Carrot wild relatives in Tunisia: genetic diversity and potential for climate change adaptation

Résumé fourni par la source

Plant genetic diversity, including crops and their wild relatives, is a critical resource to address the nutritional and agronomic challenges facing global food security. Carrot (Daucus carota L. subsp. sativus) is considered one of the leading vegetable crops in the world in terms of its nutritional and economic values. Because of its geographic location and the diversity of ecosystems and climatic conditions, Tunisia is considered one of the most important biodiversity hotspots in the Mediterranean basin for the genus Daucus. Regarding this genetic diversity and the value of germplasm resources, several collecting missions around the country were undertaken by the National Gene Bank of Tunisia in collaboration with the research laboratory of Management of Horticultural Species in Organic and Conventional System, High Agronomic Institute of Chott Mariem-Tunisia and the Vegetable Crops Research Unit, USDA-USA. In total, 209 accessions have been collected and placed into medium- and long-term storage. Morphological characterization of the Daucus collection using international descriptors and common taxonomic criteria allowed the identification of 11 taxa including not only the most common wild carrot subspecies, but also two more rare subspecies, subsp. capillifolius and subsp. gummifer, as well as one of the few other 18-chromosome carrot species, D. syrticus. Ecogeographic characterization of carrot wild relatives occurring in Tunisia highlight D. syrticus and D. carota subsp. capillifolius as endemic taxa with potential adaptation to high temperatures and low precipitation, and both heat and drought stress tolerance have been reported for D. carota subsp. capillifolius in field trials. The occurrence of D. carota subsp. gummifer growing in close proximity to Mediterranean Sea suggests this taxa as a potential candidate for salt stress tolerance. The potential contribution of such traits from wild relatives has not advanced to their use in currently grown carrot cultivars but given anticipated abiotic challenges in future production agriculture, the identification of germplasm sources for these important traits is prudent.

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