Abstract
Bisphenol A (BPA), a widely distributed pollutant, suppresses photosynthesis in leaves. In previous studies on higher plants, the plants were treated by BPA through irrigation to root. This method cannot distinguish whether the BPA directly suppresses photosynthesis in leaves, or indirectly influences photosynthesis through affecting the function of root. Here, only the leaves but not the roots of cucumber were infiltrated with BPA solution. The photosystem II and I (PSII, PSI) were insensitive to BPA under darkness. BPA aggravated the PSII but not the PSI photoinhibition under light. BPA also inhibited CO2 assimilation, and the effect of BPA on PSII photoinhibition disappeared when the CO2 assimilation was blocked. The H2O2 accumulated in BPA-treated leaves under light. And the BPA-caused PSII photoinhibition was prevented under low (2%) O2. We also proved that the BPA-caused PSII photoinhibition depend on the turnover of D1 protein. In conclusion, this study proved that BPA could directly suppress photosynthesis in leaves, however, BPA does not damage PSII directly, but inhibits CO2 assimilation and over-reduces the electron transport chain under light, which increases the production of reactive oxygen species (H2O2), the over-accumulated ROS inhibits the turnover of D1 protein and consequently aggravates PSII photoinhibition.
Highlights
Bisphenol A (2,2-bis (4-hydroxyphenyl) propane; BPA) is an intermediate compound used to produce epoxy resins, polycarbonates, polyesters, and coatings, and its global production is 5,500,000 tons per year in 20111
To explore whether the BPA has the direct effect on photosynthetic apparatus, the leaves were infiltrated with BPA solution
To verify the mechanisms by which BPA affects the photosynthesis, the leaves were infiltrated with BPA and exposed to high light under different environmental conditions to measure the activity of the photosynthetic, reactive oxygen species (ROS) content, and scavenging enzymes of ROS in leaves
Summary
Bisphenol A (2,2-bis (4-hydroxyphenyl) propane; BPA) is an intermediate compound used to produce epoxy resins, polycarbonates, polyesters, and coatings, and its global production is 5,500,000 tons per year in 20111. BPA obviously restrains the biosynthesis of chlorophyll[6] and restrains photosynthesis[7] It decreases the biomass of shoot, leaf area and net photosynthetic rate[8]. The BPA absorbed by root can be transferred to shoot and it would enrich in the leaf blade, which maybe interfere with the photosynthesis in leaves. The aim of the paper is to confirm that if the BPA could direct damage the photosynthetic apparatus in leaves independent of the root, and the mechanisms by which BPA affect the photosynthetic apparatus. It will expand our understanding of the impact of BPA on the plants, environmental and ecological. To verify the mechanisms by which BPA affects the photosynthesis, the leaves were infiltrated with BPA and exposed to high light under different environmental conditions to measure the activity of the photosynthetic, reactive oxygen species (ROS) content, and scavenging enzymes of ROS in leaves
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