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

在特定的培养条件下，一些裸子植物的愈伤组织，如Chamaparis obtusa，柳杉和红豆杉的愈伤组织产生一种心材降木脂素--扁柏树脂醇。少量的agatharesinol也被发现在C. japonica的文化。通过示踪实验证明苯丙氨酸、肉桂酸和对香豆酸是扁柏树脂酚生物合成的前体物质。相反，培养物在其他Fe（II）充足的培养基中积累15-25 mg/g细胞干重的扁柏酚。[10- 14 C] -和[10- 13 C] -香叶醇的掺入表明扁柏酚是一种单萜化合物。基于从用[1- 13 C] -、[2- 13 C] -和[U-13 C] -葡萄糖饲喂的墨西哥扁柏培养物获得的13 C-扁柏酚中的13 C-富集分布，表明生物合成扁柏酚的焦磷酸香叶酯经由非甲羟戊酸途径产生。在本研究中，我们未能找到参与香叶醇转化为扁柏酚的关键酶系统。该酶系的阐明有望为利用心材提取物基因进行植物生物技术研究提供新的可能性。

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.