Simulation of the heartwood formation by means of cell cultures of gymnosperm trees

裸子植物Chamaecyparis obtusa、Cryptomeria Japan onica和Taxodium distichum的愈伤组织在特定的培养条件下产生一种心材去木脂素--木脂素。在日本血吸虫的一种培养物中也发现了少量的刺梨脂醇。示踪实验表明，苯丙氨酸、肉桂酸和对香豆酸是胡萝卜素生物合成的前体。相反，在另一种Fe(II)充足的培养基中，培养物可积累15-25 mg/g菌体干重。[10-14C]-和[10-13C]-香叶醇的掺入表明其为单萜类化合物。根据在[1-13C]-，[2-13C]-和[U-13C]-葡萄糖中获得的~(13)C-脑硫醇中~(13)C的浓集分布，推测合成脑硫醇的香叶基焦磷酸是通过非甲氧戊酸途径产生的，但在本研究中，我们没有找到参与香叶醇转化为脑硫醇的关键酶系统(S)。这一酶系统的阐明有望为利用心材提取物基因进行植物生物技术带来新的可能性。

Callus cultures derived from some gymnosperm species, Chamaecyparis obtusa, Cryptomeria japonica and Taxodium distichum produced one of heartwood norlignans, hinokiresinol, under particular culture conditions. Smaller amounts of agatharesinol was found also in a culture of C.japonica. Phenylalanin, cinnamic acid and p-coumaric acids were demonstrated to be precursors of hinokiresinol biosynthesis by tracer experiments.Cell culture of Cupressus lusitanica grew well in a modified Fe (II) -insufficient Gamborg B5 medium. On the contrary, the culture accumulated hinokitiol of 15-25 mg/g dry cell weight in the other Fe (II) -sufficient medium. Incorporation of [10-14C] - and [10-13C] -geraniol indicated that hinokitiol is one of monoterpene compounds. Based on the 13C-enrichment distribution in 13C-hinokitiols obtained from C.lusitanica cultures fed with [1-13C] -, [2-13C] - and [U-13C] -glucoses, it is suggested that geranyl pyrophosphate, from which hinokitiol is biosynthesized, is produced via non-mevalonate pathway.However, in the present study we were not able to find the key enzyme system (s) which participate the conversion of geraniol to hinokitiol. The elucidation of this enzyme system is expected to lead new possibility of plant biotechnology using genes of heartwood extractives.