A full-length transcriptome and gene expression analysis reveal genes and molecular elements expressed during seed development in Gnetum luofuense

Abstract

Background: Gnetum is an economically important tropical and subtropical gymnosperm genus with various dietary, industrial and medicinal uses. Many carbohydrates, proteins and fibers accumulate during the ripening of Gnetum seeds. However, the molecular mechanisms related to this process remain unknown.Results: We therefore assembled a full-length transcriptome from immature and mature G. luofuense seeds using PacBio sequencing reads. We identified a total of 5,726 novel genes, 9,061 alternative splicing events, 3,551 lncRNAs, 2,160 transcription factors, and we found that 8,512 genes possessed at least one poly(A) site. In addition, gene expression comparisons of six transcriptomes generated by Illumina sequencing showed that 14,323 genes were differentially expressed from an immature stage to a mature stage with 7,891 genes upregulated and 6,432 genes downregulated. The expression of 14 differentially expressed transcription factors from the MADS-box, Aux/IAA and bHLH families was validated by qRT-PCR, suggesting that they may have important roles in seed ripening of G. luofuense.Conclusions: These findings provide a valuable molecular resource for understanding seed development of gymnosperms.