Falcioni Renan, Antunes Werner Camargos, Demattê José A M, Nanni Marcos Rafael
Department of Agronomy, State University of Maringá, Av. Colombo, 5790, Maringá 87020-900, Paraná, Brazil.
Department of Soil Science, Luiz de Queiroz College of Agriculture, University of São Paulo, Av. Pádua Dias, 11, Piracicaba 13418-260, São Paulo, Brazil.
Biology (Basel). 2023 May 11;12(5):704. doi: 10.3390/biology12050704.
The adjustments that occur during photosynthesis are correlated with morphological, biochemical, and photochemical changes during leaf development. Therefore, monitoring leaves, especially when pigment accumulation occurs, is crucial for monitoring organelles, cells, tissue, and whole-plant levels. However, accurately measuring these changes can be challenging. Thus, this study tests three hypotheses, whereby reflectance hyperspectroscopy and chlorophyll a fluorescence kinetics analyses can improve our understanding of the photosynthetic process in (L.) A. Juss, a plant with variegated leaves and different pigments. The analyses include morphological and pigment profiling, hyperspectral data, chlorophyll a fluorescence curves, and multivariate analyses using 23 JIP test parameters and 34 different vegetation indexes. The results show that photochemical reflectance index (PRI) is a useful vegetation index (VI) for monitoring biochemical and photochemical changes in leaves, as it strongly correlates with chlorophyll and nonphotochemical dissipation (Kn) parameters in chloroplasts. In addition, some vegetation indexes, such as the pigment-specific simple ratio (PSSRc), anthocyanin reflectance index (ARI1), ratio analysis of reflectance spectra (RARS), and structurally insensitive pigment index (SIPI), are highly correlated with morphological parameters and pigment levels, while PRI, moisture stress index (MSI), normalized difference photosynthetic (PVR), fluorescence ratio (FR), and normalized difference vegetation index (NDVI) are associated with photochemical components of photosynthesis. Combined with the JIP test analysis, our results showed that decreased damage to energy transfer in the electron transport chain is correlated with the accumulation of carotenoids, anthocyanins, flavonoids, and phenolic compounds in the leaves. Phenomenological energy flux modelling shows the highest changes in the photosynthetic apparatus based on PRI and SIPI when analyzed with Pearson's correlation, the hyperspectral vegetation index (HVI) algorithm, and the partial least squares (PLS) to select the most responsive wavelengths. These findings are significant for monitoring nonuniform leaves, particularly when leaves display high variation in pigment profiling in variegated and colorful leaves. This is the first study on the rapid and precise detection of morphological, biochemical, and photochemical changes combined with vegetation indexes for different optical spectroscopy techniques.
光合作用过程中发生的调节与叶片发育过程中的形态、生化和光化学变化相关。因此，监测叶片，尤其是在色素积累时，对于监测细胞器、细胞、组织和整株植物水平至关重要。然而，准确测量这些变化可能具有挑战性。因此，本研究检验了三个假设，即反射率高光谱学和叶绿素a荧光动力学分析可以增进我们对斑叶且含有不同色素的（L.）A. Juss植物光合作用过程的理解。分析包括形态和色素剖析、高光谱数据、叶绿素a荧光曲线，以及使用23个JIP测试参数和34个不同植被指数的多变量分析。结果表明，光化学反射指数（PRI）是监测叶片生化和光化学变化的有用植被指数（VI），因为它与叶绿体中的叶绿素和非光化学耗散（Kn）参数密切相关。此外，一些植被指数，如色素特异性简单比值（PSSRc）、花青素反射指数（ARI1）、反射光谱比值分析（RARS）和结构不敏感色素指数（SIPI），与形态参数和色素水平高度相关，而PRI、水分胁迫指数（MSI）、归一化差异光合（PVR）、荧光比值（FR）和归一化差异植被指数（NDVI）与光合作用的光化学组分相关。结合JIP测试分析，我们的结果表明，电子传递链中能量传递损伤的减少与叶片中类胡萝卜素、花青素、黄酮类化合物和酚类化合物的积累相关。基于PRI和SIPI，通过皮尔逊相关性分析、高光谱植被指数（HVI）算法和偏最小二乘法（PLS）选择最敏感波长时，现象学能量通量模型显示光合机构的变化最大。这些发现对于监测不均匀叶片具有重要意义，尤其是当叶片在斑叶和彩色叶片中色素剖析表现出高度变化时。这是第一项结合不同光学光谱技术的植被指数对形态、生化和光化学变化进行快速精确检测的研究。
