Accumulation of ferruginol in heartwood-forming xylem

Heartwood formation is a unique phenomenon of tree species but the mechanisms by which the substances involved accumulate are unclear. Kuroda et al. use time-of-flight secondary ion mass spectrometry (TOF-SIMS) in conjunction with quantitative analyses to study the distribution of ferruginol in a 30-year tree of Cryptomeria japonica (Taxodiaceae). They find that accumulation begins in the middle of the intermediate wood, initially in the earlywood near the annual ring boundary, then throughout the entire earlywood, and finally across to the whole annual ring in the heartwood. They conclude that the heterogeneous timing of ferruginol accumulation could be related to the distribution of ray parenchyma cells and/or water in the heartwood-forming xylem.