Diversité génétique. Atriplex
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Atriplex halimus species in Morocco (North Africa). Genetic diversity

The genus Atriplex  (Chenopodiaceae) contains various species distinguishable by different morphology, biological cycle and ecological adaptations (Le Houérou, 1992). They have different genetic diversity. Because of their favourable crude protein content, many species of Atriplex are excellent livestock fodder during off season periods when grasses are low in feed value.

Atriplex halimus. Genetic diversity in Morocco

Le genre Atriplex. Diversité génétique au Maroc (Fr)

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Atriplex species

Among the species of Atriplex in North Africa, Atriplex halimus L., a perennial shrub, is found in semi-arid and arid environments. In Morocco, Atriplex halimus is widely distributed as a wild species. Since its substantial increase in the protein content when irrigated with saline water in south Morocco, this halophyte is considered as a valuable source of forage. Many species are represented in the genus Atriplex, such as Atriplex nummularia, Atriplex lentiformis, Atriplex amnicola, ..

Atriplex. species

Genetic diversity in Atriplex halimus L. as revealed by isoenzyme markers. This genetic diversity was essentially explained by the within population component. The between populations differentiation accounted for 8% of the whole diversity (FST, averaged over all loci, is 0.08).

Genetic diversity in Morocco

Based on polyacrylamide gel electrophoresis, Nine natural populations of Atriplex halimus  L. (1-9), collected in different regions of Morocco, were studied for their genetic diversity using isoenzyme polymorphism of the highly active enzyme systems:

esterases (EST), acid phosphatases (ACP) and glutamate oxaloacetate transaminase (GOT).

Different allozyme frequencies from 7 different loci were obtained for all populations of this halophyte species. High levels of genetic diversity were revealed. The mean number of alleles per locus (A = 1.9-2.0), the percentage of polymorphic loci (P = 71.4-85.7) and the mean expected heterozygosity (He = 0.339-0.385) showed an important variability in all populations.

For details see published work: HADDIOUI & BAAZIZ. 2001. Euphytica 121, 99-106.

The relationships among the 9 populations were inferred from the Nei's genetic distances. Four major groups were formed. The northern population 'Tanger' (9), forming a unique group, was highly divergent from the other groups. It appeared that the genetic distance between all groups was related to the geographic distance that separates them.

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Genetic diversity of Atriplex species introduced to semi-arid zones of Morocco, as revealed by RAPD and ITS analyses

S. BOUDA 1,2, F.F. DEL CAMPO 3, A. HADDIOUI 2, M. BAAZIZ1* & L.E. HERNÁNDEZ 3
1 Laboratoire de Biochimie et Biotechnologies des Plantes, Université Cadi Ayyad, Faculté des Sciences-Semlalia, B.P. 2390, 40000, Marrakech, Moroc
2Laboratoire de Génétique et Biotechnologies Végétales, Université Cadi Ayyad, Faculté des Sciences et Techniques de Béni Mellal, B.P. 523, Béni Mellal, Maroc
3Laboratorio de Fisiología Vegetal, Departamento de Biología, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, España
* Corresponding author: baaziz@ucam.ac.ma, Tel: 21224434649, Fax: +21224437412

Abstract

It has been studied, by using RAPD markers and sequences of nrDNA ITS region, the genetic diversity and phylogenetic relationships of seven species of the genus Atriplex (A. amnicola, A. canescens, A. halimus from Morocco (MAR) and from USA, A. lentiformis, A. nummularia, A. semibaccata and A. undulata). As a whole, the results show a high genetic diversity among the species and a monophyletic nature of Atriplex. The biggest diversity was obtained by RAPDs. According to RAPD markers, two major groups can be distinguished, one formed by A. semibaccata and A. undulata, the least similar to the rest of species. A. lentiformis was closer to A. halimus. Phylogenetic analysis confirmed the divergence of A. semibaccata from all species and the closeness of A. lentiformis to A. halimus. The intraspecies variability was also high, as 39 individual RAPD haplotypes were obtained by analyzing 40 plants. Both RAPDs and ITS analyses revealed with some exceptions, that all individuals from one species grouped together. RAPDS turn out to be more appropriate than ITS to differentiate Atriplex species. The two markers gave rise to the same species relationships, but to a different structure of the Atriplex genetic diversity.

See: BOUDA, S., DEL CAMPO, F., HADDIOUI, A., BAAZIZ, M. & HERNÁNDEZ, E.E. 2008. RAPD and ITS-based variability revealed in Atriplex species introduced to semi-arid zones of Morocco. Scientia Horticulturae 118, 172-179



