Worldwide demands of Vanilla planifolia lead to finding new options to produce large-scale and contaminant-free crops. Particularly, the Mexican Government has classified Vanilla planifolia at risk and it subject to protection programs since wild species are in danger of extinction and no more than 30 clones have been found. Nanotechnology could help to solve both demands and genetic variability, but toxicological concerns must be solved. In this work, we present the first study of the cytotoxic and genotoxic effects promoted by AgNPs in Vanilla planifolia plantlets after a very long exposure time of six weeks. Our results show that Vanilla planifolia plantlets growth with doses of 25 and 50 mg/L is favored with a small decrease in the mitotic index. A dose-dependency in the frequency of cells with chromosomal aberrations and micronuclei was found. However, genotoxic effects could be considered as minimum due to with the highest concentration employed (200 mg/L), the total percentage of chromatic aberrations is lower than 5% with only three micronuclei in 3000 cells, despite the long-time exposure to AgNP. Therefore, 25 and 50 mg/L (1.5 and 3 mg/L of metallic silver) were identified as safe concentrations for Vanilla planifolia growth on in vitro conditions. Exposure of plantlets to AgNPs increase the polymorphism registered by inter-simple sequence repeat method (ISSR), which could be useful to promote the genetic variability of this species.

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Malanga (Colocasia esculenta) is a plant genetic resource that requires biotechnological strategies for conservation and propagation. One time-, labor-, and space-saving option is in vitro conservation and regeneration. The objective of this study was to develop a protocol for in vitro regeneration and conservation of germplasm of C. esculenta var. criolla. For conservation through minimal growth, we assessed several concentrations of Murashige and Skoog (MS) medium (one-third, one-half, and three-quarter strength), the growth retardant ancymidol (0, 1, 2, and 3 mg·L−1), and the osmoregulator polyethylene glycol (PEG-8000 mw) at different concentrations (0, 10, 20, and 30 g·L−1). For in vitro conservation, the percent survival, shoot number and length, and number of leaves and roots per explant were evaluated after 24 weeks. For in vitro regeneration, different concentrations of thidiazuron (TDZ: 0, 0.5, 1, 1.5, and 2 mg·L−1) and 6-benzylaminopurine (BAP; 0, 1, 2, 3, and 4 mg·L−1) were evaluated. After 4 weeks of cultivation, the percent response, shoot number, and number of leaves per explant were recorded. During in vitro conservation, it was noted that the treatment including 2 mg·L−1 ancymidol resulted in a retarded development, without affecting the survival of the C. esculenta germplasm. With regard to shoot regeneration, 7.60 shoots per explant were obtained using 2 mg·L−1 TDZ. Finally, 98% survival was achieved during the acclimatization process. This study will contribute to the establishment of genetic improvement programs through in vitro conservation and propagation of this valuable plant genetic resource.