Stress responses of the oil-producing green microalga Botryococcus braunii Race B

Ivette Cornejo-Corona; Hem R Thapa; Daniel R Browne; Timothy P Devarenne; Edmundo Lozoya-Gloria

doi:10.7717/peerj.2748

Stress responses of the oil-producing green microalga Botryococcus braunii Race B

PeerJ. 2016 Dec 6:4:e2748. doi: 10.7717/peerj.2748. eCollection 2016.

Authors

Ivette Cornejo-Corona¹, Hem R Thapa², Daniel R Browne², Timothy P Devarenne², Edmundo Lozoya-Gloria¹

Affiliations

¹ Genetic Engineering, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Irapuato , Irapuato , Guanajuato , Mexico.
² Department of Biochemistry and Biophysics, Texas A&M University , College Station , TX , United States.

Abstract

Plants react to biotic and abiotic stresses with a variety of responses including the production of reactive oxygen species (ROS), which may result in programmed cell death (PCD). The mechanisms underlying ROS production and PCD have not been well studied in microalgae. Here, we analyzed ROS accumulation, biomass accumulation, and hydrocarbon production in the colony-forming green microalga Botryococcus braunii in response to several stress inducers such as NaCl, NaHCO₃, salicylic acid (SA), methyl jasmonate, and acetic acid. We also identified and cloned a single cDNA for the B. braunii ortholog of the Arabidopsis gene defender against cell death 1 (DAD1), a gene that is directly involved in PCD regulation. The function of B. braunii DAD1 was assessed by a complementation assay of the yeast knockout line of the DAD1 ortholog, oligosaccharyl transferase 2. Additionally, we found that DAD1 transcription was induced in response to SA at short times. These results suggest that B. braunii responds to stresses by mechanisms similar to those in land plants and other organisms.

Keywords: Acetic acid; DAD1; Hydrocarbons; Methyl jasmonate; NaCl; NaHCO3; OST2; PCD; ROS; Salicylic acid.

Grants and funding

This work was supported by a PhD scholarship to IC-C from Consejo Nacional de Ciencia y Tecnología (CONACYT) Mexico, a grant from the 2012 Texas A&M University—CONACYT Collaborative Research Grant Program to EL-G and TPD, and grant #1240478 from the National Science Foundation (NSF) Emerging Frontiers in Research and Innovation (EFRI) to TPD. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.