The Pacific yam (<Emphasis Type="Italic">Dioscorea nummularia</Emphasis> Lam.), an under-exploited tuber crop from Melanesia

This study aims to explore the potential of Dioscorea nummularia Lam. and to gather information as a prelude to its improvement by plant breeding. After a taxonomic clarification and a review of the botanical data, its geographical areas of origin and distribution are determined. A germplasm survey conducted on nine islands of Vanuatu enabled the collection of 110 accessions corresponding to 84 cultivars. These were grouped into: (1) wild forms under domestication, (2) annual types, (3) perennial-type cultivars of D. nummularia and (4) natural interspecific hybrids with D. alata L. Within each group, remarkable morphological variation exists for stem spininess, leaf shape, emerging leaf colour, tuber shape and tuber flesh colour. Selected accessions examined for ploidy had chromosome numbers ranging from 2n = 3x = 60 to 2n = 6x = 120. Chloroplast counts conducted on stomatal guard cells confirmed the variation in ploidy levels. Eight different male cultivars were studied for pollen fertility, but <5% of the pollen grains appeared to be fertile when stained with acetocarmine. However, profuse flowering and synchrony favour pollination and result in fruit set. All accessions are resistant to anthracnose. Viruses were detected but are morphologically not discernible, with no incidence on yield. Physicochemical analyses of tubers from 16 accessions revealed that D. nummularia and interspecific hybrids have high percentages of dry matter (mean of 33.11%) and starch (82.81%). The Pacific yam could be improved through conventional hybridisation or used for interspecific crosses with related economically important species. Recommendations are made for further research.     

Meiosis and sexual fertility of autotetraploid clones of greater yam Dioscorea alata L.

Meiosis in the tetraploid (2n = 80) males of Dioscorea alata L. was investigated for the first time. During metaphase I, the chromosomes were associated mostly in 6–8 quadrivalents and the remaining ones as bivalents with no trivalents or univalents. Anaphase I and subsequent stages of meiosis were normal. The observation of quadrivalents in the tetraploids provides cytological evidence for autotetraploidy. The autotetraploid males and females were highly fertile and they produced viable seeds on artificial pollination. Pollination between diploids (2n = 40) and tetraploids (2n = 80) were also successful via embryo rescue, producing triploid (2n = 60) progenies. The discovery of fertile autotetraploids could initiate polyploidy breeding in D. alata by conventional hybridization for the first time. The reduced number of quadrivalents and the high fertility of the autotetraploids are thought to be the result of partial diploidization of meiosis. The findings also refute the assumption of the allopolyploid origin of D. alata from two putative progenitors.     

Water yam (Dioscorea alata L.) diversity pattern in Brazil: an analysis with SSR and morphological markers

Substantial progress was made in the last decade in understanding the diversity in Dioscorea species. However, most of the studies so far concentrated in the ‘yam belt in Africa’. We present a genetic diversity and structure analysis among commercial and local varieties of water yam (Dioscorea alata L.) in Brazil using microsatellite and morphological markers. Twelve microsatellite primers were used to generate DNA profiles of 72 local varieties and 17 commercial accessions of water yam collected in four different regions in Brazil. Also, four morphological traits were evaluated on individual plants under field conditions. The morphological characterization showed considerable diversity. High polymorphism was found with 100 % polymorphism observed for 11 primers and a discriminating power value of 0.92, on average. We did not observe a strong population structure among sampling regions, while most of the genetic diversity was concentrated within regions (95.9 %). Analysis of the relationship between accessions did not clearly separate the local and commercial genotypes. However, the molecular analyses of D. alata showed high intraspecific diversity in local accessions from different regions in Brazil, with the highest Shannon index value (H′ = 0.41) for the Southeast region. These results confirmed an admixture of accessions in all sampling regions, consistent with the lack of a significant correlation between geographic and genetic distances, suggesting that farmers exchanged water yam materials extensively. The genetic diversity can be explained by the result of a continuous exchange of accessions by farmers throughout Brazil.     

