Overexpression of β-cyanoalanine synthase of Prunus persica increases salt tolerance by modulating ROS metabolism and ion homeostasis

Abstract

The β-cyanoalanine synthase (β-CAS) pathway is a principal route for cyanide detoxification in plants. Recent studies suggested that β-CAS plays a pivotal role in plant stress response. However, little is known about the function and the underlying physiological mechanism of β-CAS under salt stress in perennial trees. Here we report the identification and functional characterization of PpCAS1 isolated from peach (Prunus persica). Transcripts of PpCAS1 were dramatically induced by salt and dehydration stress. Ectopic overexpression of PpCAS1 in Nicotiana benthamiana enhanced salinity tolerance, whereas down-regulation of PpCAS1 in P. persica through virus-induced gene silencing led to elevated salt sensitivity. The PpCAS1-overexpressing lines accumulated less reactive oxygen species (ROS) than the controls due to higher activities of antioxidant enzymes and expression levels of related genes. Moreover, the overexpression lines contained lower levels of Na+, higher levels of K+, thus lower Na+ : K+ ratios than the controls. When PpCAS1 was silenced, the levels of ROS and Na+ : K+ ratio were changed in an opposite manner. Additionally, the transcripts of genes involved in salt overly sensitive signaling pathway were significantly up-regulated in PpCAS1-overexpressing tobacco lines, but down-regulated in PpCAS1-silenced peach plants, compared to the corresponding controls. Altogether, our results demonstrate that PpCAS1 positively regulates salt tolerance in peach plants through the modulation of ROS and ion homeostasis.