Abstract
Mechanical injury to lettuce often leads to enzymatic browning caused by polyphenol oxidase (PPO), significantly impairing its sensory quality and processing suitability. In this study, the LsPPOs gene family was comprehensively identified and characterized using bioinformatics methods, including gene and protein structure, codon usage bias, phylogenetic relationships, and gene expression in response to wound stress. Further analysis of the relationship between LsPPOs expression profile and browning was performed. A total of 17 LsPPO family members (LsPPO1-LsPPO17) were identified from publicly available lettuce databases, encoding proteins ranging from 146 to 667 amino acids, with a G/C bias. Most were localized in the chloroplast. The motif structure was highly conserved among family members, and phylogenetic analysis revealed four distinct groups. All genes lacked introns, except LsPPO2 which contained an intron. After mechanical injury, browning at the stem site deepened over time, with PPO activity increasing. The majority of PPO members were significantly upregulated after fresh-cut processing. Among them, LsPPO3, LsPPO4, and LsPPO12 showed sustained upregulation, exhibiting a strong positive correlation with the browning phenotype and PPO activity. Notably, LsPPO4 demonstrated the highest transcriptional abundance and upregulation in response to a wound, indicating its major role in lettuce stem browning. The results of this study provide a foundation for further investigation into the functional role of LsPPOs and support the development of lettuce varieties with enhanced resistance to browning.
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Claims 13
Claim · model-written summary
Seventeen LsPPO family members were identified in lettuce.
- Taxon
- lettuce
Lactuca sativae0 - Gene
- LsPPO family memberse0
- Outcome
- LsPPO family members (LsPPO1-LsPPO17) were identifiede0
- Value
- 17e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A total of 17 LsPPO family members (LsPPO1-LsPPO17) were identified from publicly available lettuce databases”
Claim · model-written summary
LsPPO proteins ranged from 146 to 667 amino acids and showed G/C bias.
- Taxon
- LettuceLactuca sativat0
- Outcome
- proteins ranging from 146 to 667 amino acids, with a G/C biase0
- Value
- 146 to 667 amino acidse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“encoding proteins ranging from 146 to 667 amino acids, with a G/C bias.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
Most PPO family members localized to chloroplasts.
- Taxon
- LettuceLactuca sativat0
- Outcome
- localized in the chloroplaste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Most were localized in the chloroplast.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
PPO motif structures were highly conserved.
- Taxon
- LettuceLactuca sativat0
- Outcome
- motif structure was highly conservede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The motif structure was highly conserved among family members”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
PPO family phylogeny revealed four groups.
- Taxon
- LettuceLactuca sativat0
- Outcome
- four distinct groupse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phylogenetic analysis revealed four distinct groups.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
Only LsPPO2 had an intron; the other genes lacked introns.
- Taxon
- LettuceLactuca sativat0
- Gene
- LsPPO2e0
- Outcome
- contained an introne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All genes lacked introns, except LsPPO2 which contained an intron.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
Stem browning deepened over time after mechanical injury.
- Taxon
- LettuceLactuca sativat0
- Organ / stage
- steme0
- Treatment
- mechanical injurye0
- Outcome
- browning at the stem sitee0
- Direction
- deepenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After mechanical injury, browning at the stem site deepened over time”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
PPO activity increased after mechanical injury.
- Taxon
- LettuceLactuca sativat0
- Treatment
- mechanical injurye0
- Gene
- PPOe0
- Outcome
- PPO activitye0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After mechanical injury, browning at the stem site deepened over time, with PPO activity increasing.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
Most PPO members were significantly upregulated after fresh-cut processing.
- Taxon
- LettuceLactuca sativat0
- Treatment
- fresh-cut processinge0
- Gene
- PPO memberse0
- Outcome
- PPO memberse0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The majority of PPO members were significantly upregulated after fresh-cut processing.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
LsPPO3, LsPPO4 and LsPPO12 showed sustained upregulation.
- Taxon
- LettuceLactuca sativat0
- Gene
- LsPPO3, LsPPO4, and LsPPO12e0
- Outcome
- sustained upregulatione0
- Direction
- upregulatione0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LsPPO3, LsPPO4, and LsPPO12 showed sustained upregulation”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
Expression of LsPPO3, LsPPO4 and LsPPO12 correlated positively with browning and PPO activity.
- Taxon
- LettuceLactuca sativat0
- Gene
- LsPPO3, LsPPO4, and LsPPO12e0
- Outcome
- browning phenotype and PPO activitye0
- Direction
- positive correlatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LsPPO3, LsPPO4, and LsPPO12 showed sustained upregulation, exhibiting a strong positive correlation with the browning phenotype and PPO activity.”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
LsPPO4 had the highest transcriptional abundance and wound-induced upregulation.
- Taxon
- LettuceLactuca sativat0
- Treatment
- a wounde0
- Gene
- LsPPO4e0
- Outcome
- transcriptional abundance and upregulatione0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LsPPO4 demonstrated the highest transcriptional abundance and upregulation in response to a wound”
t0“Lettuce (Lactuca sativa L.)”
Claim · model-written summary
Authors inferred a major role for LsPPO4 in lettuce stem browning.
- Taxon
- lettuceLactuca sativae0
- Gene
- LsPPO4e1
- Outcome
- stem browninge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“indicating its major role in lettuce stem browning.”
e1“LsPPO4 demonstrated the highest transcriptional abundance”