13th Conference on Medicinal and Aromatic Plants of Southeast European Countries (CMAPSEEC 2026)

Hyphaene thebaica (L.) Mart. (doum palm) is a culturally and ecologically important desert palm that has become increasingly rare in Jordan. The limited availability of plant material and difficulties associated with conventional regeneration highlight the need to identify responsive tissues for ex situ conservation and future biotechnological applications. This study investigated how explant origin and culture conditions influence callus formation and callus quality in H. thebaica, with particular emphasis on differences between vegetative and reproductive tissues.

Offshoot apical meristems, root tips, and male and female inflorescences were cultured on Murashige and Skoog medium supplemented with 3% sucrose, 2,4-D and 2iP under complete darkness. The effects of carbon source type and concentration were subsequently evaluated using female inflorescence-derived cultures.

Explant origin strongly influenced both callogenesis and biomass accumulation. Female inflorescences showed the highest response, with 85% callogenesis and 5.83 ± 0.22 g dry weight, followed by offshoot apical meristems (77% and 4.77 ± 0.18 g), root tips (63% and 3.45 ± 0.15 g), and male inflorescences (35% and 1.80 ± 0.12 g). Female-derived calli were predominantly friable and yellow, whereas root- and male-derived calli were more compact and showed greater browning. Among carbon sources, 3% sucrose produced the highest callogenesis (85%) and biomass (0.33 ± 0.04 g), outperforming glucose and fructose. Increasing 2,4-D and 2iP concentrations further enhanced callogenesis, reaching 90% under 10 mg/L 2,4-D + 3 mg/L 2iP.

The pronounced tissue-dependent response demonstrates that explant selection is a critical determinant of successful in vitro establishment of H. thebaica. Identifying female inflorescences as a highly responsive source provides a valuable starting point for conservation-oriented tissue culture and future regeneration studies of this rare Jordanian palm.