The Effect of Glucose and Sucrose on the Photosynthetic Pigments Content in Arabidopsis Thalina Upon Heat Stress

Abstract

An increase in the Earth's average temperature has a negative effect on the development, growth and productivity of cultivated plants. One of the main metabolic damages caused by exposure to elevated temperatures is excessive production of reactive oxygen species (ROS). ROS, accumulating in chloroplasts, cause significant damage to the photosynthetic apparatus of plants, destroying the chloroplast membrane and damaging pigments. Carbohydrates play a key role in the regulation of the processes of photosynthesis, respiration, seed germination, flowering and aging of plants. Carbohydrates are chemical signaling and sensitive molecules that receive a specific signal under normal conditions and under the influence of stress factors. The aim of our work was to study the effect of exogenous sucrose and glucose on the content of photosynthetic pigments in A. thaliana plants under the influence of heat stress. Two lines of arabidopsiswere used for research: wild-type plants and cat2cat3 knockout line with lacking isoforms of catalase, the main antioxidant enzyme. The plants were grown under conditions of 16-hour daylight at a constant temperature of + 28º C, air humidity of 70% and illumination of 2.5 kL. Treatment was perfomed in the dark for 2 and 4 hours at temperatures of +37 (moderate stress) and +44°C (severe stress treatment). Contorl Plants were incubated in a potassium-phosphate buffer without the addition of sucrose and glucose at a temperature of +20° C. It was shown that the content of chlorophyll a, b and carotenoids in intact plants of the wild type and the knockout line was the same. Under the influence of heat stress, the content of the studied pigments in the presence of sucrose did not change in both lines. During heat stress in the presence of glucose, changes were noted during the 4-hour stress. It was shown that in the control plants incubated at room temperature in the presence of glucose, the content of chlorophyll a and carotenoids increased in wild type. Upon severe heat stress (+44°С), a decrease in the pigment content was jbserved. The data obtained indicate that in conditions of 4 hours of heat stress, exogenous glucose is involved in the plant cell stress response. No changes in the content of chlorophyll and carotenoids were observed in knockout line cat2cat3.