Spatially structured genetic diversity of the Amerindian yam (Dioscorea trifida L.) assessed by SSR and ISSR markers in Southern Brazil

Dioscorea trifida L. (Dioscoreaceae) is among the economically most important cultivated Amerindian yam species, whose origin and domestication are still unresolved issues. In order to estimate the genetic diversity maintained by traditional farmers in Brazil, 53 accessions of D. trifida from 11 municipalities in the states of São Paulo, Santa Catarina, Mato Grosso and Amazonas were characterized on the basis of eight Simple Sequence Repeats (SSR) and 16 Inter Simple Sequence Repeats (ISSR) markers. The level of polymorphism among the accessions was high, 95 % for SSR and 75.8 % for ISSR. The SSR marker showed higher discrimination power among accessions compared to ISSR, with D parameter values of 0.79 and 0.44, respectively. Although SSR and ISSR markers led to dendrograms with different topologies, both separated the accessions into three main groups: I—Ubatuba-SP; II—Iguape-SP and Santa Catarina; and III—Mato Grosso. The accessions from Amazonas State were classified in group II with SSR and in a separate group with ISSR. Bayesian and principal coordinate analyzes conducted with both molecular markers corroborated the classification into three main groups. Higher variation was found within groups in the AMOVA analysis for both markers (66.5 and 60.6 % for ISSR and SSR, respectively), and higher Shannon diversity index was found for group II with SSR. Significant but low correlations were found between genetic and geographic distances (r = 0.08; p = 0.0007 for SSR and r = 0.16; p = 0.0002 for ISSR). Therefore, results from both markers showed a slight spatially structured genetic diversity in D. trifida accessions maintained by small traditional farmers in Brazil.     

Evaluation of 28 balm and lemon balm (<Emphasis Type="Italic">Melissa officinalis</Emphasis>) accessions for content and composition of essential oil and content of rosmarinic acid

Lemon balm (Melissa officinalis L.) is a well-known aromatic and medicinal plant. Because of its proven sedative, spasmolytic and antiviral effects, it is often used in watery or alcoholic extracts for self-medication or pharmaceutical purposes. Its therapeutic effect is due to the content of essential oil and rosmarinic acid. A set of 28 balm accessions was evaluated for the variability of essential oil content and composition and the content of rosmarinic acid. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil in the first cut of the years 2009 and 2010 varied in this study in a range between 0.02 and 0.48% and in the second cut between 0.01 and 0.72%. The rosmarinic acid content of the collection ranged in the year 2009 for the first cut from 3.99 to 8.78% and in the second cut from 2.45 to 6.78%. Ploidy was determined for all accessions and two cytotypes were found: diploid 2n = 2x = 32 (15 accessions), tetraploid 2n = 4x = 64 (13 accessions). Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype germacrene D.     

Soil properties and yam yield under different tillage systems in a tropical Alfisol

In Nigeria, information is lacking regarding the most suitable tillage method in extensive yam production. Hence, five tillage methods were compared at two sites in 2008–2010 with reference to their effects on soil physical and chemical properties, leaf nutrient concentrations, growth and tuber yield of yam (Dioscorea rotundata Poir) on Alfisols at Owo (site A) and Akure (site B), south-west Nigeria. The tillage methods were: zero tillage (ZT), manual ridging (MR), manual mounding (MM), ploughing + harrowing (P + H) and ploughing + harrowing + ridging (P + H + R). P + H + R had lower soil bulk density than other tillage methods and resulted in higher leaf N, P, K, Ca and Mg and yam tuber yield. In ZT, bulk density, soil moisture content, soil organic C, N, P, K, Ca and Mg were significantly higher and temperature lower than other tillage methods. Results of multiple regressions revealed that bulk density significantly influenced the yield of yam rather than soil chemical properties. Compared with MR, MM, P + H and ZT, and averaged across years, P + H + R increased yam tuber yield by 12.3, 12.8, 34.9 and 50.7%, respectively, in site A and 12.9, 13.5, 25.2 and 44.5%, respectively, in site B. P + H + R was found to be most advantageous and is therefore recommended for yam cultivation.     

