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.     

Genetic diversity and similarity of pear (<Emphasis Type="Italic">Pyrus</Emphasis> L.) cultivars native to East Asia revealed by SSR (simple sequence repeat) markers

Simple sequence repeat (SSR) markers were used to assess genetic diversity and relationship of Pyrus L. cultivars native mainly to East Asia. A total of 168 putative alleles were generated from six primer-pairs (BGA35, KU10, BGT23b, NH004a, NH011b and NH015a). All the SSR markers showed a high level of genetic polymorphism with a mean of 28 putative alleles per locus and the heterozygosity of 0.63. The Dice’s similarity coefficient between cultivars ranged from 0.02 to 0.98 and Occidental pears generally had low affinities to Asian pears. Ten major groups were generated from all the accessions by UPGMA clusters analysis. Chinese sand pears consisted of four groups with Chinese white pears and Japanese pears, of which Chinese sand pears occurred in all four groups, presenting a large genetic diversity, Chinese white pears were included in three groups, and Japanese pears only fell into one group. In the dendrogram, Chinese sand pears and Chinese white pears did not form discrete group, even subgroups. Some Japanese pear cultivars had high affinities to Chinese sand pear cultivars. These findings supports the authors’ previous viewpoints of Chinese white pears as a variety or an ecotype of Chinese sand pears (P. pyrifolia var. sinensis (Lindley) Y. Teng et K. Tanabe) and the progenitor of Japanese pears coming from China. Cultivars of P. ussuriensis Maxim. were clustered together with one clone of P. hondoensis Nakai et Kikuchi, a relative species of P. ussuriensis. Cultivars of P. communis L. and other Occidental species formed three independent groups and were distant from most Asian pears, except for P. betulaefolia Bge.     

Diversity of aroma patterns in wild and cultivated <Emphasis Type="Italic">Fragaria</Emphasis> accessions

Plant breeders are interested in strawberry species as donors of volatile compounds in breeding programmes because of the diversity and intensity of wild strawberry aroma. Therefore, the topic of this paper is the prospective analysis of four accessions of four wild strawberry accessions in comparison to a standard cultivar of Fragaria × ananassa Duch. by using human sensory, gas chromatography mass spectrometry (GCMS) and gas chromatography–olfactometry (GCO). The wild species have higher aroma intensities compared with the cultivated one. The flavour quality differs significantly. Semiquantitative GC analysis revealed that F. × ananassa cv. ‘Elsanta’ has the lowest content of volatile compounds whereas Fragaria moschata L. ‘Cotta’ has the highest. The aroma impressions, measured by GCO, support the findings of GCMS analyses. The nasal impact frequency (NIF)-profiles of the wild types are more manifold and of higher intensities than those of the cultivated F. × ananassa cv. ‘Elsanta’ which corresponds with the overall flavour impression when tasting the fresh fruits.     

A wide range of genetic diversity in pear (<Emphasis Type="Italic">Pyrus ussuriensis</Emphasis> var. <Emphasis Type="Italic">aromatica</Emphasis>) genetic resources from Iwate,Japan revealed by SSR and chloroplast DNA markers

Iwateyamanashi (Pyrus ussuriensis var. aromatica) is one of the Pyrus species which grows wild in Japan. The number of Iwateyamanashi trees has been decreasing, so conservation and evaluation is urgently needed. Over 500 accessions of Pyrus species collected from Iwate in northern Tohoku region are maintained at Kobe University as an Iwateyamanashi germplasm collection. In order to investigate the genetic diversity, five SSR (simple sequence repeat) markers, developed from Japanese and European pear were examined for 86 Pyrus individuals including 58 accessions from Iwate. These SSR loci could discriminate between all the Iwate accessions except for 10 that bear seedless fruit, as well as determine the genetic diversity in Iwateyamanashi germplasms. High levels of variation were detected in 41 alleles and the mean observed heterozygosity across 5 loci was 0.50 for the Iwate accessions. Seedless accessions sharing identical SSR genotype with the local pear variety “Iwatetanenashi” were supposed to have been propagated vegetatively via grafting. In an UPGMA phenogram, Japanese pear varieties (P. pyrifolia) were clustered into two groups with some Iwate accessions including seedless ones. Another 38 Iwate accessions were not clustered clearly, and there was no clear relationship between these accessions and geographical distribution or morphological characters. Allele frequency revealed that the Iwate accessions were genetically more divergent than the Japanese pear varieties. Most Japanese pears possessed a 219 bp deletion at a spacer region between the accD and psaI genes in the chloroplast DNA (cpDNA), but other Pyrus species and two Iwateyamanashi trees did not. In the Iwate accessions, 79.3% had a deletion type cpDNA and others had a standard type cpDNA without deletion. These results are indicative of the wide range of genetic diversity in the Iwate accessions which include Japanese pear varieties. A combination of SSR and cpDNA analyses revealed high heterogeneity in Iwateyamanashi and coexistence of Iwateyamanashi and hybrid progeny with P. pyrifolia. These could be reasons for the wide range of continuous morphological variation described previously.     

