PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

Indian mustard (Brassica juncea L.), a vital oilseed crop of the Brassicaceae family, plays a significant role in global vegetable oil production, faces significant productivity challenges due to high-temperature stress, particularly during key developmental stages. As a C3 plant, Indian mustard experiences reduced photosynthetic efficiency, altered osmotic balance, and increased oxidative stress under heat stress conditions. Physiological disruptions include chlorophyll degradation, impaired stomatal regulation, and reduced relative water content, leading to compromised carbon assimilation and plant metabolism. Morphological traits, such as plant height, leaf area index, and dry matter accumulation, also decline, further limiting yield potential. Heat stress particularly affects reproductive traits by causing pollen sterility, flower abortion, and poor seed development, ultimately leading to lower seed yield and oil content. At the biochemical level, high temperatures trigger excessive reactive oxygen species (ROS) production, lipid peroxidation, and enzyme inactivation, affecting overall plant stability. Additionally, terminal heat stress disrupts oil biosynthesis pathways, reducing oil accumulation in seeds. To mitigate these effects, mustard plants activate complex stress-response mechanisms, including transcriptomic and proteomic adjustments, epigenetic modifications, and enhanced antioxidant enzyme activities. This review explores breeding and biotechnological strategies for developing heat-tolerant mustard varieties. Conventional breeding approaches, including the utilization of crop wild relatives, marker-assisted selection (MAS), and quantitative trait loci (QTL) mapping, have facilitated the identification of thermo-tolerant genotypes. Advanced genomic tools, such as CRISPR/Cas-based genome editing, genome-wide association studies (GWAS), and multi-omics integration, offer novel pathways for enhancing stress resilience. Agronomic interventions, including optimized nutrient and water management, microbial inoculation, and stress-mitigating foliar applications, complement genetic improvements. Given the increasing threat of climate change, a multidisciplinary approach combining genetics, biotechnology, and agronomy is essential to ensure the sustainability of mustard production and global oilseed security.