Investigation of Glandular Trichome Proteins in Artemisia annua L. Using Comparative Proteomics

Abstract

Glandular secreting trichomes (GSTs) are called biofactories because they are active in synthesizing, storing and secreting various types of plant secondary metabolites. As the most effective drug against malaria, artemisinin, a sesquiterpene lactone is derived from GSTs of Artemisia annua. However, low artemisinin content (0.001%∼1.54% of dry weight) has hindered its wide application. We investigate the GST-expressed proteins in Artemisia annua using a comparative proteomics approach, aiming for a better understanding of the trichome proteome and arteminisin metabolism. 2D-electrophoresis was employed to compare the protein profiles of GSTs and leaves. More than 700 spots were resolved for GSTs, of which ∼93 non-redundant proteins were confidently identified by searching NCBI and Artemisia EST databases. Over 70% of these proteins were highly expressed in GTSs. Functional classification of these GSTs enriched proteins revealed that many of them participate in major plant metabolic processes such as electron transport, transcription and translation.

Proteomic analysis of Artemisia annua – towards elucidating the biosynthetic pathways of the antimalarial pro-drug artemisinin

“…In general, the vast majority of proteins identified previously from A. annua by Wu et al were also found in our datasets [ 10 ]. Notably, in the trichome-enriched sample data, we found amongst others a similarly large number of ATPases/ATP synthases and oxidoreductases ( e.g.…”

“…The protocol that was applied for the isolation of glandular trichomes is based on the process of glass bead abrasion which has been described previously [ 10 , 15 , 16 ]. In these earlier studies, it was reported that the majority of the cell material enriched by this method represented glandular trichomes albeit with a significant remainder of non-glandular trichomes [ 15 , 16 ].…”

“…Typically, trichomes are divided into 2 categories: non-glandular and glandular. Non-glandular trichomes are involved in processes such as water absorption and seed dispersal, whereas glandular trichomes are involved in processes connected with secondary metabolites including biosynthesis, storage and secretion [ 10 , 11 ]. There is currently much interest in taking advantage of the glandular trichomes’ biosynthetic function in order to produce compounds, which have pharmaceutical use, such as artemisinin.…”

“…This dataset is evaluated in comparison to four other databases (three protein sequence databases and one trichome-specific Trinity contig database [ 14 ]) with regard to their suitability for proteomic analysis. In addition, a comparison is made with the only other MS-based proteomic study of A. annua trichomes, which used another different EST data set assembly [ 10 ]. More importantly, the current study provides a significantly extended proteomic data set for A. annua , potentially leading to a better understanding of the trichome machinery and its role in the production of artemisinin.…”

Artemisia (Asteraceae) essential oils: compositional variation and mechanisms of its origin, biosynthesis of constituents, correspondence between biological activities and ethnomedicinal usage and repurposement prospects

“…Biosynthesis of the volatile organic compounds, that comprise essential oil, has been studied in artemisias (Lu et al, 2002;Kessler et al, 2006;Wu et al, 2012;Bilia et al, 2014;Pratt et al, 2014;Ma et al, 2015 and2017a andSalmon et al, 2015;Shi et al, 2017) and more extensively in a variety of heterologous plant systems, including the model plant species such as Arabidopsis thaliana (Christianson 2001;Rodriguez-Concepcion 2001;Keszei et al, 2008;Degenhardt et al, 2009;Baldwin 2010;Ramak et al, 2014;Lange 2015;Nieuwenhuizen et al, 2015;Tholl 2015;Rehman 2016;Fujita et al, 2017). The information elicited from various aromatic plants collectively suggests that the quantitative variation in the productivity of volatile organic compounds in the site of their synthesis, such as glandular trichomes, depends on the availability of the starting substrates produced by primary metabolism, expression levels of MVA and MEP pathway and downstream genes and catalytic efficiency of the gene products (Estevez et al, 2001;Munoz-Bertomen et al, 2006;Cordoba et al, 2009;Ramak et al, 2014).…”