Functional Analysis of LaPCBER1 Gene During the Development of Bulbs of Lilium 'Tresor'

Objective To analyze the expression pattern of the phenylcoumaran benzylic ether reductase gene LaPCBER1 during bulb development in Lilium 'Tresor', and to investigate its effects on bulb enlargement as well as its role in regulating lignin content during this process.

Method By analyzing transcriptomic data from the bulb enlargement process of Lilium 'Tresor', a differentially expressed gene annotated as PCBER1 was screened. The LaPCBER1 gene was cloned using cDNA from Lilium 'Tresor' bulbs as the template, and the physicochemical properties of the encoded protein were analyze using bioinformatics software.The expression patterns of LaPCBER1 in different tissues and different developmental stages of Lilium 'Tresor' were detected by quantitative real-time PCR (qRT-PCR). The effects of LaPCBER1 on bulb enlargement were investigated using transient overexpression techniques, and the lignin content of lily bulbs at different stages and following overexpression was measured using assay kits.

Result The full-length DNA sequenceof LaPCBER1 is 930 bp, encoding 309 amino acids. The protein is predicted to have 51 phosphorylation sites and is characterized as a non-transmembrane, unstable, hydrophilic protein. qRT-PCR results showed that LaPCBER1 was highly expressed in the stem, with expression peaking during the S4 stage (rapid expansion stage) of bulb development. Following transient overexpression of LaPCBER1, the lignin content in transgenic bulbs increased by 49.7% compared to the vector. The fresh weight, dry weight, and relative growth rates of circumference of the bulbs increased by 29.0%, 29.7%, and 37.2 percentage points, respectively; Conversely, after silencing LaPCBER1, the fresh weight, dry weight, and relative growth rates of circumference of the bulbs decreased by 35.9%, 38.7%, and 32.2 percentage points, respectively, and the lignin content decreased by 24.3%.

Conclusion Expression pattern and functional analysis of LaPCBER1 suggest that this gene is highly expressed during the early stages of bulb development and promotes lignin accumulation and bulb expansion. It is therefore hypothesized that LaPCBER1 is involved in the bulb expansion process of Lilium 'Tresor' and plays a positive regulatory role in this process.