Najla Mezghani
Banque Nationale de Genes, Tunisia
Title: Description and analysis of phenotypic diversity in Daucus L. germplasm collection in Tunisia for species and subspecies identification
Biography
Biography: Najla Mezghani
Abstract
Statement of the problem: Daucus carota L. is a morphologically diverse species found throughout the Mediterranean regions and in many continents worldwide. Among Mediterranean regions, Tunisia is considered a center of biodiversity for Daucus and many other crops because of the diverse ecosystems and climatic conditions. Although some floristic treatments have been published in the past few decades, many of Daucus species are without an adequate description. The purpose of the present study is to analyze the patterns of phenotypic diversity in a Tunisian Daucus collection in order to elucidate the interrelationship between the conserved accessions and to verify the suitability of morphological characterization for species and subspecies identification in our collection. Plant material and methodology: A total of 120 Daucus accessions including cultivated carrot (D. carota subsp. sativus) and wild relatives from different geographic and bioclimatic regions in Tunisia were surveyed and characterized morphologically using 30 qualitative parameters related to vegetative and reproductive parts of the plant. Quantiï¬cation of variability for each character was investigated using the standardized Shannon–Weaver diversity index (H’). Diversity was established by multiple correspondence analysis and cluster analysis. Findings: The estimated H’ index 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. Multivariate analysis and cluster analysis permitted the subdivision of the Daucus collection into 9 distinct groups supporting traditional taxonomic treatments with a distinction of cultivated carrot from the closely related wild species. Conclusion: Morphological data provide considerable information that is useful to distinguish species and subspecies in the difficult Daucus genus. Our results serve as a basis for verification and possible reidentification of Daucus accessions in Tunisia and elsewhere.