Histocytological Analysis of Callogenesis and Somatic Embryogenesis from Cell Suspensions of Date Palm (Phoenix dactylifera)

• Background and Aims The date palm is a dioecious perennial species of the Arecaceae for which in vitro micropropagation is essential to ensure the renewal of palm plantations. This study presents a histocytological analysis of the traditional Mauritanian Amsekhsi cultivar beginning from the initial callogenesis and continuing up to the establishment of the cellular embryogenic cell suspensions. The formation of somatic embryos and their development into rooted plants are also described

Analysis of expressed sequence tags from oil palm (Elaeis guineensis).

This is the first report of a systematic study of genes expressed by means of expressed sequence tag (EST) analysis in oil palm, a species of the Arecales order, a phylogenetically key clade of monocotyledons that is not widely represented in the sequence databases. Five different cDNA libraries were generated from male and female inflorescences, shoot apices and zygotic embryos and unidirectional systematic sequencing was performed. A total of 2411 valid EST sequences were thus obtained. Cluster analysis enabled the identification of 209 groups of related sequences and 1874 singletons. Putative functions were assigned to 1252 of the set of 2083 non-redundant ESTs obtained. The EST database described here is a first step towards gene discovery and cDNA array-based expression analysis in oil palm. © 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved

Evolution of sex chromosomes prior to speciation in the dioecious Phoenix species

International audienceUnderstanding the driving forces and molecular processes underlying dioecy and sex chromosome evolution, leading from hermaphroditism to the occurrence of male and female individuals, is of considerable interest in fundamental and applied research. The genus Phoenix, belonging to the Arecaceae family, consists uniquely of dioecious species. Phylogenetic data suggest that the genus Phoenix has diverged from a hermaphroditic ancestor which is also shared with its closest relatives. We have investigated the cessation of recombination in the sex-determination region within the genus Phoenix as a whole by extending the analysis of P. dactylifera SSR sex-related loci to eight other species within the genus. Phylogenetic analysis of a date palm sex-linked PdMYB1 gene in these species has revealed that sex-linked alleles have not clustered in a species-dependent way but rather in X and Y-allele clusters. Our data show that sex chromosomes evolved from a common autosomal origin before the diversification of the extant dioecious species

Biotechnologies végétales, amélioration des plantes, risques et stratégies alimentaires

La micropropagation clonale du palmier à huile (#Elaeis guineensis$ Jacq.) par embryogenèse somatique est réalisée depuis plus de 20 ans par le groupe ORSTOM, CIRAD, et IDEFOR (France et Côte d'Ivoire). Les protocoles développés ont été validés par la plantation de plus de 2500 ha de palmiers régénérants dans divers pays producteurs. Les principales difficultés rencontrées lors du transfert à grande échelle des protocoles concernent : les coûts de production, qui demeurent très élevés par rapport au prix de la semence améliorée (car le procédé en cours reste long, exigeant en main-d'oeuvre et limité par des taux de prolifération relativement faibles) ; la présence de variants somaclonaux, avec une fréquence moyenne de l'ordre de 5%, dans les populations de palmiers issues d'embryogenèse somatique, les individus les plus gravement atteints pouvant présenter une stérilité totale. Ces limitations ont stimulé la mise en place de nouveaux programmes de recherche dans les domaines de la physiologie du vitroplant et de la semence, ainsi que de la biologie moléculaire. Les résultats illustrent l'importance du stade du pre-développement ainsi que des essais de comportement à grande échelle, dans les stratégies de transfert d'échelle, ce qui implique une approche fondamentale fondée sur des outils modernes de recherche. (Résumé d'auteur