The Leaf Epidermome ofCatharanthus roseusReveals Its Biochemical Specialization  

Abstract

Catharanthus roseus is the sole commercial source of the monoterpenoid indole alkaloids (MIAs), vindoline and catharanthine, components of the commercially important anticancer dimers, vinblastine and vincristine. Carborundum abrasion technique was used to extract leaf epidermis-enriched mRNA, thus sampling the epidermome, or complement, of proteins expressed in the leaf epidermis. Random sequencing of the derived cDNA library established 3655 unique ESTs, composed of 1142 clusters and 2513 singletons. Virtually all known MIA pathway genes were found in this remarkable set of ESTs, while only four known genes were found in the publicly available Catharanthus EST data set. Several novel MIA pathway candidate genes were identified, as demonstrated by the cloning and functional characterization of loganic acid O-methyltransferase involved in secologanin biosynthesis. The pathways for triterpene biosynthesis were also identified, and metabolite analysis showed that oleanane-type triterpenes were localized exclusively to the cuticular wax layer. The pathways for flavonoid and very-longchain fatty acid biosynthesis were also located in this cell type. The results illuminate the biochemical specialization of Catharanthus leaf epidermis for the production of multiple classes of metabolites. The value and versatility of this EST data set for biochemical and biological analysis of leaf epidermal cells is also discussed.

Biosynthesis and emission of insect-induced methyl salicylate and methyl benzoate from rice

“…SAMT and BAMT belong to a protein family called the SABATH [7]. In addition to SA and BA, other known carboxylic acid substrates of the SABATH family include jasmonic acid (JA) [34], indole-3-acetic acid [31,44e46], gibberellic acids [41], farnesoic acid [42], cinnamic acid and p-coumaric acid [16] and loganic acid [21]. Other members of the SABATH family are involved in caffeine biosynthesis by catalyzing nitrogen methylation [25].…”

OSC2 and CYP716A14v2 Catalyze the Biosynthesis of Triterpenoids for the Cuticle of Aerial Organs of Artemisia annua

“…To validate the physiological relevance of this finding, we determined the triterpene content of greenhouse-grown A. annua plants. Pentacyclic triterpenoids, mainly derived from a-amyrin, b-amyrin, and lupeol, often occur in the leaf, flower, and fruit cuticular wax layers of many plants (Bringe et al, 2006;Murata et al, 2008;Wang et al, 2011;Szakiel et al, 2013). Therefore, we analyzed the triterpene content of the cuticular wax layer from flower buds and leaves of two A. annua cultivars: Anamed A3, the cultivar from which OSC2 was isolated, and Meise, a low artemisinin-producing cultivar that we previously used to study phytohormonal regulation of artemisinin biosynthesis (Maes et al, 2011).…”

“…Triterpenoids are the biologically active constituents of the wax layer (Buschhaus and Jetter, 2011;Szakiel et al, 2012). Pentacyclic oleanane-, ursane-, and lupane-type triterpenes and triterpenoids have been identified in the wax layers of the cuticle covering leaves, stems, flowers, and fruits of multiple plants, such as Madagascar periwinkle (Catharanthus roseus; Murata et al, 2008), tomato (Solanum lycopersicum; Wang et al, 2011), apple (Malus domestica; Bringe et al, 2006), and heather (Calluna vulgaris; Szakiel et al, 2013).…”

A Root-Expressed l-Phenylalanine:4-Hydroxyphenylpyruvate Aminotransferase Is Required for Tropane Alkaloid Biosynthesis in Atropa belladonna

“…The broad utility of alkaloids for humankind has led to considerable interest in understanding the pathways and regulatory mechanisms underlying their synthesis. The development of functional genomics technologies, particularly deep and quantitative transcriptome profiling, has greatly facilitated these efforts (Murata et al, 2008;Liscombe et al, 2009;Desgagné-Penix et al, 2010;Giddings et al, 2011;Farrow et al, 2012;Góngora-Castillo et al, 2012;Winzer et al, 2012).…”