In Vitro Polyploidy Induction of Longshan Lilium lancifolium from Regenerated Shoots and Morphological and Molecular Characterization

Longshan Lilium lancifolium is a well-known medicinal and edible lily and has been registered as a geographical indicator in China. Polyploidization confers many advantages in lily production; however, characteristics of Longshan L. lancifolium improved by polyploidization have not been reported. Here, polyploidization was induced in regenerated Longshan L. lancifolium shoots using colchicine, and the mutant plantlets were characterized by morphological observation, flow cytometry, and inter simple sequence repeat (ISSR) marker technology. The optimal medium for inducing shoot regeneration was Murashige and Skoog (MS) media supplemented with 0.2 mg/L of naphthaleneacetic acid (NAA) and 0.4 mg/L of thidiazuron (TDZ). The greatest mutation induction effect was obtained after soaking the regenerated shoots in 0.10% colchicine for 48 h, for an 80.00% frequency of morphological variants. Forty-one mutant plantlets were subjected to flow cytometry, identifying one homozygous polyploid, ‘JD-12’, and one chimeric polyploid, ‘JD-37’. Additionally, 68 chromosomes were found in the ‘JD-12’ root tip cells. Compared with the control, both the tissue-cultured and field-generated ‘JD-12’ plantlets presented a slight decrease in plant height, a darker green leaf color, a rougher leaf surface, and a larger bulblet diameter; furthermore, the upper epidermal and guard cells of ‘JD-12’ were much larger with a significantly lower stomatal density. The ISSR marker detection indicated a genetic variation rate of 6.10% in ‘JD-12’. These results provide a basis for lily polyploidization breeding and the cultivation of superior Longshan L. lancifolium via shoot regeneration.