RESUMEN
Tropane alkaloids and terpenoids are widely used in the medicine and pharmaceutic industry and evolved as chemical defenses against herbivores and pathogens in the annual herb Datura stramonium (Solanaceae). Here, we present the first draft genomes of two plants from contrasting environments of D. stramonium. Using these de novo assemblies, along with other previously published genomes from 11 Solanaceae species, we carried out comparative genomic analyses to provide insights on the genome evolution of D. stramonium within the Solanaceae family, and to elucidate adaptive genomic signatures to biotic and abiotic stresses in this plant. We also studied, in detail, the evolution of four genes of D. stramonium-Putrescine N-methyltransferase, Tropinone reductase I, Tropinone reductase II and Hyoscyamine-6S-dioxygenase-involved in the tropane alkaloid biosynthesis. Our analyses revealed that the genomes of D. stramonium show signatures of expansion, physicochemical divergence and/or positive selection on proteins related to the production of tropane alkaloids, terpenoids, and glycoalkaloids as well as on R defensive genes and other important proteins related with biotic and abiotic pressures such as defense against natural enemies and drought.
Asunto(s)
Datura stramonium/genética , Datura stramonium/metabolismo , Defensa de la Planta contra la Herbivoria/genética , Oxidorreductasas de Alcohol/metabolismo , Alcaloides/metabolismo , Evolución Biológica , Ambiente , Evolución Molecular , Interacción Gen-Ambiente , Genómica/métodos , Solanaceae/genética , Solanaceae/metabolismo , Tropanos/metabolismo , Secuenciación Completa del GenomaRESUMEN
Brugmansia candida (syn. Datura candida) is a South American native plant that produces tropane alkaloids. Hyoscyamine, 6ß-hydroxyhyoscyamine (anisodamine), and scopolamine are the most important ones due to their anticholinergic activity. These bioactive compounds have been historically and widely applied in medicine and their demand is continuous. Their chemical synthesis is costly and complex, and thereby, these alkaloids are industrially produced from natural producer plants. The production of these secondary metabolites by plant in vitro cultures such as hairy roots presents certain advantages over the natural source and chemical synthesis. It is well known that hairy roots produced by Agrobacterium rhizogenes infection are fast-growing cultures, genetically stable and able to grow in hormone-free media. Additionally, recent progress achieved in the scaling up of hairy root cultures makes this technology an attractive tool for industrial processes. This chapter is focused on the methods for the induction and establishment of B. candida hairy roots. In addition, the scaling up of hairy root cultures in bioreactors and tropane alkaloid analysis is discussed.
Asunto(s)
Biotecnología/métodos , Datura/fisiología , Raíces de Plantas/fisiología , Tropanos/metabolismo , Agrobacterium/crecimiento & desarrollo , Reactores Biológicos , Biotecnología/instrumentación , Cromatografía Líquida de Alta Presión/métodos , Técnicas de Cultivo/instrumentación , Técnicas de Cultivo/métodos , ADN de Plantas/genética , ADN de Plantas/aislamiento & purificación , Datura/genética , Datura/crecimiento & desarrollo , Datura/microbiología , Diseño de Equipo , Fitomejoramiento/métodos , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/microbiología , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/fisiología , Esterilización/métodos , Tropanos/análisis , Tropanos/aislamiento & purificaciónRESUMEN
Plant defensive compounds may be a cost rather than a benefit when plants are attacked by specialist insects that may overcome chemical barriers by strategies such as sequestering plant compounds. Plants may respond to specialist herbivores by compensatory growth rather than chemical defense. To explore the use of defensive chemistry vs. compensatory growth we studied Brugmansia suaveolens (Solanaceae) and the specialist larvae of the ithomiine butterfly Placidina euryanassa, which sequester defensive tropane alkaloids (TAs) from this host plant. We investigated whether the concentration of TAs in B. suaveolens was changed by P. euryanassa damage, and whether plants invest in growth, when damaged by the specialist. Larvae feeding during 24 hr significantly decreased TAs in damaged plants, but they returned to control levels after 15 days without damage. Damaged and undamaged plants did not differ significantly in leaf area after 15 days, indicating compensatory growth. Our results suggest that B. suaveolens responds to herbivory by the specialist P. euryanassa by investing in growth rather than chemical defense.
Asunto(s)
Mariposas Diurnas/fisiología , Interacciones Huésped-Parásitos , Larva/fisiología , Solanaceae/crecimiento & desarrollo , Solanaceae/parasitología , Tropanos/metabolismo , Animales , Solanaceae/metabolismoRESUMEN
A rapid in vitro propagation system leading to formation of shoots from callus, roots, and plantlets was developed for Schizanthus hookeri Gill. (Solanaceae), an endemic Chilean plant. The genus Schizanthus is of particular interest due to the presence of several tropane alkaloids. So far, in vitro propagation of species of this genus has not been reported. Propagation of S. hookeri consisted of two phases, the first one for callus initiation and shoot formation and the second for rhizogenesis and plantlet regeneration. From a single callus that rapidly increased in cell biomass (from approximately 50 mg to approximately 460 mg/culture tube [25 x 130 mm] in 60 days) in the presence of 2.69 microM NAA and 2.22 microM BA, more than 10 shoots/callus explant were formed. From the latter, approx. twenty plantlets formed after 90-110 days shoot subculture in medium devoid of growth regulators that favored root formation. Ten alkaloids ranging from simple pyrrolidine derivatives to tropane esters derived from angelic, tiglic, senecioic or methylmesaconic acids were obtained from in vitro regenerated plantlets. One of them, 3alpha-methylmesaconyloxytropane, was not previously described. The same growth conditions, as well as other growth regulator levels tested, were required to induce callus and root formation in S. grahamii Gill. Root organogenesis occurred despite a high level of BA vs. NAA used, (i.e., 4.44 microM BA and 0.54 microM NAA); however no shoot formation was achieved. In the case of S. tricolor Grau et Gronbach, only callus formation was obtained in the presence of various growth regulators.