Characterization of a membrane-bound C-glucosyltransferase responsible for carminic acid biosynthesis in Dactylopius coccus Costa

Carminic acid is a widely applied red colorant that is still harvested from insects because its biosynthesis is not fully understood. Here, the authors identify and characterize a membrane-bound C-glucosyltransferase catalyzing the final step during carminic acid biosynthesis

Identification and ecology of alternative insect vectors of ‘Candidatus Phytoplasma solani’ to grapevine

Bois noir, a disease of the grapevine yellows complex, is associated with 'Candidatus Phytoplasma solani' and transmitted to grapevines in open fields by the cixiids Hyalesthes obsoletus and Reptalus panzeri. In vine-growing areas where the population density of these vectors is low within the vineyard, the occurrence of bois noir implies the existence of alternative vectors. The aim of this study was to identify alternative vectors through screening of the Auchenorrhyncha community, phytoplasma typing by stamp gene sequence analyses, and transmission trials. During field activities, conducted in Northern Italy in a vineyard where the bois noir incidence was extremely high, nine potential alternative insect vectors were identified according to high abundance in the vineyard agro-ecosystem, high infection rate, and harbouring phytoplasma strains characterized by stamp gene sequence variants found also in symptomatic grapevines. Transmission trials coupled with molecular analyses showed that at least eight species (Aphrodes makarovi, Dicranotropis hamata, Dictyophara europaea, Euscelis incisus, Euscelidius variegatus, Laodelphax striatella, Philaenus spumarius, and Psammotettix alienus/confinis) are alternative vectors of 'Candidatus Phytoplasma solani' to grapevines. These novel findings highlight that bois noir epidemiology in vineyard agro-ecosystems is more complex than previously known, opening up new perspectives in the disease management

Reconstitution of the Costunolide Biosynthetic Pathway in Yeast and Nicotiana benthamiana

The sesquiterpene costunolide has a broad range of biological activities and is the parent compound for many other biologically active sesquiterpenes such as parthenolide. Two enzymes of the pathway leading to costunolide have been previously characterized: germacrene A synthase (GAS) and germacrene A oxidase (GAO), which together catalyse the biosynthesis of germacra-1(10),4,11(13)-trien-12-oic acid. However, the gene responsible for the last step toward costunolide has not been characterized until now. Here we show that chicory costunolide synthase (CiCOS), CYP71BL3, can catalyse the oxidation of germacra-1(10),4,11(13)-trien-12-oic acid to yield costunolide. Co-expression of feverfew GAS (TpGAS), chicory GAO (CiGAO), and chicory COS (CiCOS) in yeast resulted in the biosynthesis of costunolide. The catalytic activity of TpGAS, CiGAO and CiCOS was also verified in planta by transient expression in Nicotiana benthamiana. Mitochondrial targeting of TpGAS resulted in a significant increase in the production of germacrene A compared with the native cytosolic targeting. When the N. benthamiana leaves were co-infiltrated with TpGAS and CiGAO, germacrene A almost completely disappeared as a result of the presence of CiGAO. Transient expression of TpGAS, CiGAO and CiCOS in N. benthamiana leaves resulted in costunolide production of up to 60 ng.g−1 FW. In addition, two new compounds were formed that were identified as costunolide-glutathione and costunolide-cysteine conjugates

Potato Resistance Against Insect Herbivores

Invited Review: Over the last two decades scientists have focused much attention on the physiological, molecular and functional biology of plant chitinases and there is considerable evidence suggest that chitinases play important roles in plant defense systems. Chitinases have also been shown to play a role in plant growth and development. Several review articles exist for chitinases of angiosperms but there is no such review for conifer chitinases, despite the economic and ecological significance of coniferous species in the world’s forests. Conifer chitinases consist of at least several classes of enzymes that are represented by small gene families. Class II (acidic) and class IV (basic) chitinases, expressed differentially over time and space, have been shown to be the major defense players in many conifer pathosystems. Class I and III chitinases are also reported in some conifers. This review discusses the current body of knowledge regarding conifer chitinases, including the molecular structure of chitinase genes and their regulation and function in conifer plants. Future potential uses for conifer chitinases as biopesticide