EMBRYOGENESIS AND PLANT-REGENERATION IN ANTHER CULTURE OF SUNFLOWER (HELIANTHUS-ANNUUS L.)

A protocol for high frequency callus induction and plant regeneration from sunflower (Helianthus annuus L.) anthers is described. Different variables using Murashige & Skoog (MS) basal medium supplemented with 2.0 mg/l alpha-naphthaleneacetic acid (NAA) and 1.0 mg/l N-6-benzylade nine (BA) were tested for their ability to enhance the frequency of an ther callusing and subsequent embryogenesis. Of these, agar concentrat ion, sucrose concentration, carbohydrate source had significant effect on callusing, while differences due to incubation under dark vs light conditions, cold pretreatment of capitula for 1 to 6 days prior to an ther inoculation and genotype on callusing were non-significant. Howev er, all these factors exerted highly significant influence on embryoge nesis when calli from the various media were transferred to medium sup plemented with 0.1 mg/l NAA and 0.5 mg/l BA. With the procedure develo ped, callusing as high as 100% and embryo formation at a frequency of 44% was achieved. Although complete embryos were formed the frequency of their conversion to whole plantlets was low (14.3%). Hence, the emb ryogenic pathway was bypassed to obtain multiple shoots by transferrin g embryogenic calli with developing embryos to MS medium supplemented with 0.5 mg/l BA. Elongated shoots rooted on half-strength MS medium s upplemented with 0.5 mg/l NAA. Cytological analysis of embryogenic cal lus and somatic embryos revealed haploids at a frequency of 30% while that of rooted plants showed haploid regenerants at a frequency of 8.3 %. Nevertheless, the frequency of putative haploid plants could be enh anced through mass multiplication using nodal explants of the regenera nts.