DNA extraction, library construction, and sequencing
Genomic DNA was extracted from silica-dried leaves using a modified CTAB protocol (Porebski, Bailey, & Baum, 1997). The 52 LCN genes were amplified by PCR using the protocol of Jiang et al. (2022), and the DNA library was constructed following de Sousa et al. (2014). After obtaining fragments of 300–400 bp, PCR was performed on the indexed samples, and the concentrations of the amplified library were measured using a NanoDrop 2000c (Thermo Fisher Science, USA). Gene enrichment and hybridization reactions were performed following the protocol of de Sousa et al. (2014), and the pooled samples were high-throughput sequenced using the Illumina MiSeq platform to generate 150-bp paired-end reads.