural distribution has impeded determining its center of domestication and establishing whether it has a single or multiple centers. To answer these questions, we evaluated 262 accessions of P. lunatus using two intergenic spacers of chloroplast DNA: atpB-rbcL and trnL-trnF. The data were analyzed using a maximum likelihood tree (ML), a haplotype network and two estimators of genetic differentiation (N _ST and G _ST). Nucleotide diversity (π) and haplotype (Hd) were quantified to estimate the percentage of reduction in genetic diversity (%r) as a founder effect. The ML tree and haplotype network indicated the existence of three groups (AI, MI and MII), which was supported by the high values of N _ST (0.61–0.80). Values for %r were high (58.67–60.83 %). Existence of Mesoamerican and Andean gene pools was confirmed, with two genetically and geographically distinct groups (MI and MII) within the MA gene pool. We present the first evidence for multiple origins of domestication for the MA gene pool. For MI, we propose western central Mexico as the domestication area and between Guatemala and Costa Rica for MII. We observed a founder effect in the MA gene pool as a result of domestication.     

Collection and characterization of naturalized populations of white clover (Trifolium repens L.) in Argentina

A collection formed from 53 accessions of white clover stolonswas carried out in naturalized populations from Argentina betweenparallels 26° and 37° South latitudes and 58° to 62°West longitude. Almost half of them (43%) wereobtained from grazed sites. Collected samples were grown in the fieldat Pergamino Experimental Station and compared with a local cultivar.Attributes scored or measured were petiole length, width and lengthof central leaflet, relation width/length, height, growing habit,leaf mark, stolon thickness and density, days to flowering,cyanogenesis, seed yield and winter herbage yield. There weresignificant correlations among seven pairs of characters. Allpopulations were cyanogenic within a range from 40 to 100%.Populations from grazed sites had prostrate habit and lower canopyheight than those from non grazed sites. The collection was clusteredin seven groups. Differences among groups were attributed toagroecological differences in sites of collection. Results obtainedencouraged in Argentina further collection missions for naturalizedpopulations of white clover.     

Genetic diversity of Ethiopian <Emphasis Type="Italic">Xanthosoma sagittifolium</Emphasis> (L.) Schott accessions assessed with AFLPs

Xanthosoma sagittifolium (L.) Schott originated from the American tropics. Domestication may have occurred in various places as this Araceae species is an important food source. It has been cultivated for many decades. In this study, Amplified Fragments Length Polymorphism (AFLP) markers were used to analyze the genetic relationships among 78 Ethiopian X. sagittifolium accessions, for conservation purpose. Cormels were collected from Bench-Maji, Kefa, Dawuro and Wolaita zones, representing four populations. The accessions belonged to either green (G) or purple (P) colored leaf and petiole accessions. Three different AFLP primer combinations resulted in 478 scorable bands, of which 99.2% were polymorphic. The mean Nei’s gene diversity (He) within populations was 0.35 while the G accessions featured higher He (0.38) than the P ones (0.35). The Nei’s gene diversity (He) at entire collection level was 0.38. The detected high genetic diversity may indicate the X. sagittifolium plants growing in the country may derive from diverse parental genotype stock elsewhere and/or there may be multiple introductions to the country. Low levels of genetic differentiation were detected among populations (Gst?=?0.07) and between the G and P accessions (Gst?=?0.02). Insignificant genetic and geographic correlation was revealed by Mantel test. Clustering analysis grouped 91% of the accessions together. Conservation and management of X. sagittifolium in the country should concentrate on maintaining high level genetic diversity within each population as well as at entire collection level through both ex situ and in situ conservation actions.     

Evaluation of genetic diversity in a Camelina sativa (L.) Crantz collection using microsatellite markers and biochemical traits

A genomic DNA library enriched with GA/TC repeats from Camelina sativa variety Calena has been analysed. After sequencing of about 200 randomly selected clones, approximately 60 % of them showed to contain simple or compound microsatellites with a high number of repeats. Among all microsatellite markers analysed 15 primer pairs amplified polymorphic fragments. Forty C. sativa accessions of different origin were genotyped with 15 microsatellite markers that generated 134 alleles with an average of 8.93 alleles per locus. The observed heterozygosity (Ho) among the accessions ranged from 0.0 to 0.15 with an average of 0.0370, whereas the average of expected heterozygosity (He) among accessions was 0.2769. The analysis of the average total heterozygosity (H_T = 0.651), the intrapopulation genetic diversity (H_S = 0.260), the interpopulation genetic diversity (D_ST = 0.391) and the coefficient of genetic differentiation among populations (G_ST = 0.574) demonstrated that 57.4 % of the genetic diversity is among the accessions, while 42.6 % resides within them. Phylogenetic tree of the 40 C. sativa accessions was constructed based on Nei’s genetic distance. The unweighted pair group method with arithmetic mean (UPGMA) dendrogram shows, except for CAM108 and CAM170, a clear discrimination among C. sativa accessions grouping them in five subgroups. ANOVA analysis indicates significant differences in some biochemical and agronomic parameters among the C. sativa accessions grouped according to Nei’s genetic distance. The result of the Tukey HSD test demonstrated that the A4 subgroup showed a significant higher TWS and linoleic acid (LA) content, while the subgroup A1 showed a significant higher linolenic and lower LA content compared to the remaining groups.     

