Transcriptome-Based Identification of the Desiccation Response Genes in Marine Red Algae Pyropia tenera (Rhodophyta) and Enhancement of Abiotic Stress Tolerance by PtDRG2 in Chlamydomonas

Abstract

Pyropia tenera (Kjellman) are marine red algae that grow in the intertidal zone and lose more than 90% of water during hibernal low tides every day. In order to identify the desiccation response gene (DRG) in P. tenera, we generated 1,444,210 transcriptome sequences using the 454-FLX platform from the gametophyte under control and desiccation conditions. De novo assembly of the transcriptome reads generated 13,170 contigs, covering about 12 Mbp. We selected 1160 differentially expressed genes (DEGs) in response to desiccation stress based on reads per kilobase per million reads (RPKM) expression values. As shown in green higher plants, DEGs under desiccation are composed of two groups of genes for gene regulation networks and functional proteins for carbohydrate metabolism, membrane perturbation, compatible solutes, and specific proteins similar to higher plants. DEGs that show no significant homology with known sequences in public databases were selected as DRGs in P. tenera. PtDRG2 encodes a novel polypeptide of 159 amino acid residues locating chloroplast. When PtDRG2 was overexpressed in Chlamydomonas, the PtDRG2 confer mannitol and salt tolerance in transgenic cells. These results suggest that Pyropia may possess novel genes that differ from green plants, although the desiccation tolerance mechanism in red algae is similar to those of higher green plants. These transcriptome sequences will facilitate future studies to understand the common processes and novel mechanisms involved in desiccation stress tolerance in red algae.

Seaweed nutrient physiology: application of concepts to aquaculture and bioremediation

“…However, greater levels of desiccation are typically detrimental to photosynthesis. Seaweeds that are desiccation tolerant have various cellular mechanisms for rapidly repairing cellular membranes and metabolic processes upon rehydration (Burritt et al 2002;Im et al 2017;Kim et al 2009Kim et al , 2013Kumar et al 2011).…”

Health Functionality and Quality Control of Laver (Porphyra, Pyropia): Current Issues and Future Perspectives as an Edible Seaweed

“…With respect to the life cycle, previous studies focused on characterization of the evolutionary aspects of the distinct stages [158,159], development of applied technologies including the designation of biomarkers [160], and treatments affecting the regulation of gene expression linked to reproductive processes [161]. A major focus for genomic research has been the interpretation and/or comparative analysis of transcriptomic data relating to the responses of laver species to abiotic stress [162,163], principally environmental conditions such as high temperature [164][165][166], repeated desiccation-rehydration [167,168], and hypersalinity [169].…”

Genetic toolkits of the red alga Pyropia tenera against the three most common diseases in Pyropia farms

“…, Im et al. ). The role of HSPs in host–pathogen interaction has been extensively studied, and a defensive role against pathogens has been reported in some HSPs (Maimbo et al.…”

“…Previous genome-wide expression studies showed that HSP groups are most prominently up-regulated genes in Pyropia species exposed to abiotic stresses (Choi et al 2013, Sun et al 2015. Several HSPs have been isolated from Pyropia species, and functional characterization using Chlamydomonas as an expression system confirmed their roles in enhancing tolerance against abiotic stress (Park et al 2012, Im et al 2017. The role of HSPs in host-pathogen interaction has been extensively studied, and a defensive role against pathogens has been reported in some HSPs (Maimbo et al 2007).…”