Etude de la compétition pollinique chez le sulla (Hedysarum coronarium L., Légumineuse-Papilionacée)

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Appropriate knowledge of genetic variation and mating systems is necessary to optimise conservation and utilisation of genetic resources. The present study provides estimates of mating system parameters in three natural populations of Hedysarum coronarium, using isozyme markers. There was no detectable variation among populations of single-and multilocus outcrossing rates (t s , t m), which did not differ significantly from complete outcrossing. However, in pooled populations, estimates of t s (0.820 ± 0.073) and t m (0.830 ± 0.069) were both significantly different from the unity. The fixation index (F) and the biparental inbreeding rate, given by the difference between t m and t s , were not significantly different from zero. t m and t s , estimated at the seedling stage, were both smaller than those determined at the adult phase, indicating some inbreeding depression acting between these two stages. Hedysarum coronarium / isozyme / mating system / outcrossing rate Résumé-Estimation des paramètres du régime de reproduction chez Hedysarum coronarium L. (Légumineuse, Fabacée). La connaissance de la variation génétique et des modes de reproduction est nécessaire à l'optimisation de la conservation et l'utilisation des ressources génétiques. Cette étude fournit des estimations du régime de reproduction dans trois populations naturelles d'Hedysarum coronarium L., au moyen de marqueurs isoenzymatiques. L'analyse montre que les taux d'allogamie uni-et multilocus (t s , t m) présentent de faibles variations entre populations sans qu'ils ne s'écartent significativement de l'allogamie complète. Toutefois, pour l'ensemble des populations, t s (0.820 ± 0.073) et t m (0.830 ± 0.069) sont tous deux significativement différents de l'allogamie totale (t = 1.0). L'indice de fixation (F) et le taux de croisements consanguins, donné par la différence entre t m et t s , ne sont pas significativement différents de zéro. t m et t s , estimés sur des plantes au stade juvénile, sont inférieurs à ceux obtenus au stade adulte, suggérant l'existence d'une dépression de consanguinité agissant entre la germination des graines et la maturité des plantes. Hedysarum coronarium / isozyme / régime de reproduction / taux d'allogamie

Section: Introductionmentioning

confidence: 66%

Estimation of mating system parameters inHedysarum coronariumL. (Leguminoseae, Fabaceae)

Yagoubi

Chriki

2000

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“…Estimates of heritability showed considerable differences among the other vegetative traits (H 2 = 0.072-0.602). Reproductive characters maintained by natural selection allows this allogamous species [5] to be adapted to entomophilic pollination. Flowers of large size and bright in color (in the red spectrum) attract pollinators, notably bees [10].…”

Section: Discussionmentioning

confidence: 99%

A quantitative study of some agronomic characters in Sulla (Hedysarum coronarium L.)

Namouchi¹,

Louati²,

Chriki³

2000

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-Eleven populations of Hedysarum coronarium L. collected from North Africa and Southern Italy were analyzed using both univariate and multivariate analyses on a data set for 25 quantitative traits. Broad sense heritabilities were estimated and ranged from 0.072 to 0.703. Seven principal components were found to explain 81.5% of the total variation. On the basis of these 7 principal components, populations were clustered at a similarity level estimated by euclidian distances. Three clusters were identified. Genetic divergence between these clusters was quantitatively measured by using Mahalanobis D 2 distances.cluster analysis / Hedysarum coronarium / heritability / morphological variability / multivariate analysis Résumé -Étude quantitative de quelques caractères agronomiques chez le Sulla (Hedysarum coronarium L.). Vingt cinq caractères morphologiques ont été mesurés chez 11 populations de Hedysarum coronarium collectées de l'Afrique du Nord et de l'Italie du Sud. Les données obtenues ont été soumises à une analyse univariée et une analyse multivariée. L'héritabilité au sens large a été estimée ; elle varie entre 0,072 et 0,703. L'ACP révèle que 7 composantes principales absorbent 81.5 % de la variance totale. L'application de la méthode de classification hiérarchique sur la matrice des distances euclidiennes a permis de répartir les populations en 3 groupes. L'utilisation de la distance de Mahalanobis D 2 a permis d'estimer la divergence génétique entre ces groupes.

“…Thus, higher levels of embryo abortion may be responsible for maintaining elevated levels of outcrossing rates in populations [21]. The protandrous nature of flower development in H. coronarium, sequential flowering on the same inflorescence during anthesis period and competitive inferiority of self pollen reported for this species [8] are additional causes of a high outcrossing rate.…”

Section: Plant Genetics and Breedingmentioning

confidence: 94%

Mating system and multiple paternity in Hedysarum coronarium L. (Fabaceae)

Namouchi¹,

Louati²,

Chriki³

2000

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-The mating system was studied in four populations of Hedysarum coronarium under the mixed-mating model (MMM) and the effective selfing model (ESM) by analysis of progeny arrays. Multilocus population outcrossing rates ranged from 0.822 to 1.013. Pollination experiments indicated that H. coronarium is self-compatible, and therefore the high outcrossing rates were attributed to inbreeding depression. This view was supported by high levels of seed abortion in self pollination when compared to open pollination. The effective selfing rate ranged from E = 0.026 to E = 0.183. Positive covariance of selfing with gene fixation (D = 0.085) was observed in one population and could be attributed to subpopulation structure and mating between relatives. Estimates of the level of multiple paternity under the correlated mating model (CMM) was assessed at the progeny array level. The correlation of the outcrossed paternity (r p ) ranged from 0.029 to 0.342 and according to the outcrossing rates, up to 80% of the total seeds in a progeny array may have different male parents.