Identification and expression analysis of MATE genes involved in flavonoid transport in blueberry plants.

Hongdi Liu,Yunlong Ding,Limin Kang,Haiyue Sun,Yuzhuo Gai,Yushan Liu,Jinman Geng,Yadong Li,Meixue Zhou,Li Chen

doi:10.1371/journal.pone.0118578

Hongdi Liu, Yunlong Ding + Show 8 more

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https://doi.org/10.1371/journal.pone.0118578

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Journal: PloS one	Publication Date: Mar 17, 2015
Citations: 54	License type: CC BY 4.0

Affiliation: Jilin Agricultural University

Abstract

Multidrug and toxic compound extrusion (MATE) proteins are the most recently identified family of multidrug transporters. In plants, this family is remarkably large compared to the human and bacteria counterpart, highlighting the importance of MATE proteins in this kingdom. Here 33 Unigenes annotated as MATE transporters were found in the blueberry fruit transcriptome, of which eight full-length cDNA sequences were identified and cloned. These proteins are composed of 477–517 residues, with molecular masses ~54 kDa, and theoretical isoelectric points from 5.35 to 8.41. Bioinformatics analysis predicted 10–12 putative transmembrane segments for VcMATEs, and localization to the plasma membrane without an N-terminal signal peptide. All blueberry MATE proteins shared 32.1–84.4% identity, among which VcMATE2, VcMATE3, VcMATE5, VcMATE7, VcMATE8, and VcMATE9 were more similar to the MATE-type flavonoid transporters. Phylogenetic analysis showed VcMATE2, VcMATE3, VcMATE5, VcMATE7, VcMATE8 and VcMATE9 clustered with MATE-type flavonoid transporters, indicating that they might be involved in flavonoid transport. VcMATE1 and VcMATE4 may be involved in the transport of secondary metabolites, the detoxification of xenobiotics, or the export of toxic cations. Real-time quantitative PCR demonstrated that the expression profile of the eight VcMATE genes varied spatially and temporally. Analysis of expression and anthocyanin accumulation indicated that there were some correlation between the expression profile and the accumulation of anthocyanins. These results showed VcMATEs might be involved in diverse physiological functions, and anthocyanins across the membranes might be mutually maintained by MATE-type flavonoid transporters and other mechanisms. This study will enrich the MATE-based transport mechanisms of secondary metabolite, and provide a new biotechonology strategy to develop better nutritional blueberry cultivars.

Highlights

Plants produce a large number of secondary metabolites that appear to have little function in their growth and development, but play important roles in reproduction and environmental adaptation
The complete of blueberry fruit transcriptome was sequenced using the Illumina RNA-Seq method, providing an opportunity for identification of candidate Multidrug and toxic compound extrusion (MATE) transporters related to secondary metabolism. 64,312,746 raw reads longer than 75 bp were generated and made available in the Sequence Read Archive at the NCBI with accession number SRA046311
These relatively short reads can be effectively assembled, and a total of 34,464 All-unigenes with an average length of 735 bp were generated by de novo assembly. 8,193 differentially expressed genes (DEGs) between the exocarp and sarcocarp were categorized by molecular function, among which 516 DEGs were shown to be associated with transporter activity

Summary

Introduction

Plants produce a large number of secondary metabolites that appear to have little function in their growth and development, but play important roles in reproduction and environmental adaptation. Secondary products are classified into three major groups: alkaloids, terpenoids, and phenolic compounds [1]. Flavonoids belong to a group of phenolic compounds and constitute one of the largest classes of secondary metabolites possessing a common three-ring chemical structure (C6–C3–C6). Predominant flavonoids forms include anthocyanins, proanthocyanidins (PAs, condensed tannins), flavonols, flavones, and flavanols. These compounds are widely distributed in different amounts according to the plant species, organ, developmental stage, and growth conditions [2]. Anthocyanins have been demonstrated to give rise to the red, blue, and purple colors of many ripe fruits, vegetables, flowers, and other plant tissues or products [5], which attract frugivores and pollinators for seed dissemination and fertilization [6]. PAs are thought to contribute to disease defense, stress resistance, and seed dormancy [8,9]

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