Genetic diversity analysis of yams (Dioscorea spp.) cultivated in China using ISSR and SRAP markers

Yam (Dioscorea spp.) is widely cultivated in China and many landraces are maintained by local farmers. However, there is little information available about their diversity and species identity. In this study, inter simple sequence repeat (ISSR) and sequence related amplified polymorphism (SRAP) techniques were used to assess genetic diversity within 21 yam landraces from seven cultivated populations. We observed high level of polymorphism among these landraces, specifically, 95.3 % for ISSR and 93.5 % for SRAP. Analysis of molecular variance revealed a significantly greater variation among the four yam species (40.39 %) and their populations (35.78 %) than within the populations (23.83 %). The unweighted pair group method arithmetic averages clusters and principal component analysis for 21 landraces formed four well-separated groups containing landraces of each of the four species, namely, Dioscorea opposita Thunb., Dioscorea alata L., Dioscorea persimilis Prain et Burkill, and Dioscorea fordii Prain et Burkill. The ISSR and SRAP primers were highly discriminatory among the 21 landraces; all 21 landraces could be easily differentiated using these primers. The average mean of gene flow (Nm = 0.1081) estimated from high genetic differentiation (Gst = 0.8222) suggested that gene flow among the populations was relatively restricted. The lack of genetic diversity within individual yam species suggests that it is critical to develop long-term strategies for enhancing genetic diversity within various yam species.     

Yam tuber and maize grain yield response to cropping system intensification in south-west Nigeria

Four factorial trials were conducted with yam (Dioscorea rotundata Poir.) at Ibadan, Nigeria from 2013 to 2015, investigating effects of (1) tillage (2) fertilizer (3) intercropping (4) yam plant densities. Yam tuber yields varied between years (2013: 16.44 Mg ha^?1; 2014: 10.08 Mg ha^?1; 2015 26.61 Mg ha^?1). In 2013 neither tillage nor fertilizer affected tuber yields. In 2014 tillage increased yields (+25.4%, P < 0.0001), fertilizer reduced yield (?10.5%; P = 0.0046). In 2015 tillage increased tuber yields by 8.1% (ns), fertilizer application increased yield (+17.5%, P = 0.0017). Across the years, tuber yields increased (P < 0.01) with increasing yam density with a constant increase in 2013 up to the highest density, yet yields leveled out above 14,815 plants ha^?1 in 2014 and 2015. Intercropping with maize (66,667 plants ha^?1) reduced tuber yield by 42.62% in 2013, 44.52% in 2014 and 30.68% in 2015 (P < 0.01 all years) across all yam densities. Maize grain yield was higher in sole crop in 2 years. Fertilizer increased yields in all years (P < 0.0001). Maize yield had no response to the yam densities. Ridging had a negative effect on grain yield in 2015 (?0.3 Mg ha^?1, P = 0.0002). Increasing plant density appears a safe measure to increase yam yields.     

Morphological characterization of the IVIA persimmon (Diospyros kaki Thunb.) germplasm collection by multivariate analysis

Diospyros kaki Thunb. originated in Eastern Asia, as evidenced of its culture in China as early as several centuries B.C. In the seventh century, persimmon was introduced to Japan and later, in the fourteenth century to Korea. There is no information about persimmon culture in Europe until the seventeenth century, with the spread over the world occurring in the eighteenth century. The genus Diospyros contains more than 400 species, with levels of ploidy ranging from diploid (2n = 2x = 30) up to nonaploid (2n = 9x = 135). The primary economic crop species is Diospyros kaki Thunb., which is mainly hexaploid (2n = 6x = 90) and includes hundreds of cultivars. Although a relatively recent introduction in Europe, the species has adapted well, and the genetic diversity have been expanded with culture and selection for the past 200 years in the Mediterranean basin. These locally adapted cultivars were evaluated with cultivars from Asian origin in a germplasm collection established at IVIA in Valencia, Spain. In this paper 27 cultivars from the IVIA collection were studied by multivariate analysis, and 37 variables were analyzed using a Principal Components Analysis and cluster analysis following the method UPGMA. Studies on correlations and significance among variables identified the most relevant ones, and thus provided information for a future core collection.     

Content and composition of essential oil and content of rosmarinic acid in lemon balm and balm genotypes (<Emphasis Type="Italic">Melissa officinalis</Emphasis>)

Lemon balm (Melissa officinalis L.) is used since ancient times because of its sedative, spasmolytic and antiviral effects. Its therapeutic impact is due to the content of essential oil and rosmarinic acid. A set of 68 M. officinalis genotypes was evaluated for content and composition of essential oil and the content of rosmarinic acid. For all genotypes the level of ploidy was determined. The 68 genotypes were clone plants grown and evaluated for two years at Quedlinburg. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil varied in this study in ranges from 0.03 to 0.33% for the second cut 2010 and 0.01–0.35% for the second cut 2011. The rosmarinic acid content ranged in the year 2010 from 3.67 to 7.55% and in the year 2011 from 4.92 to 8.07%. Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype β-caryophyllene oxide. Ploidy was determined for all genotypes and two cytotypes were found: diploid 2n = 2x = 32 (62 of 68 genotypes) and triploid 2n = 3x = 48 (6 of 68 genotypes).     