Evaluation of European emmer wheat germplasm for agro-morphological,grain quality traits and molecular traits

A total of 38 emmer wheat accessions, collected in several European countries, have been evaluated using agro-morphological traits, grain quality characteristics and molecular markers. The agronomic traits evaluated were: vernalisation response, winter hardiness, date of heading and flowering, lodging, plant height at harvest and resistances against powdery mildew (Erysiphe graminis), leaf rust (Puccinia recondita) and yellow rust (Puccinia striiformis). Evaluation of quality traits has been performed measuring the protein content, gluten quality and quantity. In addition, a baking test has been executed. The assessment of genetic variability has been carried out at the molecular level utilizing 6 SSR, 6 EST-SSR markers for genes with known function, and 6 ISSR primers for a total of 107 loci analyzed. Mean 1,000 kernel weight ranged from 31.6 to 39.0 g for winter emmer accessions and from 22.9 to 42.6 for spring emmer accessions. The protein content for both winter and spring emmer was considerably affected by environment and genotype. Nearly, all the spring emmer accessions showed resistance to powdery mildew. Measurement of wet gluten content revealed high values, ranging from 37.0 to 56.6 %. The molecular analysis showed a great value of genetic distance between accessions; the expected heterozygosity and the variance between accessions indicate an equal distribution of the alleles (i.e. alleles frequency almost equal) and the presence of great variability in the analyzed material. Finally, no defined clusters were obtained considering winter versus spring accessions as well as the molecular markers did not discriminate the accessions respect their origin.     

Diversity of <Emphasis Type="Italic">Ullucus tuberosus</Emphasis> (Basellaceae) in the Colombian Andes and notes on ulluco domestication based on morphological and molecular data

Ullucus tuberosus (common name ‘ulluco’) is a popular tuber crop of Andean highlands. Until now attention has been focused on ulluco from Bolivia, Peru and Ecuador, but little is known about its diversity in Colombia. Thirty-six accessions of cultivated ulluco preserved in the Gene Bank of the Universidad Nacional de Colombia were studied to assess the genetic diversity and spatial genetic structure of Colombian ulluco. We used morphological characters, molecular markers (total proteins, isozymes and RAPDs) and ploidy level. High morphological variability, especially for tuber shape and colour characters, was found. Eight accessions from north-east Colombian Andes showed some typical character-states of wild ulluco, suggesting that they could be partially domesticated forms. Genetic analysis using RAPD markers indicated that these accessions were very similar to other cultivated ullucos belonging to the same region. The regional structure observed in isozyme and RAPD dendrograms was confirmed by AMOVA results (52.6% among-region variation) and the spatial correlogram, showing the presence of two gene pools of ulluco in Colombia. Our results and the accumulated data suggest that ulluco was introduced to Colombia at least two times. Initially, semi-domesticated forms would have come from the central Andes to north-east Colombian Andes, where the native inhabitants would have completed the domestication process. Again, fully domesticated ullucos might have been introduced to south-west Colombian Andes.     

Phenotypic biodiversity of an endemic wild pear, Pyrus mamorensis Trab., in North-Western Morocco using morphological descriptors

In this paper, we report on morphological diversity, ecology and flowering phenological records of an endangered and an endemic species of Morocco Pyrus mamorensis Trab. For this study, a survey was undertaken in North-Western Morocco (Mamora forest and Zaër region) whereby 67 accessions of P. mamorensis were sampled. A set of 33 genotypes of Pyrus spp. from the international collection INRA-Angers (France) of the genus Pyrus were also analyzed. The variability of the total of 100 accessions was assessed by twenty-six characters including fourteen qualitative and twelve quantitative traits. The results demonstrated high levels of morphological variation in the sampled accessions of P. mamorensis and established the relationships among the local germplasm using the UPGMA cluster analysis and the factorial discriminant analysis. Furthermore, we were able to distinguish three types of flowering in the Mamora forest: early, intermediate and late flowering type. Otherwise, the UPGMA classification comparing local accessions of P. mamorensis to the international collection led to the formation of four major groups showing the closest correspondence to their geographical origins: (1) The North African species represented by P. mamorensis, (2) The East Asian pea species, (3) The West Asian species and (4) The European species. These findings suggest the importance of implementing a conservation strategy preserving the genetic resources of wild pear in North-Western Morocco.     

