Abstract:

Gymnosphaera podophylla Dalla Torre & Sarnth. is a famous relict tree fern with strong environmental adaptability. However, the mechanisms underlying its adaptability remain unclear. In this study, the PacBio and Illumina platforms were used to sequence the root, rachis, and pinna transcriptomes of G. podophylla, resulting in the generation of 12 879, 14 185, and 16 084 full-length unigenes, respectively. Transcript quantification showed that these unigenes were related to drought resistance and biological stress and were highly expressed. KEGG enrichment analysis indicated that the up-regulated genes in the roots, rachis, and pinna were enriched in the "phenylpropane biosynthesis pathway", while the up-regulated genes in the roots and rachis were enriched in the "flavonoid biosynthetic pathway". A total of 192 full-length unigenes were annotated as structural genes involving 13 enzymes in the flavonoid biosynthesis pathway, including 112 differentially expressed genes (DEGs), suggesting that the flavonoid biosynthesis pathway was conserved in G. podophylla, with organ-specific DEGs. This research is the first to perform a comprehensive analysis of the full-length transcriptome across multiple organs in G. podophylla and to investigate the structural genes of the flavonoid biosynthetic pathway. This study provides an abundance of genetic resources for further examination of environmental adaptation in this species.

摘要：

黑桫椤（Gymnosphaera podophylla Dalla Torre & Sarnth.）为著名的孑遗蕨类，具有很强的环境适应能力，然而其适应性机制尚不清楚。本研究采用PacBio和Illumina技术对黑桫椤的根、羽轴和羽片进行转录组测序，分别生成12 879、14 185和16 084个全长unigenes。基因表达分析结果表明，与黑桫椤抗干旱、缺水胁迫和生物胁迫相关的基因表达水平较高。根、羽轴和羽片特异性上调基因均显著富集到KEGG代谢通路中的“苯丙烷生物合成途径”，根和羽轴的器官特异性上调基因还显著富集到“类黄酮生物合成途径”。共有192个全长unigenes被注释为类黄酮生物合成途径所涉及的13个酶结构基因，其中包括112个差异表达基因（DEGs），表明黑桫椤类黄酮生物合成途径较为保守，且存在器官特异性差异表达基因。本文对黑桫椤多器官全长转录组和类黄酮生物合成途径结构基因进行了综合分析，为进一步研究其对环境的适应性提供了丰富的遗传资源。