Characteristics and phylogeny of the cyclic peptide gene family in Amanita pallidorosea: based on transcriptome analysis

Abstract:

[Background] Amanita pallidorosea is a lethal Amanita species in the sect. Phalloideae, containing abundant cyclic peptide toxins. However, its gene family (MSDIN) encoding the toxic peptides and related peptides needs further systematic study. [Objective] This paper aims to explore the diversity, conservation, and phylogeny of genes encoding toxic peptides and related peptides in A. pallidorosea. [Methods] Illumina HiSeq 2000 platform was used for the transcriptome sequencing of A. pallidorosea and TBLASTn for searching MSDIN genes. Specific primers were designed for PCR verification. The types and sequence composition of MSDIN genes were analyzed with the bioinformatics method, and the phylogenetic tree was reconstructed to clarify the evolution. [Results] A total of 60 genes encoding cyclic peptides were obtained from the transcriptome data, which encoded 32 cyclic peptides as verified by PCR, including α-amanitin, β-amanitin, and phallacidin. Among them, 8 new cyclic peptide sequences were reported for the first time in this study. Molecular phylogenetic analysis showed that all cyclic peptides were classified into three clades: amatoxins, phallotoxins, and cyclic peptides of unknown function. Seven potential and new toxic peptides were predicted according to phylogenetic analysis and conserved sequences. [Conclusion] A. pallidorosea boasts abundant cyclic peptides. Transcriptome sequencing can help discover new resources of cyclic peptides in A. pallidorosea, which lays the foundation for the overall structure analysis.