Phylloplane Biodiversity and Activity in the City at Different Distances from the Traffic Pollution Source

Abstract

The phylloplane is an integrated part of green infrastructure which interacts with plant health. Taxonomic characterization of the phylloplane with the aim to link it to ecosystem functioning under anthropogenic pressure is not sufficient because only active microorganisms drive biochemical processes. Activity of the phylloplane remains largely overlooked. We aimed to study the interactions among the biological characteristics of the phylloplane: taxonomic diversity, functional diversity and activity, and the pollution grade. Leaves of Betula pendula were sampled in Moscow at increasing distances from the road. For determination of phylloplane activity and functional diversity, a MicroResp tool was utilized. Taxonomic diversity of the phylloplane was assessed with a combination of microorganism cultivation and molecular techniques. Increase of anthropogenic load resulted in higher microbial respiration and lower DNA amount, which could be viewed as relative inefficiency of phylloplane functioning in comparison to less contaminated areas. Taxonomic diversity declined with road vicinity, similar to the functional diversity pattern. The content of Zn in leaf dust better explained the variation in phylloplane activity and the amount of DNA. Functional diversity was linked to variation in nutrient content. The fraction of pathogenic fungi of the phylloplane was not correlated with any of the studied elements, while it was significantly high at the roadsides. The bacterial classes Gammaproteobacteria and Cytophagia, as well as the Dothideomycetes class of fungi, are exposed to the maximal effect of distance from the highway. This study demonstrated the sensitivity of the phylloplane to road vicinity, which combines the effects of contaminants (mainly Zn according to this study) and potential stressful air microclimatic conditions (e.g., low relative air humidity, high temperature, and UV level). Microbial activity and taxonomic diversity of the phylloplane could be considered as an additional tool for bioindication.

Polycyclic Aromatic Hydrocarbon-Degrading Bacteria in Three Different Functional Zones of the Cities of Moscow and Murmansk

“…The leaf dust samples were taken from the surface of leaves of Betula pubescens Ehrh. (in the text, this is referred to as “leaf dust”) in accordance with the procedure that is described in [ 16 ]. In each functional zone, the birch leaves were sampled from 3 mature trees of the same age and physiological state.…”

“…The sample preparation of the leaf dust was performed as described in [ 37 ]. The bioinformatics analysis was performed as described in [ 16 ]. The raw read sequences were quality-trimmed while the adaptor sequences were removed using Trimmomatic v0.32360.…”

“…The main factor influencing the concentration of the PAHs on the plant tissues is considered to be the plant’s species, which is determined probably by the unique morphological and chemical features of the leaves at the species level [ 13 , 14 , 15 ]. The microbial community that is hosted by phylloplane, its activity, and its taxonomic structure was demonstrated to be sensitive to the distance from it to the pollution source in Betula pendula Roth, thereby making it a good indicator of the anthropogenic load [ 16 ]. In this study, we further explore the sensitivity of Betula’s phylloplane, extending the research to different climatic conditions, and taking into account the different functional zones of the cities.…”