The evolutionary dynamics of ancient and recent polyploidy in the African semiaquatic species of the legume genus Aeschynomene

2016

Article référencé dans le Web of Science WOS:000379937200027

Chaintreuil Clémence, Gully Djamel, Hervouet C., Tittabutr P., Randriambanona H., Brown S.P., Lewis G.P., Bourge M., Cartieaux Fabienne, Boursot Marc, Ramanankierana H., D'Hont A., Teaumroong N., Giraud Eric, Arrighi Jean-François

New Phytologist, 2016, 211 (3), p. 1077–1091 [en ligne] ISSN 1469-8137

The legume genus Aeschynomene is notable in the ability of certain semiaquatic species to develop nitrogen-fixing stem nodules. These species are distributed in two clades. In the first clade, all the species are characterized by the use of a unique Nod-independent symbiotic process. In the second clade, the species use a Nod-dependent symbiotic process and some of them display a profuse stem nodulation as exemplified in the African Aeschynomene afraspera. To facilitate the molecular analysis of the symbiotic characteristics of such legumes, we took an integrated molecular and cytogenetic approach to track occurrences of polyploidy events and to analyze their impact on the evolution of the African species of Aeschynomene. Our results revealed two rounds of polyploidy: a paleopolyploid event predating the African group and two neopolyploid speciations, along with significant chromosomal variations. Hence, we found that A. afraspera (8x) has inherited the contrasted genomic properties and the stem-nodulation habit of its parental lineages (4x). This study reveals a comprehensive picture of African Aeschynomene diversification. It notably evidences a history that is distinct from the diploid Nod-independent clade, providing clues for the identification of the specific determinants of the Nod-dependent and Nod-independent symbiotic processes, and for comparative analysis of stem nodulation.

Sciences du monde végétal [076] ; Biotechnologies [084]

Fonds IRD [F B010067534]

fdi:010067534