Loss of GSNOR1 Function Leads to Compromised Auxin Signaling and Polar Auxin Transport

Abstract

Cross talk between phytohormones, nitric oxide (NO), and auxin has been implicated in the control of plant growth and development. Two recent reports indicate that NO promoted auxin signaling but inhibited auxin transport probably through S-nitrosylation. However, genetic evidence for the effect of S-nitrosylation on auxin physiology has been lacking. In this study, we used a genetic approach to understand the broader role of S-nitrosylation in auxin physiology in Arabidopsis. We compared auxin signaling and transport in Col-0 and gsnor1-3, a loss-of-function GSNOR1 mutant defective in protein de-nitrosylation. Our results showed that auxin signaling was impaired in the gsnor1-3 mutant as revealed by significantly reduced DR5-GUS/DR5-GFP accumulation and compromised degradation of AXR3NT-GUS, a useful reporter in interrogating auxin-mediated degradation of Aux/IAA by auxin receptors. In addition, polar auxin transport was compromised in gsnor1-3, which was correlated with universally reduced levels of PIN or GFP-PIN proteins in the roots of the mutant in a manner independent of transcription and 26S proteasome degradation. Our results suggest that S-nitrosylation and GSNOR1-mediated de-nitrosylation contribute to auxin physiology, and impaired auxin signaling and compromised auxin transport are responsible for the auxin-related morphological phenotypes displayed by the gsnor1-3 mutant.

Involvement of reactive oxygen species in lanthanum-induced inhibition of primary root growth

“…However, we also found that high concentrations of La result in remarkable cell death in PR tips. The meristematic cell division potential and stem cell niche activity, two main factors that affected root growth (Baluska et al , 2010; Liu et al , 2015), were markedly repressed and almost completely lost after 2 d of La treatment. Both the SHR / SCR pathway and the PLT pathway are involved in WOX5 -mediated QC identity (Aida et al , 2004; Blilou et al , 2005; Grieneisen et al , 2007; Galinha et al , 2007; Dinneny and Benfey, 2008; Ding and Friml, 2010; Zhao et al , 2014; Ji et al , 2015).…”

“…Five-day-old Arabidopsis seedlings were exposed to 150 μM La(NO 3 ) 3 for 2 d, and the root IAA content was quantified according to Gao et al (2014) and Liu et al (2015). Approximately 0.1 g (fresh weight) of roots was collected and immediately frozen in liquid nitrogen.…”

“…Root growth and development is a complex process modulated by a variety of phytohormones and signaling molecules, with auxin playing a central role (Wang et al , 2009). The maintenance of a normal auxin concentration and a steep auxin gradient in root tips is essential for this hormone to regulate stem cell differentiation, gravitropic responses, and lateral organ initiation (Laskowski et al , 2008; Shi et al , 2015). REEs inhibit PR growth and improve root hair and LR development, thereby modulating RSA.…”

The role of S-nitrosoglutathione reductase (GSNOR) in human disease and therapy

“…Interestingly, GSNOR itself is a cysteine rich protein that is S-nitrosated by GSNO, which in turn initiates a feedback loop that affects GSNOR expression (Guerra et al, 2016) and activity (Brown-Steinke et al, 2010). Although it is beyond the scope of this review, it should be noted that GSNOR dysregulation in plants can result in significant biotic and abiotic nitrosative events that affect growth, development, and survival (Leterrier et al, 2011; Shi et al, 2015; Yun et al, 2016). …”

Manganese Toxicity Inhibited Root Growth by Disrupting Auxin Biosynthesis and Transport in Arabidopsis

“…The AUXIN1/LIKE AUX1 (AUX1/LAX) family and the efflux carriers of the PINFORMED (PIN) family are required for optimal auxin distribution in root tips by regulating polar auxin transport (PAT) and are vital for modulating root growth and development (Laskowski et al, 2008; Yuan et al, 2013; Li et al, 2015; Shi et al, 2015). Mutations in these carrier genes result in dramatic defects in the root system architecture (RSA) (Laskowski et al, 2008; Shi et al, 2015). The Aux/IAA proteins are the negative regulators of auxin signaling (Ouellet et al, 2001).…”