Monoterpenoids (mid-1997 to mid-1999)

Abstract

In situ RNA hybridization and immunocytochemistry were used to establish the cellular distribution of monoterpenoid indole alkaloid biosynthesis in Madagascar periwinkle (Catharanthus roseus). Tryptophan decarboxylase (TDC) and strictosidine synthase (STR1), which are involved in the biosynthesis of the central intermediate strictosidine, and desacetoxyvindoline 4-hydroxylase (D4H) and deacetylvindoline 4-O-acetyltransferase (DAT), which are involved in the terminal steps of vindoline biosynthesis, were localized. tdc and str1 mRNAs were present in the epidermis of stems, leaves, and flower buds, whereas they appeared in most protoderm and cortical cells around the apical meristem of root tips. In marked contrast, d4h and dat mRNAs were associated with the laticifer and idioblast cells of leaves, stems, and flower buds. Immunocytochemical localization for TDC, D4H, and DAT proteins confirmed the differential localiza-tion of early and late stages of vindoline biosynthesis. Therefore, we concluded that the elaboration of the major leaf al-kaloids involves the participation of at least two cell types and requires the intercellular translocation of a pathway intermediate. A basipetal gradient of expression in maturing leaves also was shown for all four genes by in situ RNA hy-bridization studies and by complementary studies with dissected leaves, suggesting that expression of the vindoline pathway occurs transiently during early leaf development. These results partially explain why attempts to produce vin-doline by cell culture technology have failed. INTRODUCTION The organs forming the plant body consist of several different cell types that are organized in relation to each other and that confer specific functions to the resulting organ. Each cell type emerges from an undifferentiated meristem according to a sophisticated and partially understood developmental program (Sylvester et al., 1996; von Arnim and Deng, 1996). The commitment to differentiate into specialized structures involves the perception by cells in the meristem of a complex array of signals, which communicate cellular age, position in relation to other cells, and hormonal balance. Environmental factors, such as light and temperature, also play a critical role in modulating these signals throughout the process of organogenesis (Bernier, 1988; Dale, 1988; Sylvester et al., 1996). In addition to morphogenesis, developmental processes result in biochemical specialization of cells for the biosyn-thesis and/or accumulation of secondary metabolites, such as phenylpropanoids (Ibrahim et al.

Essential oils for the development of eco-friendly mosquito larvicides: A review

“…The principal plant sources for these compounds include anise, cinnamon, clove, fennel, etc. (Grayson, 2000).…”

Loliolide - the most ubiquitous lactone

“…An important group among them are terpenoids (Grayson 1996, Grayson 1997, Grayson 2000, Molnár et al 2010, derived from terpenes. Terpenes are composed of interconnected isoprene particles (consisting of 5 carbon atoms) which results in the fact that these particles of terpenes are composed of 5, 10, 15, etc.…”

Potencial alelopático do extrato foliar de Annona glabra L. (Annonaceae)

“…Monoterpenóides e diterpenóides provindos de A. glabra e suas atividades já haviam sido descritos por Chang et al (1998), Chen et al (2000), Grayson (2000), Yang et al (2003) e Zhang et al, 2004. Tripernóides e esteróides também foram detectados no extrato metanólico.…”

“…Estudos químicos sobre a Annona glabra L. confi rmaram a presença de grupos de substâncias com possível potencial alelopático, como monoterpenóides (Grayson 2000) e diterpenóides, isolados de diferentes partes da planta (Chang et al 1998;Chen et al 2000;Yang et al 2003;Zhang et al 2004). Chang et al (2000) e Hsieh et al (2004) isolaram alcalóides, esteróides e outros diterpenóides.…”