Low-temperature plasma promotes growth of Haematococcus pluvialis and accumulation of astaxanthin by regulating histone H3 lysine 4 tri-methylation.

Astaxanthin exhibits strong antioxidant ability, so researchers endeavor to improve astaxanthin production in Haematococcus pluvialis (H. pluvialis). Previous work revealed that low-temperature plasma (LTP) could improve the astaxanthin yield in H. pluvialis, but the mechanism is still elusive. In this work, we therefore explored the mechanism of LTP promoting algal growth astaxanthin yield, especially from the perspective of epigenetics. Through measurements of hormones and transcription genes, it was found that the levels of strigolactone and abscisic acid in H. pluvialis increased significantly after LTP treatment, accompanied by enhanced expression of astaxanthin synthesis genes. Particularly, one of the key genes, namely CRTISO, was specifically up-regulated. Further experiments via immunofluorescence and ChIP-PCR methods confirmed that histone H3 lysine 4 tri-methylation (H3K4me3) in the promoter region of CRTISO was increased. Therefore, this study demonstrates that LTP can regulate CRTISO and promote the algal growth and astaxanthin accumulation by stimulating phytohormones and regulating H3K4me3.