Abstract The genetic diversity between 23 Moroccan date palm cultivars collected from the National Palm Collection at the INRA (National Agricultural Research Institute) experimental field in Zagora was assessed using SSR markers that are specifically designed for date palm. Among the 16 tested SSR, 13 were successfully amplified, and were selected to carry out this study. 208 bands were amplified, ranging from 10 to 25 bands per cultivar with an average of 16 alleles per cultivar. The value of heterozygosity of the studied markers ranged from 0.11 to 0.30. The pairwise genetic distances between those cultivars ranged from 0.06 to 0.46. The hierarchical cluster analysis distributed the 23 genotypes into four different groups of one to ten cultivars.

Abstract Introduction: The carob tree (Ceratonia siliqua L.) is one of the most important plant species cultivated in the Mediterranean area. The species is in high market demand, but traditional propagation methods have not been able to satisfy it. Therefore, the use of in vitro techniques seems appropriate for the establishment of large-scale carob orchards. Objectives: To assess the effects of five carob genotypes on embryogenic-calli induction and to optimize culture medium composition for better growth. Materials and methods: The mature seeds of C. siliqua of the variety "Dkar", which grow in five regions of Morocco, were used as sources of explants of cotyledons. Five genotypes (‘GH’, ‘GO’, ‘GM’, ‘GA’, and ‘GB’) and four culture media (MS, B5, WPM and DKW) supplemented with three 2,4-D concentrations (2.5, 5 and 10 µM) were evaluated in this study. Sucrose and mannitol were also tested at different concentrations (0, 45, 90, 135 and 180 µM). Results and discussion: All the tested genotypes showed high callus induction levels (75 to 100 %). The Gamborg medium (B5) supplemented with 2.5 µM 2,4-D produced the highest dry weight (32.5 g) of creamy white calli. The highest amount of friable creamy-white calli was obtained in the medium supplemented with 90 mM of sucrose. Histological analysis showed the presence of meristematic centers that became embryogenic masses and globular proembryos. Conclusion: Mature cotyledons of C. siliqua have potential for induction and proliferation of embryonic callus. This study aims to contribute to developing an appropriate protocol for mass propagation of carob.

Resumen Introducción: El algarrobo (Ceratonia siliqua L.) es una de las especies cultivadas más importantes en el área mediterránea. La especie tiene alta demanda en el mercado, pero los métodos tradicionales de propagación no han logrado satisfacerla; por tanto, el uso de técnicas in vitro parece apropiado para el establecimiento de huertos a gran escala. Objetivos: Evaluar los efectos de cinco genotipos de algarrobo en la inducción de callos embrionarios y optimizar la composición del medio de cultivo para un mejor crecimiento. Materiales y métodos: Las semillas maduras de C. siliqua de la variedad “Dkar”, que crecen en cinco regiones de Marruecos, se utilizaron como fuentes de explantes de cotiledones. Se evaluaron cinco genotipos (‘GH’, ‘GO’, ‘GM’, ‘GA’, y ‘GB’) y cuatro medios de cultivo (MS, B5, WPM y DKW) suplementados con tres concentraciones de auxina 2,4-D (2.5, 5 y 10 µM). La sacarosa y el manitol se analizaron en concentraciones de 0, 45, 90, 135 y 180 µM. Resultados y discusión: Los genotipos mostraron niveles altos de inducción de callo (75 a 100 %). El medio Gamborg (B5) suplementado con 2.5 µM 2,4-D produjo el mayor peso seco (32.5 g) de callos con coloración blanco cremoso. La mayor cantidad de callos friables de color blanco cremoso se obtuvo en el medio suplementado con 90 mM de sacarosa. El análisis histológico mostró la presencia de centros meristemáticos que se convirtieron en masas embriogénicas y proembriones globulares. Conclusión: Los cotiledones maduros de C. siliqua tienen potencial para la inducción y proliferación de callos embrionarios. Este estudio pretende contribuir al desarrollo de un protocolo apropiado para la propagación masiva de algarrobo.