激勃素（GA_3）、吲哚乙酸及頭孢噻肟應用於槲櫟微體繁殖芽之抽長

本研究將激勃素（gibberellic acid, GA_3）、吲哚乙酸（indole-3-acetic acid, IAA）及頭孢噻肟（cefotaxime, CEF）應用在槲櫟（Quercus aliena Blume var. aliena）之微體繁殖，探討其促進芽體抽長之可行性。利用組織石蠟切片技術，觀察處理後產生之大芽（＞ 1.5 cm）中髓細胞（pith cell）長度之變化，藉以瞭解添加這三種化合物，對芽體抽長及其在細胞伸長上所形成之不同效果，並追蹤芽體在後續發根及馴化階段是否受到影響。試驗步驟（對照組）採用該樹種於前人研究中已發表的最佳培養條件，係取成熟林木主幹萌櫱（epicormic shoot）之莖節（nodal segment）為材料，待誘導其側芽形成後取為培植體，以含有6-benzylaminopurine（BAP）及17.67μM硝酸銀之GD_1培養基進行8週的增殖培養，處理組則以對照組為基礎，在8週增殖培養期間各自加入三種化合物進行測試，各以添加0.5μM GA_3（2週）、1.43μM IAA及250 mg L^(-1) CEF（均為8週）之結果較對照組為佳，其中以GA_3處理者形成之大芽數為其對照組之4倍具有應用潛力。又經組織解剖觀察顯示芽體髓細胞在距離莖頂0.4 cm處會顯著伸長，然經GA_3處理形成之大芽，髓細胞伸長在鄰近莖頂0.2 cm即可開始。芽體在誘導發根時，經三種處理所得之大芽發根率相近（63～74%），但以CEF處理者，其後續小植株移盆馴化存活率最低（49.1%）。

關鍵字

抗生素；保育；微體繁殖；麻櫟屬；芽體抽長

並列摘要

Gibberellic acid (GA_3), indole-3-acetic acid (IAA), and cefotaxime (CEF) were applied for the micropropagation of Quercus aliena Blume var. aliena to evaluate their potential in promoting shoot elongation. Based on a paraffin sectioning method, we observed the length of pith cells in elongated large shoots (＞ 1.5 cm) obtained from the micropropagation experiments. These examinations provided anatomical information to demonstrate the influence of the 3 chemicals on promoting shoot growth and to understand their impacts on pith cell elongation. In vitro rooting and subsequent acclimatization of the regenerated shoots were also monitored to determine if any carryover effects existed. A procedure for the additional supplementation of the test chemicals was adopted in a documented culture method (as a control in this study), which was previously determined to be an effective treatment for culturing the same species. Nodal segments collected from epicormic shoots of mature trees were used as initial explants. Axillary shoots induced from the explants were harvested as experimental materials; they were cultured for 8 wk on GD_1 medium containing 6-benzylaminopurine (BAP) and 17.67 μM AgNO_3 as the control. The incorporation of 0.5 μM GA_3 (for 2 wk), 1.43 μM IAA, or 250 mg L^(-1) CEF (both for 8 wk) into the control proved beneficial for large shoot formation. Regeneration of large shoots from GA_3 treatment was 4-fold greater than those from the control indicating a better potential of GA_3 for practical application. The anatomical analysis revealed that pith cell elongation was clearly observed at a position 0.4 cm below the shoot apical meristem (SAM). However, such elongation was detected much closer to the SAM (0.2 cm) in large GA_3-induced shoots. The elongated shoots obtained from all chemical treatments achieved similar rooting percentages (63~74%). Plantlets derived from CEF-treated shoots exhibited the worst survival rate (49.1%).

並列關鍵字

antibiotic ； conservation ； micropropagation ； Quercus ； shoot elongation

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