Prediction Of Clitoria Ternatea Antimicrobial Peptides Based On High-throughput Transcriptome Sequencing

Clitoria ternatea commonly known as butterfly pea,Iris herb and named after the flower like butterfly,has a wide range of medical value.In India's drug system,Clitoria ternatea is often used as an effective antidepressant,antimicrobial,antipyretic,and as a nerve supplement to enhance memory and the similar records can also be found in the United States and other tropical Asian countries.According to previous studies,the decoction of Clitoria ternatea root and flower has the effect of promoting menstrual and uterine contraction.Animal experiments have shown that flower and leaf extracts show antihyperglycemic effects in rats.These medicinal properties of Clitoria ternatea are directly related to the antimicrobial peptides in blue butterfly.In addition,the natural blue pigment in the Clitoria ternatea is a pure natural food dye that can be used to make cakes and tea drinksAntimicrobial peptides are small imolecular substances with anti-fungal,anti-viral And anti-bacterial effects,which are widely found in plants,animals and insects Antimicrobial peptides are typically rich in multiple cysteine residues that form disulfide compounds give AMPs impart complex chemical structures,as well as thermal and proteolytic stability.The stable cysteine structure could modify the backbone portions between cysteine residues so that it could be moved to intracelluar targets as a biological active peptides,for its stable cystine-stabilized structure could resist digestive enzymes,and other unstable physiological conditions.This could facilitate the development of AMPs based drugs and the transgenic strategies ofplant protection.Based on the arrangement and the number of cysteines,plant AMPs are classified into different families,including cyclotides,lipid-transfer proteins,defensins,snakins,hevein-like,thionins,and ?-hairpins.In this study,the transcriptome data of Clitoria ternatea was obtained by high-throughput sequencing.We used BinPacker sofeware to assemble the transcriptome of Clitoria ternatea,and obtained 167763 transcripts with an average length of 1541 bp,a N50 of 2221bp and a N90 of 765bp,from which we got 92471 unigenes.These unigenes were aligned to the Swiss-Prot,NR,Pfam,COG,KEGG databases by BLAST,ending up with 37778,57455,20613,33285,and 6366 genes with homologous sequences,respectively.Through the comparison to the COG database,the unigenes were divided into 25 different functional annotations,which involve the distribution of functional genes,such as transcription,replication,recombination and repair functions.Analysis of the KEGG metabolic pathway yielded 392 metabolic pathways.We identified the putative AMPs sequence in the Clitoria ternatea assembly transcripts by combining methods of sequence homology searching and the cysteine motif pattern searching.Finally,148 AMPs of six different families were obtained,which were 55 lipid-transfer protein,30 thionins,26a-hairpin structural proteins,15 snakins,14 cyclotides,8 plant defensins.Among them,cyclotides are a special class of AMPs whose mature sequences are closed at N-terminal to C-terminal.Six cysteine residues form three pairs of disulfide bonds,and three pairs of disulfide bonds form a cyclic cystine knot.Seven matured sequences out of the 14 putative cyclotides(CYC01-CYC14)in the Clitoria ternatea are consistent with those found by other researchers.The CYC09 and CYC 13 sequences are identical to cT12 sequence,and the CYC01,CYC07,CYC08 and CYC 10 sequences are identical to the cT3 sequence,and the CYC14 sequence is identical to the cT19 sequence.In this study,the de novo assembly and functional annotations of the transcriptome of Clitoria ternatea flower were performed without a reference genome,and the antimicrobial peptide sequences in the transcriptome of Clitoria ternatea were predicted based on this transcriptome.Our study might provide clues for related drug development.