Stress tolerance alteration in the freshwater cnidarian green hydra ( Hydra viridissima ) via symbiotic algae mutagenesi
- PDF / 947,125 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 70 Downloads / 166 Views
Stress tolerance alteration in the freshwater cnidarian green hydra (Hydra viridissima) via symbiotic algae mutagenesis Siao Ye 1
&
Meenakshi Bhattacharjee 1 & Evan Siemann 1
Received: 29 June 2020 / Accepted: 31 August 2020 # Springer Nature B.V. 2020
Abstract Symbiotic organisms such as corals are threatened by changing climate because they are sensitive to stress, and may be unable to adapt quickly due to the long host generation time. Instead of selecting for stress tolerant hosts, manipulating their symbiotic microbes has been proposed because microbes affect holobiont phenotypes and they have rapid life cycles. Because it is timeconsuming to isolate stress tolerant symbionts from the wild even when appropriate types exist, mutation and selection of symbionts is a promising alternative approach. Using green hydra (Hydra viridissima) and symbiotic algae (Chlorella variabilis NC64A), we found symbiont mutagenesis in vitro altered their UV-B resistance as well as that of holobionts receiving mutated algae. In addition, hydra UV-B tolerance was positively correlated to that of the algae they were hosting, as the hydra associated with UV-B tolerant algal strains exhibited higher UV-B resistance. However, chronic low-level UV-B selection decreased algal resistance to acute high-level UV-B, which was unexpected, and did not affect UV-B resistance of holobionts. The variations in algal UV-B tolerance and hydra UV-B tolerance were largely due to mutagenesis rather than selection. Our results suggest symbiont mutagenesis and trait-based identification may be more effective than assisted evolution in holobiont phenotype alteration, and it highlights the need to characterize symbiont traits in vitro that are correlated to stress tolerance they can confer to hosts, which may have application in conservation, agriculture and forestry. Keywords Endosymbiosis . Green hydra . Stress tolerance . Holobiont . Mutagenesis
1 Introduction Discoveries of new functions provided by symbiotic microbes to their hosts have caused researchers to reconsider the significance of symbiosis in ecology and evolution, especially in the context of climate change (Zilber-Rosenberg and Rosenberg 2008; Bordenstein and Theis 2015). It has become clear that endosymbionts not only benefit host species by providing nutrients, protection, and energy (Selosse et al. 2004; Wernegreen 2012; Heyworth and Ferrari 2015; Wagner et al. 2015; Ishikawa et al. 2016; Hamada et al. 2018), but also alter host physiology and biochemistry, modifying their development and secondary chemical metabolism, and thus their stress tolerance (Montgomery and McFall-Ngai 1994; Mondo et al. 2017). Because both the symbiont and the host
* Siao Ye [email protected] 1
Department of Biosciences, Rice University, 6100 S. Main St., Houston, TX 77005, USA
determine the holobiont phenotype, Zilber-Rosenberg and Rosenberg [2] developed the hologenome theory which proposes that the holobiont should be considered as the unit of selection, and genetic changes in either entity help
Data Loading...
