目的:次生细胞壁(SCW)增厚是决定木材结构和性质的主要细胞发育阶段。尽管在原代生长系统中已经很好地建立了在气管元件分化过程中细胞壁沉积的分子调节,关于成熟树的多层SCW增厚所涉及的基因调控过程知之甚少。
方法:使用第三代(长读单分子实时,SMRT)和第二代(通过合成进行短读测序,SBS)测序方法,首次建立了具有综合功能和结构注释的白皮松转录组资源。使用这些方法,我们生成了血管形成层的高空间分辨率数据集,木质部扩展区,早期SCW增厚,晚期SCW增厚,和71岁的白皮松树的成熟木质部组织。
结果:总共79,390个非冗余转录本,31,808个长的非编码RNA,在所有生长和分化阶段的不同木质部组织中对5,147个转录因子进行了注释和定量。此外,使用这个高空间分辨率的数据集,我们建立了一个全面的转录组谱,发现NAC的成员,WRKY,SUS,CESA,LAC基因家族是气管早期SCW形成的主要参与者,而MYB和LBD转录因子家族的成员在SCW晚期增厚过程中高度表达。
结论:我们的结果为针叶树中多层SCW增稠的调节提供了新的分子见解。提供的高空间分辨率数据集可以作为改进软件的重要基因资源。
OBJECTIVE: Secondary cell wall (SCW) thickening is a major cellular developmental stage determining wood structure and properties. Although the molecular regulation of cell wall deposition during tracheary element differentiation has been well established in primary growth systems, less is known about the gene regulatory processes involved in the multi-layered SCW thickening of mature trees.
METHODS: Using third-generation [long-read single-molecule real-time (SMRT)] and second-generation [short-read sequencing by synthesis (SBS)] sequencing methods, we established a Pinus bungeana transcriptome resource with comprehensive functional and structural annotation for the first time. Using these approaches, we generated high spatial resolution datasets for the vascular cambium, xylem expansion regions, early SCW thickening, late SCW thickening and mature xylem tissues of 71-year-old Pinus bungeana trees.
RESULTS: A total of 79 390 non-redundant transcripts, 31 808 long non-coding RNAs and 5147 transcription factors were annotated and quantified in different xylem tissues at all growth and differentiation stages. Furthermore, using this high spatial resolution dataset, we established a comprehensive transcriptomic profile and found that members of the NAC, WRKY, SUS, CESA and LAC gene families are major players in early SCW formation in tracheids, whereas members of the MYB and LBD transcription factor families are highly expressed during late SCW thickening.
CONCLUSIONS: Our results provide new molecular insights into the regulation of multi-layered SCW thickening in conifers. The high spatial resolution datasets provided can serve as important gene resources for improving softwoods.