Identification of PAL Gene in Purple Cabbage and Functional Analysis Related to Anthocyanin Synthesis

Anthocyanin is a characteristic nutrient of purple cabbage, and phenylalanine ammonia-lyase (PAL) is the rate-limiting enzyme for the synthesis of anthocyanin by the phenylpropane pathway, which is an important part of plant secondary metabolism. In this research, 7 BrPAL, 8 BoPAL, and 15 BnPAL genes from genomes of Brassica rapa, Brassica oleracea, and Brassica napus, divided into four subgroups, evolved from 4 PAL genes in Arabidopsis. The amplification and evolution of the BrPAL gene are due to segmental duplication and purifying selection. BrPAL genes clustered in the same clade have similar intron/exon structures and motifs. The cis-regulatory elements are divided into four categories: light, growth and development, stress and hormones. The qRT-PCR assays showed that most BrPAL genes were upregulated by UVA, low temperature and MeJA and downregulated by FR, high temperature, salt, PEG, IAA, ABA and GA, and there was a positive correlation between anthocyanin content and gene expression. This study can be used as a source for the function of the cabbage PAL gene and its molecular mechanism of regulating anthocyanin synthesis and provides a theoretical basis for the molecular breeding of cabbage.