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Backgrounds: Pomegranate (Punica granatum L.) is an important commercial fruit tree, with moderate tolerance to salinity. The balance of Cl− and other anions in pomegranate tissues are affected by salinity, however, the accumulation patterns of anions are poorly understood. The chloride channel (CLC) gene family is involved in conducting Cl−, NO3−, HCO3− and I−, but its characteristics have not been reported on pomegranate. Results: In this study, we identified seven PgCLC genes, consisting of four antiporters and three channels, based on the presence of the gating glutamate (E) and the proton glutamate (E). Phylogenetic analysis revealed that seven PgCLCs were divided into two clades, with clade I containing the typical conserved regions GxGIPE (I), GKxGPxxH (II) and PxxGxLF (III), whereas clade II not. Multiple sequence alignment revealed that PgCLC-B had a P [proline, Pro] residue in region I, which was suspected to be a NO3−/H+ exchanger, while PgCLC-C1, PgCLC-C2, PgCLC-D and PgCLC-G contained a S [serine, Ser] residue, with a high affinity to Cl−. We determined the content of Cl−, NO3−, H2PO4−, and SO42− in pomegranate tissues after 18 days of salt treatments (0, 100, 200 and 300 mM NaCl). Compared with control, the Cl− content increased sharply in pomegranate tissues. Salinity inhibited the uptake of NO3− and SO42−, but accelerated H2PO4− uptake. The results of real-time reverse transcription PCR (qRT-PCR) revealed that PgCLC genes had tissue-specific expression patterns. The high expression levels of three antiporters PgCLC-C1, PgCLC-C2 and PgCLC-D in leaves might be contributed to sequestrating Cl− into the vacuoles. However, the low expression levels of PgCLCs in roots might be associated with the exclusion of Cl− from root cells. Also, the up-regulated PgCLC-B in leaves indicated that more NO3− was transported into leaves to mitigate the nitrogen deficiency. Conclusions: Our findings suggested that the PgCLC genes played important roles in balancing of Cl− and NO3− in pomegranate tissues under salt stress. This study established a theoretical foundation for the further functional characterization of the CLC genes in pomegranate. [ABSTRACT FROM AUTHOR]

Gene duplication is the major resource with which to generate new genes, which provide raw material for novel functions evolution. Thus, to elucidate the gene family evolution after duplication events is of vital importance. Anthocyanin O-methyltransferases (AOMTs) have been recognized as being capable of anthocyanin methylation, which increases anthocyanin diversity and stability and improves the protection of plants from environmental stress. Meanwhile, no detailed identification or genome-wide analysis of the AOMT gene family members in pomegranate (Punicagranatum) have been reported. Three published pomegranate genome sequences offer substantial resources with which to explore gene evolution based on the whole genome. Altogether, 58 identified OMTs from pomegranate and five other species were divided into the AOMT group and the OMT group, according to their phylogenetic tree and AOMTs derived from OMTs. AOMTs in the same subclade have a similar gene structure and protein conserved motifs. The PgAOMT family evolved and expanded primarily via whole-genome duplication (WGD) and tandem duplication. PgAOMTs expression pattern in peel and aril development by qRT-PCR verification indicated that PgAOMTs had tissue-specific patterns. The main fates of AOMTs were neo- or non-functionalization after duplication events. High expression genes of PgOMT04 and PgOMT09 were speculated to contribute to "Taishanhong" pomegranate's bright red peel color. Finally, we integrated the above analysis in order to infer the evolutionary scenario of AOMT family. [ABSTRACT FROM AUTHOR]

Most cultivated lands are suffering from soil salinization, which is a global problem affecting agricultural development and economy. High NaCl concentrations in the soil result in the accumulation of toxic Cl− and Na+ in plants. Na+/H+ antiporter (NHX) can regulate Na+ compartmentalization or efflux to reduce Na+ toxicity. This study aims to identify the NHX genes in pomegranate (Punica granatum L.) from the genome sequences and investigate their expression patterns under different concentrations of NaCl stress. In this study, we used the sequences of PgNHXs to analyze the physicochemical properties, phylogenetic evolution, conserved motifs, gene structures, cis-acting elements, protein tertiary structure and expression pattern. A total of 10 PgNHX genes were identified, and divided into three clades. Conserved motifs and gene structures showed that most of them had an amiloride-binding site (FFI/LY/FLLPPI), except for the members of clade III. There were multiple cis-acting elements involved in abiotic stress in PgNHX genes. Additionally, protein-protein interaction network analysis suggested that PgNHXs might play crucial roles in keeping a balance of Na+ in cells. The qRT-PCR analysis suggested that PgNHXs had tissue-specific expressional patterns under salt stress. Overall, our findings indicated that the PgNHXs could play significant roles in response to salt stress. The theoretical foundation was established in the present study for the further functional characterization of the NHX gene family in pomegranate. [ABSTRACT FROM AUTHOR]