A novel synthetic species of Momordica (M. × suboica Bharathi) with potential as a new vegetable crop

A new synthetic species of Momordica (2n = 56) has been developed by crossing natural tetraploid Momordica subangulata subsp. renigera (2n = 56) with induced tetraploid Momordica dioica (2n = 4x = 56). The hybrid produces adventitious root tubers through which it perpetuates and propagates like its female parent and maintains its morphological characteristics in the progeny. The hybrid is naturally fertile and has the superior agronomic traits of both parents making it a good choice as a new vegetable crop. The new species is named Momordica × suboica Bharathi and described.     

Cytological characterisation of the underutilized forage crop Onobrychis viciifolia Scop. and other members of the Onobrychis genus

Sainfoin (Onobrychis viciifolia Scop.) is a perennial forage legume that possesses beneficial properties in the context of sustainable agriculture. A germplasm collection of O. viciifolia was assembled from many geographic regions, as well as a collection of Onobrychis species that might be crossed with O. viciifolia to improve its biological and agronomic properties. The objective of the present study was to obtain cytological information for a broad range of O. viciifolia varieties and related species, in order to confirm and extend previous findings. The study set was 143 accessions of O. viciifolia as well as 34 accessions of 17 other species from the Onobrychis genus. Three of the O. viciifolia accessions were diploid (2n = 2x = 14) and the remainder tetraploid (2n = 4x = 28). Chromosomes were <5 μm in length. Among the other Onobrychis species, roughly half were found to be diploid and the other half tetraploid, with two species, O. arenaria (Kit.) DC. and O. alba subsp. laconica (Orph. ex Boiss.) Hayek, including a mixture of diploid and tetraploid accessions. The basic number of chromosomes was seven, except for O. aequidentata (Sm.) d’Urv. and O. crista-galli Lam., where it was eight. The 2C value for O. viciifolia was estimated at 2.5 pg. These cytological data will be valuable as part of a pre-breeding programme aimed at the eventual production of improved O. viciifolia varieties for use in sustainable agriculture.     

Following the track of “Híbrido de Timor” origin by cytogenetic and flow cytometry approaches

The supposedly first plant of the coffee cultivar “Híbrido de Timor” (HT) was found in 1927, being denoted as HT CIFC 4106. According to different researchers, this plant originated from a natural interspecific hybridation between Coffea arabica (4x = 44) and Coffea canephora (2x = 22). From HT CIFC 4106, other HT accessions were obtained and employed to establish germplasm banks in some countries. As HT has been widely used in Coffea breeding programs, this study aimed to characterize different HT accessions with regard to ploidy, nuclear DNA content and base composition. Based on these data, the ploidy of HT CIFC 4106 was determined, suggesting that this accession is an allotriploid formed from reduced reproductive cell of C. canephora and of C. arabica. All HT CIFC 4106 plants exhibited the same 2C-value, AT% and chromosome number, showing that vegetative propagation has enabled the multiplication and germplasm conservation of this cytotype since 1927. Further five analyzed HT accessions showed distinct nuclear 2C-value and AT%. Since HT CIFC 4106 has been considered the first HT, it is suggested that aneuploid reproductive cells of this HT originated the other plants. Considering that HT accessions are used in the development of C. arabica cultivars, the findings of this study are important for the design of strategies to obtain new cultivars for breeding programs. Moreover, these data represent the first step to understand the origin and genome evolution of the HT.     

