Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Development of structured populations and breeding lines for trait analysis and improved varieties in Bambara Groundnut (Vigna subterranea L. Verdc)

Auteur : Gao, Xiuqing

Université de soutenance : University of Nottingham

Grade : Doctor of Philosophy (PhD) 2021

Résumé partiel
Underutilised crop species have the potential to contribute significantly to increased crop diversity and to improved food and nutrition security worldwide. Bambara groundnut [Vigna subterranea (L.) Verdc.] is an underutilised, protein-rich and self-pollinating legume, which can withstand high temperatures and drought stress, and mainly grown in semi-arid Africa. The crop is still largely grown as landraces (a mixture of genotypes) and has limited established structured populations and breeding lines due to a lack of genetic improvement activities and commercial interests.

Twelve genotypes of bambara groundnut collected from East, West and Southern Africa and Southeast Asia were used to evaluate the variation in phenotypic traits and the correlation between the observed variation and the landraces’ geographical origins in randomised complete block design (RCBD). All phenotypic traits in the twelve genotypes were significantly influenced (p < 0.01) by genotypes. Principal component analysis (PCA) showed that PC1 accounted for 97.33% of the variation and was associated with four genotypes collected from East and Southern Africa. PC2 accounted for 2.48% of the variation and was associated with five genotypes collected from East, West and Southern Africa. The variation observed within the twelve genotypes of bambara groundnut provides a breeding resource pool for use in controlled crossing to develop ideotypes with desirable phenotypic traits, i.e., high harvest index, 100-seed weight, early days to flowering or short life cycle.

Two F2 bi-parental segregating populations of bambara groundnut derived from different geographical origins, IITA-686 (Tanzania, East Africa) × Tiga Nicuru (Mali, West Africa) and S19-3 (Namibia, Southern Africa) × DodR (Tanzania, East Africa) were developed to obtain structured populations and breeding lines for genetic analysis and trait dissection. Transgressive segregation for a number of traits was observed in the two F2 bi-parental populations, as some individual lines in the segregating populations showed trait values greater or less than their parents. The variability between the two F2 bi-parental segregating populations and the negative relationship between morphological traits and yield-related traits provide resources for development of structured populations and selection of breeding lines for bambara groundnut breeding programme.

Mots clés  : bambara groundnut ; plant breeding ; genetic linkage map ; drought stress ; segregating populations

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