Transcriptome Analysis in Haematococcus pluvialis: Astaxanthin Induction by Salicylic Acid (SA) and Jasmonic Acid (JA)

Abstract

Haematococcus pluvialis is an astaxanthin-rich microalga that can increase its astaxanthin production by salicylic acid (SA) or jasmonic acid (JA) induction. The genetic transcriptome details of astaxanthin biosynthesis were analyzed by exposing the algal cells to 25 mg/L of SA and JA for 1, 6 and 24 hours, plus to the control (no stress). Based on the RNA-seq analysis, 56,077 unigenes (51.7%) were identified with functions in response to the hormone stress. The top five identified subcategories were cell, cellular process, intracellular, catalytic activity and cytoplasm, which possessed 5600 (~9.99%), 5302 (~9.45%), 5242 (~9.35%), 4407 (~7.86%) and 4195 (~7.48%) unigenes, respectively. Furthermore, 59 unigenes were identified and assigned to 26 putative transcription factors (TFs), including 12 plant-specific TFs. They were likely associated with astaxanthin biosynthesis in Haematococcus upon SA and JA stress. In comparison, the up-regulation of differential expressed genes occurred much earlier, with higher transcript levels in the JA treatment (about 6 h later) than in the SA treatment (beyond 24 h). These results provide valuable information for directing metabolic engineering efforts to improve astaxanthin biosynthesis in H. pluvialis.

Discovery of Geranylgeranyl Pyrophosphate Synthase (GGPPS) Paralogs from Haematococcus pluvialis Based on Iso-Seq Analysis and Their Function on Astaxanthin Biosynthesis

“…A possible explanation would be that excessive GGPPS might inhibit the astaxanthin biosynthesis in E. coli. This hypothesis is partly supported by the evidence that no change or downregulation of GGPPS was found in the salicylic acid and jasmonic acid stressed transcriptome analysis in H. pluvialis during astaxanthin formation [39]. Further research can be conducted to test the suppressive role of GGPPS during astaxanthin biosynthesis.…”

Effects of Methanol on Carotenoids as Well as Biomass and Fatty Acid Biosynthesis in Schizochytrium limacinum B4D1

“…The astaxanthin synthetic pathway has been studied in some higher plants and microalgae (20)(21)(22). However, little is known regarding the pathway of Schizochytrium's astaxanthin biosynthesis.…”

The Discrepancy of Fatty Acid Composition of Astaxanthin Esters and Total Fatty Acids in Photoautotrophic and Heterotrophic Chlorella zofingiensis

“…PSY is regarded as a rate‐determining key enzyme or an important control point for regulation of carbon fluxes toward the carotene biosynthetic pathway, which catalyzes the first committed step of this pathway and converts two geranylgeranyl pyrophosphate (GGPP) to phytoene (Cordero et al, ; Rodríguez‐Villalón et al, ). CHYb, catalyzing β‐carotene hydroxylation, is also an important enzyme in the astaxanthin biosynthesis pathway (Gao et al, ). The accumulation of astaxanthin is always accompanied by significant upregulation of CHYb and BKT (β‐carotene ketolase gene) in H. pluvialis (Gao et al, ; Gwak et al, ).…”

“…CHYb, catalyzing β‐carotene hydroxylation, is also an important enzyme in the astaxanthin biosynthesis pathway (Gao et al, ). The accumulation of astaxanthin is always accompanied by significant upregulation of CHYb and BKT (β‐carotene ketolase gene) in H. pluvialis (Gao et al, ; Gwak et al, ). Huang et al () also found that BKT was upregulated in transcriptional expressions under mixotrophic conditions.…”