Plant Hemoglobins and Stress Response Mechanisms

Plant hemoglobins, often termed phytoglobins, constitute a family of heme-containing proteins that extend beyond the well-known leghemoglobins of nitrogen-fixing nodules to embrace non-symbiotic classes expressed in virtually all tissues. These proteins display diverse coordination states and ligand affinities that underpin functions in oxygen transport, nitric oxide scavenging and redox homeostasis. Under abiotic challenges such as hypoxia, water deficit, salinity or cold, phytoglobins modulate reactive oxygen and nitrogen species to prevent cellular damage, regulate programmed cell death and sustain metabolic activity. In biotic interactions, they fine-tune defence gene expression by controlling nitric oxide levels, while in symbiotic organs they balance oxygen supply and reactive species to maintain nitrogenase activity. Recent advances have elucidated gene-specific regulation by environmental cues and revealed opportunities to harness phytoglobin expression for improved crop resilience.

Research from Nature Portfolio

Recent work has explored the functional consequences of overexpressing a class 1 non-symbiotic hemoglobin from spinach in Arabidopsis, demonstrating that altered hemoglobin levels can modulate endogenous nitric oxide concentrations and gene networks underpinning responses to nitrate, salinity and osmotic stress. Transgenic lines with elevated hemoglobin expression exhibited reduced NO content, accompanied by diminished activation of stress-responsive genes and antioxidant enzymes, culminating in greater sensitivity to abiotic challenges. These findings highlight the critical role of plant hemoglobins in scavenging NO and shaping downstream signalling pathways that determine stress tolerance.

Plant Hemoglobins and Stress Response Mechanisms publication trend

The graph below shows the total number of articles in plant hemoglobins and stress response mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Phytoglobin: Heme-containing protein in plants that binds diatomic gases and modulates redox signalling.

Nitric oxide (NO): Reactive nitrogen species serving as a signalling molecule in plant defence and stress adaptation.

Reactive oxygen species (ROS): Highly reactive oxygen derivatives produced under stress that can damage cellular components.

Hypoxia: Condition of low oxygen availability often encountered during flooding or in dense tissues.

Nitrite reductase-like activity: Enzymatic conversion of nitrite to nitric oxide mediated by hemoglobin under anaerobic conditions.

References

1. Nitric Oxide and Globin Glb1 Regulate Fusarium oxysporum Infection of Arabidopsis thaliana. Antioxidants (2023).
2. Dynamics of hemoglobins during nodule development, nitrate response, and dark stress in Lotus japonicus. Journal of Experimental Botany (2023).
3. Redox Reactivity of Nonsymbiotic Phytoglobins towards Nitrite. Molecules (2024).
4. Overexpression of spinach non-symbiotic hemoglobin in Arabidopsis resulted in decreased NO content and lowered nitrate and other abiotic stresses tolerance. Scientific Reports (2016).