Transcriptome Analyses in a Selected Gene Set Indicate Alternative Oxidase (AOX) and Early Enhanced Fermentation as Critical for Salinity Tolerance in Rice

Abstract

Plants subjected to stress need to respond rapidly and efficiently to acclimatize and survive. In this paper, we investigated a selected gene set potentially involved in early cell reprogramming in two rice genotypes with contrasting salinity tolerance (Pokkali tolerant and IR29 susceptible) in order to advance knowledge of early molecular mechanisms of rice in dealing with salt stress. Selected genes were evaluated in available transcriptomic data over a short period of 24 h and involved enzymes that avoid ROS formation (AOX, UCP and PTOX), impact ATP production (PFK, ADH and COX) or relate to the antioxidant system. Higher transcript accumulation of AOX (ROS balancing), PFK and ADH (alcohol fermentation) was detected in the tolerant genotype, while the sensitive genotype revealed higher UCP and PTOX transcript levels, indicating a predominant role for early transcription of AOX and fermentation in conferring salt stress tolerance to rice. Antioxidant gene analyses supported higher oxidative stress in IR29, with transcript increases of cytosolic CAT and SOD from all cell compartments (cytoplasm, peroxisome, chloroplast and mitochondria). In contrast, Pokkali increased mRNA levels from the AsA-GSH cycle as cytosolic/mitochondrial DHAR was involved in ascorbate recovery. In addition, these responses occurred from 2 h in IR29 and 10 h in Pokkali, indicating early but ineffective antioxidant activity in the susceptible genotype. Overall, our data suggest that AOX and ADH can play a critical role during early cell reprogramming for improving salt stress tolerance by efficiently controlling ROS formation in mitochondria. We discuss our results in relation to gene engineering and editing approaches to develop salinity-tolerant crops.

Polymorphisms in alternative oxidase genes from ecotypes of Arabidopsis and rice revealed an environment‐induced linkage to altitude and rainfall

“…Rice is adapted to flooded soil and consequent hypoxia; however, it causes an imbalance of electrons, which interferes with its metabolism (Das & Uchimiya, 2002). The deviation of electron excess performed by AOX contributes to the maintenance of rice homeostasis under these conditions (Aziz et al, 2022; Wanniarachchi et al, 2018).…”

In Vitro Fermentation Characteristics of Pine Needles (Pinus densiflora) as Feed Additive

“…On the other hand, the antioxidant effect using LPS-treated PAE cells was strong in CON and SCF fermented for 48 h, which was similar to the ABTS result. The exposure of cells to LPS causes severe stress, resulting in cell damage, resulting in an imbalance between ROS production and elimination [58,59]. Plants have antioxidant systems such as ascorbate and glutathione metabolites, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) enzymes to minimize the effects of ROS damage [58,60].…”

“…The exposure of cells to LPS causes severe stress, resulting in cell damage, resulting in an imbalance between ROS production and elimination [58,59]. Plants have antioxidant systems such as ascorbate and glutathione metabolites, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) enzymes to minimize the effects of ROS damage [58,60]. In addition, microorganisms such as LAB and yeast are known to inhibit peroxidation by increasing the activity of SOD, CAT, and GPx [61,62].…”

Effect of Salt Stress on the Activity, Expression, and Promoter Methylation of Succinate Dehydrogenase and Succinic Semialdehyde Dehydrogenase in Maize (Zea mays L.) Leaves

“…This mechanism plays an important role in cell bioenergetics in stress conditions ( Figure 4 ). The important role of alternative oxidase in the maintenance of metabolism and in prevention of ROS formation in the conditions of salt stress has been demonstrated in several studies [ 34 , 35 , 36 , 37 , 38 ]. The involvement of alternative oxidase in “salt respiration” can explain the observed lower rate of nitric oxide (NO) production in salt stressed plants [ 39 ], which differs from the hypoxic stress when NO production increases [ 40 ].…”