Abstract：Feruloyl transferase is one of the key enzymes responsible for transferring ferulic acid from ferulic acid CoA to arabinolxylan molecules, which plays a key role in the connection between arabinoxylan and lignin molecules. Therefore, ferulolyl transferase is closely related to the formation of anti-degradation barrier in plant cell wall. In this study, the cDNA sequence of Bra1 (PlantGDB No.: 5g14720) gene in Brachypodium distachyon was cloned by qRT-PCR technique, and the length of which was up to 1 369 base pairs. The open reading frame (ORF) of Bra1 gene encoded a deduced protein with 443 amino acid residues, with a theoretical molecular weight of 48.45 kD. The prokaryotic expression and mass spectrometry analyses further confirmed that the gene can encode the protein correctly, and the molecular weight was consistent with the theoretical value. Bioinformatics analysis indicated that the amino acid sequence of Bra1 protein contained a HXXXD domain and a DFGWG conserved domain that were unique to the BAHD acyltransferase family, as indicated that Bra1 protein was a member of BAHD acyltransferase family. The phylogenetic analysis of 89 BAHD acyltransferases in Brachypodium distachyon suggested that these acyltransferases could roughly be divided into four subfamilies, each of them containing several small groups, and the Bra1 protein (subfamily I) did not belong to the same subfamily as the other previously characterized BAHD acyltransferases (subfamily Ⅲ) whose functions were mainly related to the metabolism of p-coumalic acid (p-CA), and thus, Bra1 protein may be different in function from those BAHD acyltransferases. In addition, the expression profiles of 10 BAHD acyltransferase genes in the subfamily Ⅲ and the subfamily I which was far related to the subfamily Ⅲ were analyzed by the qRT-PCR, and the results showed that the Bra1 gene was with a higher and more stable expression compared with other genes, and furthermore the expression of Bra1 gene in the mature stem, leaf and spike were almost twice as high as that in young tissues, and its expression character was consistent with the accumulation of ferulic acid (FA) in Brachypodium distachyon suggesting that the Bra1 gene may be involved in regulating the cross-linked reaction mediated by ferulic acid in plant cell walls. This study provides important data for the identification of biological function of Bra1 gene as well as for the development and utilization of grass energy crops and the recycle utilization of crop straw biomass.
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