Plant Biodiversity in Semiarid Regions: Modeling and Importance of Regeneration Methods for Overexploited Plants

Algeria has an immense plant diversity spread over its three bioclimatic zones: humid, semiarid, and arid. Most plant families are of pharmacological, ecological, and industrial importance. However, the overexploitation of particular plant families for different reasons will lead to the depletion of the flora richness and the scarcity of the germplasm. This study aimed to inventory the botanical families growing spontaneously in the semiarid Algerian region. The plant species inventory was carried out in Ain Beida in northeastern Algeria. The species identification was based on the morphological characters and then confirmed using the determination keys reported in the literature on the Algerian flora, in addition to the use of a large number of references dealing with the plants of the Mediterranean region. The study also dealt with the in vitro regeneration via axillary buds of Rosmarinus officinalis L. and Thymus algeriensis Boiss. and Reut., two species excessively used for their aromatic character. Both plants were propagated from axillary buds treated with different combinations of growth regulators (GRs): indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and N-6-furfuryladenine (Kin), cultivated on nutrient medium in test tubes and incubated in a culture chamber. The study resulted in an inventory of 19 families comprising 37 species. It showed that the most predominant families are Asteraceae, with ten species (27.0%), and Lamiaceae, with five species (13.5%), followed by Fabaceae, with three species (8.1%). The other families were represented by one and two species with rates of 2.7% and 5.4%, respectively. The obtained results showed that the concentration of 5 mg/L 2,4-D + 10 mg/L Kin induced shoot emission from buds with a rate of 17% in T. algeriensis. In R. officinalis, the best shoot formation was observed at the concentration of 1 mg/L IAA + 1 mg/L Kin with 13%, followed by the concentration of 1 mg/L IAA + 0.01 mg/L Kin with 12%. Therefore, applying optimal GR concentrations could increase the number of regenerated plants intended for different uses to avoid the overuse of natural plant populations.