ITN1, a novel gene encoding an ankyrin‐repeat protein that affects the ABA‐mediated production of reactive oxygen species and is involved in salt‐stress tolerance in Arabidopsis thaliana

Abstract

SummarySalt stress and abscisic acid (ABA) induce accumulation of reactive oxygen species (ROS) in plant cells. ROS not only act as second messengers for the activation of salt-stress responses, but also have deleterious effects on plant growth due to their cytotoxicity. Therefore, the timing and degree of activation of ROS-producing or ROS-scavenging enzymes must be tightly regulated under salt-stress conditions. We identified a novel locus of Arabidopsis, designated itn1 (increased tolerance to NaCl1), whose disruption leads to increased salt-stress tolerance in vegetative tissues. ITN1 encodes a transmembrane protein with an ankyrin-repeat motif that has been implicated in diverse cellular processes such as signal transduction. Comparative microarray analysis between wild-type and the itn1 mutant revealed that induction of genes encoding the ROS-producing NADPH oxidases (RBOHC and RBOHD) under salt-stress conditions was suppressed in the mutant. This suppression was accompanied by a corresponding reduction in ROS accumulation. The ABA-induced expression of RBOHC and RBOHD was also suppressed in the mutant, as was the case for RD29A, an ABA-inducible marker gene. However, the ABA-induced expression of another marker gene, RD22, was not impaired in the mutant. These results suggest that the itn1 mutation partially impairs ABA signaling pathways, possibly leading to the reduction in ROS accumulation under salt-stress conditions. We discuss the possible mechanisms underlying the salt-tolerant phenotype of the itn1 mutant.

The Ankyrin-Repeat Transmembrane Protein BDA1 Functions Downstream of the Receptor-Like Protein SNC2 to Regulate Plant Immunity

“…Among these proteins, only ACD6 and ITN1 have previously been characterized. ACD6 was shown to function as a positive regulator of SA signaling in local defense responses (Lu et al, 2003), whereas ITN1 is involved in salt stress tolerance (Sakamoto et al, 2008). How ACD6 and ITN1 are regulated is unknown.…”

Distribution of rutin in fava d'anta (Dimorphandra mollis) seedlings under stress

“…These defense systems protect plants from the oxidative damage caused by generated reactive oxygen species. Salt and drought stress are well known to generate reactive oxygen species in plant cells (Sakurai et al 2007;Yazici et al 2007;Sakamoto et al 2008). Flavonoids, such as rutin and quercetin, are among the compounds protecting plants from cell damage during biotic and abiotic stresses (Treutter 2006;Pourcel et al 2007).…”

Expression of Bruguiera gymnorhiza BgARP1 enhances salt tolerance in transgenic Arabidopsis plants

“…High-salt stress is known to enhance gene expression and protein accumulation of several PR-5 proteins, including osmotin in tobacco (Singh et al 1987). It was recently shown that disruption of ITN1, an ankyrin-repeat protein in Arabidopsis that has no sequence similarity to BgARP1, increases salt tolerance (Sakamoto et al 2008). It was suggested that reduced expression of NADPH oxidase genes (RBOHC and RBOHD) in the int1 mutant may be responsible for the salt-tolerant phenotype (Sakamoto et al 2008).…”

“…It was recently shown that disruption of ITN1, an ankyrin-repeat protein in Arabidopsis that has no sequence similarity to BgARP1, increases salt tolerance (Sakamoto et al 2008). It was suggested that reduced expression of NADPH oxidase genes (RBOHC and RBOHD) in the int1 mutant may be responsible for the salt-tolerant phenotype (Sakamoto et al 2008). Amplification of TUB5 was used as an internal control to normalize all data.…”