Aspects of the evolution of <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> L. and the status of the United States <Emphasis Type="Italic">Nicotiana</Emphasis> Germplasm Collection

The genus Nicotiana is a member of the nightshade (Solanaceae) family, and is comprised of 70 currently recognized, naturally occurring species. Genetic variability within N. tabacum L., the species of primary economic importance, was likely affected by several genetic bottlenecks. Nicotiana tabacum is a classic amphidiploid that arose after chance interspecific hybridization between N. sylvestris Spegazinni et Comes and a member of section Tomentosae, likely N. tomentosiformis Goodspeed, N. otophora Grisebach, or an introgressive hybrid between the two. Only a fraction of the genetic variability that existed in the diploid progenitor gene pools probably entered into N. tabacum. Genetic drift, coupled with natural and human selection, subsequently resulted in the formation of narrow genetic pools corresponding to modern commercial market classes. Genetic variability in Nicotiana has gained increased attention in recent years because of investment in Nicotiana genomics research, interest in development of tobacco products with reduced harm characteristics, and concentration on using Nicotiana species for plant-based production of commercially useful proteins. A storehouse of genetic diversity for N. tabacum is available in approximately 1,900 accessions maintained by the United States Nicotiana Germplasm Collection. Seeds of 224 accessions representing 59 wild Nicotiana species are also maintained. The collection is currently maintained by North Carolina State University and is part of the United States National Plant Germplasm System (NPGS). The collection’s curator satisfies hundreds of seed requests made annually by scientists using Nicotiana germplasm for basic biological investigations and by researchers in the area of applied tobacco science.     

Phenotypic diversity in the pigeonpea (<Emphasis Type="Italic">Cajanus cajan</Emphasis>) core collection

The pigeonpea core collection developed at ICRISAT genebank consists of 1,290 accessions from 53 countries. The core collection, which includes selected lines in extra early, early, medium and late maturity groups was evaluated for 18 qualitative and 16 quantitative characters during the 2004 rainy season, to assess the phenotypic diversity and determine the relative importance of different characters in evaluating pigeonpea germplasm accessions. The four maturity groups differed significantly for all characters under study. The medium maturity group showed significantly higher mean number of primary, secondary and tertiary branches, number of racemes, pod bearing length, pods per plant, shelling percent and plot seed yield. Late maturity group showed significantly higher mean for leaf size, plant height, pod length, seeds per pod and 100-seed weight, indicating this group as a good source of vegetable pigeonpea. Significant positive correlations were found between number of secondary branches and pods per plant in extra early group (r = 0.756), late maturity group (r = 0.776) and entire core (r = 0.728) and between number of racemes and pods per plant in all maturity groups and entire core. Principal coordinate and principal component analysis showed that seven qualitative and nine quantitative traits were important in explaining multivariate polymorphism. The Shannon–Weaver diversity index (H′) varied for different maturity groups and traits. Phenotypic diversity, averaged over all the 16 characters, increases from extra early group (0.36 ± 0.04) to late maturity group (0.42 ± 0.04) suggesting that medium and late maturity groups have greater diversity compared to extra early and early maturity groups.     

Seed inoculation with <Emphasis Type="Italic">Bacillus</Emphasis> spp. improves seedling vigour in oil-seed plant <Emphasis Type="Italic">Jatropha curcas</Emphasis> L.

Jatropha (Jatropha curcas L.) is a non-edible oil-seed plant with adaptability to marginal semi-arid lands and wastelands. The Indian Government is promoting jatropha to reduce dependence on the crude oil and to achieve energy independence by the year 2012, under the National Biodiesel Mission. Selected strains of Bacillus spp., either supplemented with or without chitin, were tested for their ability to promote growth of jatropha seedlings in pot culture studies. The strains supported growth of jatropha seedlings up to 42 days after sowing. Among all strains, Bacillus pumilus (IM-3) supplemented with chitin showed over all plant growth promotion effect resulting in enhanced shoot length (113%), dry shoot mass (360%), dry root mass (467%), dry total plant mass (346%), leaf area (256%), and chlorophyll content (74%) over control. Treating seeds with strain IM-3 without chitin resulted in enhanced dry shoot mass (473%), dry total plant mass (407%), and chlorophyll content (82%). However, Bacillus polymyxa (KRU-22) with chitin supported maximum root length (143%). Either strain IM-3 alone or in combination with other promising strains could be promoted further for enhanced initial seedling growth of jatropha.     

