The phenylalanine ammonia-lyase gene family in Isatis indigotica Fort.: molecular cloning, characterization, and expression analysis

Abstract

Phenolic compounds, metabolites of the phenylpropanoid pathway, play an important role in the growth and environmental adaptation of many plants. Phenylalanine ammonia-lyase (PAL) is the first key enzyme of the phenylpropanoid pathway. The present study was designed to investigate whether there is a multi-gene family in I. Indigotic and, if so, to characterize their properties. We conducted a comprehensive survey on the transcription profiling database by using tBLASTn analysis. Several bioinformatics methods were employed to perform the prediction of composition and physicochemical characters. The expression levels of IiPAL genes in various tissues of I. indigotica with stress treatment were examined by quantitative real-time PCR. Protoplast transient transformation was used to observe the locations of IiPALs. IiPALs were functionally characterized by expression with pET-32a vector in Escherichia colis strain BL21 (DE3). Integration of transcripts and metabolite accumulations was used to reveal the relation between IiPALs and target compounds. An new gene (IiPAL2) was identified and both IiPALs had the conserved enzymatic active site Ala-Ser-Gly and were classified as members of dicotyledon. IiPAL1 and IiPAL2 were expressed in roots, stems, leaves, and flowers, with the highest expression levels of IiPAL1 and IiPAL2 being observed in stems and roots, respectively. The two genes responded to the exogenous elicitor in different manners. Subcellular localization experiment showed that both IiPALs were localized in the cytosol. The recombinant proteins were shown to catalyze the conversion of L-Phe to trans-cinnamic acid. Correlation analysis indicated that IiPAL1 was more close to the biosynthesis of secondary metabolites than IiPAL2. In conclusion, the present study provides a basis for the elucidation of the role of IiPALs genes in the biosynthesis of phenolic compounds, which will help further metabolic engineering to improve the accumulation of bioactive components in I. indigotica.

Genome-Wide Identification and Transcriptional Expression of the PAL Gene Family in Common Walnut (Juglans Regia L.)

“…We searched the PAL genes in 40 common walnut scaffolds. (pseudo-chromosomes) by anchoring the scaffolds to the walnut linkage groups (Table S6) [61]. These 12 PAL genes were localized to eight scaffolds in the common walnut (Table 1; Figure 2) [61].…”

“…(pseudo-chromosomes) by anchoring the scaffolds to the walnut linkage groups (Table S6) [61]. These 12 PAL genes were localized to eight scaffolds in the common walnut (Table 1; Figure 2) [61]. Duplication events are important in the expansion and evolution of gene families, including whole-genome duplications, small-scale segmental duplications, local tandem duplications, or combinations of these possibilities [62,63,64].…”

Comparative genomic analysis of the PAL genes in five Rosaceae species and functional identification of Chinese white pear

“…In addition, PAL is also one of the branching enzymes linking primary and secondary metabolism (Ma et al, 2016). The first step in catalyzing cinnamic acid (a precursor) to form various phenylpropanol derivatives.…”

Quality, Bioactive Compounds, Antioxidant Capacity, and Enzymes of Raspberries at Different Maturity Stages, Effects of Organic vs. Conventional Fertilization

“…Contradictory theories in both directions show logic and sustenance. On the one hand, one theory indicates that in organic systems the plant faces stress conditions that may induce the antioxidant defense mechanism that includes enzymes: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and non-enzymatic compounds such as ascorbic acid (AsA) and phenolics [ 14 ], the latter being synthesized by the activity of the enzyme phenylalanine ammonium lyase (PAL) [ 15 ]. Another theory focuses on exposing agrochemicals as the cause of abiotic stress in the plant, activating defense mechanisms and causing an increase in bioactive compounds and antioxidant activity [ 16 ].…”