Mating type specific transcriptomic response to sex inducing pheromone in the pennate diatom Seminavis robusta

Gust Bilcke,Koen Van Den Berge,Lieven De Veylder,Cristina Maria Osuna-Cruz,Jack Dickenson,Koen Sabbe,Lieven Clement,Sam De Decker,Nicole Poulsen,Sven Mangelinckx,Klaas Vandepoele,Eli Bonneure,Petra Bulankova,Wim Vyverman,Georg Pohnert

doi:10.1038/s41396-020-00797-7

Abstract

Sexual reproduction is a fundamental phase in the life cycle of most diatoms. Despite its role as a source of genetic variation, it is rarely reported in natural circumstances and its molecular foundations remain largely unknown. Here, we integrate independent transcriptomic datasets to prioritize genes responding to sex inducing pheromones (SIPs) in the pennate diatom Seminavis robusta. We observe marked gene expression changes associated with SIP treatment in both mating types, including an inhibition of S phase progression, chloroplast division, mitosis, and cell wall formation. Meanwhile, meiotic genes are upregulated in response to SIP, including a sexually induced diatom specific cyclin. Our data further suggest an important role for reactive oxygen species, energy metabolism, and cGMP signaling during the early stages of sexual reproduction. In addition, we identify several genes with a mating type specific response to SIP, and link their expression pattern with physiological specialization, such as the production of the attraction pheromone diproline in mating type − (MT−) and mate-searching behavior in mating type + (MT+). Combined, our results provide a model for early sexual reproduction in pennate diatoms and significantly expand the suite of target genes to detect sexual reproduction events in natural diatom populations.

Highlights

These authors contributed : Gust Bilcke, Koen Van den Berge
The stronger response during the first 3 time points in MT− versus MT+ may be the result of the use of a chromatographic fraction of sex inducing pheromones (SIPs)+ for MT− while MT+ cultures were treated with a SIP− containing filtrate
Gene sets for many biological processes were significantly enriched in the conventional lists of differential expression (DE) genes: a total of 1081 and 740 enriched biological process terms were discovered for the response to sex pheromones in MT+ and MT−, respectively (Fig. 2d, Supplemenatry Fig. 2)

Summary

1234567890();,: 1234567890();,: Introduction

Mating type specific transcriptomic response to sex inducing pheromone in the pennate diatom Seminavis. Important role in primary production and biogeochemical cycling in the oceans [2, 3] Their unique life cycle is characterized by cell size reduction during vegetative growth [4]. Characteristic for pennate diatoms, sexual reproduction is initiated by the interaction of sexually mature vegetative cells (gametangia) from compatible mating types [4]. To tackle technical challenges in comparing gene expression between datasets, a workflow is introduced to integrate RNA-seq datasets This approach allowed the identification of key genes exhibiting either mating type specific or shared responses to SIP. These key genes include a sexually induced cyclin and highlight the importance of reactive. Oxygen species (ROS), energy metabolism, and ubiquitination in the mating process

Material and methods

Data availability and reproducibility

Results and discussion

Conclusion

Compliance with ethical standards