Maize phytochemicals in stressful environments: impacts and adaptation

Maize ( Zea mays L.) is a globally important cereal crop and a major source of nutrients and bioactive phytochemicals that contribute to food security, human health, and industrial applications. However, increasing environmental stresses, including drought, salinity, extreme temperatures, heavy metal contamination, nutrient deficiency, and pathogen attacks, adversely affect maize growth, productivity, and phytochemical composition. In response to these challenges, maize activates intricate adaptive mechanisms involving signaling cascades, transcriptional regulation, metabolic reprogramming, hormonal and reactive oxygen species (ROS) crosstalk, epigenetic regulation, stress-memory mechanisms, gene alteration, and diverse biochemical responses. Stress perception initiates intracellular signaling networks that activate transcription factors regulating stress-responsive genes and metabolic pathways. These processes promote the accumulation of protective phytochemicals, osmolytes, antioxidants, and defense-related metabolites that mitigate oxidative damage and maintain cellular homeostasis. Hormonal interactions with ROS coordinate growth-defense trade-offs, while epigenetic modifications and stress memory enhance tolerance to recurrent environmental stresses. Gene alterations through natural variation, molecular breeding, and genome editing further strengthen stress resilience by improving physiological and biochemical performance. Collectively, these adaptive mechanisms preserve the synthesis and beneficial utilization of maize phytochemicals, including phenolic compounds, flavonoids, carotenoids, anthocyanins, phytosterols, and terpenoids, which possess significant antioxidant, anti-inflammatory, nutraceutical, pharmaceutical, and industrial value. Understanding the integration of these molecular, physiological, and biochemical processes provides a foundation for developing climate-resilient maize cultivars with enhanced phytochemical quality, improved stress tolerance, and sustainable productivity under changing environmental conditions.