This is the first time that a simple protocol is presented for the micropropagation and short-term conservation of Quercus lusitanica, an endemic and endangered species that is found in very restricted habitats of the Iberian Peninsula and North Africa. Branch segments from 15-20-year-old trees were forced-flushed, and the forced shoots were used as a source of explants for culture initiation. The best multiplication rates were obtained on Woody Plant Medium (WPM) supplemented with 0.1 mg l-1 benzyladenine for the genotype CDL, or 0.2 mg l-1 benzyladenine, 0.5 mg l-1 indole acetic acid and 0.2 mg l-1 zeatin in the case of the genotype SC1. Although the cultivation of shoots in the horizontal position improved the proliferation rates, the shoot vitrification was increased under these conditions. The best rooting rates were obtained on half-strength WPM supplemented with 3 mg l-1 indole-3-butyric acid for 7 days with subsequent transfer to auxin-free medium supplemented with 0.4% activated charcoal. An initial 5-day dark period was detrimental to the quality of regenerated plantlets. Well-acclimatized plantlets were transferred to the field with a 70% survival rate.

Massive propagation of cork oak (Quercus suber) individuals tolerant to Phytophthora cinnamomi (Pc) is probably the most important challenge for cork production. Screening for resistance to Pc of ca. 200 seedlings obtained from a single cork oak tree that has survived the epidemic was performed by soil infestation. Twenty months after Pc inoculation, 33 seedlings survived from Pc infection and the four most vigorous seedlings were selected. The plants were forced to produce new shoots under controlled climatic conditions, and the new shoots were used to establish the plants in vitro by axillary budding. High axillary shoot proliferation rates were achieved by culturing the new shoots on Lloyd and McCown (WPM) medium, followed by subculturing for 2 weeks on 0.22 µM benzyladenine (BA) and for 2 weeks further on 0.04 µM BA. Addition of 20 µM silver thiosulphate (STS) increased the proliferation rates and improved the appearance and development of shoots. Rooting rates of 80–100% were obtained by culturing the shoots for 24 or 48 h on Gresshoff and Doy medium with ⅓ macronutrients plus 122.5 µM indole-3-butyric acid and subsequent transfer to root expression medium containing 20 µM STS. The results of this study optimize the micropropagation of a relevant and recalcitrant tree species in forestry.