Apricot (Prunus armeniaca) ‘Harcot’ anthers, were cultured in vitro for the production of haploid plants. The best androgenic response was achieved with Nitsch and Nitsch (1969) medium, supplemented with 4.52 μM 2,4-D, 4.52 μM zeatin, 2.85 μM IAA and 40 g l−1 sucrose. Cultures were maintained in the dark for 8 days, at 28°C, followed by transfer to a 16-h photoperiod, with 35 μm m−2 s−1 light intensity and 24/22°C day/night temperature. The androgenic response was correlated with the floral bud size, its phenologic stage and the level of microspore evolution. Anthers containing microspores at the tetrad/uninucleate stage were the most appropriate. The ploidy level of the calluses was evaluated by flow cytometry revealing that they range from haploid to octaploid. Mixoploid calluses have also been identified. Histological studies showed that the haploid calluses have their origin in the microspores. Nodular structures consisting of cells with dense cytoplasm and differentiated xylem elements were observed and were surrounded by an autofluorescent layer, probably due to cutin deposition.

Stone pine (Pinus pinea L.) is an economically important forest tree in Mediterranean climates and has been the target for selection efforts through micropropagation. Previous attempts on microshoots, derived from mature seed cotyledons, reached incipient rooting after induction with a combination of auxin and hypertonic shock, but their development in vitro was not sustained. At this stage, co-culturing plantlets with some fungi isolated from ectomycorrhizas succeeded in overcoming this barrier, enabling satisfactory development in vermiculite and later in soil. About half of the fungal isolates tested helped the plants resume root growth. Although control plants (in the absence of fungi) developed roots at a later stage, i.e. during the post-transplanting acclimation in vermiculite, their growth was weaker. The root systems of some inoculated plants had ectomycorrhizas from the introduced fungi being carried over when the plants were transferred from the co-cultures to vermiculite. In conclusion, co-culturing rooted microshoots with ectomycorrhizal fungi can be an effective means to overcome the difficulties encountered in the use of micropropagation methods on this species.