Differential Gene Profiling of the Heartwood Formation Process in Taiwania cryptomerioides Hayata Xylem Tissues

Abstract

Taiwania (Taiwania cryptomerioides) is an important tree species in Taiwan because of the excellent properties of its wood and fascinating color qualities of its heartwood (HW), as well as the bioactive compounds therein. However, limited information is available as to the HW formation of this species. The objective of this research is to analyze the differentially expressed genes (DEGs) during the HW formation process from specific Taiwania xylem tissues, and to obtain genes that might be closely associated with this process. The results indicated that our analyses have captured DEGs representative to the HW formation process of Taiwania. DEGs related to the terpenoid biosynthesis pathway were all up-regulated in the transition zone (TZ) to support the biosynthesis and accumulation of terpenoids. Many DEGs related to lignin biosynthesis, and two DEGs related to pinoresinol reductase (PrR)/pinoresinol lariciresinol reductase (PLR), were up-regulated in TZ. These DEGs together are likely involved in providing the precursors for the subsequent lignan biosynthesis. Several transcription factor-, nuclease-, and protease-encoding DEGs were also highly expressed in TZ, and these DEGs might be involved in the regulation of secondary metabolite biosynthesis and the autolysis of the cellular components of ray parenchyma cells in TZ. These results provide further insights into the process of HW formation in Taiwania.

Integrated mRNA and Small RNA Sequencing Reveals microRNAs Associated With Xylem Development in Dalbergia odorifera

“…However, only a limited number of studies ( Cui et al, 2019 ) are available that describe the molecular mechanism of wood formation of D. odorifera , which is comprised of multiple and complex pathways. RNA-seq technology now provides a convenient tool for a better understanding of the mechanisms of plant growth and development at the molecular level ( Yeh et al, 2020 ). In this study, we explored the potential mechanism of xylem differentiation by investigating the accumulation of miRNAs and mRNAs in different xylem tissues.…”

“…These three trees were used for all the experiments. Samples of sapwood (Dosw1, Dosw2, Dosw3) and transition zone (Dotz1, Dotz2, Dotz3) were taken from xylem tissues near the cambium and near the heartwood of each tree, respectively, by following the previously described protocols ( Yeh et al, 2020 ). All the samples were isolated from the trees with the help of a sharp chisel after removing the bark, and the tissues were immediately frozen in liquid nitrogen and stored at −80°C until RNA isolation.…”

“…The xylem tissue of the transition zone is often regarded as an important material for studying wood formation. For example, in Taiwania cryptomerioides , the molecular mechanism of the autolysis of the cellular components of ray parenchyma cells in the transition zone, during the heartwood formation, was elucidated by transcriptome sequencing of sapwood and transition zone, in combination with the microscopy and high-performance liquid chromatography technology ( Yeh et al, 2020 ). In Pinus sylvestris , transcriptomic sequencing revealed that stilbene and resinic acid were synthesized in transition zone and sapwood, respectively ( Lim et al, 2016 ).…”

“…In Pinus sylvestris , transcriptomic sequencing revealed that stilbene and resinic acid were synthesized in transition zone and sapwood, respectively ( Lim et al, 2016 ). These studies suggest that sapwood and transition zone are ideal plant parts for studying the dynamics of gene expression and molecular regulatory mechanisms of wood formation ( Yeh et al, 2020 ).…”

Evaluation of reference genes and characterization of the MYBs in xylem radial change of Chinese fir stem

“…Samples excised at breast height (1.3 m) of 26 years old Chinese fir stem were successfully used to study cellular changes from cambium to heartwood in Chinese fir 57 . Increment cores were taken from 35 years old Taiwanina ( Taiwania cryptomerioides Hayata) stems to analyze the expression profiling of the heartwood formation process 31 . In this study, increment cores were sampled from breast height of three well-grown individuals (of each) of 15 years old and 30 years old Chinese fir stems in summer (August 2019).…”