Proline as a key player in heat stress tolerance: insights from maize

Proline, a multifunctional amino acid, plays a pivotal role in mitigating heat stress in maize. This review analyses proline's role in enhancing heat tolerance. Proline functions as an osmoprotectant, maintaining cellular hydration and turgor, and as an antioxidant, scavenging reactive oxygen species (ROS) to protect cellular components. These dual functions contribute significantly to cellular homeostasis under heat stress conditions. The biosynthesis and accumulation of proline in maize are regulated by complex genetic and metabolic pathways. Environmental cues, particularly heat stress, induce proline accumulation through the upregulation of biosynthetic genes and the suppression of catabolic pathways. Proline interacts with other molecular modulators, including glycine betaine, trehalose, ascorbate, glutathione, heat shock proteins (HSPs), spermidine, and abscisic acid (ABA), to collectively enhance heat stress tolerance. Moreover, proline is integrated into complex signaling networks, including ROS scavenging and calcium signaling pathways, to orchestrate cellular responses to heat stress. Understanding the regulatory networks governing proline's role in heat stress tolerance is crucial for developing maize varieties with improved resilience to climate change. By elucidating the molecular mechanisms underlying proline's multifunctional role, we can identify potential targets for genetic manipulation and biotechnological interventions to enhance crop performance under heat stress conditions.