Variations in morphological and agronomic traits among Jerusalem artichoke (Helianthus tuberosus L.) accessions

Jerusalem artichoke is a diversely-utilized crop. Selection for high yield, inulin content and other economically important traits are useful for improving this crop. The objectives of the present study were to evaluate genetic variability for qualitative and quantitative traits among Jerusalem artichoke accessions and to identify different groups of accessions using morphological and agronomic traits. Seventy-nine accessions were evaluated in a randomized complete block design with two replications in the late rainy season 2008, the early rainy season 2009 and the late rainy season 2009 at Khon Kaen University agronomy farm, Thailand. Morphological and agronomic characteristics were evaluated for genetic variations. High variations were found among Jerusalem artichoke accessions for qualitative and quantitative characters, and selection for these characters is possible. High variations were observed for tuber width, number of tubers/plant, biomass, fresh tuber yield and tuber size. Correlation coefficient between fresh tuber yield and tuber size was positive and significant (0.58, P ≤ 0.01). Improvement of tuber size is a means to improve yield and tuber quality. Based on morphological and agronomic characteristics, Jerusalem artichoke accessions were clustered into four distinct groups (R² = 0.88). These groups may be used as parental material to generate progenies for further improvement of this crop. This information will enable breeders to make informed decisions about possible heterotic groups for their breeding programs and germplasm conservation.     

Effects of organic fertilizers on yam productivity and some soil properties of a nutrient-depleted tropical Alfisol

Field experiments were conducted at Owo, southwest Nigeria to select organic fertilizer treatments most suitable for sustaining high soil fertility and yam productivity on a nutrient-depleted tropical Alfisol. Eight organic fertilizer treatments were applied at 20 t ha^?1 with a reference treatment inorganic fertilizer (NPK 15–15–15) at 400 kg ha^?1 and natural soil fertility (control), laid out in a randomized complete block design with three replications. Results showed that organic fertilizers significantly increased (p = 0.05) tuber weight and growth of yam, soil and leaf N, P, K, Ca and Mg, soil pH and organic C concentrations compared with the NSF (control). The oil palm bunch ash + poultry manure treatment increased tuber weight, vine length, number of leaves and leaf area of yam by 66, 25, 21 and 52%, respectively, compared with inorganic fertilizer (NPK) and 37, 22, 19 and 44%, respectively, compared with poultry manure alone. Sole or mixed forms of organic fertilizers showed significant improvement in soil physical conditions compared with IF (NPK) and NSF (control). Synergistic use of oil palm bunch ash + poultry manure at 10 t ha^?1 each was most effective for sustainable management of soils and for improving agronomic productivity of yam.     

Molecular characterization of <Emphasis Type="Italic">Triticum militinae</Emphasis> derived introgression lines carrying leaf rust resistance

Triticum militinae Zhuk. et Migusch. belongs to timopheevii [Triticum timopheevii (Zhuk.) Zhuk.] group of wheats with 2n = 4x = 28 chromosomes and genome formula A^tA^tGG. Triticum militinae Zhuk. et Migusch. is known to carry resistance to fungal diseases including rusts and powdery mildew. Genes from timopheevii wheat can be incorporated into cultivated wheat by either direct hybridization or through development of amphiploids. Three T. militinae derived introgression lines (ILs) Triticum Militinae Derivative (TMD) 6-4, TMD7-5 and TMD11-5 were selected for the current study based on cytological stability. All three ILs showed resistance against wide spectrum of Indian pathotypes of leaf rust. More than 1200 SSR markers were used for genotyping of ILs and parental lines. The ILs showed variable and multiple introgressions in different chromosomes of A, B and D genome of wheat. The introgression points were distributed mostly in the distal regions though significant introgressions were also observed in proximal regions of some chromosomes. The extent of introgression in ILs TMD6-4, TMD7-5 and TMD11-5 was 2.8, 8.3 and 8.6% respectively. The set of ‘informative markers’ in the Molecularly Tagged Chromosome Regions (MTCR) of T. militinae origin can also be used in future for tagging of genes associated with traits of economic importance apart from leaf rust resistance. The transferability of Triticum aestivum L. SSR markers to T. militinae was 96.4% for A genome, 95.8% for B genome and 84.3% for D genome. Transferability of wheat SSR markers to T. militinae can be used in preparing genetic maps in timopheevii group of wheats.     

