Cloning and expression analysis of an Actin gene fragment from the halophyte Atriplex canescens

The Actin gene is one of the most commonly used reference genes for studying functional gene expression patterns. In this study, total RNA was extracted from the leaves of 4-week-old Atriplex canescens seedlings, and an Actin gene fragment was obtained by reverse transcription-polymerase chain reaction (RT-PCR) and linked into pMD19-T vector using primers designed based on conserved Actin gene sequences from similar plant species. The positive clones identified by PCR were sequenced, and the results showed that the Actin gene fragment of A. canescens contains 598 bp encoding 198 amino acids. Homology comparison with Actin genes from other higher plants in GenBank indicate that this gene fragment shared more than 84% nucleotide sequence similarity and 94% amino acids sequence homology with other plants, suggesting strong conservation of this gene. Our results confirmed that the cloned gene was an Actin gene fragment, which we named as AcACT. Phylogenetic analysis showed a close relationship between AcACT and the Actin genes from Beta vulgaris and Suaeda glauca. Meanwhile, AcACT expression was constant in different tissues under salt treatment based on quantitative PCR analysis, which suggests that AcACT can be used as a reference gene for studying the expression patterns of salt tolerance-related genes of A. canescens.