Nakaba Satoshi, Arakawa Izumi, Morimoto Hikaru, Nakada Ryogo, Bito Nobumasa, Imai Takanori, Funada Ryo
Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.
Forestry and Forest Products Research Institute, Forest Tree Breeding Center, Hokkaido Regional Breeding Office, 561-1 Bunkyodai-midorimachi, Ebetsu, Hokkaido, 069-0836, Japan.
Planta. 2016 May;243(5):1225-36. doi: 10.1007/s00425-016-2473-y. Epub 2016 Feb 19.
The work demonstrates a relationship between the biosynthesis of the secondary metabolite, agatharesinol, and cytological changes that occur in ray parenchyma during cell death in sapwood sticks of Cryptomeria japonica under humidity-regulated conditions. To characterize the death of ray parenchyma cells that accompanies the biosynthesis of secondary metabolites, we examined cell death in sapwood sticks of Cryptomeria japonica under humidity-regulated conditions. We monitored features of ray parenchyma cells, such as viability, the morphology of nuclei and vacuoles, and the amount of starch grains. In addition, we analyzed levels of agatharesinol, a heartwood norlignan, by gas chromatography-mass spectrometry in the same sapwood sticks. Dramatic changes in the amount of starch grains and in the level of agatharesinol occurred simultaneously. Therefore, the biosynthesis of agatharesinol appeared to originate from the breakdown of starch. Furthermore, we observed the expansion of vacuoles in ray parenchyma cells prior to other cytological changes at the final stage of cell death. In our experimental system, we were able to follow the process of cell death and to demonstrate relationships between cytological changes and the biosynthesis of a secondary metabolite during the death of ray parenchyma cells.
这项研究揭示了在湿度调节条件下，日本柳杉边材枝条细胞死亡过程中，次生代谢产物阿加雷辛醇的生物合成与射线薄壁组织中发生的细胞学变化之间的关系。为了表征伴随次生代谢产物生物合成的射线薄壁组织细胞死亡，我们在湿度调节条件下研究了日本柳杉边材枝条中的细胞死亡。我们监测了射线薄壁组织细胞的特征，如活力、细胞核和液泡的形态以及淀粉粒的数量。此外，我们通过气相色谱 - 质谱法分析了同一边材枝条中心材去甲木脂素阿加雷辛醇的含量。淀粉粒数量和阿加雷辛醇含量同时发生了显著变化。因此，阿加雷辛醇的生物合成似乎源于淀粉的分解。此外，在细胞死亡的最后阶段，我们观察到射线薄壁组织细胞中的液泡在其他细胞学变化之前就开始膨胀。在我们的实验系统中，我们能够追踪细胞死亡过程，并证明在射线薄壁组织细胞死亡期间细胞学变化与次生代谢产物生物合成之间的关系。
