Abstract
Alfalfa (Medicago sativa L.) is an important forage crop, and its productivity is severely affected by salt stress. Although proline is a compatible osmolyte that plays an important role in regulating plant abiotic stress resistance, the basic mechanism of proline requires further clarification regarding the effect of proline in mitigating the harmful effects of salinity. Here, we investigate the protective effects and regulatory mechanisms of proline on salt tolerance of alfalfa. The results show that exogenous proline obviously promotes seed germination and seedling growth of salt-stressed alfalfa. Salt stress results in stunted plant growth, while proline application alleviates this phenomenon by increasing photosynthetic capacity and antioxidant enzyme activities and decreasing cell membrane damage and reactive oxygen species (ROS) accumulation. Plants with proline treatment maintain a better K+/Na+ ratio by reducing Na+ accumulation and increasing K+ content under salt stress. Additionally, proline induces the expression of genes related to antioxidant biosynthesis (Cu/Zn-SOD and APX) and ion homeostasis (SOS1, HKT1, and NHX1) under salt stress conditions. Proline metabolism is mainly regulated by ornithine-δ-aminotransferase (OAT) and proline dehydrogenase (ProDH) activities and their transcription levels, with the proline-treated plants displaying an increase in proline content under salt stress. In addition, OAT activity in the ornithine (Orn) pathway rather than Δ1-pyrroline-5-carboxylate synthetase (P5CS) activity in the glutamate (Glu) pathway is strongly increased under salt stress, made evident by the sharp increase in the expression level of the OAT gene compared to P5CS1 and P5CS2. Our study provides new insight into how exogenous proline improves salt tolerance in plants and that it might be used as a significant practical strategy for cultivating salt-tolerant alfalfa.
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Claims 13
Claim · model-written summary
Exogenous proline promotes seed germination and seedling growth of salt-stressed alfalfa.
- Taxon
- alfalfa
Medicago sativat0 - Treatment
- exogenous prolinee0
- Outcome
- seed germination and seedling growthe0
- Direction
- promotese0
- Qualifier
- salt-stressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e0“exogenous proline obviously promotes seed germination and seedling growth of salt-stressed alfalfa”
Claim · model-written summary
Proline application alleviates the stunted plant growth caused by salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline applicatione1
- Outcome
- stunted plant growthe1
- Direction
- alleviatese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e1“Salt stress results in stunted plant growth, while proline application alleviates this phenomenon by increasing photosynthetic capacity and antioxidant enzyme activities and decreasing cell membrane damage and reactive oxygen species (ROS) accumulation”
Claim · model-written summary
Proline application increases photosynthetic capacity and antioxidant enzyme activities under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline applicatione1
- Outcome
- photosynthetic capacity and antioxidant enzyme activitiese1
- Direction
- increasinge1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e1“Salt stress results in stunted plant growth, while proline application alleviates this phenomenon by increasing photosynthetic capacity and antioxidant enzyme activities and decreasing cell membrane damage and reactive oxygen species (ROS) accumulation”
Claim · model-written summary
Proline application decreases cell membrane damage and ROS accumulation under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline applicatione1
- Outcome
- cell membrane damage and reactive oxygen species (ROS) accumulatione1
- Direction
- decreasinge1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e1“Salt stress results in stunted plant growth, while proline application alleviates this phenomenon by increasing photosynthetic capacity and antioxidant enzyme activities and decreasing cell membrane damage and reactive oxygen species (ROS) accumulation”
Claim · model-written summary
Proline-treated plants maintain a better K+/Na+ ratio under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline treatmente2
- Outcome
- K+/Na+ ratioe2
- Direction
- maintain a bettere2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e2“Plants with proline treatment maintain a better K+/Na+ ratio by reducing Na+ accumulation and increasing K+ content under salt stress”
Claim · model-written summary
Proline treatment reduces Na+ accumulation under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline treatmente2
- Outcome
- Na+ accumulatione2
- Direction
- reducinge2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e2“Plants with proline treatment maintain a better K+/Na+ ratio by reducing Na+ accumulation and increasing K+ content under salt stress”
Claim · model-written summary
Proline treatment increases K+ content under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline treatmente2
- Outcome
- K+ contente2
- Direction
- increasinge2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e2“Plants with proline treatment maintain a better K+/Na+ ratio by reducing Na+ accumulation and increasing K+ content under salt stress”
Claim · model-written summary
Proline induces expression of the antioxidant genes Cu/Zn-SOD and APX under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- prolinee3
- Gene
- Cu/Zn-SOD and APXe3
- Outcome
- expression of genese3
- Direction
- inducese3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e3“proline induces the expression of genes related to antioxidant biosynthesis (Cu/Zn-SOD and APX) and ion homeostasis (SOS1, HKT1, and NHX1) under salt stress conditions”
Claim · model-written summary
Proline induces expression of the ion homeostasis genes SOS1, HKT1 and NHX1 under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- prolinee3
- Gene
- SOS1, HKT1, and NHX1e3
- Outcome
- expression of genese3
- Direction
- inducese3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e3“proline induces the expression of genes related to antioxidant biosynthesis (Cu/Zn-SOD and APX) and ion homeostasis (SOS1, HKT1, and NHX1) under salt stress conditions”
Claim · model-written summary
Proline metabolism is mainly regulated by OAT activity and transcription, according to the authors.
- Taxon
- alfalfaMedicago sativat0
- Gene
- ornithine-δ-aminotransferase (OAT)e4
- Outcome
- Proline metabolisme4
- Qualifier
- mainly regulatede4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e4“Proline metabolism is mainly regulated by ornithine-δ-aminotransferase (OAT) and proline dehydrogenase (ProDH) activities and their transcription levels, with the proline-treated plants displaying an increase in proline content under salt stress”
Claim · model-written summary
Proline-treated plants show an increase in proline content under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- proline-treated plantse4
- Outcome
- proline contente4
- Direction
- an increasee4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e4“Proline metabolism is mainly regulated by ornithine-δ-aminotransferase (OAT) and proline dehydrogenase (ProDH) activities and their transcription levels, with the proline-treated plants displaying an increase in proline content under salt stress”
Claim · model-written summary
OAT activity rather than P5CS activity is strongly increased under salt stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- salt stresse5
- Gene
- OATe5
- Outcome
- OAT activity in the ornithine (Orn) pathwaye5
- Direction
- strongly increasede5
- Comparator
- Δ1-pyrroline-5-carboxylate synthetase (P5CS) activity in the glutamate (Glu) pathwaye5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e5“OAT activity in the ornithine (Orn) pathway rather than Δ1-pyrroline-5-carboxylate synthetase (P5CS) activity in the glutamate (Glu) pathway is strongly increased under salt stress”
Claim · model-written summary
The OAT gene expression level increases sharply compared with P5CS1 and P5CS2.
- Taxon
- alfalfaMedicago sativat0
- Gene
- OAT genee6
- Outcome
- expression levele6
- Direction
- sharp increasee6
- Comparator
- P5CS1 and P5CS2e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Exogenous Proline Improves Salt Tolerance of Alfalfa”
e6“the sharp increase in the expression level of the OAT gene compared to P5CS1 and P5CS2”
The same questions in other papers
proline · growth · Medicago sativa (alfalfa)Results differ
1 paper in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
proline · molecular: expression · Medicago sativa (alfalfa)Results agree
1 paper in the same direction as this paper
- positive
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.