Alternating oxidase catalyzes the oxidation of panthenol and reduces molecular oxygen to water at the same time. This prevents the formati
Alternating oxidase catalyzes the oxidation of panthenol and reduces molecular oxygen to water at the same time. This prevents the formation of o- due to the electron leakage of mitochondrial complex Roman numeral 3 (Moller, 200 1 year). Therefore, mitochondrial alternating oxidase can be regarded as a component of antioxidant system.
The expression level of alternative oxidase genes in plants has been shown to increase under the influence of various unfavorable factors, including extreme temperature (Searle et al., 20 1 1).
In wheat, two genes encoding alternative oxidases, WAOX 1a and WAOX 1c, have been identified, and the number of transcripts increased during cold training (Tuohai et al., 2002; Mizuno et al., 2008). With the accumulation of transcripts, the ability of the enzyme to transfer electrons increases, especially in winter wheat which is more frost-resistant than spring wheat (Mizuno et al., 2008). The results of transformation of Arabidopsis plants with wheat WAOX 1a gene support the hypothesis of antioxidant function of alternative oxidase at low temperature (Su Ji et al., 2006).
Low molecular weight antioxidant
Ascorbic acid is the most common low molecular weight antioxidant in plants (Kaul and nayar, 20 14). There is evidence that its content in plants increases during cold adaptation (hardening). Therefore, an increase in the content of reduced ascorbic acid was found in Scotch pine (Wlngsle et al., 1999), rye (Galiba, 20 13) and barley (Raduk et al., 2009). However, the positive correlation between ascorbic acid content and plant cold resistance is not always obvious. For example, the ascorbic acid content of strawberry varieties with strong cold resistance is lower than that of strawberry varieties with weak cold resistance (Luo et al., 20 1 1). Obviously, despite the universality of ascorbic acid as the most common antioxidant, it is possible for it to participate in the characteristics of species and varieties in the adaptation process.
Glutathione (L-γ-glutamyl-cysteine-glycine), as an antioxidant containing sulfhydryl groups, can directly interact with hydrogen peroxide and also participate in the reduction of dehydroascorbic acid (foyle and Noctol, 2009). The permanent removal of hydrogen peroxide requires the levels of reduced ascorbic acid and glutathione to be high enough. Therefore, several enzymes work together in the so-called ascorbic acid-glutathione cycle to provide hydrogen peroxide neutralization. This cycle includes interrelated redox reactions involving ascorbic acid, glutathione and reduced coenzyme II (Asada Press, 1999). There is evidence that the content of reduced glutathione increases during the cold adaptation of Scottish pine (Wensler et al. 1999), strawberry (Luo et al., 20 1 1); (Raduk et al., 2009), and many other species of plants. The content values of glutathione and ascorbic acid are generally considered to be interdependent (Galiba, 20 13).
Flavonoids are polyphenol antioxidants widely distributed in the plant kingdom (Khlestkina, 20 13 years), all of which participate in the antioxidant protection of cells to some extent. According to the generally accepted view, the antioxidant properties of flavonoids are due to their ability to capture free radicals and chelate metal ions involved in the process of free radicals (Es-Safi et al., 2007).
Cold and other stressors have significant effects on flavonoid content in plant tissues. For example, in maize plants exposed to cold (10 degrees Celsius), the gene expression of phenylalanine ammonia-lyase and other enzymes involved in flavonoid synthesis increased (Christie et al., 1994). Compared with non-resistant wheat seedlings, yellowed rye seedlings characterized by a certain level of constitutive frost resistance contain significantly higher amounts of anthocyanins (Kolupayev et al., 20 16 years). During cold training of frost-resistant wheat varieties, flavonoid content increased by 3 times, while non-resistant wheat varieties increased by 1.5 times (Olenichenko et al., 2008). In the seedlings of different triticale varieties, the relationship between frost resistance (relative to hardened background) and anthocyanin content was found (Kolupayev et al., 2020a).
Multifunctional low molecular weight compound
Soluble carbohydrates are a group of low molecular weight organic compounds, and their contribution to freezing resistance and cold resistance has been studied for decades. Moderate low temperature, which usually leads to hardening effect, can lead to sugar accumulation in various plants (Kochi et al., 20 1 1 year).