Genetic and bioclimatic variation in <Emphasis Type="Italic">Solanum pimpinellifolium</Emphasis>

Solanum pimpinellifolium, due to its close relationship to S. lycopersicum, has been a genetic source for many commercially important tomato traits. It is a wild species found in the coastal areas of Peru and Ecuador. In this study, the genetic variation of S. pimpinellifolium was studied using the diversity found in 10 microsatellites in 248 plants spread throughout its entire distribution area, including Ecuador, which has been underrepresented in previous studies. Peruvian and Ecuadorian accessions are genetically quite differentiated. A possible cause of these differences could be the non-uniform nature of the coastal Ecuadorian and Peruvian climates, seeing as an important correlation between genetic differentiation and climate has been found. In addition, Ecuadorian and south Peruvian accessions have a lower genetic diversity and a higher homozygosity due to their higher autogamy, lower population size, and possible colonization bottlenecks. The Galápagos Islands population is an extreme case, with no diversity, likely caused by a recent colonization from the northern continental Ecuadorian region where genetically identical plants have been found. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Elena Zuriaga and José M. Blanca contributed equally to this work.     

Genetic relationships and variation in the tropical mimosoid legume Desmanthus assessed by random amplified polymorphic DNA

A number of Desmanthus spp. are being evaluated for forage potential on clay soils in the tropics and subtropics and three cultivars have already been released in Australia. These accessions have been chosen from the large number of Desmanthus accessions collected from the Americas over the last 40 years. The utilization of this genetic resource is dependent on understanding the diversity within and between species. Hence 284 accessions, representing 11 species, were analysed using RAPD markers. There was considerable polymorphism in D. virgatus, D. leptophyllus and D. pernambucanus but this was not always uniform across the geographical range of these species. There was little polymorphism in D. pubescens. Few accessions of D. acuminatus, D. paspalaceus and D. tatuhyensis were represented in the collection, but these species, which have an almost sympatric distribution in Paraguay/Uruguay/Argentina/Brazil, showed affinities to D. leptophyllus and to each other. D. pernambucanus was the only species with representatives from regions other than the Americas, suggesting that this species in particular has the capacity to colonize new regions. The analysis indicated that the non-American D. pernambucanus germplasm probably originated from Brazil.     

Genetic variation and phylogenetic relationships among Indian Citrus taxa revealed by DAMD-PCR markers

Genetic variation and phylogenetic relationships among 50 wild and cultivated accessions of 19 Indian Citrus genotypes were examined through comparison of Directed Amplification of Minisatellite DNA (DAMD) markers and morphological characters. DAMD-PCR analysis with four primers resulted in amplification of a total of 45 bands, of which 35 (78 %) were polymorphic. Morphometric evaluation using 76 morphological characters showed high level of variability ranging from 0.18 to 1.00 (avg 0.39), whereas the Jaccard’s coefficient values of genetic similarity calculated from DAMD data ranged from 0.41 to 1.00 (avg 0.68), indicating moderate genetic divergence among the accessions studied. UPGMA dendrograms generated separately from morphometric and DAMD data segregated all the accessions of Citrus into four main clusters, each containing a true basic species and their probable hybrids. The grouping of individual accessions/genotypes under respective species or cultivars in DAMD dendrogram was based purely on their genetic relationships rather than geographical origin. There was no absolute congruence between the data and dendrograms generated from morphometric and DAMD analyses. The study demonstrates the resolving power of DAMD markers for discrimination of individual genotypes of Citrus under its respective species, hybrid or cultivar groups and inferring their genetic and phylogenetic relationships as well. This is the first report on application of DAMD markers in Citrus.     

Wild melon diversity in India (Punjab State)

We present here the first comprehensive genetic characterization of wild melon accessions from northern India. The genetic diversity among 43 wild melon accessions collected from the six agro-ecological regions of the Punjab State of India was assessed by measuring variation at 16 Simple Sequence Repeat (SSR) loci, morphological traits of plant habit and fruit morphological traits, two yield-associated traits, root nematode resistance and biochemical composition (ascorbic acid, carotenoids, titrable acidity). Variation among accessions was observed in plant habit and fruit traits and wild melon germplasm with high acidity and elevated carotenoid content and possessing resistance to Meloidogyne incognita was identified in the collection. A high level of genetic variability in wild melon germplasm was suggested by SSR analysis. Comparative analysis using SSRs of the genetic variability between wild melons from the north and other melons from the south and east regions of India and also reference accessions of cultivated melon from Spain, Japan, Korea, Maldives, Iraq and Israel, showed regional differentiation among Indian melon accessions and that Indian germplasm was not closely related to melon accessions from other parts of the world. A highly drought tolerant accession belonging to var. agrestis Naud. was also identified.