BACKGROUND Pennisetum giganteum, an abundant, fast-growing perennial C4 grass that belongs to the genus Pennisetum, family Poaceae, has been developed as a source of biomass for mushroom cultivation and production, as a source of forage for cattle and sheep, and as a tool to remedy soil erosion. However, having a chilling-sensitive nature, P. giganteum seedlings need to be protected while overwintering in most temperate climate regions. RESULTS To elucidate the cold stress responses of P. giganteum, we carried out comprehensive full-length transcriptomes from leaf and root tissues under room temperature (RT) and chilling temperature (CT) using PacBio Iso-Seq long reads. We identified 196,124 and 140,766 full-length consensus transcripts in the RT and CT samples, respectively. We then systematically performed functional annotation, transcription factor identification, long non-coding RNAs (lncRNAs) prediction, and simple sequence repeat (SSR) analysis of those full-length transcriptomes. Isoform analysis revealed that alternative splicing events may be induced by cold stress in P. giganteum, and transcript variants may be involved in C18 unsaturated fatty acid biosynthesis and metabolism pathways at chilling temperature in P. giganteum. Furthermore, the fatty acid composition determination and gene expression level analysis supported that C18 unsaturated fatty acid biosynthesis and metabolism pathways may play roles during cold stress in P. giganteum. CONCLUSIONS We provide the first comprehensive full-length transcriptomic resource for the abundant and fast-growing perennial grass Pennisetum giganteum. Our results provide a useful transcriptomic resource for exploring the biological pathways involved in the cold stress responses of P. giganteum.

中文翻译：

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全长转录组的SMRT测序揭示了在低温下狼尾草中涉及C18不饱和脂肪酸生物合成和代谢途径的转录物变体。

背景技术狼尾草（Pennisetum giganteum）是属于狼尾草属（禾本科）的一种丰富，快速生长的多年生C4草，已被开发为蘑菇栽培和生产的生物量来源，牛羊的草料来源以及补救土壤侵蚀的工具。但是，由于具有低温敏感性，所以在大多数温带气候地区过冬时，都需要保护巨大的P. giganteum幼苗。结果为阐明P. giganteum的冷胁迫响应，我们使用PacBio Iso-Seq长读本在室温（RT）和冷却温度（CT）下从叶片和根组织进行了全面的全长转录组分析。我们在RT和CT样本中分别确定了196,124和140,766个全长共有转录本。然后，我们系统地执行功能注释，转录因子鉴定，较长的非编码RNA（lncRNA）预测以及这些全长转录组的简单序列重复（SSR）分析。同工型分析表明，巨大的体育低温胁迫可能诱导其他剪接事件，而在寒冷的低温下转录本变体可能参与C18不饱和脂肪酸的生物合成和代谢途径。此外，脂肪酸组成的测定和基因表达水平分析支持C18不饱和脂肪酸的生物合成和代谢途径可能在巨大假单胞菌冷胁迫期间发挥作用。结论我们为丰富和快速生长的多年生禾本科狼尾草提供了第一个综合的全长转录组资源。