State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China.
Research Institute of Fast-Growing Trees, Chinese Academy of Forestry, Zhanjiang, China.
BMC Plant Biol. 2023 Oct 18;23(1):500. doi: 10.1186/s12870-023-04500-8.
Wood is a secondary xylem generated by vascular cambium. Vascular cambium activities mainly include cambium proliferation and vascular tissue formation through secondary growth, thereby producing new secondary phloem inward and secondary xylem outward and leading to continuous tree thickening and wood formation. Wood formation is a complex biological process, which is strictly regulated by multiple genes. Therefore, molecular level research on the vascular cambium of different tree ages can lead to the identification of both key and related genes involved in wood formation and further explain the molecular regulation mechanism of wood formation.
In the present study, RNA-Seq and Pac-Bio Iso-Seq were used for profiling gene expression changes in Eucalyptus urophylla × Eucalyptus grandis (E. urograndis) vascular cambium at four different ages. A total of 59,770 non-redundant transcripts and 1892 differentially expressed genes (DEGs) were identified. The expression trends of the DEGs related to cell division and differentiation, cell wall biosynthesis, phytohormone, and transcription factors were analyzed. The DEGs encoding expansin, kinesin, cycline, PAL, GRP9, KNOX, C2C2-dof, REV, etc., were highly expressed in E. urograndis at three years old, leading to positive effects on growth and development. Moreover, some gene family members, such as NAC, MYB, HD-ZIP III, RPK, and RAP, play different regulatory roles in wood formation because of their sophisticated transcriptional network and function redundantly.
These candidate genes are a potential resource to further study wood formation, especially in fast-growing and adaptable eucalyptus. The results may also serve as a basis for further research to unravel the molecular mechanism underlying wood formation.
木材是由维管形成层产生的次生木质部。维管形成层的活动主要包括通过次生生长进行的形成层增殖和维管组织形成，从而使新的次生韧皮部向内和次生木质部向外产生，导致树木不断增粗和木材形成。木材形成是一个复杂的生物学过程，受到多个基因的严格调控。因此，对不同树龄的维管形成层进行分子水平的研究，可以鉴定出参与木材形成的关键基因和相关基因，并进一步解释木材形成的分子调控机制。
本研究利用 RNA-Seq 和 Pac-Bio Iso-Seq 技术，对不同年龄的尾叶桉×巨桉（E. urograndis）维管形成层进行基因表达谱分析。共鉴定出 59770 个非冗余转录本和 1892 个差异表达基因（DEGs）。分析了与细胞分裂和分化、细胞壁生物合成、植物激素和转录因子相关的 DEGs 的表达趋势。鉴定出的 DEGs 编码扩展蛋白、驱动蛋白、细胞周期蛋白、PAL、GRP9、KNOX、C2C2-dof、REV 等，在 3 年生尾叶桉中高表达，对生长发育有积极影响。此外，一些基因家族成员，如 NAC、MYB、HD-ZIP III、RPK 和 RAP，由于其复杂的转录网络和功能冗余，在木材形成中发挥着不同的调控作用。
这些候选基因是进一步研究木材形成的潜在资源，特别是在快速生长和适应性强的桉树中。研究结果也可为进一步研究木材形成的分子机制提供基础。
