Abstract
Photosynthesis of tomato fruit was studied using green fruit from six heritage cultivars of Lycopersicon esculentum Mill. and one of Lycopersicon pimpinellifolium. Chlorophyll concentrations in the green shoulder, pericarp and locular parenchyma of the fruit were determined and the apparent photosynthetic electron transport activity (ETR) and chlorophyll fluorescence quenching characteristics of these tissues and the calyx were compared. In all cultivars, green shoulder formation, apparent as intense pigmentation of the proximal pericarp shoulder, was positively related to the degree of shading of the fruit during development. Appearing as a photosynthetic adaptive trait for increasing the photoautotrophic capacity of fruit grown under low light, the green shoulder contained 17–57% of the total pericarp chlorophyll content. The pericarp below the green shoulder had lower chlorophyll a+b concentrations than in the locular parenchyma. The proportion of light-harvesting chlorophyll to active centre chlorophyll was also lower in the pericarp than in the locular parenchyma as indicated by higher ratios of chlorophyll a/b. At a photon flux density (PFD) of 1200 µmol m−2 s−1, different fruit tissues were found to have different levels of ETR. In ‘Yellow Pear’, the upper surface of the calyx had an ETR of 154 µmol m−2 s−1, while the lower surface had an ETR of 88 µmol m−2 s−1. On the green shoulder, ETR was 203 µmol m−2 s−1, whereas in the pericarp distal to the green shoulder, ETR was 97 µmol m−2 s−1. In the locular parenchyma, ETR was 66 µmol m−2 s−1. This trend towards a lower ETR in distal and internal fruit tissues appeared to indicate a shift towards a more shade-type photosynthesis. Concomitant with this shift were changes in chlorophyll fluorescence quenching characteristics. Generally when tissues displayed reduced levels of ETR they also displayed a faster decrease in the photochemical quenching coefficient qP and a more rapid diversion of absorbed photon energy to non-photochemical pathways which was seen by the rise in the non-photochemical quenching coefficient qN. However, the response of the locular parenchyma was an exception, under equivalent levels of PFD the qP levels in this tissue were much lower than those in the pericarp, but qN levels were similar. This finding indicated that the lower ETR of the locular parenchyma was due to a lower capacity to utilize electrons generated from water splitting rather than a greater diversion of absorbed photon energy to nonphotochemical pathways. The levels of photosynthetic activity found in the calyx, green shoulder, pericarp, and locular parenchyma suggest that all of these tissues have significant roles in CO2 scavenging and the provision of carbon assimilates. The potential role of fruit photosynthesis in influencing the fruit acid to sugar ratio and hence fruit quality is discussed.
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Claims 15
Claim · model-written summary
Green shoulder formation was positively related to fruit shading.
- Taxon
- tomato
Solanum lycopersicumt0 - Organ / stage
- fruite0
- Treatment
- degree of shading of the fruite0
- Outcome
- green shoulder formatione0
- Direction
- positivelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all cultivars, green shoulder formation, apparent as intense pigmentation of the proximal pericarp shoulder, was positively related to the degree of shading of the fruit during development”
t0“tomato fruit”
Claim · model-written summary
The green shoulder contained 17–57% of total pericarp chlorophyll.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- green shouldere0
- Outcome
- total pericarp chlorophyll contente0
- Value
- 17–57%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the green shoulder contained 17–57% of the total pericarp chlorophyll content”
t0“tomato fruit”
Claim · model-written summary
Pericarp below the green shoulder had lower chlorophyll a+b than locular parenchyma.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- pericarp below the green shouldere0
- Outcome
- chlorophyll a+b concentrationse0
- Direction
- lowere0
- Comparator
- locular parenchymae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pericarp below the green shoulder had lower chlorophyll a+b concentrations than in the locular parenchyma”
t0“tomato fruit”
Claim · model-written summary
Pericarp had a lower light-harvesting to active-centre chlorophyll proportion than locular parenchyma.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- pericarpe0
- Outcome
- proportion of light-harvesting chlorophyll to active centre chlorophylle0
- Direction
- lowere0
- Comparator
