%0 Journal Article
%T Global characterization of Artemisia annua glandular trichome transcriptome using 454 pyrosequencing
%A Wei Wang
%A Yejun Wang
%A Qing Zhang
%A Yan Qi
%A Dianjing Guo
%J BMC Genomics
%D 2009
%I BioMed Central
%R 10.1186/1471-2164-10-465
%X We present a global characterization of A. annua glandular trichome transcriptome using 454 pyrosequencing. Sequencing runs using two normalized cDNA collections from glandular trichomes yielded 406,044 expressed sequence tags (average length = 210 nucleotides), which assembled into 42,678 contigs and 147,699 singletons. Performing a second sequencing run only increased the number of genes identified by ~30%, indicating that massively parallel pyrosequencing provides deep coverage of the A. annua trichome transcriptome. By BLAST search against the NCBI non-redundant protein database, putative functions were assigned to over 28,573 unigenes, including previously undescribed enzymes likely involved in sesquiterpene biosynthesis. Comparison with ESTs derived from trichome collections of other plant species revealed expressed genes in common functional categories across different plant species. RT-PCR analysis confirmed the expression of selected unigenes and novel transcripts in A. annua glandular trichomes.The presence of contigs corresponding to enzymes for terpenoids and flavonoids biosynthesis suggests important metabolic activity in A. annua glandular trichomes. Our comprehensive survey of genes expressed in glandular trichome will facilitate new gene discovery and shed light on the regulatory mechanism of artemisinin metabolism and trichome function in A. annua.Secreting glandular trichomes (GTs) are a major site for biosynthesis and accumulation of a wide range of plant natural products. These plant natural products often function to protect the plants against insect predation [1,2], and contribute to the flavour and aroma of plants. Many of the natural products also have pharmacological effects, such as the analgesic drug morphine, the anticancer compound taxol, and the antimalarial drug artemisinin. Artemisinin, a sesquiterpene lactone, is currently recognized as one of the most prominent anti-malarial treatment [3]. A complete understanding of the artemisinin
%U http://www.biomedcentral.com/1471-2164/10/465