Abstract
Plant defense against pathogens and abiotic stresses is regulated differentially by communicating signal transduction pathways in which nitric oxide (NO) plays a key role. Here, we show the biological role of Arabidopsis thaliana wall-associated kinase (AtWAK) Like10 (AtWAKL10) that exhibits greater than a 100-fold change in transcript accumulation in response to the NO donor S-nitroso-L-cysteine (CysNO), identified from high throughput RNA-seq based transcriptome analysis. Loss of AtWAKL10 function showed a similar phenotype to wild type (WT) with, however, less branching. The growth of atwakl10 on media supplemented with oxidative or nitrosative stress resulted in differential results with improved growth following treatment with CysNO but reduced growth in response to S-nitrosoglutatione (GSNO) and methyl-viologen. Further, atwakl10 plants exhibited increased susceptibility to virulent Pseudomonas syringae pv tomato (Pst) DC3000 with a significant increase in pathogen growth and decrease in PR1 transcript accumulation compared to WT overtime. Similar results were found in response to Pst DC3000 avrB, resulting in increased cell death as shown by increased electrolyte leakage in atwakl10. Furthermore, atwakl10 also showed increased reactive oxygen species accumulation following Pst DC3000 avrB inoculation. Promoter analysis of AtWAKL10 showed transcription factor (TF) binding sites for biotic and abiotic stress-related TFs. Further investigation into the role of AtWAKL10 in abiotic stresses showed that following two weeks water-withholding drought condition most of the atwakl10 plants got wilted; however, the majority (60%) of these plants recovered following re-watering. In contrast, in response to salinity stress, atwakl10 showed reduced germination under 150 mM salt stress compared to WT, suggesting that NO-induced AtWAKL10 differentially regulates different abiotic stresses. Taken together, this study further elucidates the importance of NO-induced changes in gene expression and their role in plant biotic and abiotic stress tolerance.
Highlights
Nitric oxide (NO), diatomic molecule is a gaseous free radical known for its signaling role under stress condition (Delledonne et al, 1998)
Our results suggested that the loss-offunction mutant, atwakl10, showed significantly higher cotyledon development frequency (CDF) compared to wild type (WT) under CysNO-induced nitrosative stress, in case of growth in response to S-nitrosoglutatione (GSNO), there was no significant difference (Figs. 1B and 1C)
On MV media there was no significant difference in CDF among WT and atwakl10 plants (Fig. 1C)
Summary
Nitric oxide (NO), diatomic molecule is a gaseous free radical known for its signaling role under stress condition (Delledonne et al, 1998). Nitric oxide in the presence of oxygen form different important oxides like NO2 that may further react with cellular amines and thiols It can react with superoxide anion radical (O2-̇) producing such ions that later on cause significant damage to cell structure (Wendehenne et al, 2001). These molecules are called reactive nitrogen species (RNS). Contrary to well-studied ROS, little is known about the RNS and their roles in plants
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