Nitric oxide is important for sensing and survival under hypoxia in Arabidopsis

Abstract

Nitric oxide (NO) is a free radical molecule that plays an important role in hypoxic stress. We studied the impact of hypoxia-induced NO production on the expression of genes and production of metabolites involved in carbon, oxygen sensing, nitrogen, and antioxidant metabolism using wild type (WT), non-symbiotic haemoglobin-overexpressing (Hb+) and nitrate reductase double mutant (nia1,2) of Arabidopsis. Futher application of NO scavenger cPTIO was used to confirm NO role. We found that imposing hypoxia leads to the increaseof NO and reactive oxygen species (ROS) levels in WT, while the reduced levels of NO and higher levels of ROS were observed in roots of Hb+ and nia1,2 mutant. Expression of the genes encoding oxygen sensing and the enzymes involved in fermentative pathways, their activities and metabolite levels were highly induced in WT suggesting that NO plays a role in the induction of fermentation. Several genes and metabolites involved in the TCA cycle were also induced in WT in comparison to Hb+ and nia mutant line suggesting that NO can accelerate TCA cycle to regenerate reducing equivalents under hypoxia. Interestingly, we found that the genes and metabolites involved in the ascorbate-glutathione cycle were modulated by NO under hypoxia. The alternative oxidasegene (AOX1A) was induced under hypoxia in WTdue to increased levels of NO rather than ROS. Futher, we found that NO improves plant survival. Overall these findings suggest that NO is a major player in plant survival under hypoxia by modulating gene expression and metabolite levels of carbon, nitrogen, oxygen sensing and antioxidant metabolism.HighlightHypoxia-induced nitric oxide plays a central role in activation of genes and metabolites involved in fermentation, TCA cycle, nitrogen and antioxidant metabolism

RNA-Seq reveals novel genes and pathways associated with hypoxia duration and tolerance in tomato root

“…For normalization and estimation of P-values the TMM (trimmed means of M values 78 ) and the edger algorithm 79 were used respectively. The log fold change values are provided as calculated by the edgeR algorithm.…”

Trichoderma asperellumT42 induces local defense againstXanthomonas oryzaepv.oryzaeunder nitrate and ammonium nutrients in tobacco

“…1 Ammonium ions are readily available to plants in comparison to nitrate ions, but an excess amount cause toxic effects to plant. 1,6 However, plants prefer NO 3…”

“…Nitrogen plays a crucial role in plant development and disease management. [1][2][3][4][5][6] The primary issue of N scarcity in soil is due to its slow mineralization, leaching, and de-nitrication process. Accordingly, a lack of N availability to plants results in several physiological and morphological responses.…”

“…1,2 These defense mechanisms are associated with the involvement of PAMP or ETI (effector-triggered immunity), which reprograms different nuclear genes, 8,9 and thus N is required for enhancing plant immunity. 6 The PAMP defense response involving the rapid development of plant immunity in response to pathogen infections is referred to as the hypersensitive response (HR), which seems to appear aer avirulent pathogen and plant interactions. 10 A characteristic of this local HR is the rapid generation of reactive oxygen species (O 2 À and H 2 O 2 ) and nitric oxide (NO).…”

“…Moreover, the colonization of Trichoderma with plant roots activated different defense-related enzyme activities and regulation of PR pathogenesis gene. 6,12 Perhaps, the activation of these defense responses is due to the modulation of metabolites and defense genes involved in the resistance mechanism. 20,23 If Trichoderma initiates an enhanced N uptake efficiency 6 and NO accumulation, 12 it may be implicated in plant defense via HR-mediated cell death.…”