Ag4CL3 Related to Lignin Synthesis in Apium graveolens L.

Abstract

4-Coumarate: coenzyme A ligase (4CL; EC 6.2.1.12) is an important enzyme in the phenylpropanoid metabolic pathway that controls the biosynthesis of lignin and flavonoids. In this study, to identify the function of the Ag4CL3 gene of celery, the Ag4CL3 gene was cloned from celery cv. “Nanxuan Liuhe Ziqin”. Sequence analysis results showed that the Ag4CL3 gene contained an open reading frame (ORF) with a length of 1688 bp, and 555 amino acids were encoded. The Ag4CL3 protein was highly conserved among different plant species. Phylogenetic analysis demonstrated that the 4CL proteins from celery and carrot belonged to the same clade. The Ag4CL3 protein was mainly composed of 31.89% α-helixes, 18.02% extended strands, 6.67% β-turns, and 43.42% random coils, and the signal peptide was unfound. A total of 62 phosphorylation sites and a class-I superfamily of adenylate-forming domains were found. As the growth time increased, the plant height and stem thickness also increased, and the petiole lignin content increased and became lignified gradually. The relative expression levels of the Ag4CL3 gene in “Nanxuan Liuhe Ziqin” petioles were higher than those in other tissues, with the highest level occurring 70 d after sowing. The lignin contents in the transgenic Arabidopsis thaliana lines hosting the Ag4CL3 gene were higher than those in the WT. In this study, the overexpression of Ag4CL3 led to the significant upregulation of lignin biosynthesis gene expression in transgenic A. thaliana plants, except for AtPAL, AtCCR, and AtLAC. This study speculates that Ag4CL3 genes are related to lignin synthesis in A. graveolens.

The Recognition and Utilization of Natural Genetic Resources for Advances in Plant Biology through Genomics and Biotechnology

“…Its stem sections are prone to browning, with Zhao et al reporting a comparative physiological analysis of the lignification, anthocyanin metabolism, and correlated gene expression in red T. sinensis buds during cold storage [11]. The lignin biosynthesis gene 4CL (4-coumarate: coenzyme A ligase) of Apium graveolens L. was also identified by Zhong et al using gene cloning, bioinformatics analysis, and transgenic Arabidopsis thaliana [12]. The effect of bee pollination efficiency on the quality and yield of strawberries was investigated by Liu et al, who analyzed the composition of strawberry flower volatiles and their effects on the behavior of strawberry pollinators, Bombus terrestris and Apis mellifera.…”