~ 2366 ~ Journal of Pharmacognosy and Phytochemistry 2020; 9(2): 2366-2375 E-ISSN: 2278-4136 P-ISSN: 2349-8234 www.phytojournal.com JPP 2020; 9(2): 2366-2375 Received: 16-01-2020 Accepted: 20-02-2020 Manne Hemanthkumar Ph.D., Scholar, Department of Biochemistry, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India Babith Raj Goud Ph.D., Scholar, Department of Crop Physiology, College of Agriculture, PJTSAU, Rajendranagar, Hyderabad, Telangana, India Kodidhala Vaishnavi M.Sc. Scholar, Department of Plant Pathology, Uttar Banga Krishi Viswavidyalay, Cooch Behar, West Bengal, India Mousumi Thakur M.Sc. Scholar, Department of Biochemistry and Agricultural Chemistry, AAU, Jorhat, Assam, India Penumajji Ganesh Kumar Ph.D., Scholar, Department of Entomology, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India Corresponding Author: Manne Hemanthkumar Ph.D., Scholar, Department of Biochemistry, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India Physical, Molecular gene expression and Biochemical changes occurring in a plant during elevated atmospheric CO 2 Manne Hemanthkumar, Babith Raj Goud, Kodidhala Vaishnavi, Mousumi Thakur and Penumajji Ganesh Kumar DOI: https://doi.org/10.22271/phyto.2020.v9.i2am.11230 Abstract Carbon dioxide being a harmful gas to mankind its rise in atmosphere affecting the plants in physical, molecular process that modulate photosynthetic gene expression and biochemical processes that changes in CO2 concentration to the production of metabolite signal. Increasing temperature and elevated carbon dioxide were the main reason for change in the climatic factors that affect plant strength and flowering allied events. Reduction in ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) protein results from species dependent variation in differential use of molecular processes. Many studies indicates that hexokinase functioning as a hexose flux sensor that ultimately affecting transcription products were the key for repression in photosynthetic gene expression. Hexoses are produced as signals primarily by sucrose cycling and secondarily by starch hydrolysis. Finally, this review gives research knowledge over the changes in physical, molecular gene expression and biochemical processes during elevated carbon dioxide levels. Keywords: Carbon dioxide, gene expression, Rubisco, photosynthesis Introduction Carbon dioxide in the recent years is becoming the most dangerous gas by warming the earth’s surface to a greater extent. Its concentration increased from 300 ppm to 402 ppm within a century and “Todays rate of increase is more than 100 times faster than the incr ease that occurred when the last ice age ended” undoubtedly, the most important greenhouse gas in the atmosphere. Changes in land use pattern, land clearing, agriculture, and other activities has led to rise in the carbon dioxide emission. CO2 is released naturally into the atmosphere through volcanic eruptions and animal respiration but it is also released through human activities such as deforestation and the burning of fossil fuels for energy. Most of the CO2 emitted by fossil fuel combustion remains in the earth’s atmosphere while the remains are absorbed by the natural land, ocean and reservoir. CO2 also spends a long time in the atmosphere increasing its impact. Table 1: Atmospheric carbon dioxide growth rate over a years. Decade Atmospheric CO2 growth rate 2010-2019 2.40 ppm per year 2000-2009 1.97 ppm per year 1990-1999 1.50 ppm per year 1980-1989 1.61 ppm per year 1970-1979 1.28 ppm per year 1960-1969 0.85 ppm per year Atmospheric CO2 concentration has risen at an accelerating pace since the start of the Industrial Revolution. For the 1000 years prior to the Industrial Revolution, CO2 was stable at about 270 ppm. Today CO2 concentration in the atmosphere is approximately at 402 ppm and by the middle of this century it is predicted to reach 550 ppm and to surpass 700 ppm by the end of the century. Since the industrial revolution, humans have increased atmospheric CO2 concentration by 30%. Systematic monitoring of the atmospheric concentration of CO2 dates back to 1958 and the creation of the monitoring program at the Mauna Loa Observatory in Hawaii. The current observations taken at the Mauna Loa Observatory at Hawaii ensures that 2018 will be the year