In Vitro Propagation of Alyssum Species with Different Metal Accumulation Strategies

The Alyssum genus, with its many metal-adapted species, is a good candidate for research on phytoremediation and metal tolerance mechanisms. These goals can be supported by elaborating on an in vitro multiplication protocol. Our study aimed to determine the aseptic conditions for the growth and effective propagation of Alyssum murale, A. alyssoides, and A. montanum, each exhibiting different adaptation strategies to nickel ions. Firstly, hydrogen peroxide (H₂O₂) or sodium nitroprusside (SNP) were investigated in the biological Lepidium test to find their optimal concentrations that could improve the germination attributes of tested Alyssum species. The concentration of 0.5 mM H₂O₂ or SNP was selected for research on Alyssum seeds, which were the initial material to start in vitro cultivation. Regardless of the species, H₂O₂ harmed germination percentage; however, its application accelerated radicle emergence, especially in metal-sensitive genotypes, while in both metal-tolerant ones, the germination time of H₂O₂-treated seeds was similar to that of treated with SNP. These findings provide a novel insight into the effect of H₂O₂ or SNP on seeds, contributing to a better understanding of their role in the germination of different genotypes. Among tested media compositions, the synchronous plant regeneration of all species was achieved on MS medium supplemented with 0.5 mg/L 2iP and 0.1 mg/L IAA, making an essential advancement in the in vitro protocols for metallophytes.