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Shang C.,South China Agricultural University | Shang C.,Key Laboratory of Energy Plants Resource and Utilization | Shang C.,Key Laboratory of Biomass Energy of Guangdong Regular Higher Education Institutions | Shang C.,CAS Guangzhou Institute of Energy Conversion | And 10 more authors.
Journal of Applied Phycology | Year: 2016

Dunaliella parva can thrive and adapt to salt stress over a wide range of NaCl concentrations which also is related to carotenoid accumulation in Dunaliella. Dunaliella parva can accumulate carotenoids; however, the underlying mechanism of carotenoid accumulation needs further research. Thus, it is necessary to study biosynthesis and regulation of carotenoids for understanding carotenoid accumulation. In the present study, a gene encoding geranylgeranyl diphosphate synthase (GGPS) from the halophilic green alga D. parva has been cloned and analyzed. It is in the branch of terpene metabolism and named as DpGGPS (D. parva GGPS). The full-length complementary DNA (cDNA) of DpGGPS was 1612 bp, including an open reading frame (ORF) of 1059 bp, 189 bp 5′-untranslated region (5′-UTR) and 364 bp 3′-UTR. The 5′-flanking region was obtained by the genome walking method. Potential regulatory elements, associated with hormones, defense, and stress, were found in the 1310 bp 5′-flanking region. Functional characterization of DpGGPS in E. coli BL21(DE3) demonstrated that DpGGPS encoded a functional GGPS. Analysis of DpGGPS expression revealed a correlation between GGPS expression and the shift of NaCl concentration, which indicated that GGPS could be a salt stress responsive gene. Cloning and expression analysis of GGPS provides a foundation for studying the regulatory mechanism of carotenoid biosynthesis, adaptation mechanism to salt stress, and massive accumulation of carotenoids in D. parva. © 2016 Springer Science+Business Media Dordrecht

Wang X.,University of South China | Wang X.,Key Laboratory of Biomass Energy of Guangdong Regular Higher Education Institutions | Wang X.,Key Laboratory of Energy Plants Resource and Utilization | Chen D.,University of South China | And 8 more authors.
PLoS ONE | Year: 2015

The plant Dioscorea composita has important applications in the medical and energy industries, and can be used for the extraction of steroidal sapogenins (important raw materials for the synthesis of steroidal drugs) and bioethanol production. However, little is known at the genetic level about how sapogenins are biosynthesized in this plant. Using Illumina deep sequencing, 62,341 unigenes were obtained by assembling its transcriptome, and 27,720 unigenes were annotated. Of these, 8,022 unigenes were mapped to 243 specific pathways, and 531 unigenes were identified to be involved in 24 secondary metabolic pathways. 35 enzymes, which were encoded by 79 unigenes, were related to the biosynthesis of steroidal sapogenins in this transcriptome database, covering almost all the nodes in the steroidal pathway. The results of real-time PCR experiments on ten related transcripts (HMGR, MK, SQLE, FPPS, DXS, CAS, HMED, CYP51, DHCR7, and DHCR24) indicated that sapogenins were mainly biosynthesized by the mevalonate pathway. The expression of these ten transcripts in the tuber and leaves was found to be much higher than in the stem. Also, expression in the shoots was low. The nucleotide and protein sequences and conserved domains of four related genes (HMGR, CAS, SQS, and SMT1 ) were highly conserved between D. composita and D. zingiberensis; but expression of these four genes is greater in D. composita. However, there is no expression of these key enzymes in potato and no steroidal sapogenins are synthesized. © 2015 Wang et al.

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