- locular parenchymae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The proportion of light-harvesting chlorophyll to active centre chlorophyll was also lower in the pericarp than in the locular parenchyma as indicated by higher ratios of chlorophyll a/b”
t0“tomato fruit”
Claim · model-written summary
In Yellow Pear the upper calyx surface had ETR of 154 µmol m−2 s−1.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- Yellow Peare0
- Organ / stage
- upper surface of the calyxe0
- Outcome
- ETRe0
- Value
- 154 µmol m−2 s−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In ‘Yellow Pear’, the upper surface of the calyx had an ETR of 154 µmol m−2 s−1”
t0“tomato fruit”
Claim · model-written summary
In Yellow Pear the lower calyx surface had ETR of 88 µmol m−2 s−1.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- lower surfacee0
- Outcome
- ETRe0
- Value
- 88 µmol m−2 s−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the lower surface had an ETR of 88 µmol m−2 s−1”
t0“tomato fruit”
Claim · model-written summary
Green shoulder ETR was 203 µmol m−2 s−1.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- green shouldere0
- Outcome
- ETRe0
- Value
- 203 µmol m−2 s−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On the green shoulder, ETR was 203 µmol m−2 s−1”
t0“tomato fruit”
Claim · model-written summary
Distal pericarp ETR was 97 µmol m−2 s−1.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- pericarp distal to the green shouldere0
- Outcome
- ETRe0
- Value
- 97 µmol m−2 s−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the pericarp distal to the green shoulder, ETR was 97 µmol m−2 s−1”
t0“tomato fruit”
Claim · model-written summary
Locular parenchyma ETR was 66 µmol m−2 s−1.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- locular parenchymae0
- Outcome
- ETRe0
- Value
- 66 µmol m−2 s−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the locular parenchyma, ETR was 66 µmol m−2 s−1”
t0“tomato fruit”
Claim · model-written summary
Lower ETR tissues had a faster decrease in qP.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- tissuese0
- Outcome
- photochemical quenching coefficient qPe0
- Direction
- faster decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when tissues displayed reduced levels of ETR they also displayed a faster decrease in the photochemical quenching coefficient qP”
t0“tomato fruit”
Claim · model-written summary
Lower ETR tissues diverted absorbed energy more rapidly to non-photochemical pathways.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- tissuese0
- Outcome
- diversion of absorbed photon energy to non-photochemical pathwayse0
- Direction
- more rapide0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when tissues displayed reduced levels of ETR they also displayed a faster decrease in the photochemical quenching coefficient qP and a more rapid diversion of absorbed photon energy to non-photochemical pathways”
t0“tomato fruit”
Claim · model-written summary
Locular parenchyma had much lower qP than pericarp at equivalent PFD.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- qP levelse0
- Direction
- much lowere0
- Qualifier
- equivalent levels of PFDe0
- Comparator
- pericarpe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under equivalent levels of PFD the qP levels in this tissue were much lower than those in the pericarp”
t0“tomato fruit”
Claim · model-written summary
Locular parenchyma and pericarp had similar qN levels.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- qN levelse0
- Direction
- similare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“qN levels were similar”
t0“tomato fruit”
Claim · model-written summary
The authors attributed lower locular parenchyma ETR to lower electron-use capacity.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- lower ETR of the locular parenchymae0
- Qualifier
- lower capacity to utilize electrons generated from water splittinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the lower ETR of the locular parenchyma was due to a lower capacity to utilize electrons generated from water splitting”
t0“tomato fruit”
Claim · model-written summary
Photosynthetic activity in all four tissues suggests contributions to CO2 scavenging and carbon assimilates.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- calyx, green shoulder, pericarp, and locular parenchymae0
- Outcome
- CO2 scavenging and the provision of carbon assimilatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The levels of photosynthetic activity found in the calyx, green shoulder, pericarp, and locular parenchyma suggest that all of these tissues have significant roles in CO2 scavenging and the provision of carbon assimilates”
t0“tomato fruit”