TRANSFER OF THE ABILITY TO FLOWER IN WINTER-WHEAT VIA CALLUS-TISSUE REGENERATED FROM IMMATURE INFLORESCENCES

Using two wheat varieties (Triticum aestivum L., winter 'Grana' and sp ring 'Jara') the ability of callus from immature inflorescences to dif ferentiate into new plants was studied. In the case of the winter whea t the requirement for vernalization of the newly developed plants to a ttain the ability for heading was investigated. Callus was developed f rom 1-2 mm fragments of immature inflorescences, 5-10 mm in length, on Murashige and Skoog medium containing 1 mg l(-1) 2,4-D, 3% sucrose an d 0.6% agar, at 25 degrees C and in continuous light of about 6.4 W m( -2) PAR energy. After 6 weeks of culture green centres of differentiat ion were observed. During the following 4 weeks culture on MS medium f ree of 2,4-D, leaf-like structures as well as a small number of roots were obtained. The regenerants were rooted on a half-strength MS mediu m, then transferred to pots of soil and placed in a glasshouse with 16 h photoperiod at a temperature day/night 23/17 degrees C. After about 6 weeks of culture in the glasshouse, almost all regenerants (98%) he aded and were fertile, producing normal seeds, including the winter va riety. The heading of winter plants under conditions excluding vernali zation indicates that the callus tissue derived from a generative orga n transmits the state of generative induction onto the developing new plants.