Zhejiang Provincial Key Laboratory of Tree Breeding, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, 311400, Zhejiang, China.
Department of Hydraulic Engineering, Zhejiang Tongji Vocational College of Science and Technology, Hangzhou, 311231, Zhejiang, China.
BMC Plant Biol. 2022 May 28;22(1):265. doi: 10.1186/s12870-022-03651-4.
Camellia oleifera (C.oleifera) is one of the most important wood oil species in the world. C.oleifera was propagated by nurse seedling grafting. Since the morphology of rootstocks has a significant impact on grafting efficiency and seedling quality, it is necessary to understand the molecular mechanism of morphogenesis for cultivating high-quality and controllable rootstocks. However, the genomic resource for this species is relatively limited, which hinders us from fully understanding the molecular mechanisms of seed germination in C.oleifera.
In this paper, using transcriptome sequencing, we measured the gene expression in the C.oleifera cotyledon in different stages of development and the global gene expression profiles. Approximately 45.4 gigabases (GB) of paired-end clean reads were assembled into 113,582 unigenes with an average length of 396 bp. Six public protein databases annotate 61.5% (68,217) of unigenes. We identified 11,391 differentially expressed genes (DEGs) throughout different stages of germination. Enrichment analysis revealed that DEGs were mainly involved in hormone signal transduction and starch sucrose metabolism pathways. The gravitropism regulator UNE10, the meristem regulators STM, KNAT1, PLT2, and root-specific transcription factor WOX11 all have higher gene expression levels in the CAM2 stage (seed soaking), which indicates that the cotyledon-regulated program for germination had initiated when the seeds were imbibition. Our data showed differentially reprogrammed to multiple hormone-related genes in cotyledons during C.oleifera seed germination.
Cotyledons play vital roles, both as the main nutrient provider and as one primary instructor for seed germination and seedling growth. Together, our study will significantly enrich the genomic resources of Camellia and help us understand the molecular mechanisms of the development in the seed germination and seedling growth of C.oleifera. It is helpful to culture standard and superior quality rootstock for C.oleifera breeding.
油茶树（C.oleifera）是世界上最重要的木本油料树种之一。C.oleifera 通过芽苗砧嫁接进行繁殖。由于砧木的形态对嫁接效率和苗木质量有重要影响，因此有必要了解其形态发生的分子机制，以培育高质量和可控的砧木。然而，该物种的基因组资源相对有限，这阻碍了我们对油茶种子萌发的分子机制的全面理解。
本文利用转录组测序，测量了油茶子叶在不同发育阶段的基因表达情况和全基因组基因表达谱。约 45.4 千兆碱基（GB）的配对末端清洁读取序列组装成 113582 个平均长度为 396bp 的 Unigenes。6 个公共蛋白质数据库注释了 61.5%（68217 个）的 Unigenes。我们在不同的萌发阶段鉴定了 11391 个差异表达基因（DEGs）。富集分析表明，DEGs 主要参与激素信号转导和淀粉蔗糖代谢途径。向性调节剂 UNE10、分生组织调控因子 STM、KNAT1、PLT2 和根特异性转录因子 WOX11 在 CAM2 阶段（种子浸泡）的基因表达水平较高，这表明种子吸水时，子叶启动了萌发的调节程序。我们的数据显示，油茶种子萌发过程中，子叶中多个激素相关基因的表达发生了差异重编程。
子叶在种子萌发和幼苗生长过程中起着重要的作用，既是主要的营养供应者，也是主要的指导者之一。总之，我们的研究将极大地丰富山茶的基因组资源，帮助我们理解油茶种子萌发和幼苗生长过程中的分子机制。这有助于油茶标准和优质砧木的培育。
