Comparative transcriptomics reveals colony formation mechanism of a harmful algal bloom species Phaeocystis globosa

• Published in: The Science of the total environment 2020-06, Vol.719, p.137454-137454, Article 137454
• Main Authors: Zhang, Shu-Feng, Zhang, Kun, Cheng, Hua-Min, Lin, Lin, Wang, Da-Zhi
• Format: Article
• Language: English
• Subjects: Colony formation; Haptophyta; Harmful Algal Bloom; Harmful algal blooms; Phaeocystis globosa; Temperature; Transcriptome
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.137454

Phaeocystis globosa is a major causative agent of harmful algal blooms in the global ocean, featuring a complex polymorphic life cycle alternating between free-living solitary cells and colonial cells. Colony is the dominant morphotype during P. globosa bloom. However, the underlying mechanism of colony formation is poorly understood. Here, we comprehensively compared global transcriptomes of P. globosa cells at four distinctive colony formation stages: free-living solitary cells, two cell-, four cell- and multi-cell colonies, under low (20 °C) and high (32 °C) temperatures, and characterized the genes involved in colony formation. Glycosaminoglycan (GAG) synthesis was enhanced while its degradation was decreased during colony formation, resulting in the accumulation of GAGs that are an essential substrate of the colony matrix. Nitrogen metabolism and glutamine synthesis were remarkably increased in the colonial cells, which provided precursors for GAG synthesis. Furthermore, cell defense and motility were down-regulated in the colonial cells, thereby conserving energy for GAG synthesis. Notably, high temperature led to decreased synthesis and increased degradation of GAGs, resulting in insufficient substrates to form the colony. Our study indicates that GAGs accumulation is critical for colony formation of P. globosa, but high temperature inhibits GAGs' accumulation and colony formation. [Display omitted] •Colonies are the major morphotype of Phaeocistis globosa during the bloom period.•This study compared P. globosa transcriptomes at different colony formation stages and temperatures.•Glycosaminoglycan (GAG) synthesis was enhanced while its degradation was decreased during the colony formation.•Decreased cell defense and motility saved energy for GAG biosynthesis, and GAG precursors synthesis was enhanced.•Temperature is a critical factor regulating colony formation through mediating the intracellular accumulation of GAGs.