Research Institution of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou 311400, Zhejiang, China.
Research Institution of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou 311400, Zhejiang, China.
Gene. 2021 Mar 10;772:145355. doi: 10.1016/j.gene.2020.145355. Epub 2021 Jan 5.
Calanthe tsoongiana is a rare orchid species native to China. Asymbiotic seed germination is of great importance in the ex situ conservation of this species. Based on morphological characteristics and anatomical structures, the C. tsoongiana developmental process from seeds to seedlings was divided into four stages (SA, PB, PC and PD), and subsequently, changes in endogenous hormone contents and gene expression were assessed using RNA-seq analysis. K-means analysis divided the DEGs into eight clusters. The gene expression decreased markedly between the imbibed seed and globular protocorm stages, with this being the most notably enriched cluster. During the seed germination period, DEGs were dominated by ATP metabolic processes, respiration and photosynthesis. A small change in gene expression was found in the globular protocorm versus the finger-like protocorm stages. During the last developmental stage, DEGs were significantly enriched in lignin catabolic processes and plant-type secondary cell wall biogenesis. DEG homologs, such as TSA1, DAO, NCED1, STM, and CUC2, were related to phytohormones and the morphogenesis of shoots, leaves and roots. Particularly, interactions between CUC2 and STM as well as AS1 and STM were likely involved in protocorm formation and development. Furthermore, TSA1 and DAO were distinctly validated and implicated in the synthesis and metabolism of auxin, which has a pivotal role in plant development. Our study is the first to combine morphological and transcriptome analysis to examine the process of protocorm formation and development. The results provide a foundation for understanding the mechanisms of seed germination and protocorm development of C. tsoongiana.
宝华玉兰是中国特有的珍稀兰科植物。非共生种子萌发对该物种的离体保存具有重要意义。基于形态特征和解剖结构，将 C. tsoongiana 从种子到幼苗的发育过程分为四个阶段（SA、PB、PC 和 PD），然后使用 RNA-seq 分析评估内源激素含量和基因表达的变化。K-means 分析将 DEGs 分为 8 个簇。在吸胀种子和球形原球茎阶段之间，基因表达明显下降，这是最明显的富集簇。在种子萌发期间，DEGs 主要涉及 ATP 代谢过程、呼吸和光合作用。球形原球茎与指状原球茎阶段之间的基因表达变化较小。在最后一个发育阶段，DEGs 在木质素分解代谢过程和植物型次生细胞壁生物发生中显著富集。DEG 同源物，如 TSA1、DAO、NCED1、STM 和 CUC2，与植物激素和芽、叶和根的形态发生有关。特别是，CUC2 和 STM 以及 AS1 和 STM 之间的相互作用可能参与了原球茎的形成和发育。此外，TSA1 和 DAO 明显得到验证，并与生长素的合成和代谢有关，生长素在植物发育中起着关键作用。我们的研究首次结合形态学和转录组分析来研究原球茎形成和发育的过程。研究结果为了解 C. tsoongiana 种子萌发和原球茎发育的机制提供了基础。
