Email updates

Keep up to date with the latest news and content from BMC Genomics and BioMed Central.

Open Access Research article

Pyrosequencing of the Camptotheca acuminata transcriptome reveals putative genes involved in camptothecin biosynthesis and transport

Yongzhen Sun1, Hongmei Luo1, Ying Li1, Chao Sun1, Jingyuan Song1, Yunyun Niu1, Yingjie Zhu1, Liang Dong1, Aiping Lv2, Enzo Tramontano3 and Shilin Chen1*

Author affiliations

1 The Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, P. R. China

2 Institute of Basic Theory, China Academy of Traditional Chinese Medicine, Beijing, China

3 Department of Applied Sciences in Biosystems, University of Cagliari, Monserrato (Cagliari), Italy

For all author emails, please log on.

Citation and License

BMC Genomics 2011, 12:533  doi:10.1186/1471-2164-12-533

Published: 30 October 2011

Abstract

Background

Camptotheca acuminata is a Nyssaceae plant, often called the "happy tree", which is indigenous in Southern China. C. acuminata produces the terpenoid indole alkaloid, camptothecin (CPT), which exhibits clinical effects in various cancer treatments. Despite its importance, little is known about the transcriptome of C. acuminata and the mechanism of CPT biosynthesis, as only few nucleotide sequences are included in the GenBank database.

Results

From a constructed cDNA library of young C. acuminata leaves, a total of 30,358 unigenes, with an average length of 403 bp, were obtained after assembly of 74,858 high quality reads using GS De Novo assembler software. Through functional annotation, a total of 21,213 unigenes were annotated at least once against the NCBI nucleotide (Nt), non-redundant protein (Nr), Uniprot/SwissProt, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Arabidopsis thaliana proteome (TAIR) databases. Further analysis identified 521 ESTs representing 20 enzyme genes that are involved in the backbone of the CPT biosynthetic pathway in the library. Three putative genes in the upstream pathway, including genes for geraniol-10-hydroxylase (CaPG10H), secologanin synthase (CaPSCS), and strictosidine synthase (CaPSTR) were cloned and analyzed. The expression level of the three genes was also detected using qRT-PCR in C. acuminata. With respect to the branch pathway of CPT synthesis, six cytochrome P450s transcripts were selected as candidate transcripts by detection of transcript expression in different tissues using qRT-PCR. In addition, one glucosidase gene was identified that might participate in CPT biosynthesis. For CPT transport, three of 21 transcripts for multidrug resistance protein (MDR) transporters were also screened from the dataset by their annotation result and gene expression analysis.

Conclusion

This study produced a large amount of transcriptome data from C. acuminata by 454 pyrosequencing. According to EST annotation, catalytic features prediction, and expression analysis, novel putative transcripts involved in CPT biosynthesis and transport were discovered in C. acuminata. This study will facilitate further identification of key enzymes and transporter genes in C. acuminata.