Guangxi Forestry Research Institute of Science, Nanning, 530002, People's Republic of China.
Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Nanning, 530002, People's Republic of China.
Sci Rep. 2021 Apr 27;11(1):9033. doi: 10.1038/s41598-021-87787-7.
Knot-free timber cultivation is an important goal of forest breeding, and lateral shoots affect yield and stem shape of tree. The purpose of this study was to analyze the molecular mechanism of lateral bud development by removing the apical dominance of Pinus massoniana young seedlings through transcriptome sequencing and identify key genes involved in lateral bud development. We analyzed hormone contents and transcriptome data for removal of apical dominant of lateral buds as well as apical and lateral buds of normal development ones. Data were analyzed using an comprehensive approach of pathway- and gene-set enrichment analysis, Mapman visualization tool, and gene expression analysis. Our results showed that the contents of auxin (IAA), Zea and strigolactone (SL) in lateral buds significantly increased after removal of apical dominance, while abscisic acid (ABA) decreased. Gibberellin (GA) metabolism, cytokinin (CK), jasmonic acid, zeatin pathway-related genes positively regulated lateral bud development, ABA metabolism-related genes basically negatively regulated lateral bud differentiation, auxin, ethylene, SLs were positive and negative regulation, while only A small number of genes of SA and BRASSINOSTEROID, such as TGA and TCH4, were involved in lateral bud development. In addition, it was speculated that transcription factors such as WRKY, TCP, MYB, HSP, AuxIAA, and AP2 played important roles in the development of lateral buds. In summary, our results provided a better understanding of lateral bud differentiation and lateral shoot formation of P. massoniana from transcriptome level. It provided a basis for molecular characteristics of side branch formation of other timber forests, and contributed to knot-free breeding of forest trees.
无节材培育是林木育种的重要目标，侧枝影响树木的产量和干形。本研究旨在通过转录组测序分析马尾松幼树去除顶端优势后侧芽发育的分子机制，并鉴定参与侧芽发育的关键基因。我们分析了去除侧芽顶端优势以及正常发育的顶芽和侧芽的激素含量和转录组数据。采用通路和基因集富集分析、Mapman 可视化工具和基因表达分析的综合方法对数据进行分析。结果表明，去除顶端优势后，侧芽中的生长素（IAA）、玉米素和独脚金内酯（SL）含量显著增加，而脱落酸（ABA）含量降低。赤霉素（GA）代谢、细胞分裂素（CK）、茉莉酸、玉米素途径相关基因正向调控侧芽发育，ABA 代谢相关基因基本负向调控侧芽分化，生长素、乙烯、SLs 呈正、负调控，而 SA 和油菜素内酯（BRASSINOSTEROID）的少数基因，如 TGA 和 TCH4，参与侧芽发育。此外，推测 WRKY、TCP、MYB、HSP、AuxIAA 和 AP2 等转录因子在侧芽发育中发挥重要作用。综上所述，本研究从转录组水平为马尾松侧芽分化和侧枝形成提供了更好的理解，为其他用材林侧枝形成的分子特征提供了基础，为林木无节材培育做出了贡献。
