Agatharesinol biosynthesis-related changes of ray parenchyma in sapwood sticks of Cryptomeria japonica during cell death

• Published in: Planta Vol. 243; no. 5; pp. 1225 - 1236
• Main Authors: Nakaba, Satoshi, Arakawa, Izumi, Morimoto, Hikaru, Nakada, Ryogo, Bito, Nobumasa, Imai, Takanori, Funada, Ryo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Science + Business Media 01.05.2016; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Agriculture; Biomedical and Life Sciences; Cell Death; Cryptomeria - cytology; Cryptomeria - metabolism; Ecology; Forestry; Gas Chromatography-Mass Spectrometry; Life Sciences; Lignans - metabolism; Microscopy, Electron, Transmission; ORIGINAL ARTICLE; Plant Cells - metabolism; Plant Cells - ultrastructure; Plant Sciences; Secondary Metabolism; Starch - metabolism; Wood - cytology; Wood - metabolism; Heartwood substance; Agatharesinol; Ray parenchyma cell; Cell death; Cryptomeria japonica
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-016-2473-y

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.