Detection and Microscopy of Alnus glutinosa Pollen Fluorescence Peculiarities

Abstract

Alnus glutinosa is an important woody plant in Lithuanian forest ecosystems. Knowledge of fluorescence properties of black alder pollen is necessary for scientific and practical purposes. By the results of the study, we aimed to evaluate possibilities of identifying Alnus glutinosa pollen fluorescence properties by modeling ozone effect and applying two different fluorescence-based devices. To implement the experiments, black alder pollen was collected in a typical habitat during the annual flowering period in 2018–2019. There were three groups of experimental variants, which differed in the duration of exposure to ozone, conditions of pollen storage before the start of the experiment, and the exposure time. Data for pollen fluorescence analysis were collected using two methods. The microscopy method was used in order to evaluate the possibility of employing image analysis systems for investigation of pollen fluorescence. The second data collection method is related to an automatic device identifying pollen in real time, which uses the fluorescence method in the pollen recognition process. Data were assessed employing image analysis and principal component analysis (PCA) methods. Digital images of ozone-exposed pollen observed under the fluorescence microscope showed the change of the dominant green colour toward the blue spectrum. Meanwhile, the automatic detector detects more pollen whose fluorescence is at the blue light spectrum. It must be noted that assessing pollen fluorescence several months after exposure to ozone, no effect of ozone on fluorescence remains.

Patterns of Phenolic Compounds in Betula and Pinus Pollen

“…The inner layers of the exine of Pinus pollen strictly control the permeability of carbohydrates to the central part, it is likely that there is also a serious barrier to the entry of water, alcohols, ampholytes and cations into the pollen [ 30 ], and compounds of higher molecular weight, including phenolic compounds, can enter only after rupture of the exine [ 8 , 57 ]. However, pollen stored for a long time loses some of its properties [ 58 ], the ability of pollen to release cytoplasmic contents to the environment weakens [ 39 ]. Forced release of Pinus pollen content into the environment requires stressful conditions: pressure and processing of pollen with inorganic acids, but even after Pinus pollen bursts, the spilled content is likely to remain enveloped in the intina layer [ 30 ].…”

Clustering approach for the analysis of the fluorescent bioaerosol collected by an automatic detector

“…The use of clusters for the analysis of fluorescent aerosol has supplemented the results of our previous studies [13,47] and provided new knowledge on the use of the automatic detector for operational information on airborne pollen concentration. Occasionally, authors [5,6,13] encounter unexplained cases due to specific identification issues related to pollen features.…”

“…Our openness strategy allows anyone to benefit from laboratory experiments data of tested pollen with the Rapid-E device [ 31 , 32 ]. The developed digital data library is valuable material [ 13 , 47 ] and allows successfully improve the knowledge on the features of particles present in the atmospheric bioaerosol. This study has revealed that the clustering of pollen data in the stage of identification is valuable in various aspects.…”

“…In this study, clusters of pollen from the same taxa originated in different geographical areas is not compared but plan to do this in the future. We previously observed that the fluorescence properties of Alnus pollen change due to ozone exposure [ 47 ]. It is also known about Fagaceae high species‐specific differences in pollen’s chemical composition and high phenotypic plasticity due to either location or year [ 50 ].…”