Antifungal Activity and Effect of Plant-Associated Bacteria on Phenolic Synthesis of Quercus robur L

Svitlana Bilous; Artur Likhanov; Vira Boroday; Yurii Marchuk; Liubov Zelena; Oleksandr Subin; Andrii Bilous

doi:10.3390/plants12061352

Antifungal Activity and Effect of Plant-Associated Bacteria on Phenolic Synthesis of Quercus robur L

Plants (Basel). 2023 Mar 17;12(6):1352. doi: 10.3390/plants12061352.

Authors

Svitlana Bilous^{1

2

3}, Artur Likhanov^{1

2}, Vira Boroday¹, Yurii Marchuk¹, Liubov Zelena⁴, Oleksandr Subin⁵, Andrii Bilous¹

Affiliations

¹ Education and Research Institute of Forestry and Landscape-Park Management, National University of Life and Environmental Sciences of Ukraine, 03041 Kyiv, Ukraine.
² Institute for Evolutionary Ecology NAS of Ukraine, 37 Lebedeva Str., 03143 Kiev, Ukraine.
³ Forestry Department, Weihenstephan-Triesdorf University of Applied Sciences, Germany, Hans-Carl-von-Carlowitz-Platz 3, 85354 Freising, Germany.
⁴ Danylo Zabolotny Institute of Microbiology and Virology National Academy of Sciences of Ukraine, 154 Zabolotnogo Str., 03143 Kyiv, Ukraine.
⁵ State Enterprise "State Centre of Agricultural Products Certification and Examination", Janusha Korchaka Str. 9/12, 03143 Kyiv, Ukraine.

Abstract

Europe's forests, particularly in Ukraine, are highly vulnerable to climate change. The maintenance and improvement of forest health are high-priority issues, and various stakeholders have shown an interest in understanding and utilizing ecological interactions between trees and their associated microorganisms. Endophyte microbes can influence the health of trees either by directly interacting with the damaging agents or modulating host responses to infection. In the framework of this work, ten morphotypes of endophytic bacteria from the tissues of unripe acorns of Quercus robur L. were isolated. Based on the results of the sequenced 16S rRNA genes, four species of endophytic bacteria were identified: Bacillus amyloliquefaciens, Bacillus subtilis, Delftia acidovorans, and Lelliottia amnigena. Determining the activity of pectolytic enzymes showed that the isolates B. subtilis and B. amyloliquefaciens could not cause maceration of plant tissues. Screening for these isolates revealed their fungistatic effect against phytopathogenic micromycetes, namely Fusarium tricinctum, Botrytis cinerea, and Sclerotinia sclerotiorum. Inoculation of B. subtilis, B. amyloliquefaciens, and their complex in oak leaves, in contrast to phytopathogenic bacteria, contributed to the complete restoration of the epidermis at the sites of damage. The phytopathogenic bacteria Pectobacterium and Pseudomonas caused a 2.0 and 2.2 times increase in polyphenol concentration in the plants, respectively, while the ratio of antioxidant activity to total phenolic content decreased. Inoculation of Bacillus amyloliquefaciens and Bacillus subtilis isolates into oak leaf tissue were accompanied by a decrease in the total pool of phenolic compounds. The ratio of antioxidant activity to total phenolic content increased. This indicates a qualitative improvement in the overall balance of the oak leaf antioxidant system induced by potential PGPB. Thus, endophytic bacteria of the genus Bacillus isolated from the internal tissues of unripe oak acorns have the ability of growth biocontrol and spread of phytopathogens, indicating their promise for use as biopesticides.

Keywords: antagonistic activity; endophytic bacteria; oak; polyphenols.

Grants and funding

The research was carried out with the funds of the Ministry of Education and Culture of Ukraine: grant No. 110/540 (0117U004402) 2017–2019 “Biotechnological ways of preserving the gene pool of historically valuable centuries-old trees” (leader—S. Bilous); grant No. 37 (Basic funding) “Agrarian sciences and veterinary medicine” 2021 (leader—A. Likhanov); and grant No. 110/14-pr-2022 “Innovative solutions for measuring the quality of hardwood wood for forecasting and organizing the integrated use of forest resources” (leader—R. Vasylyshyn, co-leader—A. Likhanov, co-inventor—S. Bilous).