**1. Introduction**

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose and other organic molecules [1]. This process is essential for the survival of nearly all life on Earth, as it forms the basis of the food chain and is responsible for the production of oxygen in the atmosphere [2]. Photosynthesis consists of two main phases: the light-dependent reactions, which occur in the thylakoid membranes of the chloroplasts and generate ATP and NADPH; and the light-independent reactions, also known as the dark phase or the Calvin-Benson-Bassham (CBB) cycle, which occur in the stroma of the chloroplasts and utilize the ATP and NADPH produced in the light-dependent reactions to fix CO2 into organic molecules [3].

Phosphorus (P) is an essential element for all living organisms, as it is a key component of several biomolecules, such as nucleic acids, ATP, and phospholipids. P is beneficial to plants both in its elemental form and as a component of other molecules such as phosphates. After nitrogen (N), P is quantitatively the most significant inorganic nutrient for plant growth, and often limits primary productivity in natural systems as well as agricultural systems, unless supplied as fertilizer [4]. In plants, P

plays a crucial role in various physiological processes, including energy metabolism, nucleic acid synthesis, and membrane function, as well as in the regulation of enzyme activity and signal transduction pathways [5, 6]. P is known to play a critical role in several biochemical pathways involved in the dark phase of photosynthesis, including its involvement in ATP synthesis, NADPH production, and its presence in several key enzymes. Carbon fixation, the initial step in the dark phase of photosynthesis, is a phosphate-driven metabolic process [7].

To minimize the adverse effects of global warming, it is crucial to achieve efficient carbon fixation by increasing vegetation cover and nutrient availability. Baslam et al. highlighted the significant contribution of P in addressing this pressing global challenge, as it impacts the dark phase of photosynthesis directly and indirectly [8]. As global P reserves continue to deplete, it becomes increasingly vital to comprehend the multifaceted role of phosphorus in the dark phase of photosynthesis [9]. In agricultural production, P-deficiency presents a significant limitation, and a better understanding of its contribution to the dark phase of photosynthesis could hold significant implications for improving crop productivity and sustainability [10].

Given above, the goal of this literature review is to provide a detailed understanding of the importance of P in the dark phase of photosynthesis, particularly in the regulation of the CBB cycle and the production of energy-rich molecules, such as ATP and NADPH and its overall significance in the process of photosynthesis.