Analyses of the seed protein contents on the cultivated and wild buckwheat <Emphasis Type="Italic">Fagopyrum esculentum</Emphasis> resources

The seed protein contents of 179 accessions belonging to ten species of genus Fagopyrum were determined by means of the Kjeldahl method. The results indicated that there are significant differences of seed protein content among different accessions within the same species. The average protein content of F. esculentum is 12.94%, ranging from 8.81–18.71%, and the protein content of Sibano is the highest, up to 18.71%, Gantian 1 the lowest with 8.81%. The average protein content of tartary buckwheat is 12.17%, with the range from 7.82–18.94%, and the protein content of cultivated tartary buckwheat Qianku 2 is the highest (18.59%), and that of Ganku 1 (7.82%) the lowest. Moreover, there are significant differences of seed protein content among different buckwheat species and between the different buckwheat types (between common buckwheat and tartary buckwheat, between the diploid and the tetraploid, between the cultivated and the wild, and between the big-achene group and the small-achene group). The average seed protein content of F. giganteum is the highest in all tested species, up to 17.81% with the range of 13.91–21.27%, and that of F. callianthum the lowest, only 8.31%. This study was financed by the Natural Science Foundation of China (30270852, 30471116), Program for New Century Excellent Talents in University (NCET-2004-0913), Guizhou Key International Cooperation Project (Qianke Hewai G Zi 2005#400108), Guizhou Oversea Talent Project (Qianren Xiangmu Zizhu Hetong 2004#02), and Key Project of Students in Guizhou Normal University (GNU-SP-2005-SJXY-A01)     

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

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

Capturing genetic diversity of wild populations for <Emphasis Type="Italic">ex situ</Emphasis> conservation: Texas wild rice (<Emphasis Type="Italic">Zizania texana</Emphasis>) as a model

Genebanks complement other conservation programs because they preserve genetic diversity needed for future breeding and restoration. We evaluated efficiency of capturing genetic diversity, using endangered Zizania texana (Texas wild rice) as a model for plants with recalcitrant seeds. This perennial aquatic grass is restricted to 4 km of the San Marcos River in Texas. An early conservation collection included plants from stands throughout the river, based on the assumption stands would be unique genotypes. Using microsatellite markers, we found that genetic diversity was concentrated in five of 15 large, demographically stable stands; 96 stands smaller than 2 m² contributed no unique alleles. High heterozygosity and few duplicate genotypes suggested that sexual reproduction occurs more often than presumed. Simulations of stratified sampling of large stands captured all alleles in only 45 individuals, while random sampling along the river captured much less diversity. The early conservation collection captured as much diversity as expected from random sampling. Texas wild rice stands resemble a mainland-island metapopulation; our analyses suggest that stratified sampling maximizes genetic diversity for this population dynamic. Demographic and genetic information is important for validating the design of efficient ex situ collections and guiding in situ conservation.     

RAPD and ISSR fingerprinting in cultivated chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) and its wild progenitor <Emphasis Type="Italic">Cicer reticulatum</Emphasis> Ladizinsky

Detection of genetic relationships between 19 chickpea cultivars and five accessions of its wild progenitor Cicer reticulatum Ladizinsky were investigated by using RAPD and ISSR markers. On an average, six bands per primer were observed in RAPD analysis and 11 bands per primer in ISSR analysis. In RAPD, the wild accessions shared 77.8% polymorphic bands with chickpea cultivars, whereas they shared 79.6% polymorphic bands in ISSR analysis. In RAPD analysis 51.7% and 50.5% polymorphic bands were observed among wild accessions and chickpea cultivars, respectively. Similarly, 65.63% and 56.25% polymorphic bands were found in ISSR analysis. The dendrogram developed by pooling the data of RAPD and ISSR analysis revealed that the wild accessions and the ICCV lines showed similar pattern with the dendrogram of RAPD analysis. The ISSR analysis clearly indicated that even with six polymorphic primers, reliable estimation of genetic diversity could be obtained, while nearly 30 primers are required for RAPD. Moreover, RAPD can cause genotyping errors due to competition in the amplification of all RAPD fragments. The markers generated by ISSR and RAPD assays can provide practical information for the management of genetic resources. For the selection of good parental material in breeding programs the genetic data produced through ISSR can be used to correlate with the relationship measures based on pedigree data and morphological traits to minimize the individual inaccuracies in chickpea.     

