Revealing the developmental dynamics in male strobilus transcriptome of Gnetum luofuense using nanopore sequencing technology.

Gnetum is a pantropical distributed gymnosperm genus. As being dioecious, Gnetum species apply female and male strobili to attract and provide nutrition to insect pollinators. Due to its unique gross morphology, a Gnetum male strobilus receives much attention in previous taxonomic and evolutionary studies. However, underlying molecular mechanisms that control male strobilus development and pollination adaptation have not been well studied. In the present study, nine full-length transcriptomes were sequenced from three developmental stages of the G. luofuense male strobili using Oxford Nanopore Technologies. In addition, weighted gene co-expression network analysis (WGCNA), and RT-qPCR analysis were performed. Our results show that a total of 3138 transcription factors and 466 long non-coding RNAs (lncRNAs) were identified, and differentially expressed lncRNAs and TFs reveal a dynamic pattern during the male strobilus development. Our results show that MADS-box and Aux/IAA TFs were differentially expressed at the three developmental stages, suggesting their important roles in the regulation of male strobilus development of G. luofuense. Results of WGCNA analysis and annotation of differentially expressed transcripts corroborate that the male strobilus development of G. luofuense is closely linked to plant hormone changes, photosynthesis, pollination drop secretion and reproductive organ defense. Our results provide a valuable resource for understanding the molecular mechanisms that drive organ evolution and pollination biology in Gnetum.