Abstract
BackgroundPhenylalanine ammonia-lyase (PAL, EC 4.3.1.24) is the first key enzyme in the phenylpropanoid pathway. The pal gene has been widely studied in plants and participates in plant growth, development and defense systems. However, in Pleurotus ostreatus, the biological functions of pal during organismal development and exposure to abiotic stress have not been reported.ResultsIn this study, we cloned and characterized the pal1 (2232 bp) and pal2 (2244 bp) genes from the basidiomycete P. ostreatus CCMSSC 00389. The pal1 and pal2 genes are interrupted by 6 and 10 introns, respectively, and encode proteins of 743 and 747 amino acids, respectively. Furthermore, prokaryotic expression experiments showed that PAL enzymes catalyzed the conversion of L-phenylalanine to trans-cinnamic acid. The function of pal1 and pal2 was determined by constructing overexpression (OE) and RNA interference (RNAi) strains. The results showed that the two pal genes had similar expression patterns during different developmental stages. The expression of pal genes was higher in the reproductive growth stage than in the vegetative growth stage. And the interference of pal1 and pal2 delayed the formation of primordia. The results of heat stress assays showed that the RNAi-pal1 strains had enhanced mycelial tolerance to high temperature, while the RNAi-pal2 strains had enhanced mycelial resistance to H2O2.ConclusionsThese results indicate that two pal genes may play a similar role in the development of P. ostreatus fruiting bodies, but may alleviate stress through different regulatory pathways under heat stress.
Highlights
Phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) is the first key enzyme in the phenylpropanoid pathway
DNA sequence analysis showed that 7 exons are interrupted by 6 introns in pal1, while 11 exons are interrupted by 10 introns in pal2 (Fig. 1b)
The PAL1 and PAL2 protein sequences in both P. ostreatus CCMSSC 00389 and PC15 were highly similar to one another (Additional file 1: Figure S1), and the consistency reached 99.73 and 99.59%, respectively
Summary
Phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) is the first key enzyme in the phenylpropanoid pathway. The pal gene has been widely studied in plants and participates in plant growth, development and defense systems. The pal gene has been widely studied in plants and participates in plant growth, development and defense systems [5, 6], including lignin synthesis in cell. Zou et al studied proteome changes in P. ostreatus mycelia during heat stress and recovery and identified 204 proteins, including PAL, exhibiting altered expression during heat stress or the recovery phase [26]. These finding laid a foundation for studying the biological functions of pal in P. ostreatus under heat stress
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