LlLRP1, an SHI/SRS transcription factor, mediates bulbil formation in Lilium lancifolium via regulation by LlWOX11 and response to NaCl stress.

Bulbil formation in Lilium lancifolium represents a pivotal vegetative reproduction strategy, yet the transcriptional regulatory network governing this process remains largely uncharacterized. Here, we identify LlLRP1 by full-length cloning, sequence analysis and subcellular localization, an SHI/SRS family transcription factor, as a key mediator of bulbil morphogenesis. Transcriptomic profiling revealed that LlLRP1 is a downstream target of LlWOX11, with its promoter harboring conserved binding motifs (AAAG, AGTA) validated by yeast one-hybrid, dual-luciferase reporter, and electrophoretic mobility shift assays. Functional characterization showed that LlLRP1 overexpression enhanced bulbil formation rate by 18.3 % in leaf axils, whereas virus-induced gene silencing (VIGS) reduced bulbil initiation by 54 %. Hormone responsiveness assays demonstrated that LlLRP1 expression is induced by cytokinin (6-BA) and auxin (IAA), which is consistent with the response pattern of LlWOX11 to cytokinins. Under salt stress, LlLRP1 was rapidly upregulated, and its overexpression promoted antioxidant enzyme gene (SOD, ROS) expression, suggesting a dual role in bulbil development and stress adaptation. These findings establish a LlWOX11-LlLRP1 regulatory module driving bulbil formation and highlight LlLRP1 as a promising target for optimizing asexual propagation in lily.