TRITICALE (X TRITICOSECALE WITTMACK) IN-VITRO ANDROGENESIS IN ISOLATED MICROSPORE CULTURE

Triticale (X Triticosecale Wittmack ex. A. Camus) microspore culture e xperiments were carried out to study the induction conditions required for triticale androgenesis. This is the first description in the lite rature of the sporophytic development of triticale microspores in isol ated microspore culture. In the experiments, five winter type hexaploi d (AABBRR) triticale entries were involved: one variety and four cross ing combinations. The micropores were mechanically isolated in 0.3 M m annitol using a microblender to avoid the laborious process of anther isolation. A density gradient centrifuge was used to separate viable a nd unviable microspores, the viable ones being collected from the malt ose/mannitol gradient interphase. Microspore sporophytic development w as successfully induced in modified 190-2 medium supplemented with one of two growth regulators (190-D/K and 190-PAA) or without hormones (1 90-0). The highest induction of microspore embryogenesis was obtained using the hormone-free medium (190-0). This indicates that triticale i n dba microspore development does not require an exogenous hormone sig nal for cell division in microspore culture. In conclusion, adventitio us embryogenesis was observed during the in vitro development of triti cale microspores. Albinism remained a serious problem in triticale mic rospore culture which was reflected by more than 50% of the regenerant s being albino. In total, 126 green plantlets were transplanted into t he soil and grown in the greenhouse. In a cytological study 90% of the transplanted regenerants were found to be haploid. In order to differ entiate between haploid, mixo- and spontaneous diploid derivatives, an indirect ploidy evaluation method (stomatal guard cell length measure ment) was successfully used. In the case of 56 plants, the stomatal gu ard cell length ploid level estimation was confirmed by root tip cytol ogy.