http://biol.unt.edu/~rmittler/Papers/Reactive%20oxygen%20gene%20network%20of%20plants.pdf

Reactive oxygen gene network of plants

Reactive oxygen species (ROS) are produced as a normal product of plant cellular metabolism. Various environmental stresses lead to excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, they are well-described second messengers in a variety of cellular processes, including conferment of tolerance to various environmental stresses. Whether ROS would serve as signaling molecules or could cause oxidative damage to the tissues depends on the delicate equilibrium between ROS production, and their scavenging. Efficient scavenging of ROS produced during various environmental stresses requires the action of several nonenzymatic as well as enzymatic antioxidants present in the tissues. In this paper, we describe the generation, sites of production and role of ROS as messenger molecules as well as inducers of oxidative damage. Further, the antioxidative defense mechanisms operating in the cells for scavenging of ROS overproduced under various stressful conditions of the environment have been discussed in detail.

https://downloads.hindawi.com/archive/2012/217037.pdf

Reactive Oxygen Species, Oxidative Damage, and Antioxidative Defense Mechanism in Plants under Stressful Conditions

The production of reactive oxygen species (ROS), via consumption of oxygen in a so-called oxidative burst, is one of the earliest cellular responses following successful pathogen recognition. Apoplastic generation of superoxide (O2−), or its dismutation product hydrogen peroxide (H2O2), has been

Reactive Oxygen Species Signaling in Response to Pathogens

The OsNAC6 gene is a member of the NAC transcription factor gene family in rice. Expression of OsNAC6 is induced by abiotic stresses, including cold, drought and high salinity. OsNAC6 gene expression is also induced by wounding and blast disease. A transactivation assay using a yeast system demonstrated that OsNAC6 functions as a transcriptional activator, and transient localization studies with OsNAC6-sGFP fusion protein revealed its nuclear localization. Transgenic rice plants over-expressing OsNAC6 constitutively exhibited growth retardation and low reproductive yields. These transgenic rice plants showed an improved tolerance to dehydration and high-salt stresses, and also exhibited increased tolerance to blast disease. By utilizing stress-inducible promoters, such as the OsNAC6 promoter, it is hoped that stress-inducible over-expression of OsNAC6 in rice can improve stress tolerance by suppressing the negative effects of OsNAC6 on growth under normal growth conditions. The results of microarray analysis revealed that many genes that are inducible by abiotic and biotic stresses were upregulated in rice plants over-expressing OsNAC6. A transient transactivation assay showed that OsNAC6 activates the expression of at least two genes, including a gene encoding peroxidase. Collectively, these results indicate that OsNAC6 functions as a transcriptional activator in response to abiotic and biotic stresses in plants. We conclude that OsNAC6 may serve as a useful biotechnological tool for the improvement of stress tolerance in various kinds of plants.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2007.03168.x

Functional analysis of a NAC-type transcription factor OsNAC6 involved in abiotic and biotic stress-responsive gene expression in rice

Plant peroxidases (class III peroxidases) are present in all land plants. They are members of a large multigenic family. Probably due to this high number of isoforms, and to a very heterogeneous regulation of their expression, plant peroxidases are involved in a broad range of physiological processes all along the plant life cycle. Due to two possible catalytic cycles, peroxidative and hydroxylic, peroxidases can generate reactive oxygen species (ROS) (•OH, HOO•), polymerise cell wall compounds, and regulate H2O2 levels. By modulating their activity and expression following internal and external stimuli, peroxidases are prevalent at every stage of plant growth, including the demands that the plant meets in stressful conditions. These multifunctional enzymes can build a rigid wall or produce ROS to make it more flexible; they can prevent biological and chemical attacks by raising physical barriers or by counterattacking with a large production of ROS; they can be involved in a more peaceful symbiosis. They are finally present from the first hours of a plant’s life until its last moments. Although some functions look paradoxical, the whole process is probably regulated by a fine-tuning that has yet to be elucidated. This review will discuss the factors that can influence this delicate balance.

