Abstract
Abstract A biosynthetic precursor of tetrapyrrol, 5-aminolevulinic acid (ALA), is widely used in agricultural production, as an exogenous regulatory substance that effectively regulates plant growth. Previous studies have shown that heme and chlorophyll accumulate in plants under salt stress, when treated with exogenous ALA. In this study, we explored the regulatory role of heme in plants, by spraying 25 mg L –1 ALA onto the leaves of cucumber seedlings treated with heme synthesis inhibitor (2,2'-dipyridyl, DPD) and heme scavenger (hemopexin, Hx), under 50 mmol L –1 NaCl stress. The results showed that NaCl alone and DPD + Hx treatments to cucumber seedlings subjected to salt stress adversely affected their growth, by decreasing biomass accumulation, root activity, and root morphology. In addition, these treatments induced an increase in membrane lipid oxidation, as well as enhancement of anti-oxidase activities, proline content, and glutamate betaine. However, exogenous ALA application increased the plant growth and root architecture indices under NaCl stress, owing to a lack of heme in the seedlings. In addition, cucumber seedlings treated with DPD and Hx showed inhibition of growth under salt stress, but exogenous ALA effectively improved cucumber seedling growth as well as the physiological characteristics; moreover, the regulation of ALA in plants was weakened when heme synthesis was inhibited. Heme biosynthesis and metabolism genes, HEMH and HO1 , which are involved in the ALA metabolic pathway, were upregulated under salinity conditions, when ferrochelatase activity was inhibited. Application of exogenous ALA increased the heme content in the leaves. Thus, exogenous ALA may supplement the substrates for heme synthesis. These results indicated that heme plays a vital role in the response of plants to salinity stress. In conclusion, heme is involved in ALA-mediated alleviation of damage caused to cucumber seedlings and acts as a positive regulator of plant adaption.
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Claims 7
Claim · model-written summary
Salt and heme inhibition reduced cucumber seedling biomass, root activity and root morphology.
- Taxon
- cucumber seedlings
Cucumis sativuse0 - Treatment
- NaCl alone and DPD + Hx treatmentse0
- Outcome
- biomass accumulation, root activity, and root morphologye0
- Direction
- decreasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NaCl alone and DPD + Hx treatments to cucumber seedlings subjected to salt stress adversely affected their growth, by decreasing biomass accumulation, root activity, and root morphology”
Claim · model-written summary
These treatments increased membrane lipid oxidation, anti-oxidase activities, proline and glutamate betaine.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- these treatmentse0
- Outcome
- membrane lipid oxidation, as well as enhancement of anti-oxidase activities, proline content, and glutamate betainee0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these treatments induced an increase in membrane lipid oxidation, as well as enhancement of anti-oxidase activities, proline content, and glutamate betaine”
t0“cucumber seedlings”
Claim · model-written summary
Exogenous ALA increased growth and root architecture under NaCl stress.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- exogenous ALA applicatione0
- Outcome
- plant growth and root architecture indicese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenous ALA application increased the plant growth and root architecture indices under NaCl stress”
t0“cucumber seedlings”
Claim · model-written summary
ALA improved growth and physiological characteristics of DPD- and Hx-treated seedlings under salt stress.
- Taxon
- cucumber seedlingsCucumis sativuse0
- Treatment
- exogenous ALAe0
- Outcome
- cucumber seedling growth as well as the physiological characteristicse0
- Direction
- improvede0
- Comparator
- cucumber seedlings treated with DPD and Hxe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cucumber seedlings treated with DPD and Hx showed inhibition of growth under salt stress, but exogenous ALA effectively improved cucumber seedling growth as well as the physiological characteristics”
Claim · model-written summary
Inhibiting heme synthesis weakened ALA regulation.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- heme synthesis was inhibitede0
- Outcome
- regulation of ALA in plantse0
- Direction
- weakenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the regulation of ALA in plants was weakened when heme synthesis was inhibited”
t0“cucumber seedlings”
Claim · model-written summary
HEMH and HO1 were upregulated under salinity when ferrochelatase activity was inhibited.
- Taxon
- cucumber seedlingsCucumis sativust0
- Gene
- HEMH and HO1e0
- Outcome
- HEMH and HO1e0
- Direction
- upregulatede0
- Qualifier
- under salinity conditions, when ferrochelatase activity was inhibitede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heme biosynthesis and metabolism genes, HEMH and HO1 , which are involved in the ALA metabolic pathway, were upregulated under salinity conditions, when ferrochelatase activity was inhibited”
t0“cucumber seedlings”
Claim · model-written summary
Exogenous ALA increased leaf heme content.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- exogenous ALAe0
- Outcome
- heme content in the leavese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of exogenous ALA increased the heme content in the leaves”
t0“cucumber seedlings”
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