Agricultural activity has changed significantly in recent years. There is a clear trend towards monoculture and the replacement of traditional crops for others which are more productive and achieve better economic results. These factors have two fundamental consequences: on the one hand, the abandonment of agricultural activity, with the subsequent loss of rurality; on the other hand, a negative effect on the maintenance of biodiversity, because traditional varieties disappear. In this context, this paper analyses the situation of consumers and farmers of a traditional crop in the southeast of Spain: the tomato. In order to understand the current situation and the forecasted future, a choice experiment was conducted on 217 tomato consumers. Furthermore, 40 tomato farmers of this area underwent an in-depth interview. On the one hand, analysis of the consumer study established a potential segment of the population that prefers traditional varieties due to their high organoleptic properties. Meanwhile, the farmer study revealed a segment of this population that is willing to produce these types of crops. Therefore, the possibility that a certain sector of producers cultivates traditional varieties is suggested, and for these varieties to be aimed at a market niche that values them positively, making the activity of Small and Medium Enterprises (agricultural SMEs) profitable. This would improve the sustainability of the rural territory and would strengthen the preservation of genetic heritage.

The use of silver nanoparticles (AgNPs) is increasing nowadays due to their applications against phytopathogens. Temporary Immersion Systems (TIS) allow the micropropagation of plants in liquid media. This work aims to develop an effective protocol for apricot micropropagation in TIS and to study the necessary conditions to introduce AgNPs in apricot plants, as well as the effect of its application on proliferation-related parameters. AgNPs were introduced in different media at a concentration of 100 mg L−1 to test the incorporation of silver to plant tissues. Silver content analysis was made by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The effect of initial shoot density and the addition of AgNPs on micropropagation were evaluated after four weeks in culture on TIS. Productivity, proliferation, shoot-length and leave surface were measured. The better micropropagation rate was obtained with 40 initial shoots, 2 min of immersion every 6 h and 3 min of aeration every 3 h. To introduce AgNPs in apricot plants it is necessary to culture them in liquid media without chloride in its composition. These results will contribute to the development of an in vitro protocol for virus inhibition by AgNPs application. This depends on the introduction of Ag nanoparticles within the plant tissues, and this is not possible if AgNPs after interaction with Cl- ions precipitate as silver chloride salts.

The improvement of previously described protocols for the regeneration of shoots from ‘Canino’ mature seed hypocotyl slices has been accomplished. The effects of different factors such as the part of the hypocotyl used, vacuum-infiltration, 2,4-Dichlorophenoxyacetic acid pulse, vacuum-infiltration and sonication on regeneration and transient transformation were analyzed. When the three slices obtained from the hypocotyls were evaluated separately on regeneration medium, the highest percentages of regenerating explants were achieved in the part close to the epicotyl and in the central part. On the other hand, sonication of the explants for 30 s followed by vacuum-infiltration during Agrobacterium infection for 20 min allowed for an increase in the transformation events. The application of these modifications to the procedure increased the regeneration efficiencies, and transient transformation events and may reduce the frequency of failed experiments. An efficient regeneration/transformation protocol could facilitate its use as a biotechnological technique for apricot breeding.

Trans-grafting could be a strategy to transfer virus resistance from a transgenic rootstock to a wild type scion. However contradictory results have been obtained in herbaceous and woody plants. This work was intended to determine if the resistance to sharka could be transferred from transgenic plum rootstocks to wild-type apricot scions grafted onto them. To this end, we conducted grafting experiments of wild- type apricots onto plum plants transformed with a construction codifying a hairpin RNA designed to silence the PPV virus and studied if the resistance was transmitted from the rootstock to the scion. Our data support that the RNA-silencing-based PPV resistance can be transmitted from PPV-resistant plum rootstocks to non-transgenic apricot scions and that its efficiency is augmented after successive growth cycles. PPV resistance conferred by the rootstocks was robust, already occurring within the same growing cycle and maintained in successive evaluation cycles. The RNA silencing mechanism reduces the virus titer progressively eliminating the virus from the wild type scions grafted on the transgenic resistant PPV plants. There was a preferential accumulation of the 24nt siRNAs in the scions grafted onto resistant rootstocks that was not found in the scions grafted on the susceptible rootstock. This was coupled with a significant lower quantification of the hpRNA in the resistant than in the susceptible or tolerant rootstocks. Using transgenic rootstocks should mitigate public concerns about transgenes dispersion and eating transgenic food and allow conferring virus resistance to recalcitrant to transformation cultivars or species.