High-frequency direct shoot organogenesis from garlic (Allium sativum L.) inflorescence and clonal fidelity assessment in regenerants

Garlic (Allium sativum L.) is an important bulb vegetable with high culinary and medicinal values. It is cultivated by exclusively vegetative propagation which leads to complex virus infection, biodiversity reduction, inhibition of multiple breeding strategies. An efficient and widely applicable shoot regeneration system was established from garlic inflorescence as explant. By optimizing the basal medium type, pH value and explant size, a mean shoot regeneration rate of 97% and mean shoot number of 23.4 per explant were achieved in 14 commercial cultivars with various characteristics and origins. Histological observation revealed that shoots were regenerated through direct organogenesis when meristemoid initiated from subepidermal cells without callus formation followed by periclinal and anticlinal division of epidermal and subepidermal cells. No polymorphic bands were detected by simple sequence repeat (SSR) analysis between regenerants and donor plants. Furthermore, flow cytometry analysis indicated that there was no significant variability of genome size, and all plants maintained their ploidy. These results confirmed the clonal fidelity of regenerants. In conclusion, the present study provides a shoot regeneration system with great potential in micropropagation, germplasm preservation, genetic transformation and ploidy manipulation of garlic. Our study developed a widely applicable procedure for direct shoot regeneration via inflorescence of garlic and ascertained the clonal fidelity of regenerants by using simple sequence repeat (SSR) and flow cytometry.