大蒜的莖頂生長點及組織培養

Meristem Tip and Tissue Culture of Garlic (Allium sativum L.)

近年來，臺灣的大蒜（Allium sativum L.）發生毒素病的情形非常嚴重。為了獲得無病毒（Virus-free）大蒜植株作為研究病原病毒（causal viruses）的材料，並探討以組織培養法獲得無病毒株供栽培之可行性，故進行本實驗。使用之材料係以大蒜鱗莖種於溫室中，俟長至株高30cm時切取假莖部分供用，先以1%之次氯酸納作表面消毒，然後切取生長點附近之組織行培養。莖頂生長點培養用經變更後之Vacin & Went培養基另加30%之椰子汁及2,4D 2mg/l, kinetin 0.2 mg/l。組織培養則應用Murashige & Skoog（1962）之培養基另加10%之椰子汁。莖頂生長點培養有兩種生長情形，—為形成單一之芽，一為形成芽球（protocorm）。每個芽球有10〜15個球形小芽，培養經100天左右，即形成類似大蒜鱗莖之球狀體，基部長出根系。組織培養時用從生長點頂端切取之組織片僅分化成葉片，未見長出callus，用生長點基部近根系之組織片培養時，callus之生長情形最佳，但callus生長仍顯緩慢，培養30天後，直徑僅1mm左右。至培養後75天，callus長至1.5〜2mm時，將kinetin之含量增至5mg/1，2,4-D之含量減至0.5mg/l，部份之callus細胞即逐漸變成綠色，並開始分化，至120天左右才可看到芽之分化。由莖頂生長點及組織培養所得到之蒜苗，大部份外觀正常，但是否為無病毒株，其遺傳特性是否改變，尚待進一步之觀察及證明。

In recent years, there were serious outbreaks of garlic virus diseases in Taiwan. The purpose of this study was to obtain virus-free garlic plants for identification of the causal viruses and trying to produce healthy propagating materials. Garlic plants were grown in greenhouse, these meristem tips were cut off under binocular microscope using small scaples and transferred to the culture mediums. For meristem tip culture, modified Vacin and Went's medium was used with the addition of 2,4-D in 2mg/ι; Kinetin 0.2 mg/ι and coconut miik in 30%. For tissue culture, Murashige and Skoog's medium was used with the addition of 2,4-D in 0.5-5 mg/ι, kinetin 0.5-5 mg/ι and coconut milk in 10%. Two types of growth reactions were observed in meristem tip culture.1. e. single bud and protocorm formation. In most cases, single bud was formed from each meristem tip explant, protocorms were formed only in several cases. Each protocorm mass consisted of 10~15 small ball-like corms and finally they were so similar in shape to that of garlic bulb with several roots at its base. Callus formation were obtained in tissue culture from explant of tissue slices cut from lower part of meristem tip. Callus growth was very slow, after 30 days in culture, the tissue was measured only 1mm in diameter and after 75 days, it measured 1.5~2.0 mm. The callus tissue turned green and differentiation of buds occurred after transferred to medium with increased concentration (from 0.5 to 5mg/ι) and decreased concentration of 2,4-D (from 5 to 0.5 mg/ι. The majority of garlic plantlets obtained from meristem tip and tissue culture were healthy looking. Their genetic identifi cation and virus situation need further investigation.