Diversity and relationships of eggplants from three geographically distant secondary centers of diversity

Eggplant (Solanum melongena L.) was domesticated in the Indo-Birmanian region, which is also the primary center of diversity for this crop. From there eggplant spread to other regions, and diversity accumulated in several secondary centers of diversity. We have assessed the diversity and relationships of 52 accessions of eggplant from three geographically distant secondary centers of diversity (China, Spain, and Sri Lanka) using 28 morphological descriptors and 12 highly polymorphic genomic SSRs. A wide variation was found for most morphological traits, and significant differences among the three centers of diversity were detected for 22 of these traits. The PCA analysis showed that eggplants from the three origins were morphologically differentiated, and accessions from each of the three secondary centers of diversity presented a typical combination of morphological characteristics. In this respect, discriminant analysis showed that accessions could be correctly classified to their origin using only six traits. The SSR characterization identified 110 alleles and allowed obtaining a unique genetic fingerprint for each accession. Many alleles were found to be private to each origin, but no universal alleles were found for any of the origins. The PCA analysis showed that the genetic differentiation among origins was less clear than for morphological traits, although the analysis of the population structure shows that accessions mostly group according to the origin, but also provides evidence of migration among the three secondary centers of diversity. The genetic diversity (HT) within each origin was high, ranging between H-T = 0.5400 (Sri Lanka) and H-T = 0.4943 (China), while the standardized genetic differentiation (G'(ST)) among origins was moderate (G'(ST) = 0.2657). The correlation between morphological and SSR distances was non-significant (r = 0.044), indicating that both data are complementary for the conservation of germplasm and breeding of eggplant. These results are relevant for the management of genetic resources, breeding programmes, and evolutionary studies of eggplant.This work was financed by the Ministerio de Ciencia e innovacion (grants AGL2009-07257 and RF-2008-00008-00-00) (http://www.micinn.es). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Hurtado Ricart, M.; Vilanova Navarro, S.; Plazas Ávila, MDLO.; Gramazio, P.; Fonseka, HH.; Fonseka, R.; Prohens Tomás, J. (2012). Diversity and relationships of eggplants from three geographically distant secondary centers of diversity. PLoS ONE. 7:41748-41748. https://doi.org/10.1371/journal.pone.0041748S4174841748

Solanum insanum L. (subgenus Leptostemonum Bitter, Solanaceae), the neglected wild progenitor of eggplant ( S. melongena L.): a review of taxonomy, characteristics and uses aimed at its enhancement for improved eggplant breeding

[EN] Solanum insanum L. (Solanaceaeae) is the wild progenitor of common eggplant (S. melongena L.) and is naturally distributed in south and southeast Asia, Madagascar and Mauritius. Despite interest in its potential for eggplant breeding it has not been studied extensively. Solanum insanum has been subjected to various taxonomic treatments, with several discussions and arguments on its delimitation as a species, due to its close similarities with the cultivated S. melongena and the wild species S. incanum L. from the Middle East and northern Africa. Solanum insanum has long been used in a variety of medicinal and culinary preparations across many different Asian ethnolinguistic groups. Limited studies carried out on its chemical composition and pharmacognostical properties coupled with ethnobotanic studies reveal that S. insanum has potential for eggplant improvement with respect to phytochemical properties of interest for human health. Further study of morphological and genetic diversity in S. insanum is essential to promote its utilization in eggplant breeding, in light of its potential to hybridize with cultivated eggplant successfully. Here we compile and review the taxonomy, phytogeography, ecology and habitat characteristics, cytology, ethnobotany, breeding and phytochemical analysis of S. insanum. A comprehensive botanical description and illustrations for S. insanum are provided. A detailed comparison of S. insanum and its closely allied species, S. melongena and S. incanum is also made. The potential of S. insanum for crop improvement and future research priorities are discussed.This work was undertaken as part of the initiative "Adapting Agriculture to Climate Change: Collecting, Protecting and Preparing Crop Wild Relatives" (http://www.cwrdiversity.org/) that is supported by the Government of Norway, managed by the Global Crop Diversity Trust with the Millennium Seed Bank of the Royal Botanic Gardens Kew, and implemented in partnership with national and international gene banks and plant breeding institutes around the world; work constructing the database underpinning Solanaceae Source was funded by the National Science Foundation (DEB-0316614 "PBI Solanum: a worldwide treatment" to SK); herbarium visits for SK and XA were funded from the SYNTHESYS Project (http://www.synthesys.info/) which is financed by European Community Research Infrastructure Action under the FP6 and FP7 "Structuring the European Research Area" Programmes.Ranil, R.; Prohens Tomás, J.; Aubriot, X.; Niran, H.; Plazas Ávila, MDLO.; Fonseka, R.; Vilanova Navarro, S.... 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Plant materials used for the study of morphological and molecular (SSR) variation of a collection of eggplants from China, Spain, and Sri Lanka.

