Garlic Micro-propagation and Polyploidy Induction In Vitro by Colchicine

In most garlic producing countries, the yield of local garlic varieties is low due to small size bulbs and limited production area. Garlic in vitro culture can be induced in Basal Dunstan Short (BDS) or Murashige and Skoog medium (MS) medium supplemented with 2,4-D and Kinetin or with 2,4-D (2,4-dichlorophenoxyacetic acid) and BAP (Benzylaminopurine) for better callus production, cell and shoot proliferation from callus. This review aimed to describe the effect of growth hormones, colchicine concentration, and immersion time for increasing ploidy level of garlic varieties for genetic variability. Colchicine is effective to induce the meristematic basal discs of garlic plants at a concentration of 0.25-0.5% and immersion time at 24, 36, and 48 hours in vitro. High concentration and longer duration of colchicine could reduce the survival rate, whereas low concentration with a longer duration of colchicine treatment results in a higher polyploidy induction rate. A high percentage of polyploidy induction occurs in high colchicine concentration and longest time duration, but it leads to a high percentage of dead plants. Ploidy induction of diploid garlic genome can be induced by treating garlic stem discs up to 0.75% colchicine. The application of colchicine at 0.5% treatment improved the genetic potential of garlic varieties in vitro, but a lower duplication rate at 0.75% due to higher toxicity. The application of colchicine increased the ploidy level and an increase in ploidy is expected to have a larger bulb size. Larger tuber size is expected to increase the overall tuber weight and total garlic production.