Full-length transcriptome sequencing and comparative transcriptomic analysis of different developmental stages of the sporophyll in Undaria pinnatifida (Laminariales: Alariaceae)
Shan T, Li Q, Wang X, Pang S#
Sporophyll development is an important biological process which is crucial to reproduction of the sporophyte of the brown alga Undaria pinnatifida. However, the molecular foundation underlying this process is largely unknown due to lack of genomic information in this important alga. Full-length transcriptome, which covered male and female gametophytes at vegetative and gametogenic phases, and the blade, stipe, immature and mature parts of the sporophyll of sporophytes, was obtained for the first time through single molecule real-time sequencing in this study. After removing potentially polluted sequences derived from microorganisms, we obtained a total of 61,181 transcripts with average and N50 length being 1639 and 1815 bp, respectively, and annotated 21,915 of them (35.8%). By using the full-length transcriptome as reference, we performed Illumina sequencing to analyze the difference of gene expression among different developmental stages of the sporophyll and validated the results by quantitative real-time PCR. A large number of transcripts related to flagellar components and fucoidan biosynthesis as well as a few transcripts coding for meiotic nuclear division protein were found to be significantly upregulated with development of the sporophyll, and thus the over-expression of them is likely essential for the sporophyll to perform its biological function. These findings contribute to our understanding of sporophyll development in U. pinnatifida at the transcriptional level.