Abstract
BACKGROUND: Cadmium (Cd) exposure and sulfate limitation induce root sulfate uptake to meet the metabolic demand for reduced sulfur. Although these responses are well studied, some aspects are still an object of debate, since little is known about the molecular mechanisms by which changes in sulfate availability and sulfur metabolic demand are perceived and transduced into changes in the expression of the high-affinity sulfate transporters of the roots. The analysis of the natural variation occurring in species with complex and highly redundant genome could provide precious information to better understand the topic, because of the possible retention of mutations in the sulfate transporter genes. RESULTS: The analysis of plant sulfur nutritional status and root sulfate uptake performed on plants of Brassica juncea - a naturally occurring allotetraploid species - grown either under Cd exposure or sulfate limitation showed that both these conditions increased root sulfate uptake capacity but they caused quite dissimilar nutritional states, as indicated by changes in the levels of nonprotein thiols, glutathione and sulfate of both roots and shoots. Such behaviors were related to the general accumulation of the transcripts of the transporters involved in root sulfate uptake (BjSultr1;1 and BjSultr1;2). However, a deeper analysis of the expression patterns of three redundant, fully functional, and simultaneously expressed Sultr1;2 forms (BjSultr1;2a, BjSultr1;2b, BjSultr1;2c) revealed that sulfate limitation induced the expression of all the variants, whilst BjSultr1;2b and BjSultr1;2c only seemed to have the capacity to respond to Cd. CONCLUSIONS: A novel method to estimate the apparent kM for sulfate, avoiding the use of radiotracers, revealed that BjSultr1;1 and BjSultr1;2a/b/c are fully functional high-affinity sulfate transporters. The different behavior of the three BjSultr1;2 variants following Cd exposure or sulfate limitation suggests the existence of at least two distinct signal transduction pathways controlling root sulfate uptake in dissimilar nutritional and metabolic states.
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Claims 8
Claim · model-written summary
Cd exposure increased root sulfate uptake capacity.
- Taxon
- Brassica juncea
Brassica junceae1 - Treatment
- Cd exposuree1
- Outcome
- root sulfate uptake capacitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both these conditions increased root sulfate uptake capacity”
e1“Brassica juncea - a naturally occurring allotetraploid species - grown either under Cd exposure or sulfate limitation”
Claim · model-written summary
Sulfate limitation increased root sulfate uptake capacity.
- Taxon
- Brassica junceaBrassica junceae1
- Treatment
- sulfate limitatione1
- Outcome
- root sulfate uptake capacitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both these conditions increased root sulfate uptake capacity”
e1“Brassica juncea - a naturally occurring allotetraploid species - grown either under Cd exposure or sulfate limitation”
Claim · model-written summary
The conditions produced dissimilar nutritional states.
- Taxon
- Brassica junceaBrassica junceae1
- Outcome
- dissimilar nutritional statese0
- Direction
- dissimilare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“they caused quite dissimilar nutritional states, as indicated by changes in the levels of nonprotein thiols, glutathione and sulfate of both roots and shoots”
e1“Brassica juncea”
Claim · model-written summary
BjSultr1;1 and BjSultr1;2 transcripts generally accumulated under these conditions.
- Taxon
- Brassica junceaBrassica junceae1
- Gene
- BjSultr1;1 and BjSultr1;2e0
- Outcome
- accumulation of the transcriptse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“general accumulation of the transcripts of the transporters involved in root sulfate uptake (BjSultr1;1 and BjSultr1;2)”
e1“Brassica juncea”
Claim · model-written summary
Sulfate limitation induced all three Sultr1;2 variants.
- Taxon
- Brassica junceaBrassica junceae1
- Treatment
- sulfate limitatione0
- Gene
- Sultr1;2e2
- Outcome
- expression of all the variantse0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sulfate limitation induced the expression of all the variants”
e1“Brassica juncea”
e2“Sultr1;2 forms (BjSultr1;2a, BjSultr1;2b, BjSultr1;2c)”
Claim · model-written summary
Only BjSultr1;2b and BjSultr1;2c appeared responsive to Cd.
- Taxon
- Brassica junceaBrassica junceae1
- Gene
- BjSultr1;2b and BjSultr1;2ce0
- Outcome
- capacity to respond to Cde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“BjSultr1;2b and BjSultr1;2c only seemed to have the capacity to respond to Cd”
e1“Brassica juncea”
Claim · model-written summary
A radiotracer-free apparent kM method identified the named transporters as functional high-affinity sulfate transporters.
- Taxon
- Brassica junceaBrassica junceae1
- Gene
- BjSultr1;1 and BjSultr1;2a/b/ce0
- Outcome
- fully functional high-affinity sulfate transporterse0
- Comparator
- radiotracerse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A novel method to estimate the apparent kM for sulfate, avoiding the use of radiotracers, revealed that BjSultr1;1 and BjSultr1;2a/b/c are fully functional high-affinity sulfate transporters.”
e1“Brassica juncea”
Claim · model-written summary
The differing responses suggest at least two sulfate uptake signaling pathways.
- Taxon
- Brassica junceaBrassica junceae1
- Outcome
- root sulfate uptakee0
- Qualifier
- at least two distinct signal transduction pathwayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggests the existence of at least two distinct signal transduction pathways controlling root sulfate uptake in dissimilar nutritional and metabolic states”
e1“Brassica juncea”
The same questions in other papers
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1 paper in the same direction as this paper · 4 in the opposite direction
- negative
- negative
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See all 6 papers →sulfate · nutrient: content · Brassica juncea (Indian mustard)Results agree
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heavy metal · nutrient: content · Brassica juncea (Indian mustard)Positive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- negative
- negative
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See all 5 papers →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.