Author: Debasish Maity
Abstract: The Poaceae family had been recognized as one of the most ecologically and economically important plant groups, with C4 photosynthesis representing a key evolutionary innovation that enhanced adaptation to high temperatures, water scarcity, and low atmospheric CO₂. This study had examined the evolutionary trends of C4 photosynthesis in Poaceae by integrating fossil, isotopic, and molecular evidence from both global and Indian perspectives. Fossil phytoliths, carbon isotope records, and genomic data had revealed multiple independent origins of C4 pathways during the late Oligocene to Miocene, with rapid expansion in the late Miocene driven by CO₂ decline, aridity, and open-habitat spread. In the Indian subcontinent, the transition from C3- to C4- dominated grasslands had been closely linked to monsoon intensification and the development of semi-arid ecosystems, leading to present-day dominance of C4 species in over 75% of grass cover in arid and semiarid regions. The convergent evolution of C4 photosynthesis had been facilitated by anatomical, biochemical, and regulatory adaptations, offering valuable lessons for climate-resilient agriculture. Understanding these evolutionary patterns had been considered critical for improving crop productivity and sustaining grassland ecosystems under changing climate conditions.
Keywords: Poaceae, C4 Photosynthesis, Fossil Records, Monsoon Intensification, Convergent Evolution, Carbon Isotopes, Grassland Expansion.
Page No: 113-119