The original features of rice (Oryza sativa L.) genetic diversity and the importance of within-variety diversity in the highlands of Madagascar build a strong case for in situ conservation

Radanielina Tendro, Ramanantsoanirina Alain, Raboin Louis-Marie, Frouin Julien, Perrier Xavier, Brabant Philippe, Ahmadi Nourollah. 2013. The original features of rice (Oryza sativa L.) genetic diversity and the importance of within-variety diversity in the highlands of Madagascar build a strong case for in situ conservation. Genetic Resources and Crop Evolution, 60 (1) : 311-323.

https://doi.org/10.1007/s10722-012-9837-3

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Quartile : Q2, Sujet : AGRONOMY / Quartile : Q2, Sujet : PLANT SCIENCES

Résumé : In situ conservation of crop genetic resources is widely recommended but, as yet, no methods have been developed to rank the genetic entities to preserve and the social organisations to involve. The highlands of Madagascar have been identified as a key site for rice, Oryza sativa, genetic diversity. To define conservation strategies, we performed multidisciplinary analysis of rice genetic diversity and factors shaping its distribution in the target region. Along with the indica and japonica rice subspecies of O. sativa, we confirmed the presence of an atypical rice group with a preferential habitat of 1,250-1,750 m. Spatial distribution of genetic diversity was uneven. The most determining factor of this unevenness was the altitude authorising or not the presence of different rice cropping systems and the associated types of varieties. Village and individual farmer's wealth also had a determining role on the amount of rice diversity they hosted. While molecular variance between villages in a given interval of altitude represented 16 % of the total variance, within-village variance represented more than 75 % of the total, and within-farm variance 70 % of within-village variance. This hierarchical distribution of molecular variance suggests that a small number of samples per scale (altitude interval, village and farm) could allow to capture most of the genetic diversity observed. However, within-variety diversity was also important making ex situ conservation strategies impractical and costly. Implications of the within-variety diversity are discussed in terms of adaptive advantages, evolutionary processes, and need for in situ conservation.

Mots-clés Agrovoc : Oryza sativa, conservation des ressources, conservation du matériel génétique, variation génétique, variété, distribution spatiale, région d'altitude

Mots-clés géographiques Agrovoc : Madagascar

Mots-clés complémentaires : Oryza sativa japonica, Oryza sativa indica

Classification Agris : F30 - Génétique et amélioration des plantes
P01 - Conservation de la nature et ressources foncières

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

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