Organogenesis from ‘Passe Crassane’ and ‘Old Home’ pear (Pyrus communis L.) protoplasts and isoenzymatic trueness-to-type of the regenerated plants

Abstract

Large numbers of highly viable mesophyll protoplasts were isolated from shoot cultures of the scion cv 'Passe Crassane' and the rootstock genotype 'Old Home' of common pear (Pyrus communis L.). Protoplasts were cultured for both genotypes either as liquid layers or as liquid-over-agar cultures, in ammonium-free MS medium with 0.5 M mannitol, 50 mg/l casein enzymatic hydrolysate (CEH), 2.0 mg/l NAA and 1.0 mg/l BAP, plus either 0.5 mg/l IAA (for 'Old Home') or 2.0 mg/l IAA (for 'Passe Crassane'). Protoplast microcalli, obtained by day 60 ('Passe Crassane') or day 80 ('Old Home'), were transferred for further growth to ammonium-free MS medium with 2.0 mg/l NAA and 1.0 mg/l BAP. Shoot bud regeneration from the protoplastderived callus was first attempted between 100 ('Passe Crassane') and 120 ('Old Home') days after protoplast isolation. For 'Passe Crassane', shoot buds were regenerated (day 130) on a half-strength MS medium with 0.1 mg/l IBA, 0.5 mg/l BAP, 50 mg/l CEH and 20 mg/l Ca-panthotenate. For 'Old Home', shoot but regeneration only occurred 30 days later and on the same medium as above, which was additionally supplemented with double the concentration of the group B vitamins found in the original MS formulation and 0.05 mg/l GA3. Following micropropagation and in vitro rooting of shoots, the plants were transferred to soil following standard procedures. Trueness-to-type of the regenerated plants was assessed by analysing their leaf isozyme banding profiles (for EST, AP, PRX, SOD, ENP, LAP, PGI, AAT, ADH, MDH and PGM) and comparing them to those corresponding to the original shoots that provided the protoplasts. No differences between the mother shoots and the protoclones were observed for any one of the 11 isozyme systems studied.

Plant regeneration from stem and petiole protoplasts of sweet potato (Ipomoea batatas) and its wild relative, I. lacunosa

“…Plant formation was enhanced by the addition of GA3 on the regeneration medium (Shimonishi et al 1992;Ochatt et al 1992;Pattat-Ochatt et at. 1988).…”

Protoplast technology for the breeding of top-fruit trees (Prunus, Pyrus, Malus, Rubus) and woody ornamentals

“…Plants were recovered from mesophyll protoplasts of the variety Williams' Bon Chretien, one of the most commercially important scions worldwide . Plants were also regenerated from leaf protoplasts of the rootstock genotype Old Home and the scion variety Passe Crassane, and trueness-to-type of such regenerated plants was established through phenotypic characters and by the study of the banding profiles for 13 different isoenzymatic systems, as compared to conventionally propagated mother plants of each genotype (Ochatt et al ., 1992b) . Plants have also been produced from leaf protoplasts of the rootstock genotype Old Home X Farmingdale (OHF) 333 and the scion variety Cornice (Ochatt, 1993a), and the strategy as developed for apple stem protoplasts above has been applied to both these genotypes and `Old Home' with the proliferation of stem protoplast-derived callus for all three genotypes (Rosati & Ochatt, 1994) .…”