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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #335000
Title: Multivariate analysis of morphological diversity among closely related Daucus species and subspecies in Tunisia

Author
item MEZGHANI, NAJLA - National Bank Of Genes
item BEN AMOR, JIHENE - Higher Institute Of Agronomic Sciences Of Chott-Mariem
item Spooner, David
item Simon, Philipp
item MEZGHANI, NEILA - University Of Quebec
item BOUBAKER, HIBA - Higher Institute Of Agronomic Sciences Of Chott-Mariem
item M'RAD NAMJI, AHMED - Higher Institute Of Agronomic Sciences Of Chott-Mariem
item RUIZ, SLIM - Higher Institute Of Agronomic Sciences Of Chott-Mariem
item HANNACHI, CHERIF - Higher Institute Of Agronomic Sciences Of Chott-Mariem
item NEFFATI, MOHAMED - Institute Of The Arid Regions
item GHRABI, ZEINEB - Tunisian National Institute Of Agronomy
item TARCHOUN, NEJI - Higher Institute Of Agronomic Sciences Of Chott-Mariem

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2017
Publication Date: 3/27/2017
Publication URL: http://handle.nal.usda.gov/10113/5851545
Citation: Mezghani, N., Ben Amor, J., Spooner, D.M., Simon, P.W., Mezghani, N., Boubaker, H., M'Rad Namji, A., Rouz, S., Hannachi, C., Neffati, M., Tarchoun, N. 2017. Multivariate analysis of morphological diversity among closely related Daucus species and subspecies in Tunisia. Genetic Resources and Crop Evolution. 64(8):2145-2159. https://doi.org/10.1007/s10722-017-0505-5.

Interpretive Summary: Wild and cultivated carrots are technically classified in the genus Daucus that includes about 20-25 species worldwide. Northern Africa represents a major center of diversity of Daucus. We assessed the diversity of the outward form of the plant (morphological diversity) from a Daucus germplasm collection of 103 accessions at the National Gene Bank of Tunisia. A prior study showed the effectiveness of fruit characters to identify several species and subspecies in the collection, but distinction between some closely related D. carota subspecies was difficult, so we here used additional characters other than the fruit such as those from the leaves, stems and flowers, assessed from a field collection in Tunisia under uniform conditions. Analyses of the data showed that there was much diversity within species, but also identified characters useful to better identify the collection into five somewhat distinct groups supporting traditional taxonomic treatments. The characters will assist in the development of identification keys for Daucus species worldwide, including the Daucus collection in the US Daucus Germplasm Bank.

Technical Abstract: The genus Daucus includes about 20-25 species worldwide. Northern Africa represents a major center of diversity of Daucus, with Tunisia thought to contain 11 species and seven subspecies. We assessed morphological diversity from a Daucus germplasm collection of 103 accessions at the National Gene Bank of Tunisia. A prior study showed the effectiveness of fruit characters to identify several species and subspecies in the collection, but distinction between some closely related D. carota subspecies was difficult. In order to resolve the taxonomic classification, we tested 34 morphological characters from leaves, stems and flowers on a field collection of 50 accessions corresponding to the different species/subspecies. The Shannon-Weaver diversity (H’) index was used to study the phenotypic diversity. The estimated H’ ranged from monomorphic for umbel type and position of involucral bracts on primary umbel to highly polymorphic for other traits. The highest (0.99) and the lowest (0.24) H’ values were recorded for flowering pattern within plants and foliage coverage traits respectively. Analysis of variance revealed significant differences among accessions for all quantitative characters. Stepwise multivariate analyses were carried out to identify the useful characters that can distinguish among species and subspecies. The study showed that qualitative characters were the best for the delimitation of the taxa by statistical analysis. Cluster analysis permitted the subdivision of the Daucus collection into five somewhat distinct groups supporting traditional taxonomic treatments. The selected characters will assist in the development of identification keys for Daucus species.