Changes in Endogenous Gibberellin Contents during Bulb Development Period in the Cold-type Cultivar of Garlic (Allium sativum L.) of Korea

This study was performed to investigate the role of phytohormones in the bulbing of garlic in order to assess the yield and quality. The effect on endogenous plant hormones such as gibberellin (GA) content was also examined during growth stage i.e. clove differentiation to bulbing in garlic. More than 18 gibberellins in garlic were identified with extensive gas chromatograph-mass spectrometry-selected ion monitoring (GC-MS-SIM) quantitative analysis. The results showed that GAs were biosynthesized by both non C-13 hydroxylation pathway (NCH) and early C-13 hydroxylation pathway (ECH) in garlic plant. It was also revealed that NCH pathway leading to synthesis of bioactive GA₄ was the more prominent GA biosynthesis pathway than ECH pathway in which bioactive GA₁ was synthesized. Total GAs level was gradually increased from clove differentiation to bulbing and later decreased, which portrays the active role of GA in differentiation. The biosynthesis ratio of bioactive GA₄ and GA₁ concentration was similar to that of total GAs content, which was closely related with bulb development in garlic.