Explant Types Derived from Flower Stalk Culture and 6-Benzyladenine Concentrations Affect Shoot Differentiation of Phalaenopsis Hybrid in Subculture

Phalaenopsis (Taisuco Snow × Wataboushi) ‘T343’在可見第一朵花蕾分化時期之花梗節為培植體，進行初代花梗芽誘導，再利用初代花梗節誘導長出之營養芽的短縮莖、葉片、根，以及切除營養芽後保留約2-3 mm 莖基組織之原花梗節，作為繼代培養芽體誘導之材料，接種於含不同濃度(0.0、1.25、2.5、5.0、10.0 及 15.0mg•L-1)苯基腺嘌呤(6benzyladenine, BA)與0.01 mg•L-1 萘乙酸(α-naphthalene aceticacid, NAA)之半量Murashige & Skoog 基本鹽類培養基中8 週。試驗結果顯示，保留少量莖基組織之原花梗節培植體，其繼代培植體分化率在71%-100%之間，隨著BA濃度的提升，平均最高可誘導4.8 個芽體；BA 濃度除對增殖芽數有顯著影響外，對芽體分化之型態亦有顯著影響，誘導產生之芽體型態可分為單一營芽、叢生營養芽、芽體與擬原球體(protocorm-like bodies, PLBs)共存，以及芽體與綠色團塊類癒合組織共存等四種。以營養芽去除葉片及根部後之短縮莖作為繼代培養之培植體，於0.0-1.25 mg•L-1 BA 中，有較高的根誘導率，為50%-70%，隨著BA 濃度提升至5.0-10.0mg•L-1，分化型態以芽體為主，平均誘導之芽體數可達3.3-3.5 個。以營養芽上長出之葉與根作為培植體，在0.0-10.0 mg•L-1 BA 的濃度下，葉片可誘導出PLBs，根可誘導出癒傷組織(callus)之分化型態，誘導率於10.0 mg•L-1 BA 之培養基中達最高，其PLBs 與callus 誘導率分別為20%與8%。 Flower-stalk nodes of Phalaenopsis (Taisuco Snow × Wataboushi) ‘T343’, taken at the developmental stage when the first flower bud was visible, were used as explants in tissue culture. Four types of explants were subsequently taken from the induced buds of the initial flower stalk culture. They were leaves, roots,leafless-basal-stems of the new buds, and the original flower-stalk nodes containing 2-3 mm basal stems after removing the new buds. Explants were then cultured on a 1/2MS basal salt medium containing 0.01 mg•L-1 NAA and various concentrations of BA (0.0, 1.25, 2.5, 5.0, 10.0 and 15.0 mg•L-1) for 8 weeks. Those explants of original flower nodes with 2-3 mm basal stems had 70% to 100% survival rates after the subculture. The number of shoots produced from each explant increased with BA concentration increase, and 4.8 shoots per explant was the highest. Besides the effect on shoot number, BA concentration also had a significant influence on the type of shoot differentiation. There were four differentiation types, namely: single vegetative shoot, multiple vegetative shoots, shoot plus PLBs, and shoot plus callus-like tissue. For the explants of leafless-basal-stems of the new buds, the highest root induction rate was 50% to 70%, which was at 0.0 or 1.25 mg•L-1 BA level. At higher concentrations of BA, more adventitious shoots were produced. They had 3.5 shoots per explant at 10.0 mg•L-1 BA. When leaves and roots were used as explants, PLBs and callus were developed respectively. The former had 20% and the latter had 8% of induction rate at 10.0 mg•L-1 BA