Cloning and Functional Characterization of LlAS1 in Lilium lancifolium

Bulbils, originating from axillary meristem, are known to have a significant impact on the propagation of Lilium lancifolium. Transcription factor ASYMMETRIC LEAVES 1 has been shown to be involved in the regulation of bulbil formation based on the transcriptome data of L. lancifolium. The present investigation involved the cloning of the LlAS1 gene from L. lancifolium by RT-PCR and further be characterized. The open reading frame of LlAS1 comprised 1035 bp, which encoded 344 amino acids. The LlAS1 protein contained two conserved SANT domains in series at the N-terminus. Phylogenetic analysis revealed that LlAS1 belongs to the monocot group and was closely related to the AS1 of Musa acuminata subsp. malaccensis. Expression analysis showed that LlAS1 was strongly expressed in bulbil, especially in primary bulbils. It was highly expressed during the process of bulbil primordium establishment and bulbil formation. Transient overexpression and virus-induced gene silencing (VIGS) of LlAS1 in leaf axils significantly promoted and inhibited bulbil formation of L. lancifolium, respectively. The findings of the study indicated that LlAS1 was positively correlated with bulbil formation of L. lancifolium, laying a foundation for further understanding the regulation of LlAS1 gene for bulbil formation and application in molecular genetic improvement of lilies.