Genetic diversity of Atriplex genus in Morocco as revealed by RAPD markers

Abstract
Atriplex halimus L. (Chenopodiaceae) is a monoecious C4 perennial shrub native to the Mediterranean Basin, used as fodder shrub for livestock and useful for rehabilitation of degraded rangelands. To assess the levels and patterns of genetic diversity of this species, 99 samples of 11 populations collected throughout the natural range in Morocco plus 9 samples obtained from one population originating from USA, were analyzed using RAPD. 157 reproducible amplified bands were obtained with 17 primers. Out of 157 bands amplified, 146 (93%) were polymorphic, and only 11 (7%) monomorphic. Global AMOVA (Analysis of Molecular Variance) showed that the most genetic variation was within populations (66.57), with the reminder occurring between populations (33.43%). Hierarchical AMOVA analysis revealed that variation among regions (Morocco versus USA) accounted only for 5.87% of the total genetic variation, suggesting that there is not a significant genetic differentiation of populations located at the opposite sides of the Atlantic Ocean. The present genetic structure could have arisen by a combination of genetic drift effect and limited level of gene flow (0.50). The genetic diversity maintained by the species (0.238) was somewhat higher in comparison to other species with similar life histories and ecological traits. A neighbour- joining dendrogram based on Dice's coefficient resolved five major groups of populations correlated in part with bioclimatic type. Nevertheless, Geographic distance did not explain the genetic differentiation among populations (r = 0.103, P = 0.646). The data obtained in this study should have important implications for the conservation and management strategies of genetic variation of Atriplex halimus in Morocco.

Genetic diversity characterization of genus Atriplex using RAPD markers
S. Bouda, A. Haddioui, M. Baaziz, F.F. Del Campo & L.E. Hernández
- Atriplex. Biodiversité du genre Atriplex et diversité génétique de ses espèces. Doctorat Thesis, Said Bouda, May 5, 2012, Marrakech, Morocco


Selected publications, communications and thesis

BOUDA, S., DEL CAMPO, F., HADDIOUI, A., BAAZIZ, M. & HERNÁNDEZ, E.E. 2008. RAPD and ITS-based variability revealed in Atriplex species introduced to semi-arid zones of Morocco. Scientia Horticulturae 118, 172-179.

HADDIOUI, A. & BAAZIZ, M. 2006. Effect of salinity on seed germination and early growth of five natural populations of Atriplex halimus L. in Morocco. Physiol. Mol. Biol. Plants 12, 247-251.

BOUDA, S., HADDIOUI, A., BAAZIZ, M., DEL CAMPO, F. F., HERNANDEZ, L. E. 2006. Genetic diversity characterization of genus Atriplex usinf RAPD markers.. In Actes du deuxième congrès International de Biochimie, Baaziz, M., Hakkou, A. & Serghini, A. ed. p :64-68.

HADDIOUI A. & BAAZIZ, M. 2001. Genetic diversity of natural populations of Atriplex halimus L. in Morocco. An isoenzyme-based overview . Euphytica 121, 99-106.

HADDIOUI, A. & BAAZIZ, M. 2000. Apport des marqueurs isoenzymatiques dans l'étude de la diversité génétique des populations naturelles d'Atriplex halimus L. . deuxième congrès de la Société Marocaine de génétique et Biologie Moléculaire, Fes, 15-17 Novembre. pp.39.

BAAZIZ, M., BENDIAB, K. & HADDIOUI, M. 2000. Aperçu sur la diversité des ressources vvégétales des zones arides et semi-arides au Maroc. Cas de Phoenix dactylifera L. et Atriplex halimus. u palmier dattier. deuxième congrès de la Société Marocaine de génétique et Biologie Moléculaire, Fes, 15-17 Novembre. pp. 37.

HADDIOUI, A. & BAAZIZ, M. 2000. Etude de la diversité génétique de populations naturelles d'Atriplex halimus L. au Maroc. VIIes Journées Scientifiques-AUPELF-UREF, 3-5 Juillet, Montpellier (France).

HADDIOUI, A. & BAAZIZ, M. 1999. Effet du traitement salin sur la germination et les premiers stades de croissance d'Atriplex halimus L. et Atriplex nummularia Lindl. African Crop Science Conference Proceedings, Vol.4. (in press).

HADDIOUI, A. & BAAZIZ, M. 1999. Analysis of the morphological variation in some natural populations of Atriplex halimus. First International Conference on Biodiversity and Natural Ressources Preservation, Ifrane (Morocco), May 13-14.

HDADOU, H. & BAAZIZ, M. 1996. Croissance et développement de l'Atriplex en présence de sel. Relation avec les peroxydases.Première Rencontre Nationale des Etudiants chercheurs en Biologie, 17-19 Décembre, Marrakech, pp. 13.

HDADOU, H., BAAZIZ, M., POURRAT, Y., DUTUIT, P. & KENNY, L. 1995. Evaluation des peroxydases comme marqueurs dans la croissance et le développement de l'Atriplex en présence du sel. 5èmes Journées scientifiques du Réseau Biotechnologie/Génie génétique des Plantes de l'AUPELF-UREF. Dakar (Sénégal),13-15 Décembre.

Thesis

HADDIOUI, A. 2001. Contribution à l'étude de la diversité génétique d'Atriplex halimus au Maroc à l'aide des marqueurs morphologiques et isoenzymatiques. Apport dans l'amélioration de la plante pour la résistance à la salinité. Doctorat d'Etat en Biologie, Université Cadi Ayyad, Marrakech

HDADOU, H. 1996. Contribution à l'étude des peroxydases de l'Atriplex en relation avec la tolérance de la plante à la salinité. Diplôme d'Etudes Supérieures, Université Cadi Ayyad, Marrakech (Maroc).


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Atriplex genus. Genetic diversity in Morocco