Impact of salinity stress on rice regeneration and molecular defense: insights from IR64 and Cigeulis varieties

Over the past few decades, rice (Oryza sativa L.) has remained a fundamental staple crop and a primary nutritional energy source for nearly 3.5 billion people worldwide, particularly in Asia. With the global population projected to reach 9.6 billion by 2050, rice production must significantly increase to meet the escalating food demand. However, salinity stress poses a major abiotic challenge that severely hampers plant growth and productivity. Soil salinization, driven by climate change and rising temperatures, leads to an excessive accumulation of salts in the soil (Sri et al., 2023). This phenomenon disrupts plant physiology through water deficit, cytotoxic effects of Na⁺ and Cl⁻ ion accumulation, and nutrient imbalances (Isayenkov and Maathuis, 2019). In coastal regions, salinity stress is further intensified by seawater intrusion into groundwater reserves (Muhardi et al., 2020), while in arid and semi-arid areas, low rainfall limits salt leaching, resulting in excessive salt accumulation (Karolinoerita and Yusuf, 2020). Exposure to salinity stress induces the overproduction of reactive oxygen species (ROS), a group of highly reactive free radicals that can damage essential cellular components, including DNA, proteins, lipids, and pigments, ultimately impairing plant function (Ghosh et al., 2021). To mitigate these detrimental effects, plants activate various adaptive responses (Huong et al., 2020), including the upregulation of antioxidant enzyme systems (Jan et al., 2019), which play a crucial role in ROS scavenging and oxidative stress alleviation. These responses involve both well-developed enzymatic and non-enzymatic scavenging pathways or detoxification systems to counter the destructive effects of ROS that include the enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and so forth (Hasanuzzaman et al., 2011).