Abstract
The 5-aminolevulinic acid (ALA), a new type of plant growth regulator, can relieve the toxicity of cadmium (Cd) to plants. However, its mechanism has not been thoroughly studied. In the study, the roles of ALA have been investigated in the tolerance of Chinese cabbage ( Brassica pekinensis L.) seedlings to Cd stress. The results showed that Cd significantly reduced the biomass and the length of the primary root of seedlings but increased the malondialdehyde (MDA) and the hydrogen peroxide (H 2 O 2 ) contents. These can be effectively mitigated through the application of ALA. The ALA can further induce the activities of antioxidant enzymes in the ascorbate-glutathione (AsA-GSH) cycle under Cd stress, which resulted in high levels of both GSH and AsA. Under ALA + Cd treatment, the seedlings showed a higher chlorophyll content and photosynthetic performance in comparison with Cd treatment alone. Microscopic analysis results confirmed that ALA can protect the cell structure of shoots and roots, i.e., stabilizing the morphological structure of chloroplasts in leaf mesophyll cells. The qRT-PCR results further reported that ALA downregulated the expressions of Cd absorption and transport-related genes in shoots ( HMA2 and HMA4 ) and roots ( IRT1, IRT2, Nramp1 , and Nramp3 ), which resulted in the low Cd content in the shoots and roots of cabbage seedlings. Taken together, the exogenous application of ALA alleviates Cd stress through maintaining redox homeostasis, protecting the photosynthetic system, and regulating the expression of Cd transport-related genes in Chinese cabbage seedlings.
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Claims 11
Claim · model-written summary
Cadmium reduced seedling biomass and primary-root length.
- Taxon
- Chinese cabbage
Brassica rapa subsp. pekinensist0 - Treatment
- Cde0
- Outcome
- biomass and the length of the primary roote0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cd significantly reduced the biomass and the length of the primary root of seedlings”
t0“Chinese Cabbage”
Claim · model-written summary
Cadmium increased MDA and hydrogen peroxide contents.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Treatment
- Cde0
- Outcome
- malondialdehyde (MDA) and the hydrogen peroxide (H 2 O 2 ) contentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cd significantly reduced the biomass and the length of the primary root of seedlings but increased the malondialdehyde (MDA) and the hydrogen peroxide (H 2 O 2 ) contents.”
t0“Chinese Cabbage”
Claim · model-written summary
ALA mitigated the cadmium-associated effects.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Treatment
- ALAe0
- Outcome
- mitigatede0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These can be effectively mitigated through the application of ALA.”
t0“Chinese Cabbage”
Claim · model-written summary
ALA induced antioxidant enzyme activities under cadmium stress.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Treatment
- ALAe0
- Outcome
- activities of antioxidant enzymese0
- Direction
- inducee0
- Qualifier
- under Cd stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The ALA can further induce the activities of antioxidant enzymes in the ascorbate-glutathione (AsA-GSH) cycle under Cd stress”
t0“Chinese Cabbage”
Claim · model-written summary
ALA raised GSH and AsA levels.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Outcome
- levels of both GSH and AsAe0
- Direction
- highe0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which resulted in high levels of both GSH and AsA.”
t0“Chinese Cabbage”
Claim · model-written summary
ALA plus cadmium increased chlorophyll content versus cadmium alone.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Treatment
- ALA + Cd treatmente0
- Outcome
- chlorophyll contente0
- Direction
- highere0
- Comparator
- Cd treatment alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under ALA + Cd treatment, the seedlings showed a higher chlorophyll content and photosynthetic performance in comparison with Cd treatment alone.”
t0“Chinese Cabbage”
Claim · model-written summary
ALA plus cadmium improved photosynthetic performance versus cadmium alone.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Treatment
- ALA + Cd treatmente0
- Outcome
- photosynthetic performancee0
- Direction
- highere0
- Comparator
- Cd treatment alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under ALA + Cd treatment, the seedlings showed a higher chlorophyll content and photosynthetic performance in comparison with Cd treatment alone.”
t0“Chinese Cabbage”
Claim · model-written summary
ALA protected shoot and root cell structure, including chloroplast morphology.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Organ / stage
- shoots and rootse0
- Treatment
- ALAe0
- Outcome
- cell structure of shoots and rootse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ALA can protect the cell structure of shoots and roots, i.e., stabilizing the morphological structure of chloroplasts in leaf mesophyll cells.”
t0“Chinese Cabbage”
Claim · model-written summary
ALA downregulated HMA2 and HMA4 expression in shoots.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Organ / stage
- shootse0
- Treatment
- ALAe0
- Gene
- HMA2 and HMA4e0
- Outcome
- expressions of Cd absorption and transport-related genese0
- Direction
- downregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ALA downregulated the expressions of Cd absorption and transport-related genes in shoots ( HMA2 and HMA4 )”
t0“Chinese Cabbage”
Claim · model-written summary
ALA downregulated IRT1, IRT2, Nramp1 and Nramp3 expression in roots.
- Taxon
- Chinese cabbageBrassica rapa subsp. pekinensist0
- Organ / stage
- rootse0
- Gene
- IRT1, IRT2, Nramp1 , and Nramp3e0
- Outcome
- rootse0
Not reportedTreatmentComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“and roots ( IRT1, IRT2, Nramp1 , and Nramp3 )”
t0“Chinese Cabbage”
Claim · model-written summary
ALA lowered cadmium content in shoots and roots.
- Taxon
- cabbage
Brassica oleracea var. capitatae0 - Outcome
- Cd content in the shoots and rootse0
- Direction
- lowe0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which resulted in the low Cd content in the shoots and roots of cabbage seedlings.”
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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.