Developmental, hormone- and stress-modulated expression profiles of four members of the Arabidopsis copper amine oxidase gene family.

Eight genes encoding copper amine oxidases (AtCuAOs) have been identified in the Arabidopsis thaliana genome. Here, a comprehensive investigation of the expression pattern of four genes encoding AtCuAOs from two different phylogenetic subfamilies, namely the two peroxisomal AtCuAOα2 (At1g31690) and AtCuAOα3 (At1g31710) and the two apoplastic AtCuAOγ1 (At1g62810) and AtCuAOγ2 (At3g43670) has been carried out by both RT-qPCR and promoter::GFP-β-glucuronidase fusion. Analysis were performed at different developmental stages, under stress conditions (dehydration and wounding) as well as after hormone (abscisic acid, salicylic acid, methyl jasmonate and indoleacetic acid) and polyamine (putrescine and spermidine) treatments. AtCuAOα2/α3 and AtCuAOγ1/γ2 are expressed in hydathodes (α2, γ1, γ2) and vascular tissues (α3, γ1, γ2) as well as in differentiating tissues (α2, γ1, γ2). RT-qPCR analysis and GUS-staining revealed that dehydration and wounding as well as indoleacetic acid and putrescine treatments induced all the four analyzed AtCuAOs. The expression of AtCuAOα2/3 and AtCuAOγ1/2 in tissues and structures involved in water supply and water loss such as vascular tissues and hydathodes suggests a role in water balance homeostasis and immune system. Moreover, their expression in zones where an auxin maximum has been observed support a role in tissue and xylem maturation events.