Doctor Namraj Dhami

Candidature

Graduated PhD 2019

Thesis Title

Environmental and developmental regulation of carotenoid metabolism in Arabidopsis leaves

Research Project

Carotenoids are tetraterpenoid pigments synthesized in plants and other photosynthetic organisms. They are involved in the light and temperature regulated metabolic processes in plants. The oxidative degradation of carotenoids produces phytohormones such as abscisic acid and strigolactones, which play key roles on the plant acclimation to the altered environmental conditions. In addition, carotenoids such as β-carotene, lutein, etc. are among the essential nutrients for non-photosynthetic organisms including human, which can only obtained from the plant based dietary sources. The ever changing environmental conditions immensely affect biosynthesis, accumulation, and degradation of carotenoids in plants.

My dissertation project will investigate the effect of various environmental conditions on the carotenoid landscape in plants. I will mainly focus on elevated CO₂ and cold temperature in the context of two major factors affecting the global climate change. Using wild type and carotenoid pathway mutants of Arabidopsis and Tomato (Lycopersicon esculantum var. Microtom), I will investigate how elevated CO₂ and cold exposure affect carotenogenesis at molecular and physiological level. Findings of this research will underpin the role of carotenoids in plants to acclimate short- and long-term environmental changes. In addition, it will be a valuable resource for agricultural industries in crop biofortification endeavours to ensure optimum amount of health promoting carotenoids in food crops under the future environmental conditions.

(Research gate profile: https://www.researchgate.net/profile/Namraj_Dhami (opens in a new window)

Publications

Dhami N, Cazzonelli CI, (2021) 'Short photoperiod attenuates CO2 fertilization effect on shoot biomass in Arabidopsis thaliana', Physiology and Molecular Biology of Plants, vol.27, pp 825–834

Cazzonelli CI, Hou X, Alagoz Y, Rivers J, Dhami N, Lee J, Marri S, Pogson BJ, (2020) 'A cis-carotene derived apocarotenoid regulates etioplast and chloroplast development', ELife, vol.9, Article no.e45310

Dhami N, Cazzonelli, CI, (2020) 'Environmental impacts on carotenoid metabolism in leaves', Plant Growth Regulation, vol.92, pp 455-477

Dhami N, Cazzonelli CI, (2020) 'Prolonged cold exposure to Arabidopsis juvenile seedlings extends vegetative growth and increases the number of shoot branches', Plant Signaling and Behavior, Article no.1789320

Dhami N, Drake JE, Tjoelker MG, Tissue DT, Cazzonelli CI, (2020) ' An extreme heatwave enhanced the xanthophyll de-epoxidation state in leaves of Eucalyptus trees grown in the field', Physiology and Molecular Biology of Plants, vol.26, no.2, pp 211-218

Alagoz Y, Nayak P, Dhami N, Cazzonelli CI, (2018) 'cis-carotene biosynthesis, evolution and regulation in plants: The emergence of novel signaling metabolites', Archives of Biochemistry and Biophysics, vol.654, pp 172-184

Dhami N, Tissue DT, Cazzonelli CI, (2018) 'Leaf-age dependent response of carotenoid accumulation to elevated CO₂ in Arabidopsis', Archives of Biochemistry and Biophysics, vol.647, pp 67-75

Dhami N, Mishra AD, (2015) 'Phytochemical variation: How to resolve the quality controversies of herbal medicinal products?', Journal of Herbal Medicine, vol.5, no.2, pp 118-127

Research Supervisors

Dr Christopher Cazzonelli, Professor David Tissue, Professor Barry Pogson (ANU)