CONTINUOUS CALLUS PRODUCTION AND REGENERATION OF GARLIC (ALLIUM-SATIVUM L.) USING ROOT SEGMENTS FROM SHOOT TIP-DERIVED PLANTLETS

Root segments from shoot tip-derived plantlets of the garlic (Allium s ativum L.) clones 'DDR7099', 'PI383819', and 'Piacenza' were utilized as an explant source for continuous, friable callus production. The be st callus production occurred on root segments initially cultured on m edium with 4,5 mu M 2,4-dichlorophenoxyacetic acid (2,4-D) for 8 weeks , then subcultured to medium with 4.7 mu M 4-amino-3,5,6-trichloropico linic acid (picloram) +0.49 mu M 6-(gamma-gamma-dimethylallylamino)pur ine (2iP) for 8 weeks. Embryogenic, friable callus was transferred to liquid medium for 1 month and then transferred to solid regeneration m edium for 14 weeks. The best shoot and root regeneration (85.3% and 35 .8%, respectively) occurred on 4-month-old calli from the clone 'DDR70 99'. In all clones, regeneration rate decreased as callus age increase d.