Genetic improvement of medicinal and aromatic plant species: Breeding techniques, conservative practices and future prospects

Throughout history, herbal medicine has played a vital role in understanding and treating various ailments in humans and animals. The medicinal aromatic plant species, with their chemical compounds, offer potential solutions for addressing numerous diseases. Enhancing the genetic makeup of these plant species for both medicinal and economic purposes is now imperative. Mutation breeding is a significant strategy, having led to the development of nearly 3500 plant species. Polyploidy induction, doubling chromosomes, can result in larger and more valuable plant parts with medicinal and economic value. Plant tissue culture (PTC) is a crucial breeding technique, allowing for artificial polyploidy and Agrobacterium-mediated gene transformation to manipulate medicinal plant genomes, producing pharmaceutical secondary metabolites. The introduction of the third-generation clustered regularly interspaced short repeats (CRISPR)-Cas9 gene editing system has enabled the correction of defects seen in the first- and second-generation gene editing technologies, which relied on synthetic endonucleases like zinc finger endonuclease (ZFN) and transcription activator-like receptor nuclease (TALEN). These gene editing methods facilitate the manipulation of secondary metabolite pathways in medicinal plants. Virus-induced gene silencing (VIGS) based on short interfering RNA-mediated RNA silencing provides a rapid alternative for knocking out gene expression in medicinal and aromatic plant species that may not easily undergo stable genetic transformation. This article offers an overview of global trends, advancements, and prospects in conserving and breeding of medicinal aromatic plants, and helping as a valuable reference for sustainable resource utilization.