Enhancing temperature tolerance of Pyropia tenera (Bangiales) by inducing mutation

Abstract

We induced a mutation in Pyropia tenera using gamma irradiation to obtain strains with improved tolerance to high temperatures. We selected a mutant Pt1k with improved heat tolerance and different blade colour at high temperatures (20°C) after an irradiation dose of 1 kGy. We observed physiological changes and responses in the wild-type (WT) and Pt1k blades under high-temperature stress. The selected Pt1k mutant blades were dark green, which was different from the natural red of the WT. At 12°C, Pt1k blade growth rate and biomass were four times higher than those of the WT, and phycocyanin (PC) content also increased. When cultured at 20 and 25°C, blade shapes and growth rates of Pt1k were maintained; however, WT blades were considerably decayed and growth rate was inhibited. When cultured at 25°C for 3 weeks, chlorophyll a and PC contents were higher in Pt1k than in WT strains, whereas the phycoerythrin (PE) level was constant. Changes in hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) content after 3 weeks at 25°C Pt1k showed a slow increase; however, activities in the WT strain were highly increased. Under these conditions, activities of the antioxidant enzymes (superoxide dismutase and ascorbate peroxidase) of the two strains similarly increased when subjected to high-temperature stress for 1 week; however, the WT enzymes decreased rapidly during long-term exposure. Conversely, the Pt1k mutant had constant activities even when exposed to longterm high temperatures. These results indicate that the isolated mutant Pt1k had improved growth and tolerance to higher temperatures than the WT. In conlusion, we suggest that antioxidant enzyme activity, which is more abundant in the mutant Pt1k than in WT at high temperatures, is involved in the tolerance mechanism against temperature.

Heat stress memory differentially regulates the expression of nitrogen transporter genes in the filamentous red alga ‘Bangia’ sp. ESS1

“…These results indicate that heat stress memory reduces the sensitivity of the red alga to lethal high temperatures; this results in a reduction in H 2 O 2 content at 32°C by lowering the threshold to initiate the response to heat stress. Heat stress increased H 2 O 2 contents in the red alga Pyropia tenera , a response that was attenuated in a P. tenera mutant with increased heat stress tolerance ( Lee and Choi, 2019 ). These findings support the tight relationship between reduced H 2 O 2 accumulation and the acquisition of heat stress tolerance with low sensitivity to heat stress, although the contribution of heat stress memory to the acquisition of heat stress tolerance in P. tenera has yet to be analyzed.…”

Aquaculture Production of the Brown Seaweeds Laminaria digitata and Macrocystis pyrifera: Applications in Food and Pharmaceuticals

“…Enabling the expansion required for successful extensive bioproduct production from all three seaweeds groups will require the cultivation of domesticated seaweed cultivars, as well as the domestication of new species, and further streamlining of cultivation techniques, to include more comprehensive quality control methods, to enable higher quality seaweed bioproducts to be produced [ 6 ]. A temperature-tolerant mutant strain for Neopyropia tenera (formerly Pyropia tenera ) was produced using gamma irradiation [ 259 ]. The potential to produce heat-tolerant seaweed strains for commercial seaweed species could become extremely important, with climate change affecting increases in ocean temperatures across the globe.…”

Effects of extraction methods for a new source of biostimulant from Sargassum horneri on the growth of economically important red algae, Neopyropia yezoensis

“…Neopyropia tenera grows slower and deteriorates as temperature increases from 12 to 25 °C. Chlorophyll a and phycocyanin of N. tenera gradually decreases when the species is cultured at 25 °C for prolonged periods of time 10 . High temperature also causes oxidative damage by triggering intracellular reactive oxygen species (ROS) in algae 11 – 14 .…”

“…and Saccharina spp. (Phaeophyceae) 10 , 15 – 17 . For instance, Umanzor et al 16 exposed Saccharina latissima and S. angustissima to Ascophyllum (Phaeophyceae) (Acadian) Marine plant extract powder (AMPEP, Acadian Seaplants, LLC.…”