**6. Elicitation**

An alternative to new varieties is using beneficial bacteria or parts of the same as a tool to trig‐ ger plant metabolism in field production in order to cause a mild-biotic stress in the plant that smoothly and constantly triggers secondary metabolism to achieve constant concentrations of bioactives in the edible fruits [77, 78]. The ability of many beneficial bacteria to trigger plant metabolism in different species has been reported and there is increasing evidence of bacterial derived elicitors with the same effect [79]. These bacterial derived molecules are termed as MAMPs (microbe-associated molecular patterns) and can be either structural molecules from the bacterial cell wall, or derived metabolites that bacteria release to trigger the plant in their intimate relationship. Each MAMP or strain has to be evaluated for each plant species, since genome-genome specificity has been occasionally reported.

To support the value of this strategy in the study of blackberry metabolism, a transcriptome analysis from field grown blackberry fruits was performed to study this plant species; contigs were obtained and blasted to the genome of *Fragaria*, the model plant within the Rosaceae finding 73.5% similarity with *Fragaria vesca* subspecies *vesca* [80]. Once the gene information was available, field grown blackberry plants were inoculated with a beneficial bacteria strain (*Pseudomonas fluorescens* N21.4) as a biostimulant, aiming to trigger flavonoid biosynthesis as part of an induced systemic response (ISR). Fruits were studied in three states along matura‐ tion, carrying on a bioactive characterization and studying core and regulatory gene expres‐ sion. As a result, the concentration of flavonoids increased in the fruit along with maturation over the noninoculated controls; hence, core and regulatory genes were characterized and their expression was studied demonstrating genes likely involved in controlling the activity of pathway branches, associated with enhanced accumulation of anthocyanins, catechins, and flavonols in developing fruits of blackberry [81].

These results prove that elicitation is a very interesting tool to achieve better fruit quality in terms of higher amounts of bioactives, as flavonoid biosynthesis can be modulated without genetic manipulation. Using this method, we can achieve two different goals at the same time: first we increase plant defense by a natural way without using any chemicals, which are harmful for the environment and humans also, therefore contributing to environmentally friendly agricultural practices. The second one would be obtaining a food with reliable ben‐ eficial effects for human health, since delivering the bacteria through the roots will attenuate fluctuations in bioactive compounds. This second statement is nowadays one of the world's great concerns, since achieving food security refers to both ends of society: those that are hungry should have enough amounts of healthy and nutritious foods, as well as those that have a lot of food, but unbalanced and low quality. Therefore, healthy eating is becoming really popular as population is trying to have a good diet to prevent development of disease rather than healing, so to decrease the intake of different drugs in a long time period. Both this two goals can be achieved by the application of these rhizobacterias that will increase these secondary metabolites by a natural method. Beyond health-related issues in food production, these elicitors and elicitation technology [80] can be used to unravel metabolic pathways and their regulation for further application in metabolic engineering and cell cultures.
