Phenotypic and molecular diversity of litchi cultivars in Mauritius

Abstract

-Introduction. Litchi has gained considerable economic importance in Mauritius as it is highly prized on the local and export markets for its size, colour and flavour, although no characterisation work has been performed so far. Materials and methods. In order to optimise litchi germplasm management in Mauritius, we evaluated 34 litchi accessions from three different agroclimatic regions. Phenotypic and morphological characters, and microsatellite markers were studied. Results and discussion. Phenological observations conducted over four consecutive fruiting cycles (2003/2004 to 2006/2007) showed that accessions could be grouped into early-and late-flowering cultivars, which initiated floral panicles from June to July and July to August, respectively. The harvesting season of litchi lasted from mid-November to mid-January with early-maturing cultivars being ready for harvest in the first month of the season. Phenological characters and fruit characterisation showed that the newly-introduced cultivar 'Yook Ho Pow' had a high commercial potential. Molecular studies using twelve pairs of SSR primers showed that, despite phenotypic variations among 'Tai So' genotypes in different locations (such as percentage of chicken-tongued seeds and leaflet size), the SSR profiles of leaf samples from all the studied 'Tai So' accessions were identical, suggesting that phenotypic differences could probably be attributed to environmental conditions rather than to genetic variations. Molecular characterisation revealed different cases of synonymies and homonymies in the genotypes studied. La saison de récolte du litchi a duré de la mi-novembre à mi-janvier, les varié-tés précoces ayant été récoltables dès le premier mois de la campagne. Les caractères phéno-logiques et la caractérisation des fruits a montré que le cultivar nouvellement introduit 'Yook Ho Pow' avait un fort potentiel commercial. Des études moléculaires utilisant douze paires d'amorces de RSS ont montré que, malgré les variations phénotypiques chez les génotypes de 'Tai So' dans différents environnements (tels que le pourcentage de noyaux 'langue de poulet' ou la taille du foliole), les profils de RSS des échantillons de feuilles de toutes les accessions de 'Tai So' étudiées étaient identiques ; cela suggèrerait que les différences phénotypiques observées pourraient être attribuables aux conditions environnementales plutôt qu'à des variations génétiques. La caractérisation moléculaire a révélé différents cas de synonymies et homonymies dans les génotypes étudiés.Mauritius / Sapindaceae / Litchi chinensis / caractère agronomique / microsatellite / phénologie / RSS