The effect of drying and submersion pretreatment on adventitious shoot regeneration from hypocotyl explants of flax (Linum usitatissimum L.)

Hypocotyl explants of 3 flax cultivars were cultured for adventitious shoot regeneration in 3 different ways. Two pretreatment applications were compared with the routinely applied conventional regeneration protocol of culturing explants directly on Murashige and Skoog (MS) medium containing 1 mg 6-benzylaminopurine (BAP) and 0.02 mg L-1 naphthalene acetic acid (NAA). In the first pretreatment application, explants kept in a sterile cabin under an air flow for 30 min were immersed in MS solution containing 1 mg L-1 BAP and 0.02 mg NAA for 15 min; then pretreated explants were cultured on MS medium without any growth regulators (MS0). In the second pretreatment application, explants were kept in a sterile cabin under air flow for 30 min and then immersed in MS solution containing 1 mg L-1 BAP and 0.02 mg NAA for 15 min. The pretreated explants were then transferred to a culture medium enriched with 1 mg L-1 BAP and 0.02 mg L-1 NAA. Fresh and dry weights of hypocotyl explants, shoot regeneration percentage, shoot number per hypocotyl, shoot length, and total chlorophyll content were recorded. From the results, it could be seen that treating explants before culture initiation for regeneration with a liquid MS medium containing 1 mg L-1 BAP and 0.02 mg L-1 NAA for 15 min after keeping hypocotyls under an air flow in a sterile cabin for 30 min gave rise to the highest scores for tissue culture response.