Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China.
Mudanjang Institute of Tobacco Science, Harbin, China.
Ecotoxicol Environ Saf. 2021 Feb;209:111844. doi: 10.1016/j.ecoenv.2020.111844. Epub 2020 Dec 28.
Nitrogen dioxide (NO) is a major air pollutant that affects plant growth, development and yields. Previous studies have found that atmospheric NO changes plant photosynthesis in a concentration-dependent manner. Low concentrations of NO (4.0 μL L) can increase photosynthetic rates, while high concentrations of NO (16.0 μL L) can have an inhibitory effect. However, the specific effects of a critical intermediate concentration of NO on the photosynthetic apparatus of plants has remained unknown. Therefore, in this study, tobacco seedlings at three-leaf ages were fumigated with a intermediate concentration of 8.0 μL L NO for 15 days to determine the effects on leaf weight, leaf number per plant, chlorophyll content, net photosynthetic rate, the reaction center activity of photosystems I and II (PSI and PSII, respectively) and core protein gene expression (PsbA and PsaA). Fumigation with 8.0 μL L NO increased the number of leaves per plant and the weight of leaves, and the leaves became dark green and curly after 10 days of fumigation. During NO fumigation for 15 days, the chlorophyll content, PSII maximum photochemical efficiency (F/F), electron transfer rate (ETR) and non-photochemical quenching (NPQ) increased most in the oldest leaves (L leaves), but decreased PSI activity (∆I/I). The F/F, ETR and NPQ in the youngest leaves (L leaves) were lower than those of L leaves, but the actual photochemical efficiency (Φ) of PSII increased most and ∆I/I was the highest in these samples. The F/F, ETR, NPQ and Φ in the leaves at the middle leaf age (L leaves) were lower than those of L and L leaves, but the relative fluorescence intensity of point L (V) and the relative fluorescence intensity of point K (V) decreased the most in these samples. Thus, this critical concentration of atmospheric NO increased the activity of PSII and inhibited PSI activity in expanded leaves of tobacco seedlings.
二氧化氮（NO）是一种主要的空气污染物，会影响植物的生长、发育和产量。先前的研究发现，大气中 NO 以浓度依赖的方式改变植物的光合作用。低浓度的 NO（4.0 μL·L-1）可以提高光合速率，而高浓度的 NO（16.0 μL·L-1）则会产生抑制作用。然而，NO 的一个关键中间浓度对植物光合器官的具体影响仍不清楚。因此，本研究中，三叶期的烟草幼苗以 8.0 μL·L-1 的中间浓度 NO 处理 15 天，以确定其对叶片重量、单株叶片数、叶绿素含量、净光合速率、光系统 I 和 II 的反应中心活性（PSI 和 PSII）以及核心蛋白基因表达（PsbA 和 PsaA）的影响。8.0 μL·L-1 的 NO 处理增加了单株叶片数和叶片重量，处理 10 天后叶片呈深绿色卷曲。在 15 天的 NO 处理期间，最老叶（L 叶）的叶绿素含量、PSII 最大光化学效率（F/F）、电子传递速率（ETR）和非光化学猝灭（NPQ）增加最多，但 PSI 活性（∆I/I）下降。最幼叶（L 叶）的 F/F、ETR 和 NPQ 低于 L 叶，但 PSII 的实际光化学效率（Φ）增加最多，这些样本中的 ∆I/I 最高。中叶龄叶片（L 叶）的 F/F、ETR、NPQ 和 Φ 低于 L 和 L 叶，但这些样本中 L 点相对荧光强度（V）和 K 点相对荧光强度（V）的相对荧光强度下降最多。因此，大气中这个关键浓度的 NO 增加了烟草幼苗展开叶中 PSII 的活性并抑制了 PSI 活性。