Production and analysis of reciprocal hybrids between <Emphasis Type="Italic">Asparagus officinalis</Emphasis> L. and <Emphasis Type="Italic">A. schoberioides</Emphasis> Kunth

The genus Asparagus (Asparagaceae) encompasses 100–300 species, including the important vegetable crop, A. officinalis (garden asparagus). Previous attempts to hybridize garden asparagus with A. densiflorus (Kunth) Jessop, with the aim of introducing disease resistance, were unsuccessful because of the failure of endosperm development. In the present study, reciprocal interspecific hybrids between garden asparagus and A. schoberioides Kunth were generated by hand pollination. The F1 hybrids were analyzed by using both morphological and molecular techniques. This is the first report describing the production of an interspecific hybrid between garden asparagus at the diploid level (2n = 2x = 20) and its diploid (2n = 2x = 20) wild relative, A. schoberioides. Morphological characteristics of candidate hybrids were a mixture of those found in the parents, and cytological and RFLP analyses confirmed that morphologically intermediate plants were indeed diploid hybrids of those two species. In other words, post-zygotic isolation is not complete between phylogenetically distinct these two species. Our results suggest that other Asparagus species may be capable of hybridizing with A. officinalis and that introducing wild characters through interspecific hybridization may offer advantages for breeding for novel traits. Takuro Ito and Toshinori Ochiai authors are contributed equally to this work     

Analysis of Genetic Variation Among Accessions of <Emphasis Type="Italic">Pueraria montana</Emphasis> (Lour.) Merr. var. <Emphasis Type="Italic">lobata</Emphasis> and <Emphasis Type="Italic">Pueraria phaseoloides</Emphasis> (Roxb.) Benth. based on RAPD Markers

Pueraria montana var. lobata and P. phaseoloides originating from tropical Asia and parts of Oceania are ecologically and economically important legumes that are used as green manure, cover crop or forage plants. Conservation and use of plant genetic resources require an understanding of the extent and distribution of genetic diversity in any given region. In this study, genetic variation of five P. montana var. lobata and 16 P. phaseoloides accessions was analysed developing a random amplified polymorphic DNA (RAPD) marker methodology for Pueraria species and thereby creating basic data for follow-up research and the development of conservation strategies. Seeds were collected from native populations in Bac Kan Province, a mountainous region in Northeast Vietnam. P. montana var. lobata presented a high level of variation with 54.3% of the detected markers being polymorphic, whereas P. phaseoloides exhibited an intermediate to high level of variation (45.5%). The P. montana var. lobata accessions clustered in congruence with their eco-geographical origin. For P. phaseoloides no correspondence between sampling sites and genetic differentiation was found. Inter-population differentiation was measured as Jaccard's similarity coefficient (JSC). Mean JSC amounted to 0.35 in P. montana var. lobata and 0.52 in P. phaseoloides. Results are compared to other genetic studies of herbaceous legumes and conservation strategies are suggested.     

Evaluation of genetic diversity in Turkish melons (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.) based on phenotypic characters and RAPD markers

The genetic relationships among 56 melon (Cucumis melo L.) genotypes collected from various parts of Turkey were determined by comparing their phenotypic and molecular traits with those of 23 local and foreign melon genotypes to investigate the taxonomic relationships and genetic variation of Turkish melon germplasm. Sixty-one phenotypic characters and 109 polymorphic RAPD markers obtained from 33 primers were used to define the genetic similarity among the melon genotypes by dendrograms or two and three dimensional scaling. There were high correlations (r ≥ 0.97) among the four resulting matrices used in molecular characterization. The correlations between phenotypic (Euclidean) and molecular Euclidean, Jaccard, Simple matching, and Nei analyses were r = 0.41, r = −0.40, r = −0.43 and r = −0.40, respectively. Related genotypes or genotypes collected from similar regions were partitioned to similar clusters. Both analyses (phenotypic and molecular) indicated that non-sweet melon types were dissimilar from sweet types and diversity of Turkish melon genotypes was higher than that of sweet foreign cultivars examined, but similar to that of the reference accessions employed. It was also observed that sweet Turkish melon genotypes belonging to groups inodorus and group cantalupensis were highly variable and could have intermated or have crossed with other non-sweet types.     