<p>Plant materials used for the study of morphological and molecular (SSR) variation of a collection of eggplants from China, Spain, and Sri Lanka.</p

PCA relationships between morphological traits.

<p>The two first components (PC1 and PC2) of the principal components analysis account for 22.9% and 16.2% of the total variation, respectively. Results were obtained after the characterization of 52 <i>S. melongena</i> accessions from China, Spain, and Sri Lanka using 28 morphological descriptors (see text and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone-0041748-t002" target="_blank">Table 2</a>).</p

Morphological traits measured in a scale with pre-determined values of the descriptor states, and description of the scale used for the study of morphological variation in the eggplant accessions studied [4], [19], [30].

<p>Morphological traits measured in a scale with pre-determined values of the descriptor states, and description of the scale used for the study of morphological variation in the eggplant accessions studied <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone.0041748-MuozFalcn1" target="_blank">[4]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone.0041748-Prohens1" target="_blank">[19]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone.0041748-vanderWeerden1" target="_blank">[30]</a>.</p

PCA SSR-based relationships between accessions.

<p>A total of 52 <i>S. melongena</i> accessions from China (white squares), Spain (grey triangles), and Sri Lanka (black circles) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone-0041748-t001" target="_blank">Table 1</a>) were evaluated using 12 polymorphic SSRs (see text and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone-0041748-t003" target="_blank">Tables 3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone-0041748-t005" target="_blank">5</a>) and were represented on the three first components (PC1, PC2 and PC3) of the principal components analysis (22.0%, 19.1%, and 17.9% of the total variation explained by the first, second, and third principal components, respectively). Scatterplots show the projections of the accessions on the first and second principal components (above) and on the first and third principal components (below).</p

Mean and range for the traits measured in the eggplant accessions originating from China, Spain, and Sri Lanka used for the present study, and probability of the <i>F</i>-statistic, obtained from ANOVA analyses, for differences among means.

a<p>Means separated by different letters within a row are significantly different according to the Student-Newman-Keuls multiple range test at P≤0.05.</p

PCA morphology-based relationships between accessions.

<p>A total of 52 <i>S. melongena</i> accessions from China (white squares), Spain (grey triangles), and Sri Lanka (black circles) (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone-0041748-t001" target="_blank">Table 1</a>) were morphologically evaluated with 28 morphological traits (see text and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041748#pone-0041748-t002" target="_blank">Table 2</a>) and were represented on the two first components (PC1 and PC2) of the principal components analysis (22.9% and 16.2% of the total variation explained by the first and second component, respectively).</p

SSR-based estimates of genetic distances (above the diagonal) and genetic identities (below the diagonal) between different eggplant origins.

<p>SSR-based estimates of genetic distances (above the diagonal) and genetic identities (below the diagonal) between different eggplant origins.</p

Total genetic diversity (H_T), among groups genetic diversity (D_ST), within groups genetic diversity (H_S), relative magnitude of genetic differentiation (G_ST) and standarized G_ST (G’_ST), estimated from SSR data for the eggplant accessions according to their origin.

<p>Total genetic diversity (H_T), among groups genetic diversity (D_ST), within groups genetic diversity (H_S), relative magnitude of genetic differentiation (G_ST) and standarized G_ST (G’_ST), estimated from SSR data for the eggplant accessions according to their origin.</p