FERTILE WHEAT (TRITICUM-AESTIVUM L) REGENERANTS FROM PROTOPLASTS OF EMBRYOGENIC SUSPENSION-CULTURE

We report regeneration of fertile, green plants from wheat (Triticum a estivum L. cv. Aura) protoplasts isolated from an embryogenic suspensi on initiated from somatic early-embryogenic callus. The present approa ch combines the optimization of protoplast culture conditions with scr eening for responsive genotypes. In addition to the dominant effect of the culture media, the increase in fresh mass and the embryogenic pot ential of somatic callus cultures varied considerably between the vari ous genotypes tested. Establishment of suspension cultures with the re quired characters for protoplast isolation was improved by reduction o f the ratio between cells and medium and by less frequent (monthly) tr ansfer into fresh medium. A new washing solution was introduced to avo id the aggregation of protoplasts. However, the influence of the cultu re medium on cell division was variable in the different genotypes. We could identify cultures from cultivar Aura that showed approximately a 9% cell division frequency and morphogenic response. The protoplast- derived microcolonies formed both early and late-embryogenic callus on regeneration medium and green fertile plants were obtained through so matic embryogenesis. The reproducibility of plant regeneration from pr otoplast culture based on the cultivar Aura was demonstrated by severa l independent experiments. The maintenance of regeneration potential i n Aura suspension cultures required establishment of new cultures with in a 9-month period.