Morphological switch to a resistant subpopulation in response to viral infection in the bloom-forming coccolithophore Emiliania huxleyi

PLoS Pathogens

Shifra Ben-Dor¹  Helena Sabanay²  Miguel José Frada³  Assaf Vardi³  Shilo Rosenwasser³  Adva Shemi³ 

[1] Bioinformatics and Biological Computing Unit–Department of Biological Services, Weizmann Institute of Science, Rehovot, Israel;Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel;Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel

关键词: Meiosis;    Viral transmission;    infection;    Flow cytometry;    Diplobiontic life cycle;    Marine ecology;    Gene expression;    Life cycles;    Ploidy;   

DOI  :  10.1371/journal.ppat.1006775

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Recognizing the life cycle of an organism is key to understanding its biology and ecological impact. Emiliania huxleyi is a cosmopolitan marine microalga, which displays a poorly understood biphasic sexual life cycle comprised of a calcified diploid phase and a morphologically distinct biflagellate haploid phase. Diploid cells (2N) form large-scale blooms in the oceans, which are routinely terminated by specific lytic viruses (EhV). In contrast, haploid cells (1N) are resistant to EhV. Further evidence indicates that 1N cells may be produced during viral infection. A shift in morphology, driven by meiosis, could therefore constitute a mechanism for E. huxleyi cells to escape from EhV during blooms. This process has been metaphorically coined the ‘Cheshire Cat’ (CC) strategy. We tested this model in two E. huxleyi strains using a detailed assessment of morphological and ploidy-level variations as well as expression of gene markers for meiosis and the flagellate phenotype. We showed that following the CC model, production of resistant cells was triggered during infection. This led to the rise of a new subpopulation of cells in the two strains that morphologically resembled haploid cells and were resistant to EhV. However, ploidy-level analyses indicated that the new resistant cells were diploid or aneuploid. Thus, the CC strategy in E. huxleyi appears to be a life-phase switch mechanism involving morphological remodeling that is decoupled from meiosis. Our results highlight the adaptive significance of morphological plasticity mediating complex host–virus interactions in marine phytoplankton.

【 授权许可】

CC BY