/pdf/peroxidases-have-more-functions-than-a-swiss-army-knife-49s5dfpkwk.pdf

Peroxidases have more functions than a Swiss army knife

3Core Research for Evolutional Science and Technology (CREST), Chiyoda-ku, Tokyo, 101-0062 Japan ; Class III plant peroxidase (POX), a plant-specific oxidoreductase, is one of the many types of peroxidases that are widely distributed in animals, plants and microorganisms. POXs exist as isoenzymes in individual plant species, and each isoenzyme has variable amino acid sequences and shows diverse expression profiles, suggesting their involvement in various physiological processes. Indeed, studies have provided evidence that POXs participate in lignification, suberization, auxin catabolism, wound healing and defense against pathogen infection. Little, however, is known about the signal transduction for inducing expression of the pox genes. Recent studies have provided information on the regulatory mechanisms of wound- and pathogen-induced expression of some pox genes. These studies suggest that pox genes are induced via different signal transduction pathways from those of other known defense-related genes.

/pdf/a-large-family-of-class-iii-plant-peroxidases-1plxqcbkk0.pdf

A large family of class III plant peroxidases.

Class III plant peroxidases are believed to function in diverse physiological processes including disease resistance and wound response, but predicted low substrate specificities and the presence of 70 or more isoforms have made it difficult to define a specific physiological function(s) for each gene. To select pathogen-responsive POX genes, we analyzed the expression profiles of 22 rice POX genes after infection with rice blast fungus. The expression of 10 POX genes among the 22 genes was induced after fungal inoculation in both compatible and incompatible hosts. Seven of the 10 POX genes were expressed at higher levels in the incompatible host than in the compatible host 6-24 h after inoculation by which time no fungus-induced lesions have appeared. Organ-specific expression and stress-induced expression by wounding and treatment with probenazole, an agrichemical against blast fungus, jasmonic acid, salicylic acid and 1-aminocyclopropane-1-carboxylate, a precursor of ethylene, indicated that rice POXs have individual characteristics and can be classified into several types. A comparison of the amino acid sequences of POXs showed that multiple isoforms with a high sequence similarity respond to stress in different or similar ways. Such redundant responses of POX genes may guarantee POX activities that are necessary for self-defense in plant tissues against environmental stresses including pathogen infection.

/pdf/ten-rice-peroxidases-redundantly-respond-to-multiple-4bg24xrg02.pdf

Ten Rice Peroxidases Redundantly Respond to Multiple Stresses Including Infection with Rice Blast Fungus

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2800%2901409-5

Diverse expression profiles of 21 rice peroxidase genes.

In Tobacco mosaic virus (TMV)-infected tobacco plants carrying the N resistance gene, a hypersensitive reaction or response (HR) occurs to enclose the virus in the infected tissue. Although a contribution of peroxidases to the resistance has been proposed, no evidence has been presented that tobacco peroxidase genes respond to HR. Here, we describe the HR-induced expression of a tobacco peroxidase gene (tpoxC1) whose induction kinetics were slightly different from those of acidic and basic tobacco pathogenesis-related (PR) protein genes. Interestingly, tpoxC1 was insensitive to the inducers of PR genes such as salicylic acid, methyl jasmonate, and ethephon. Spermine activated tpoxC1 gene expression at a low level and both acidic and basic PR gene expression at a considerably higher level. These results indicate that the induced expression of tpoxC1 is regulated differently from that of classical tobacco PR genes in the N gene-mediated self-defense system in tobacco plants.

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/MPMI.2000.13.2.210

An HR-induced tobacco peroxidase gene is responsive to spermine, but not to salicylate, methyl jasmonate, and ethephon.

http://directory.umm.ac.id/Data%20Elmu/jurnal/P/PlantScience/PlantScience_Elsevier/Vol155.Issue1.2000/5339.pdf

Susumu Hiraga

Papers

A large family of class III plant peroxidases.

Ten Rice Peroxidases Redundantly Respond to Multiple Stresses Including Infection with Rice Blast Fungus

Diverse expression profiles of 21 rice peroxidase genes.

An HR-induced tobacco peroxidase gene is responsive to spermine, but not to salicylate, methyl jasmonate, and ethephon.

Xylem-specific expression of wound-inducible rice peroxidase genes in transgenic plants.