In vitro embryo formation and plant regeneration from anther culture of different cultivars of Mexican husk tomato (Physalis ixocarpa Brot.)

Eight cultivars and two accessions of Physalis ixocarpa Brot. were tested for their capacity to regenerate embryos and plants from anther cultures. Anthers were pretreated at 4A degrees C for 2 days and then at 35A degrees C for 8 days in the dark while cultured on MS medium supplemented with 0.045 mu M 2,4-D + 0.03 mg l(-1) vitamin B-12 (MS1) or with 2.26 mu M 2,4-D + 0.1 mg l(-1) vitamin B-12 (MS3). Anther incubation proceeded under a 16 h photoperiod at 25 +/- A 2A degrees C. Embryo formation occurred after 6 weeks of incubation in these conditions. Androgenetic responses were cultivar- and culture medium-dependent, with the greatest embryo yields recorded for cv. Chapingo (36.3%) on MS1 medium, and with wild-type 2 (21.8%) on MS3. Further development of regenerated embryos was promoted on MS medium supplemented with 0.54 mu M NAA, 8.88 mu M BA and 50 mg l(-1) casein hydrolysate. The regenerated plants were cultured on half-strength mineral salts MS medium with 2.85 mu M IAA to enhance root formation. Rooted plantlets were transferred to pots and acclimatized to the greenhouse. Ploidy analysis of regenerated plants using flow cytometry revealed 72% diploids, 15% haploids and 7% triploids. AFLP analysis of regenerated plants from anthers of a single parental plant showed different polymorphic patterns indicating their gametophytic origin.