Effect of Defoliation on the Defense Reactions of Silver Birch (<i>Betula pendula</i>) Infected with <i>Phytophthora plurivora</i>

• Main Authors: Daria Berezovska, Tomasz Oszako, Tadeusz Malewski, Marcin Stocki, Aleh Marozau, Natalia Stocka, Warren Keith Moser, Larry Scott Baggett, Lassaad Belbahri, Justyna Anna Nowakowska
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Forests
• Subjects: plant pathogens; defoliation; leaf damage; chlorophyll fluorescence; heat shock proteins (<i>Hsps</i>); roots
• Online Access: https://www.mdpi.com/1999-4907/12/7/910

In natural environments, plants develop adaptive mechanisms at the cellular and molecular levels to cope with many external factors, e.g., insects and soil pathogens. We studied physiological stress induced by different levels of foliage removal (defoliation 30% and 60%) and by infection of root rot pathogen <i>Phytophthora plurivora</i> on the common Polish tree species, <i>Betula pendula</i>, grown in an open greenhouse. This study showed that <i>P. plurivora</i> damaged the root system which negatively impacted all morphological parameters. However the loss of 30% of the leaves had a positive effect on defense responses. Chlorophyll-a fluorescence parameters indicated a decrease in photosynthetic efficiency in defoliated plants, but plants inoculated with the pathogen had a higher performance index showing increased vigor of the infected plant than birches. The study demonstrated the intense immunity response of birch to <i>P. plurivora</i> through the expression of <i>Hsp</i>90 and <i>Hsp</i>83 genes. The trees weakened by <i>P. plurivora</i> became more susceptible to infection by <i>Erysiphe ornata</i> var. <i>ornata</i>.