Systematic identification and expression pattern analysis of the Aux/IAA and ARF gene families in moso bamboo (Phyllostachys edulis)

Auxin plays a central role in many aspects of plant growth and development. The auxin/indole-3-acetic acid (Aux/IAA) and auxin response transcription factor (ARF) genes are key components of plant auxin signaling. However, little is known about the Aux/IAA and ARF gene families in moso bamboo (Phyllostachys edulis). In this paper, we first identified 35 putative PeIAAs and 24 PeARFs in the moso bamboo genome. These genes were clustered into two major groups (A and B) and four groups (I-IV), respectively, based on phylogenetic analysis. Next, analyses of evolutionary patterns and divergence demonstrated that both the PeIAAs and PeARFs experienced a large-scale duplication event around 15 million years ago (MYA). The divergence times of the two gene families were 31 MYA between moso bamboo and rice, and 46 MYA between moso bamboo and maize. Furthermore, the expression profiling of PeIAA and PeARF genes in various tissues and developmental stages revealed tissue-specific expression. qRT-PCR analysis confirmed the differential expression patterns of selected PeIAA and PeARF genes. And then a comprehensive expression analysis of these genes was also performed under exogenous hormone treatment by qRT-PCR. Many PeIAAs and PeARFs showed differential expression in response to IAA treatment. Subcellular localization results show that PeIAA8 is a nuclear localization protein. Most importantly, we demonstrate that single moso bamboo ARF can interact with multiple Aux/IAA proteins and vice versa. Collectively, the detailed analyses presented here will help in understanding the roles of the PeIAA and PeARF gene families and contribute to further research on their biological functions during development in moso bamboo.