Expression of a Heat Shock Protein 70 from the brown alga Ectocarpus sp. imparts salinity and temperature stress tolerance in Arabidopsis thaliana

Authors: RATHOR, PRAMOD - Dalhousie University; BORZA, TUDOR - Dalhousie University; BAHMANI, RAMIN - Dalhousie University; STONE, SOPHIA - Dalhousie University; TONON, THIERRY - University Of York; Yurgel, Svetlana; POTIN, PHILIPPE - The Sorbonne University; PRITHIVIRAJ, BALAKRISHNAN - Dalhousie University

Submitted to: Journal of Applied Phycology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2022
Publication Date: 1/9/2023
Citation: Rathor, P., Borza, T., Bahmani, R., Stone, S., Tonon, T., Yurgel, S., Potin, P., Prithiviraj, B. 2023. Expression of a Heat Shock Protein 70 from the brown alga Ectocarpus sp. imparts salinity and temperature stress tolerance in Arabidopsis thaliana. Journal of Applied Phycology. 35:809-813. https://doi.org/10.1007/s10811-022-02897-7.
DOI: https://doi.org/10.1007/s10811-022-02897-7

Interpretive Summary: High temperature events are becoming more severe and frequent due to the change in the environment caused by climate change. High soil salinity and high temperature stress are the predominant among various abiotic stresses which causes severe crop loss globally. Plants face these stresses and respond by adjusting their metabolism and physiology. Seaweeds are an integral component of marine coastal ecosystem. During the billions year of evolution brown alga Ectocarpus sp. have developed high tolerance to biotic and abiotic stresses. In our previous study we identify a set of brown alga genes which might play a significant role in the plant stress adaptation. In this study we evaluated the effect of overexpression of one of these genes, Heat Shock Protein 70 (HSP70), in Arabidopsis. The expression of the EsHSP70 promoted the salt and heat stresses tolerance by up-regulating the stress responsive genes in Arabidopsis. Our results suggest that, in addition to the land plants and microbes, brown algae can be employed as a genetic source to generate transgenic plants with promoted tolerance to various abiotic stresses.

Technical Abstract: Brown alga Ectocarpus sp. belongs to Phaeophyceae, a class of macroalgae in the phylum Heterokonts, which is also known as Stramenopiles lineage that made transition from unicellularity to complex multicellularity during long evolutionary history. Ectocarpus sp. is a dominant seaweed in the temperate regions around the globe, abundant mostly in the intertidal zones, an environment with harsh environmental conditions resulting from tidal cycles. Analysis of previously generated transcriptomic data of brown alga exhibited the up-regulation of the Esi0379_0027 gene, encoding HSP70 protein, in response to various abiotic stresses. Bioinformatics study demonstrated that the HSP70 protein is soluble, monomeric and well conserved in other organisms. To explore the role of HSP70 in stress tolerance, it was expressed in Arabidopsis under constitutive and stress inducible promoters. Transgenic Arabidopsis plants generated using both promoters exhibited higher tolerance to salinity and heat stresses compared to wild type plant. Transcript analysis of various abiotic stress-responsive genes showed that genes participated in Na+ efflux and sequestration and ABA-mediated stress tolerance were remarkably upregulated in the HSP70-expressing transgenic Arabidopsis. Overall, our results showed that the expression of the EsHSP70 promotes the salt and heat stresses tolerance by upregulating the stress responsive genes in Arabidopsis.