Colchicine-induced tetraploidy in garlic (<i>Allium sativum</i>L.) and its effect on allicin concentration

Abstract

SummaryColchicine is known to affect the concentrations of metabolites by changing the ploidy level of the genome. Allicin is the most important, pharmaceutically-active metabolite in garlic (Allium sativum L.) and is known for its anti-bacterial, anti-fungal, and anti-atherosclerotic activities. Duplication of the diploid garlic genome was induced by treating garlic stem discs with 0.5% (w/v) colchicine. The tetraploids possessed thicker and darker-green leaves compared to untreated control plants and also showed pronounced differences in stomatal size. Leaves on the tetraploid clones exhibited smaller length-to-width ratios, but their leaf areas were up to three-times higher than in control diploid plants. These morphological characteristics were used as reliable phenotypic markers to screen for autotetraploid clones from a mixed population of polyploids and control diploid plants. In comparison to control diploid garlic plants, autotetraploid plants exhibited an average 30.7% increase in allicin concentration. The increase was measured indirectly as a significant increase in pyruvate concentration (87.15 ± 0.86 µmol g–1 FW), which is a by-product of allicin biosynthesis. This study demonstrated that autotetraploids of garlic with increased concentrations of secondary metabolites can be generated successfully through in vitro stem-disc culture with 0.5% (w/v) colchicine.