Advanced techniques and applications in fennel (Foeniculum vulgare Mill.) breeding.

Fennel (Foeniculum vulgare Mill.) is a widely cultivated medicinal and aromatic plant valued for its essential oils used in pharmaceutical, culinary, and industrial applications. Breeding activities for fennel have been historically limited, but recent genomic advances have revealed substantial genetic diversity and variability among its populations, offering new opportunities to improve yield, oil composition, and stress resilience. Studies using molecular markers including RAPD, ISSR, SSR, and SNPs have characterized the genetic structure of fennel germplasm and identified key loci for traits such as seed yield, essential oil profile, and disease tolerance. Quantitative trait locus (QTL) mapping and principal component analysis (PCA) have refined genotype selection. Transcriptomic studies related to t-anethole biosynthesis and expression profiles under stress conditions have enabled functional gene discovery. Biotechnological tools such as callus induction, doubled haploid protocols, and in vitro selection techniques have emerged as adjunct strategies to accelerate breeding outcomes. Integration of classical breeding methods with molecular and biotechnological approaches enables precision breeding of fennel cultivars tailored for modern agricultural needs. Enhancing genetic diversity utilization and targeting key traits will support the development of high-performing, resilient varieties. This direction advances both the sustainability of fennel cultivation and its utility in agro-industrial sectors.