Sprout differentiation and mutation induction of garlic (Allium sativum L.) callus exposed to gamma radiation

Germplasm enhancement and breeding is difficult for garlic (Allium sativum L.) as it can only be vegetatively propagated. Hence, mutation induction is still the most effective way to create new varieties. Calli from two Chinese commercial garlic varieties, Zhoumou (ZM) and Yongnian (YN), were treated with different dosages (1, 3, 5 and 7 Gy) of gamma (γ) radiation. The results showed that the two genotypes differed in their sensitivity to γ-radiation. YN was sensitive to high dosage, while ZM showed better growth at higher dosage. More specifically, the average number of calli producing sprouts, sprout number per callus, total sprouts number, the number of sprouts forming plantlets and plantlet lengths were higher when calli of variety YN were treated with 1 Gy. However, the corresponding parameters in ZM were higher for 7 Gy. Simple sequence repeat analysis with two of 16 novel primers showed genetic variation among the plantlets following γ-radiation treatments of 5 Gy for variety YN and 7 Gy for variety ZM. The methods and mutant materials in this study could be used in future garlic breeding programs.