Plant stem cells under low oxygen: metabolic rewiring by phytoglobin underlies stem cell functionality

Area of Science:

• Plant Biology
• Molecular Biology
• Biochemistry

Background:

• Root growth in maize (Zea mays L.) depends on quiescent center (QC) stem cells in the root apical meristem.
• QC stem cells are surprisingly vulnerable to hypoxic stress, leading to root growth inhibition.

Purpose of the Study:

• To investigate the metabolic responses of maize QC stem cells under hypoxic stress.
• To identify mechanisms that protect QC stem cells from oxygen deficiency.

Main Methods:

• Analysis of carbohydrate metabolism, enzyme activity (including pyruvate dehydrogenase - PDH), and gene expression (PYRUVATE DECARBOXYLASE - PDC, ALCOHOL DEHYDROGENASE - ADH) in QC stem cells under varying oxygen levels.
• Investigating the effect of PHYTOGLOBIN 1 (ZmPgb1.1) overexpression on QC stem cell function and metabolism during hypoxia.

Main Results:

• Under low oxygen, QC stem cells depleted sugars, relied on fermentation, and showed impaired TCA cycle activity.
• Hypoxia-responsive genes (PDC, ADH) were not activated, and specific metabolites (PEP, succinate) showed atypical changes.
• Overexpression of ZmPgb1.1 preserved QC stem cell function by activating the TCA cycle and retaining carbohydrates, indicating efficient energy production.

Conclusions:

• Maize QC stem cells exhibit unique metabolic vulnerabilities and responses to hypoxia compared to mature root cells.
• ZmPgb1.1 plays a crucial role in maintaining QC stem cell viability and function under oxygen-deficient conditions through metabolic adaptation.