Physico-chemical characterisation of yam (Dioscorea alata L.) tubers from Vanuatu

The objectives of this study were: (1) to analyse the physico-chemical characteristics of 48 Dioscorea alata varieties representing a core sample of the Vanuatu national germplasm collection; (2) to relate those characteristics with the varieties eating quality; and (3) to assess the possibility of selecting varieties according to their chemotype. Overall, 331 accessions were collected from 15 different islands of Vanuatu, planted in an ex situ germplasm collection and described during 3 years. The 48 varieties included in the core sample were selected according to their island of origin, eating quality, tuber shape, tuber flesh colour and morphotype. Analyses of their tubers were made for percentage dry matter, starch, amylose, lipids, minerals, proteins, sugars and gelatinisation temperature range. Significant variation exists for each of these characteristics except for gelatinisation temperature. Varieties with good eating quality are characterised with high dry matter, starch and amylose contents. Chemotypes appear to be genetically controlled and further screening of germplasm and/or breeding will have to take into consideration these characteristics, important for farmers’ adoption.     

Antioxidant activities of dioscorin, the storage protein of yam (Dioscorea batatas Decne) tuber

Dioscorin, the storage protein of yam (Dioscorea batatas Decne) tuber (which is different from dioscorine found in tubers of Dioscorea hirsuta), was purified to homogeneity after DE-52 ion exchange column according to the methods of Hou et al. (J. Agric. Food Chem. 1999, 47, 2168-2172). A single band of 32 kDa dioscorin was obtained on a sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel with 2-mercaptoethanol treatment. This purified dioscorin was shown by spectrophotometric method to have scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical in a pH-dependent manner. There is a positive correlation between scavenging effects against DPPH (8-46%) and amounts of 32 kDa dioscorin (5.97-47.80 nmol) added in Tris-HCl buffer (pH 7.9), which are comparable to those of glutathione at the same concentrations. Using electron paramagnetic resonance (EPR) spectrometry for DPPH radical detection, it was found that the intensities of the EPR signal were decreased by 28.6 and 57 nmol of 32 kDa dioscorin in Tris-HCl buffer (pH 7.9) more than in distilled water compared to controls. EPR spectrometry was also used for hydroxyl radical detection. It was found that 32 kDa dioscorin could capture hydroxyl radical, and the intensities of the EPR signal were significantly decreased dose-dependently by 1.79-14.32 nmol of 32 kDa dioscorin (r = 0.975) compared to the control. It is suggested that 32 kDa dioscorin, the storage protein of yam tuber, may play a role as antioxidant in tubers and may be beneficial for health when people take it as a food additive or consume yam tubers.     

Genetic Diversity of the Greater Yam (<Emphasis Type="Italic">Dioscorea alata</Emphasis> L.) and Relatedness to <Emphasis Type="Italic">D. nummularia</Emphasis> Lam. and <Emphasis Type="Italic">D. transversa</Emphasis> Br. as Revealed with AFLP Markers

Amplified fragment length polymorphism markers were used to assess the genetic relatedness between Dioscorea alata and nine other edible Dioscorea. These species include D. abyssinica Hoch., D. bulbifera L., D. cayenensis-rotundata Lamk. et Poir., D. esculenta Burk., D. nummularia Lam., D. pentaphylla L., D. persimilis Prain. et Burk., D. transversa Br. and D. trifida L. Four successive studies were conducted with emphasis on the genetic relationship within D. alata and among species of the Enantiophyllum section from Vanuatu. Study 1 was carried out to select a set of polymorphic primer pairs using 11 combinations and eight species belonging to five distinct sections. The four most polymorphic primer pairs were used in study 2 among six species of the Enantiophyllum section. Study 3 focussed mainly on the genetic relationship among 83 accessions of D. alata, mostly from Vanuatu (78 acc.) but also from Benin, Guadeloupe, New Caledonia and Vietnam. The ploidy level of 53 accessions was determined and results indicated the presence of tetraploid, hexaploid and octoploid cultivars. Study 4, included 35 accessions of D. alata, D. nummularia and D. transversa and was conducted using two primer pairs to verify the taxonomical identity of the cultivars `langlang', `maro' and `netsar' from Vanuatu. The overall results indicated that each accession can be fingerprinted uniquely with AFLP. D. alata is an heterogeneous species which shares a common genetic background with D. nummularia and `langlang', `maro' and `netsar'. UPGMA cluster analysis revealed the existence of three major groups of genotypes within D. alata, each assembling accessions from distant geographical origins and different ploidy levels. The analysis also revealed that `langlang', `maro' and `netsar' clustered together with the cultivar `wael' (D. transversa) from New Caledonia. Results are discussed in the paper.