Interaction of Culture Medium and Artificial Light Type on Pigmentation of Micro-Propagated Opuntia Plants

Abstract

Opuntia is recognized economically as a significant crop for its nutritional, functional, and therapeutic properties and its potential in the pharmaceutical, cosmetic, and bioenergy industries. Opuntia is conventionally propagated by seed or vegetative propagation via rooted scions or grafting. However, multiplication procedures are insufficient for extensive spreading. One of the alternative techniques is in vitro. For this reason, the objective was to evaluate the growth of different components combined with light conditions to induce callus, embryogenesis, and the possible synthesis of a component in the genus Opuntia. The existence of genes involved in pigment synthesis in genotypes of different fruit colors was complementarily analyzed. In this study, we used different combinations of fructose (2 g/L) with prickly pear juice (2 mL/L), mannitol (4 g/L), silver nitrate (AgNO3: 1 mg/L), 2,4-dichlorophenoxyacetic acid (2,4-D: 2 mg/L), and indole-3-acetic acid (IAA: 1 g/L), with white, blue, and red LEDs (light-emitting diodes) and laser beams. These explants yielded sufficient contents of simple phenols, gallic acid equivalents (GAE: 2283.30 ± 6.29 mg/100 g), and coumaric (2155.0 ± 35.0 mg/100 g) and ferulic (2176 ± 27.9 mg/100 g) acids for the genotype Tapón aguanoso, and chlorogenic acid (CGA: 380.22 ± 22.05 mg/100 g) for the Copena V1 genotype. Upon analyzing the genotypes of different fruit pigmentations, we also observed the following: enzyme 4,5 estradiol dioxygenases can be present in all genotypes (regardless of pigmentation); enzyme 5,3 glucosyltransferases (GTs) could be induced in pigment synthesis in the genotypes of orange to purple fruits. Sequencing primer-amplified fragments for GT showed high similarity to uridine diphospho (UDP)-glucose from other species. This allows us to infer that it is possible to obtain products of high therapeutic value in the near future under controlled conditions.