Proteomic analysis provides an insight into the molecular mechanism of development and flowering in Lycoris radiata

Lycoris radiata Herb is an important ornamental and medicinal plant native in China. Its productive and reproductive phases are separate. However, the molecular mechanisms governing this unique process of development and flowering are still unclear at the proteome level. In the present study, we used a label-free quantitative proteomic approach to investigate the dynamic changes in the proteome of the bulb tips at six developmental stages in L. radiata, including dormancy (Dor), flowering (Flo), leafing out (LO), rapid leaf extension (RLE), leaf maturity (LMa) and leaf withering (LWi). A total of 2,090 proteins were identified in bulb tips, and each pair of the stages shared 242 (Flo vs. Dor), 82 (LO vs. Flo), 156 (RLE vs. LO), 76 (LMa vs. RLE), 438 (LWi vs. LMa) and 164 (Dor vs. LWi) differentially expressed proteins (DEPs). Analysis of Gene Ontology (GO) and pathway enrichment revealed that the DEPs of Flo vs. Dor were mainly involved in "energy reserve metabolic process", "cellular polysaccharide metabolic process" and "cellular glucan metabolic process", whereas the DEPs in LO vs. Flo and RLE vs. LO were mainly involved in "negative regulation of intracellular steroid hormone receptor signaling pathway". Weighted gene coexpression network analysis showed that there were temperature stimuli, stress responses and immune responses at the dormancy and flowering stages; several proteins, including heat shock protein 83, heat shock cognate 70 kDa protein 2-like isoform X1 and superoxide dismutase [Cu-Zn] 4A, can contribute to these responses. Additionally, 40S ribosomal protein and cell division cycle 5-like protein participated in protein synthesis, cell division and cell expansion during the leaf phase. These results can help us better understand the molecular mechanism of L. radiata development and flowering and provide valuable information about the proteins involved in the development and stress response in other plants of the Lycoris genus.