Abstract
Root growth in maize (Zea mays L.) is regulated by the activity of the quiescent center (QC) stem cells located within the root apical meristem. Here, we show that despite being highly hypoxic under normal oxygen tension, QC stem cells are vulnerable to hypoxic stress, which causes their degradation with subsequent inhibition of root growth. Under low oxygen, QC stem cells became depleted of starch and soluble sugars and exhibited reliance on glycolytic fermentation with the impairment of the TCA cycle through the depressed activity of several enzymes, including pyruvate dehydrogenase (PDH). This finding suggests that carbohydrate delivery from the shoot might be insufficient to meet the metabolic demand of QC stem cells during stress. Some metabolic changes characteristic of the hypoxic response in mature root cells were not observed in the QC. Hypoxia-responsive genes, such as PYRUVATE DECARBOXYLASE (PDC) and ALCOHOL DEHYDROGENASE (ADH), were not activated in response to hypoxia, despite an increase in ADH activity. Increases in phosphoenolpyruvate (PEP) with little change in steady-state levels of succinate were also atypical responses to low-oxygen tensions. Overexpression of PHYTOGLOBIN 1 (ZmPgb1.1) preserved the functionality of the QC stem cells during stress. The QC stem cell preservation was underpinned by extensive metabolic rewiring centered around activation of the TCA cycle and retention of carbohydrate storage products, denoting a more efficient energy production and diminished demand for carbohydrates under conditions where nutrient transport may be limiting. Overall, this study provides an overview of metabolic responses occurring in plant stem cells during oxygen deficiency.
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Claims 9
Claim · model-written summary
Hypoxia degraded QC stem cells and inhibited root growth.
- Treatment
- hypoxic stresse0
- Outcome
- degradation with subsequent inhibition of root growthe0
- Direction
- inhibitione0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“QC stem cells are vulnerable to hypoxic stress, which causes their degradation with subsequent inhibition of root growth”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
Low oxygen depleted starch and soluble sugars in QC stem cells.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low oxygen, QC stem cells became depleted of starch and soluble sugars”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
Low oxygen increased QC reliance on glycolytic fermentation and impaired the TCA cycle.
- Treatment
- low oxygene0
- Gene
- pyruvate dehydrogenase (PDH)e0
- Outcome
- impairment of the TCA cyclee0
- Direction
- impairmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low oxygen, QC stem cells became depleted of starch and soluble sugars and exhibited reliance on glycolytic fermentation with the impairment of the TCA cycle through the depressed activity of several enzymes, including pyruvate dehydrogenase (PDH)”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
Hypoxia did not activate PDC and ADH genes in the QC.
- Treatment
- hypoxiae0
- Gene
- PYRUVATE DECARBOXYLASE (PDC) and ALCOHOL DEHYDROGENASE (ADH)e0
- Outcome
- were not activatede0
- Direction
- not activatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hypoxia-responsive genes, such as PYRUVATE DECARBOXYLASE (PDC) and ALCOHOL DEHYDROGENASE (ADH), were not activated in response to hypoxia”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
ADH activity increased under hypoxia.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hypoxia-responsive genes, such as PYRUVATE DECARBOXYLASE (PDC) and ALCOHOL DEHYDROGENASE (ADH), were not activated in response to hypoxia, despite an increase in ADH activity”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
PEP increased with little change in succinate under low oxygen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increases in phosphoenolpyruvate (PEP) with little change in steady-state levels of succinate were also atypical responses to low-oxygen tensions”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
Succinate levels changed little under low oxygen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“little change in steady-state levels of succinate were also atypical responses to low-oxygen tensions”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
ZmPgb1.1 overexpression preserved QC stem cell function during stress.
- Treatment
- Overexpression of PHYTOGLOBIN 1 (ZmPgb1.1)e0
- Gene
- PHYTOGLOBIN 1 (ZmPgb1.1)e0
- Outcome
- functionality of the QC stem cellse0
- Direction
- preservede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overexpression of PHYTOGLOBIN 1 (ZmPgb1.1) preserved the functionality of the QC stem cells during stress”
e1“Root growth in maize (Zea mays L.)”
Claim · model-written summary
ZmPgb1.1-associated QC preservation involved TCA activation and retained carbohydrate storage.
- Outcome
- QC stem cell preservatione0
- Qualifier
- activation of the TCA cycle and retention of carbohydrate storage productse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The QC stem cell preservation was underpinned by extensive metabolic rewiring centered around activation of the TCA cycle and retention of carbohydrate storage products”
e1“Root growth in maize (Zea mays L.)”
The same questions in other papers
flooding · disease · Zea mays (maize)Positive and negative results
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- positive
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