Abstract
Abstract Background Low temperature severely depresses the uptake, translocation from the root to the shoot, and metabolism of nitrate and ammonium in thermophilic plants such as cucumber ( Cucumis sativus ). Plant growth is inhibited accordingly. However, the availability of information on the effects of low temperature on nitrogen transport remains limited. Results Using non-invasive micro-test technology, the net nitrate (NO 3 − ) and ammonium (NH 4 + ) fluxes in the root hair zone and vascular bundles of the primary root, stem, petiole, midrib, lateral vein, and shoot tip of cucumber seedlings under normal temperature (NT; 26 °C) and low temperature (LT; 8 °C) treatment were analyzed. Under LT treatment, the net NO 3 − flux rate in the root hair zone and vascular bundles of cucumber seedlings decreased, whereas the net NH 4 + flux rate in vascular bundles of the midrib, lateral vein, and shoot tip increased. Accordingly, the relative expression of CsNRT1.4a in the petiole and midrib was down-regulated, whereas the expression of CsAMT1.2a – 1.2c in the midrib was up-regulated. The results of 15 N isotope tracing showed that NO 3 − -N and NH 4 + -N uptake of the seedlings under LT treatment decreased significantly compared with that under NT treatment, and the concentration and proportion of both NO 3 − -N and NH 4 + -N distributed in the shoot decreased. Under LT treatment, the actual nitrate reductase activity (NRA act ) in the root did not change significantly, whereas NRA act in the stem and petiole increased by 113.2 and 96.2%, respectively. Conclusions The higher net NH 4 + flux rate in leaves and young tissues may reflect the higher NRA act in the stem and petiole, which may result in a higher proportion of NO 3 − being reduced to NH 4 + during the upward transportation of NO 3 − . The results contribute to an improved understanding of the mechanism of changes in nitrate transportation in plants in response to low-temperature stress.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 12
Claim · model-written summary
Low temperature decreased net nitrate flux in the root hair zone and vascular bundles.
- Taxon
- cucumber
Cucumis sativuse0 - Organ / stage
- root hair zone and vascular bundlese0
- Treatment
- LT treatmente0
- Outcome
- net NO 3 − flux ratee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under LT treatment, the net NO 3 − flux rate in the root hair zone and vascular bundles of cucumber seedlings decreased”
Claim · model-written summary
Low temperature increased net ammonium flux in midrib, lateral vein and shoot tip vascular bundles.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- midrib, lateral vein, and shoot tipe0
- Treatment
- low temperaturet0
- Outcome
- net NH 4 + flux ratee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the net NH 4 + flux rate in vascular bundles of the midrib, lateral vein, and shoot tip increased”
t0“cucumber seedlings to low temperature stress”
Claim · model-written summary
CsNRT1.4a expression was downregulated in petiole and midrib.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- petiole and midribe0
- Treatment
- low temperaturet0
- Gene
- CsNRT1.4ae0
- Outcome
- relative expressione0
- Direction
- down-regulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“relative expression of CsNRT1.4a in the petiole and midrib was down-regulated”
t0“cucumber seedlings to low temperature stress”
Claim · model-written summary
CsAMT1.2a – 1.2c expression was upregulated in midrib.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- midribe0
- Treatment
- low temperaturet0
- Gene
- CsAMT1.2a – 1.2ce0
- Outcome
- expressione0
- Direction
- up-regulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of CsAMT1.2a – 1.2c in the midrib was up-regulated”
t0“cucumber seedlings to low temperature stress”
Claim · model-written summary
Low temperature significantly decreased seedling nitrate uptake.
- Taxon
- cucumberCucumis sativust0
- Treatment
- LT treatmente0
- Outcome
- NO 3 − -Ne0
- Direction
- decreasede0
- Comparator
- NT treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO 3 − -N and NH 4 + -N uptake of the seedlings under LT treatment decreased significantly compared with that under NT treatment”
t0“cucumber seedlings”
Claim · model-written summary
Low temperature significantly decreased seedling ammonium uptake.
- Taxon
- cucumberCucumis sativust0
- Treatment
- LT treatmente0
- Outcome
- NH 4 + -N uptakee0
- Direction
- decreasede0
- Comparator
- NT treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO 3 − -N and NH 4 + -N uptake of the seedlings under LT treatment decreased significantly compared with that under NT treatment”
t0“cucumber seedlings”
Claim · model-written summary
Shoot nitrate concentration and proportion decreased under low temperature.
- Taxon
- cucumberCucumis sativust0
- Treatment
- low temperaturet0
- Outcome
- concentration and proportion of both NO 3 − -N and NH 4 + -N distributed in the shoote0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the concentration and proportion of both NO 3 − -N and NH 4 + -N distributed in the shoot decreased”
t0“cucumber seedlings to low temperature stress”
Claim · model-written summary
Root nitrate reductase activity did not change significantly.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- roote0
- Treatment
- LT treatmente0
- Outcome
- actual nitrate reductase activity (NRA act )e0
- Direction
- did not changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under LT treatment, the actual nitrate reductase activity (NRA act ) in the root did not change significantly”
t0“cucumber seedlings”
Claim · model-written summary
Stem nitrate reductase activity increased by 113.2%.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- steme0
- Treatment
- low temperaturet0
- Outcome
- NRA acte0
- Direction
- increasede0
- Value
- 113.2e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NRA act in the stem and petiole increased by 113.2 and 96.2%, respectively”
t0“cucumber seedlings to low temperature stress”
Claim · model-written summary
Petiole nitrate reductase activity increased by 96.2%.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- petiolee0
- Treatment
- low temperaturet0
- Outcome
- NRA acte0
- Direction
- increasede0
- Value
- 96.2%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NRA act in the stem and petiole increased by 113.2 and 96.2%, respectively”
t0“cucumber seedlings to low temperature stress”
Claim · model-written summary
Higher leaf and young-tissue ammonium flux may reflect higher stem and petiole nitrate reductase activity.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- leaves and young tissuese0
- Outcome
- net NH 4 + flux ratee0
- Qualifier
- higher NRA act in the stem and petiolee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The higher net NH 4 + flux rate in leaves and young tissues may reflect the higher NRA act in the stem and petiole”
t0“cucumber seedlings”
Claim · model-written summary
More nitrate may be reduced to ammonium during upward transport under low temperature.
- Taxon
- cucumberCucumis sativust0
- Outcome
- higher proportion of NO 3 − being reduced to NH 4 +e0
- Qualifier
- upward transportation of NO 3 −e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which may result in a higher proportion of NO 3 − being reduced to NH 4 + during the upward transportation of NO 3 −”
t0“cucumber seedlings”
The same questions in other papers
cold · molecular: metabolites · Cucumis sativus (cucumber)Positive and negative results
6 papers in the same direction as this paper · 6 in the opposite direction
- positive
- positive
- positive
9 papers more in this group
See all 13 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.