CHARACTERIZATION OF ANTHER CULTURE-DERIVED CELL-SUSPENSIONS EXCLUSIVELY REGENERATING GREEN PLANTLETS IN WHEAT (TRITICUM-AESTIVUM L)

A reproducible procedure for deriving highly regenerable cell suspensi ons that can readily and consistently regenerate green plantlets in wh eat is described. Initiation and selection of the right type of callus from anther cultures, which consisted of friable early embryogenic po rtions that can easily disperse in liquid medium was important for the establishment of rapidly growing embryogenic suspensions. Using this type of inoculum no significant variation between three different inde pendent replications was noted when cell suspensions from eleven speci ally recombined doubled haploid lines were maintained in General mediu m supplemented with dicamba and a predominance of amino acid nitrogen. This approach also enhanced a long-term embryogenic competence of the cell cultures, with some of the suspensions retaining their morphogen ic capacity over a period of more than 15 months. Depending on the med ium composition high frequencies of embryogenesis (over 70%) and green plantlet regeneration (repeatedly producing 90-100% of green regenera nts) were obtained from the cell aggregates for most of the embryogeni c cell lines. Potential advantages of anther culture-derived embryogen ic cell suspensions for transformation purposes are the high number of cell lines which can be established routinely and the apparent mainte nance of a stable haploid genome by the regenerants in culture. It is anticipated that an increased use of anther or microspore derived doub led haploid techniques in future wheat breeding programmes may favour selection in the breeding material of plant types generally responsive to such protocols.