Abstract
Chloroplast movement rapidly ameliorates the effects of suboptimal light intensity by accumulating along the periclinal cell walls, as well as the effects of excess light by shifting to the anticlinal cell walls. These acclimation responses are triggered by phototropins located at the plasma membrane and chloroplast envelope. Here, we used a recently developed non-invasive system sensitive to very small changes in red light leaf transmittance to perform long-term continuous measurements of dark–light transitions. As a model system, we used variegated Pelargonium zonale leaves containing green sectors (GS) with fully developed chloroplasts and achlorophyllous, white sectors (WS) with undifferentiated plastids, and higher phototropin expression levels. We observed biphasic changes in the red-light transmittance and oscillations triggered by medium intensities of white light, described by a transient peak preceded by a constant decrease in transmittance level. A slight change in red-light transmittance was recorded even in WS. Furthermore, the chloroplast position at lower light intensities affected the rapid light curves, while high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids. Our results extend the knowledge of light-dependent chloroplast movements and thus contribute to a better understanding of their role in regulating photosynthesis under fluctuating light conditions.
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Claims 5
Claim · model-written summary
Biphasic changes in red-light transmittance and oscillations were observed under medium intensities of white light.
- Taxon
- Pelargonium zonale
Pelargonium zonalet0
- Treatment
- medium intensities of white lighte1
- Outcome
- biphasic changes in the red-light transmittancee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Variegated Pelargonium zonale”
e1“We observed biphasic changes in the red-light transmittance and oscillations triggered by medium intensities of white light”
Claim · model-written summary
A slight change in red-light transmittance was recorded even in white sectors.
- Taxon
- Pelargonium zonale
- Organ / stage
- WSe2
- Outcome
- slight change in red-light transmittancee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Variegated Pelargonium zonale”
e2“A slight change in red-light transmittance was recorded even in WS”
Claim · model-written summary
Chloroplast position at lower light intensities affected the rapid light curves.
- Taxon
- Pelargonium zonale
- Treatment
- lower light intensitiese3
- Outcome
- rapid light curvese3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Variegated Pelargonium zonale”
e3“the chloroplast position at lower light intensities affected the rapid light curves”
Claim · model-written summary
High light intensity decreased saturated electron transport and maximum quantum efficiency of photosystem II.
- Taxon
- Pelargonium zonale
- Treatment
- high light intensitye4
- Outcome
- saturated electron transport, maximum quantum efficiency of photosystem IIe4
- Direction
- decreasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Variegated Pelargonium zonale”
e4“high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids”
Claim · model-written summary
High light intensity increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids.
- Taxon
- Pelargonium zonale
- Treatment
- high light intensitye4
- Outcome
- non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoidse4
- Direction
- increasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Variegated Pelargonium zonale”
e4“high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids”