The Variation of Selected Physiological Parameters in Elm Leaves (Ulmus glabra Huds.) Infested by Gall Inducing Aphids.

Katarzyna Kmieć,Edyta Górska-Drabik,Izabela Kot,Katarzyna Golan,Hubert Sytykiewicz,Katarzyna Rubinowska

doi:10.3390/plants11030244

Abstract

Three aphid species, Eriosoma ulmi (L.), Colopha compressa (Koch) and Tetraneura ulmi (L.) induce distinct gall morphotypes on Ulmus glabra Huds.; opened and closed galls. Because the trophic relationship of aphids and their galls shows that throughout the gall formation aphids can elicit multiple physiological regulations, we evaluated the changes of hydrogen peroxide content (H2O2), cytoplasmic membrane condition, expressed as electrolyte leakage (EL) and concentration of thiobarbituric acid reactive substances (TBARS), as well as, the activity of catalase (CAT), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) in gall tissues, as well as, in damaged and undamaged parts of galled leaves. All aphid species increased EL from gall tissues and significantly upregulated APX activity in galls and galled leaves. Alterations in H2O2 and TBARS concentrations, as well as GPX and CAT activities, were aphid- and tissue-dependent. The development of pseudo- and closed galls on elm leaves did not have a clear effect on the direction and intensity of the host plant’s physiological response. The different modes of changes in H2O2, TBARS, CAT and GPX were found in true galls of C. compressa and T. ulmi. Generally, physiological alterations in new plant tissues were quite different compared to other tissues and could be considered beneficial to galling aphids.

Highlights

Host plants and insects interact at various levels, and gall formation is seen as a unique and extreme form of relationship
Many phytophagous species possess the ability to interfere with the tissues of their host plants to produce galls, which are often highly specialized structures [1,3]
Recent studies indicated that host plant physiological response to galling aphids is not unequivocal and depends on the insect species

Summary

Introduction

Host plants and insects interact at various levels, and gall formation is seen as a unique and extreme form of relationship. Colopha compressa (Koch), Eriosoma ulmi (L.) and Tetraneura ulmi (L.) aphids have complex life cycles, with alternating sexual and parthenogenetic generations In the spring, they induce galls on the leaf surfaces of various elm (Ulmus spp.) species as the primary host. Guaiacol peroxidase (GPX) is a member of a large multigenic heme-containing enzyme family that controls ROS generation when plants are challenged with various stressors [23] It oxidizes a variety of phenolic compounds and participates in a broad range of physiological processes, like auxin catabolism, lignification and degradation of the cell wall [24]. A similar pattern of host plant physiological reactions caused by C. compressa and T. ulmi feeding was expected, as both aphid species stimulate plant tissue to produce true (closed) galls on the upper side of the leaf blade, as opposed to E. ulmi, which induces pseudogalls

Plant Material and Samplings

Assay of Antioxidant Enzymes Activities

Data Analysis

Results

Activity of Antioxidant Enzymes

Discussion