Abstract
Alkaline soils comprise 30% of the earth and have low plant-available iron (Fe) concentration, and can cause iron deficiency chlorosis (IDC). IDC causes soybean yield losses of $260 million annually. However, it is not known whether molecular responses to IDC are equivalent to responses to low iron supply. IDC tolerant and sensitive soybean lines provide a contrast to identify specific factors associated with IDC. We used RNA-seq to compare gene expression under combinations of normal pH (5.7) or alkaline pH (7.7, imposed by 2.5 mM bicarbonate, or pH 8.2 imposed by 5 mM bicarbonate) and normal (25 μM) or low (1 μM) iron conditions from roots of these lines. Thus, we were able to treat pH and Fe supply as separate variables. We also noted differential gene expression between IDC sensitive and tolerant genotypes in each condition. Classical iron uptake genes, including ferric-chelate reductase (FCR) and ferrous transporters, were upregulated by both Fe deficiency and alkaline stress, however, their gene products did not function well at alkaline pH. In addition, genes in the phenylpropanoid synthesis pathway were upregulated in both alkaline and low Fe conditions. These genes lead to the production of fluorescent root exudate (FluRE) compounds, such as coumarins. Fluorescence of nutrient solution increased with alkaline treatment, and was higher in the IDC tolerant line. Some of these genes also localized to previously identified QTL regions associated with IDC. We hypothesize that FluRE become essential at alkaline pH where the classical iron uptake system does not function well. This work could result in new strategies to screen for IDC tolerance, and provide breeding targets to improve crop alkaline stress tolerance.
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Claims 8
Claim · model-written summary
Classical iron uptake genes were upregulated by iron deficiency in soybean.
- Taxon
- soybean
Glycine maxt0 - Treatment
- Fe deficiencye0
- Gene
- Classical iron uptake genese0
- Outcome
- Classical iron uptake genese0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Classical iron uptake genes, including ferric-chelate reductase (FCR) and ferrous transporters, were upregulated by both Fe deficiency and alkaline stress”
t0“Soybean”
Claim · model-written summary
Classical iron uptake genes were upregulated by alkaline stress in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- alkaline stresse0
- Gene
- Classical iron uptake genese0
- Outcome
- Classical iron uptake genese0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Classical iron uptake genes, including ferric-chelate reductase (FCR) and ferrous transporters, were upregulated by both Fe deficiency and alkaline stress”
t0“Soybean”
Claim · model-written summary
The products of classical iron uptake genes functioned poorly at alkaline pH in soybean.
- Taxon
- soybeanGlycine maxt0
- Outcome
- gene products did not function welle0
- Qualifier
- alkaline pHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“their gene products did not function well at alkaline pH”
t0“Soybean”
Claim · model-written summary
Phenylpropanoid synthesis genes were upregulated under alkaline conditions in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- alkalinee0
- Gene
- genes in the phenylpropanoid synthesis pathwaye0
- Outcome
- genes in the phenylpropanoid synthesis pathwaye0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“genes in the phenylpropanoid synthesis pathway were upregulated in both alkaline and low Fe conditions”
t0“Soybean”
Claim · model-written summary
Phenylpropanoid synthesis genes were upregulated under low iron conditions in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- low Fe conditionse0
- Gene
- genes in the phenylpropanoid synthesis pathwaye0
- Outcome
- genes in the phenylpropanoid synthesis pathwaye0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“genes in the phenylpropanoid synthesis pathway were upregulated in both alkaline and low Fe conditions”
t0“Soybean”
Claim · model-written summary
Nutrient solution fluorescence increased with alkaline treatment of soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- alkaline treatmente0
- Outcome
- Fluorescence of nutrient solutione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fluorescence of nutrient solution increased with alkaline treatment”
t0“Soybean”
Claim · model-written summary
Nutrient solution fluorescence was higher for the IDC tolerant soybean line.
- Taxon
- soybeanGlycine maxt0
- Material
- IDC tolerant linee0
- Outcome
- Fluorescence of nutrient solutione0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fluorescence of nutrient solution increased with alkaline treatment, and was higher in the IDC tolerant line”
t0“Soybean”
Claim · model-written summary
Some phenylpropanoid pathway genes mapped to previously identified IDC QTL regions.
- Taxon
- soybeanGlycine maxt0
- Gene
- genese0
- Outcome
- localized to previously identified QTL regions associated with IDCe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Some of these genes also localized to previously identified QTL regions associated with IDC”
t0“Soybean”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.