Phenolic Compounds Content and Genetic Diversity at Population Level across the Natural Distribution Range of Bearberry (Arctostaphylos uva-ursi, Ericaceae) in the Iberian Peninsula.

Bearberry (Arctostaphylos uva-ursi) is a medicinal plant traditionally employed for the treatment of urinary tract infections due to high contents of arbutin (hydroquinone ß-D-glucoside), which is now mainly used as a natural skin-whitening agent in cosmetics. Bearberry has also been proposed as a natural antioxidant additive due to the high contents of phenolic compounds in leaves. We studied the variation on phenolic compounds in 42 wild populations of bearberry, aiming to elucidate if intrinsic biological, climatic, and/or geographic factors affect phenolic contents across its natural distribution in the Iberian Peninsula. Bearberry leaves were collected during autumn over a three-year period (2014-2016) in populations across a latitude and altitude gradient. Methanolic extracts showed a wide range of variation in total phenols content, and different phenolic profiles regarding arbutin (levels of this major constituent varied from 87 to 232 mg/g dr wt), but also catechin and myricetin contents, which were affected by geographic and climatic factors. Moderate levels of variation on genome size-assessed by flow cytometry-and on two plastid DNA regions were also detected among populations. Genetic and cytogenetic differentiation of populations was weakly but significantly associated to phytochemical diversity. Elite bearberry genotypes with higher antioxidant capacity were subsequently identified.

Antioxidant and antimicrobial markers by UPLC®-ESI-Q-TOF-MSE of a new multilayer active packaging based on Arctostaphylos uva-ursi.

49 different non-volatile compounds were determined in Spanish Arctostaphylos uva-ursi leaves using UPLC®-ESI-Q-TOF with MSE technology. Both positive and negative electrospray ionization were applied. MarkerLynx® was proposed as a powerful tool to distinguish samples from eight wild populations of Spain by determining their non-volatile markers. Development of HRMS methods let to analysis of metabolites in plants. Antioxidant and antimicrobial capacities of different extracts were evaluated. Plant extract with the strongest antioxidant and simultaneous good antimicrobial capacity (Lierta) was chosen and incorporated in a multilayer packaging. Then, antioxidant capacity of the new packaging was evaluated and the efficient free radical scavenging properties were demonstrated.

Enhancement of cardenolide and phytosterol levels by expression of an N-terminally truncated 3-hydroxy-3-methylglutaryl CoA reductase in Transgenic digitalis minor.

Pathway engineering in medicinal plants attains a special significance in Digitalis species, the main industrial source of cardiac glycosides, steroidal metabolites derived from mevalonic acid via the triterpenoid pathway. In this work, the Arabidopsis thaliana HMG1 cDNA, coding the catalytic domain of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR1S), a key enzyme of the MVA pathway, was expressed in the cardenolide-producing plant Digitalis minor. Transgenic plants were morphologically indistinguishable from control wild plants and displayed the same developmental pattern. Constitutive expression of HMG1 resulted in an increased sterol and cardenolide production in both in vitro- and greenhouse-grown plants. This work demonstrates that transgenic D. minor plants are a valuable system to study and achieve metabolic engineering of the cardenolide pathway and in consequence for the genetic improvement of Digitalis species.

Agrobacterium tumefaciens-mediated genetic transformation of the cardenolide-producing plant Digitalis minor L.

A repeatable transformation system has been established for Digitalis minor using Agrobacterium tumefaciens. Leaf explants from 30-day-old seedlings were inoculated with either EHA105 (carrying the nptII and gusA genes) or AGL1 (with the bar and gusA genes) strains. Among the tested factors influencing T-DNA transfer to plants, the EHA105 strain and the addition of acetosyringone to the co-culture medium increased transformation. The highest transformation efficiency (8.4 %) was obtained when freshly isolated explants, soaked in a bacterial suspension with an OD550 of 0.9, were subcultured on selection medium after a 4-day co-culture with the bacteria. Evidence of stable transgene integration was obtained by PCR, growth on media selective for nptII or bar genes, and expression of the gusA gene. Southern hybridisation, performed in six plants, provided information about the number of inserts. More than 200 transgenic plants were recovered from 65 independent explants. Thirty of these plants were successfully established in soil. This is the first report on transgenic Digitalis spp plants using an A. tumefaciens-mediated leaf disc transformation procedure.