Agromorphological and molecular variability in the genus <Emphasis Type="Italic">Sesbania</Emphasis>

Green manuring especially in rice wheat cropping systems of many tropical and subtropical countries is regaining importance due to increased fertilizer costs and environmental considerations. Many species of Sesbania genus have been reported as potential green manure crops. The genus is not well characterized and there is a lot of ambiguity over the nomenclature and classification of the species of this genus. A pilot study based on agro-morphological and molecular data was conducted to examine the interspecific and intraspecific variability in the selected species of Sesbania genus that were collected from diverse geographical locations and are recommended or traditionally used as green manures. The study revealed a lot interspecific variability at both morphological and molecular level. It was also shown that species-specific genetic markers could be generated. The potential use of such markers in Sesbania breeding program is discussed. The study also emphasizes the utilization of molecular profiling for proper identification and classification of the species of this genus. In addition, various limitations in breeding and utilization of Sesbania as a green manure crop and the potential of a radiation induced late flowering mutant (Trombay Sesbania rostrata-1; TSR-1) for crop improvement is also discussed.     

Diversity among landraces of Indian snapmelon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">momordica</Emphasis>)

Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew, Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base of melon germplasm available with the scientific community. N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors.     

Ex situ collections of cultivated flax (<Emphasis Type="Italic">Linum usitatissimum</Emphasis> L.) and other species of the genus <Emphasis Type="Italic">Linum</Emphasis> L.

An overview of ex situ collections of cultivated flax (Linum usitatissimum L.) and 53 other species of the genus Linum L. is presented. The names of 33 genebanks in 23 countries preserving Linum germplasm and the species preserved at these places are provided. World genebanks engage in ex situ preservation of about 48,000 accessions of cultivated flax (Linum usitatissimum). However, possibly only 10,000 accessions of these are unique. Of the ca. 200 species of the genus Linum, other than L. usitatissimum, 53 are reported to be represented in the world’s ex situ collections with a total of about 900 accessions. Of these, 279 accessions alone refer to the wild progenitor of cultivated flax, Linum bienne Mill. However, L. bienne from the region of origin of cultivated flax is rarely represented in genebank collections. References to publications describing the techniques for ex situ conservation and the infraspecific variation of cultivated flax are made. It is suggested that taxonomic species delimitation within the genus Linum is in need of clarification and that the variation in Linum species for ornamental use or use in breeding is investigated.     

Genetic basis of species differentiation between <Emphasis Type="Italic">Coffea liberica</Emphasis> Hiern and <Emphasis Type="Italic">C. canephora</Emphasis> Pierre: Analysis of an interspecific cross

The phenotypic and genetic differentiation between the two related Coffea species (C. liberica Hiern and C. canephora Pierre) was examined. These species differed markedly in terms of leaf, inflorescence, fruit and seed characters. A genetic map of the interspecific cross Coffea liberica × C. canephora was constructed on the basis of 72 BC1 hybrids. Eighty-three AFLP markers, four inter simple sequence repeats (ISSR) and five microsatellites corresponding to Coffea liberica species-specific markers were mapped into 16 linkage groups. The total length of the map was 1502.5 cM, with an average of 16.3 cM between markers and an estimated genome coverage of 81%. The two species were evaluated relative to 16 quantitative traits and found to be significantly different for 15 of them. Eight QTLs were detected, associated with variations in petiole length, leaf area, number of flowers per inflorescence, fruit shape, fruit disc diameter, seed shape and seed length. Results on segregation distortion and the under-representation of particular markers were interpreted in terms of genome differentiation. The implications for the introgression of QTLs involved in advantageous morphological traits (number of flowers per inflorescence, fruit and seed shape) are discussed.     

Isozyme Variation in <Emphasis Type="Italic">Passiflora</Emphasis> Subgenus <Emphasis Type="Italic">Tacsonia</Emphasis>: Geographic and Interspecific Differentiation Among the Three Most Common Species

In a general study of banana passion fruit genetic resources, diversity was analyzed in the two main cultigens, P. tripartita var. mollissima and P. tarminiana, and their closest wild relative, P. mixta, scoring isozyme bands (IDH,PGM,ACP,PGD,DIA,andPRX) on288 plants from 31 accessions. Polymorphismandallelic richness, Nei diversity indices, and neighbor joining clustering showed that variation was poor in the cultigens in northern and central Colombia, while P. mixta appeared much more polymorphic. The populations of P. tripartita var. mollissima and P. mixta from southern Colombia and Ecuador show higher diversity values and are clearly differentiated from those of central and northern Colombia. This geographic component of variation is even stronger than the interspecific one, which suggests a close relation and a regular gene flow between these two species. In contrast, all the accessions of P. tarminiana constitute a clearly differentiated group, even if some introgression with P. tripartita var. mollissima is also suspected. The high variation observed in the southern region indicates the proximity of a center of diversity for banana passion fruit and collecting in Ecuador, Peru and Bolivia is recommended. The high diversity of P. mixta and the evidence of gene flow with P. tripartita var. mollissima constitute a favorable context for the implementation of in situ conservation strategies.