Regulation of Two Carotenoid Biosynthesis Genes Coding for Phytoene Synthase and Carotenoid Hydroxylase during Stress-Induced Astaxanthin Formation in the Green Alga Haematococcus pluvialis

Abstract

Astaxanthin is a high-value carotenoid used as a pigmentation source in fish aquaculture. In addition, a beneficial role of astaxanthin as a food supplement for humans is becoming evident. The unicellular green alga Haematococcus pluvialis seems to be a suitable source for natural astaxanthin. Astaxanthin accumulation in H. pluvialis occurs in response to environmental stress such as high light and salt stress. Here, the isolation of the H. pluvialis carotenoid biosynthesis gene phytoene synthase is reported. Furthermore, the expression of phytoene synthase and carotenoid hydroxylase, two key enzymes in astaxanthin biosynthesis, was investigated at the transcriptional level. The application of environmental stress resulted in increased steady-state mRNA levels of both genes. High-light intensity led to a transient increase in carotenoid hydroxylase mRNA followed by moderate astaxanthin accumulation. In contrast, salt stress in combination with high light resulted in a sustained increase in both transcripts. The addition of compounds inducing reactive oxygen species did not influence transcript levels of phytoene synthase and carotenoid hydroxylase. The application of an inhibitor of photosynthesis, 3-(3, 4-dichlorophenyl)-1,1-dimethylurea, indicated that the light-induced expression of these carotenoid biosynthesis genes may be under photosynthetic control.

Transcriptome sequencing and annotation of the halophytic microalga Dunaliella salina

“…The reconstructed pathway is consistent with those proposed for plants (Kim et al, 2009) and algae (Steinbrenner and Linden, 2001;Ramos et al, 2011).…”

“…Four precursors, geranylgeranyl-phosphates (GGPPs), are condensed to form phytoene, the basic precursor of all carotenoids, and catalyzed by the enzyme phytoene synthase (PSY, EC: 2.5.1.32). Usually, this rate-limiting step is regulated through heterologous overexpression of this gene or environmental modification to enhance carotenoid production (Steinbrenner and Linden, 2001;Couso et al, 2011). Previous studies indicated that this gene is duplicated in the genome sequences in D. salina (Tran et al, 2009).…”

Identification of ABA-responsive genes in rice shoots via cDNA macroarray

“…Results were shown in Tab 2. Among the identified clones, some cDNAs have been reported from rice, including phytoene synthase and putative bZIP (basic/leucine zipper) transcription factors coding genes, have been demonstrated to be induced under stress situations [27] and cold stress [28], [29]. Most of them were not reported before.…”

“…Sequence analyses and homologous searches indicated that some clones, identified by cDNA macroarray, were indeed regulated by environmental factors, which suggested the possible relation to ABA and the involvement in ABA-related signal transduction pathways. Protein encoded by clone Xd423 shared high homology (95%) to maize phytoene synthase, which was demonstrated to be induced under stress situations (Steinbrenner and Linden, 2001). Protein encoded by clone Xd426 (X57325), a basic/leucine zipper transcription factor, was shown to be induced under cold treatment [28], [29].…”

The accumulation and metabolism of astaxanthin in Scenedesmus obliquus (Chlorophyceae)

“…One is the factors that enhance the astaxanthin yield in algae such as culturing media [14], higher temperature [15], intensive illumination [16], oxidative stress [17,18] and salt stress [19]. The other is to elucidate the biosynthetic pathway of astaxanthin in algal cells [20,21] and extensive studies focused on the utilization of the modern molecular technology to clone and identify the genes related to the enzymes which are involved in the biosynthesis of astaxanthin [22,23]. In these reports, H. pluvialis was regarded as an ideal model to research the formation of astaxanthin [24].…”