Abstract
Improving crop yield to feed rapidly growing population under the conditions of limited cultivable land and climate change is a global concern. Besides different genetic and environmental factors, plant carbon (C) and nitrogen (N) levels largely influence plant growth and development. Key genes from both C and N assimilation pathways have been utilized for overexpression aiming to improve yield in transgenic plants. However, majority of these studies primarily focused on molecular and biochemical characterization of transgenic plants, providing limited or no data on yield or other growth related parameters. In addition, there are cases where the same target transgene produced variable effect on the physiological traits of host plant. This review summarizes different studies where genes from C and/or N assimilation pathways have been utilized for heterologous expression in plants. More specifically, we aim to provide an overview of different genetic modifications to enhance C and N assimilation vis-à-vis their physiological consequences in transgenic plants. Further, significance of simultaneous enhancement of C and N assimilation in plants for higher yield is being discussed.