Thermostability of antioxidant enzymes in tissues of Scots pine in heat shock conditions

Samples of needles from the middle part of the crown and cambial zone scrapings, which includes cambium cells and nonlignified xylem cells from five stems of 15 years old Scots pine Pinus sylvestris L. trees from green moss-forb groups stands on sod-podzolic soil in Krasnoyarsk forest steppe were investigated. Thermal stability of the antioxidant enzymes: superoxide dismutase (SOD), peroxidase, catalase, glutathione reductase (GR); enzymes of carbohydrate and phenolic metabolism: amylase, invertase and phenylalanine ammonia-lyase (PAL) which are involved in providing the xylogenesis process; and markers of oxidative stress: peroxide hydrogen and malondialdehyde (MDA) were studied in the temperature interval 20–80 °C. It was found that the positive effect on the antioxidant enzymes activity mainly manifested up to 40 °C. As the temperature increases, antioxidant protection weakens. The mechanisms of oxidative stress in cambium zone and needles in condition of pyrogenic heat shock are distinguished due to different thermal stability of antioxidant enzymes in these tissues. The most sensitive to elevated temperatures was catalase both in cambium zone and needles. In the cambium zone, peroxidase and GR detect low resistance to high temperature, while SOD has a higher level of. In the needles on the contrary, peroxidase and GR exhibit high thermal stability, whereas SOD activity rapidly reduces at higher temperatures. Amylase, invertase and PAL exceed, according to the thermal stability of examined antioxidant enzymes, what allow quick restoration of carbohydrate and phenolic metabolism after pyrogenic heat shock to providing of xylogenesis process