State Key Lab of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong Province, China.
Sci Rep. 2018 Mar 9;8(1):4253. doi: 10.1038/s41598-018-22486-4.
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 CO assimilation, and the effect of BPA on PSII photoinhibition disappeared when the CO assimilation was blocked. The HO accumulated in BPA-treated leaves under light. And the BPA-caused PSII photoinhibition was prevented under low (2%) O. 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 CO assimilation and over-reduces the electron transport chain under light, which increases the production of reactive oxygen species (HO), the over-accumulated ROS inhibits the turnover of D1 protein and consequently aggravates PSII photoinhibition.
双酚 A（BPA）是一种广泛分布的污染物，它会抑制叶片中的光合作用。在以往对高等植物的研究中，通常通过灌溉根部的方式来处理植物，以使其接触 BPA。这种方法无法区分 BPA 是直接抑制叶片中的光合作用，还是通过影响根部功能间接影响光合作用。在这里，我们仅用 BPA 溶液浸润黄瓜的叶片而不浸润根部。在黑暗条件下，BPA 对光系统 II 和光系统 I（PSII、PSI）不敏感。在光照条件下，BPA 加重了 PSII 但没有加重 PSI 的光抑制。BPA 还抑制了 CO 同化，当 CO 同化被阻断时，BPA 对 PSII 光抑制的影响消失。HO 在光照下积聚在 BPA 处理的叶片中。在低（2%）O 下，BPA 引起的 PSII 光抑制得到缓解。我们还证明了 BPA 引起的 PSII 光抑制依赖于 D1 蛋白的周转。总之，这项研究证明 BPA 可以直接抑制叶片中的光合作用，但它不会直接损伤 PSII，而是在光照下抑制 CO 同化和过度还原电子传递链，从而增加活性氧物种（HO）的产生，积累的过量 ROS 抑制 D1 蛋白的周转，进而加重 PSII 光抑制。
