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Universidade de Tras os Montes E Alto Douro (2018)

Genetic diversity and molecular responses to drought stress in Vigna unguiculata L. Walp.

Genetic diversity and molecular responses to drought stress in Vigna unguiculata L. Walp.

Titre : Genetic diversity and molecular responses to drought stress in Vigna unguiculata L. Walp.

Auteur : Carvalho, Márcia Raquel Gomes de

Université de soutenance : Universidade de Tras os Montes E Alto Douro

Grade : Doctoral in Agricultural Production Chains - From Fork to Farm 2018

Résumé partiel
Climate change is considered as one of the major threats to agriculture sustainability and biodiversity. Drought is a severe environmental stress with major impacts on plant development and productivity. The use and improvement of crops with the ability to mitigate the effects of drought will be a key step for future crop sustainability. Cowpea (Vigna unguiculata L. Walp) is a warm-season grain legume, considered as an interesting crop, due to its high adaptability to heat and drought, as well as to its association with nitrogen fixing rhizobia. As other legumes, cowpea plays a major role in the global food security by providing an affordable dietary source of nutrients mainly proteins. The thesis main objective is to contribute for a higher cowpea production in Europe, anticipating the upcoming climate changes. To achieve this goal, multidisciplinary approaches were undertaken involving field trials and molecular genetics, physiology and biochemistry approaches. Regarding genetic diversity, the morphological and agronomical characterization of 24 Iberian Peninsula cowpea genotypes was performed, thus emphasizing the high genetic diversity among genotypes. From this characterization, ten cowpea genotypes were selected and further used for determining the stability of morphological and agronomical traits in three different environments (two in Portugal and one in Spain), during two consecutive years. A high interaction between genotype and environment was found and Elvas (Portugal) revealed to have the most appropriated environment for the production of this set of cowpea genotypes. The recently developed Cowpea iSelect Consortium Array (Illumina, Inc.) provided an excellent opportunity for further determination of cowpea genetic diversity. This array contains 51,128 SNPs and was used in a set of 96 cowpea genotypes, 43 of which from Iberian Peninsula and 23 from 22 other worldwide countries. Cowpea genotypes were clustered in four subpopulations, mainly differentiated by their geographical origin, allowing the suggestion of a new hypothesis about cultivated cowpea dispersion routes. Most of Iberian Peninsula genotypes and those from other Southern European and Northern African countries were grouped in the same subpopulation, indicating a high genetic similarity among them. However, three Iberian Peninsula cowpea genotypes did not belong to this subpopulation, being two of them classified as ‘admixed’ and another from a different subpopulation.

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