Global Change Research Institute of the Czech Academy of Sciences, Bělidla 4a, 603 00 Brno, Czech Republic.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Nov 15;281:121531. doi: 10.1016/j.saa.2022.121531. Epub 2022 Jun 20.
Probing insights into understanding photosynthetic processes via non-invasive means has an added advantage when used in phenotyping or precision agriculture. We employed Raman spectroscopy and fluorescence-based methods to investigate both the changes in the photosynthetic processes and the underlying protective mechanisms on Arabidopsis thaliana wild-type (WT), and ros1, which is a mutant of a repressor of transcriptional gene silencing, both grown under low light (LL: 100 μmol ms) and high light (HL: 400 μmol ms) regimes. Raman imaging detected a lower carotenoid intensity after two weeks in those plants grown under HL, compared to those grown under the LL regime; we interpret this as the result of oxidative damage of β-carotene molecules. Further, the data revealed a significant depletion in carotenoids with enhanced phenolics around the midrib and tip of the WT leaves, but not in the ros1. On the contrary, small necrotic zones appeared after two weeks of HL in the ros1 mutant, pointing to the starting oxidative damage. The lower maximum quantum yield of the photochemistry (F/F) in the WT as well as in the ros1 mutant grown in HL (compared to those in the LL two weeks post-exposure), indicates the HL partially inactivated photosystems. Chlorophyll a fluorescence imaging further showed high non-photochemical quenching (NPQ) in the plants grown under the HL regime for both the WT and the ros1 mutant, but the spatial heterogeneity of NPQ images was much higher in the HL-grown ros1 mutant. Fluorescence screening methods revealed significantly high values of chlorophyll proxies in the WT as well as in the ros1 mutant two weeks after in the HL compared to those under LL. The data generally revealed an increased accumulation of phenolics under HL in both the WT and ros1 mutant plants, but the proxies of anthocyanin and flavonols were significantly lower in the ros1 mutant than in the WT. The comparatively low accumulation of anthocyanin in the ros1 mutant compared to the WT supports the Raman data. We conclude that integrated use of these techniques can be efficiently applied for a better understanding of insights into photosynthetic mechanisms.
通过非侵入性手段深入了解光合作用过程具有附加优势，尤其在表型分析或精准农业中。我们采用拉曼光谱和荧光方法研究了拟南芥野生型（WT）和转录基因沉默抑制剂突变体 ros1 在低光（LL：100 μmol ms）和高光（HL：400 μmol ms）条件下光合作用过程的变化及其潜在的保护机制。拉曼成像检测到在高光条件下生长两周后，与在低光条件下生长的植物相比，类胡萝卜素的强度较低；我们将其解释为β-胡萝卜素分子氧化损伤的结果。此外，数据显示 WT 叶片中叶脉和叶尖周围的类黄酮显著减少，而 ros1 则没有。相反，在 HL 条件下生长两周后，ros1 突变体出现了小的坏死区，表明氧化损伤开始。与 HL 条件下生长的 WT 和 ros1 突变体相比，WT 和 ros1 突变体在 HL 条件下的光合作用最大量子产量（F/F）较低（与暴露后两周的 LL 相比），这表明 HL 部分失活了光系统。叶绿素 a 荧光成像进一步显示，WT 和 ros1 突变体在 HL 条件下生长时的非光化学猝灭（NPQ）较高，但在 HL 条件下生长的 ros1 突变体的 NPQ 图像空间异质性更高。荧光筛选方法显示，与 LL 条件相比，HL 条件下生长的 WT 和 ros1 突变体两周后叶绿素的荧光代理值明显较高。总的来说，在 HL 条件下，WT 和 ros1 突变体植物中积累了更多的类黄酮，但 ros1 突变体中的花青苷和类黄酮的荧光代理值明显低于 WT。与 WT 相比，ros1 突变体中花青苷的积累较低，这与拉曼数据一致。我们得出的结论是，这些技术的综合应用可以有效地用于深入了解光合作用机制。
