Nicotiana plumbaginifolia抗5－甲基色氨酸變異體之篩選及定性

Abstract

利用單倍體Nicotiana plumbaginifolia Viviani (2n＝20)的葉肉原生質體，碟養在含有抑制生長濃度的5-甲基色氨酸(5-methyltryptophan)培養基，共篩選出8個抗性品系。抗性品系再生植株維持在蔗糖濃度為3％的MS培養基，會有頂芽優勢丟失，葉片發育受阻，莖切口處形成癒合組織及不長根等現象。抗性品系與野生型癒合組織內芳香族氨基酸的含量並無顯著差異。以14C標定的色氨酸(tryptophan)做吸收試驗，發現抗性品系的葉片對色氨酸的吸收量比野生型顯著降低（約為野生型的50?64％）。這些結果顯示抗性品系對5－甲基色氨酸的抗性可能與5－甲基色氨酸的吸收能力降低有關。

Eight 5-methyltryptophan-resistant lines were isolated from Micotiana plumbaginifolia Vivinia (2n=20) upon plating mesophyll protoplasts of haploid plants in agarose medium containing a growth inhibitory concentration of the analogue. The resistant plants lost apical dominance, showed impeded leaf development, formed callus at the cut end of the stem, and could not form root in MS medium containing 3% sucrose. There were no significant differences in the content of aromatic amino acids between resistant and wild-type callusse. In a (14C) tryptophan uptake experiment, leaf slices of resistant plants uptook significantly reduced amount of tryptophan than those of wild-type (about 50 ? 64% of wild-type). These results showed that the resistance of the variants was related to a reduced uptake of 5-methyltryptophan.