NorWood: A gene expression resource for evo-devo studies of conifer wood development

The secondary xylem of conifers is composed mainly of tracheids that differ anatomically and chemically from angiosperm xylem cells. There is currently no high-spatial-resolution data available profiling gene expression during wood formation for any coniferous species, which limits insight into tracheid development. RNA-Sequencing data from replicated, high-spatial-resolution section series throughout the cambial and woody tissues of Picea abies were used to generate the NorWood.conGenIE.org web resource, which facilitates exploration of the associated gene expression profiles and co-expression networks. Integration within PlantGenIE.org enabled a comparative regulomics analysis, revealing divergent co-expression networks between P. abies and the two angiosperm species Arabidopsis thaliana and Populus tremula for the secondary cell wall (SCW) master regulator NAC Class IIB transcription factors. The SCW cellulose synthase genes (CesAs) were located in the neighbourhoods of the NAC factors in A. thaliana and P. tremula, but not in P. abies. The NorWood co-expression network enabled identification of potential SCW CesA regulators in P. abies. The NorWood web resource represents a powerful community tool for generating evo-devo insights in the divergence of wood formation between angiosperms and gymnosperms and for advancing understanding of the regulation of wood development in P. abies.针叶树的次生木质部主要由管胞构成，其解剖学与化学特征均与被子植物的木质部细胞存在显著差异。目前尚无针对任意针叶树种木材形成过程中基因表达谱的高空间分辨率分析数据，这极大限制了学界对管胞发育机制的深入认知。研究人员通过对欧洲云杉（Picea abies）形成层与木质组织开展全段高空间分辨率切片并设置生物学重复，获取了RNA测序（RNA-Sequencing）数据，以此构建了NorWood.conGenIE.org在线资源平台，该平台可支持相关基因表达谱与共表达网络的探索分析。该资源整合至PlantGenIE.org平台后，助力完成了比较调控组学分析，研究发现欧洲云杉与拟南芥（Arabidopsis thaliana）、欧洲山杨（Populus tremula）这两种被子植物在次生细胞壁（SCW）核心调控因子NAC IIB类转录因子的共表达网络上存在显著分化。在拟南芥与欧洲山杨中，次生细胞壁纤维素合酶基因（CesAs）位于该类NAC转录因子的调控邻域内，但欧洲云杉中并未观察到这一特征。借助NorWood共表达网络，研究人员成功鉴定出欧洲云杉中潜在的次生细胞壁纤维素合酶基因调控因子。NorWood在线资源平台作为一款强大的社区共享工具，可为解析被子植物与裸子植物（gymnosperms）木材形成的进化发育（evo-devo）差异提供支撑，同时也推动了学界对欧洲云杉木材发育调控机制的认知深化。