Abstract
Polyphenol oxidases (PPOs) have been implicated in plant defence reactions. From an applied point of view, high PPO activity is associated with browning / darkening of fresh and processed food. Owing to its complex genome and economic importance, wheat (Triticum aestivum L.) represents an interesting system to advance our understanding of plant PPO function. We have previously shown that wheat PPOs are organised in a multigene family, consisting of two distinct phylogenetic clusters with three members each. In this study, we demonstrate that members of one cluster are not expressed in developing kernels or senescing flag leaves. Transcriptional regulation of one major gene in the other cluster largely controls PPO levels in these tissues, at least in the wheat varieties used for this study. Our data further indicate that the product of this gene is present as a latent enzyme during early kernel development, and that the latent enzyme is activated during later developmental phases. Enzyme activation can be achieved in vitro by limited tryptic digestion, but our data do not indicate activation by a proteolytic mechanism in vivo. Together, results presented in this study provide important insights into the regulation of wheat PPO function.
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Claims 6
Claim · model-written summary
Members of one PPO gene cluster are not expressed in developing kernels or senescing flag leaves
- Taxon
- wheat
Triticum aestivume0 - Organ / stage
- developing kernels or senescing flag leavese1
- Outcome
- members of one clustere1
- Qualifier
- not expressede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.) represents an interesting system”
e1“members of one cluster are not expressed in developing kernels or senescing flag leaves”
Claim · model-written summary
Transcriptional regulation of one major PPO gene in the other cluster largely controls PPO levels in kernels and flag leaves
- Taxon
- wheatTriticum aestivume0
- Gene
- one major gene in the other clustere1
- Outcome
- PPO levelse1
- Qualifier
- Transcriptional regulatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.) represents an interesting system”
e1“Transcriptional regulation of one major gene in the other cluster largely controls PPO levels in these tissues”
Claim · model-written summary
The PPO gene product is present as a latent enzyme during early kernel development
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- early kernel developmente1
- Outcome
- latent enzymee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.) represents an interesting system”
e1“the product of this gene is present as a latent enzyme during early kernel development”
Claim · model-written summary
The latent PPO enzyme is activated during later developmental phases
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- later developmental phasese1
- Outcome
- latent enzymee1
- Qualifier
- activatede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.) represents an interesting system”
e1“the latent enzyme is activated during later developmental phases”
Claim · model-written summary
Limited tryptic digestion increased PPO enzyme activation in vitro
- Taxon
- wheatTriticum aestivume0
- Treatment
- limited tryptic digestione1
- Outcome
- Enzyme activatione1
- Direction
- increaseinferrede1
- Setting
- in vitroe1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.) represents an interesting system”
e1“Enzyme activation can be achieved in vitro by limited tryptic digestion”
Claim · model-written summary
The data do not indicate that PPO activation in vivo occurs by a proteolytic mechanism
- Taxon
- wheatTriticum aestivume0
- Outcome
- activatione1
- Qualifier
- in vivoe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat (Triticum aestivum L.) represents an interesting system”
e1“our data do not indicate activation by a proteolytic mechanism in vivo”