Effect of sucrose and glucose on oxidative modification of proteins upon heat stress in Arabidopsis thaliana cat2cat3 knockout mutant

Abstract

High temperature negatively affects the plants. In particular, under the heat stress he production of reactive oxygen species increases in the plant cell. It leads to the development of oxidative stress. The formation of carbonyl groups in proteins is a marker of oxidative damage of plant cells. Plants have a defense system that consists of soluble carbohydrates such as sucrose and glucose and antioxidant enzymes, including catalase. Carbohydrates have protective mechanisms and can activate different signaling pathways with following changes in gene expression. Despite the data available, information on the effects of sucrose and glucose on the oxidative modification of proteins under heat stress is insufficient. The aim of our work was to study the role of sucrose and glucose for the carbonyl groups content in cat2cat3 knockout plants of A. thaliana under heat stress. We used 7-week-old Arabidopsis thaliana plants of wild-type and knockout cat2cat3 line, which lacks the expression of two catalase genes – cat2 and cat3. Plants were grown under 16-hour light day at a temperature of + 20°C and an illumination of 2.5 kL. Heat treatment was performed on a water bath in glass flasks with 15-20 leaves which were incubated in 1 mm potassium phosphate buffer without carbohydrates and with addition of sucrose or glucose (1% final concentration) during 2 and 4 hours at the +37°C and +44° C. The content of carbonyl groups and total protein was determined photometrically. It has been shown that intact knockout cat2cat3 plants have a higher content of carbonyl groups, which indicates chronic oxidative stress. Addition of exogenous sucrose or glucose to the incubation buffer had a protective effect during 4 hours of stress. Carbonyl groups formation in wild type decreased under the +37ºС and +44ºС, while in the cat2сat3 line only under the moderate (+37ºС) heat stress. In the knockout mutant alternative ways of defense are exhausted under +44ºC.