Original Research ARTICLE
Barley yellow dwarf virus infection leads to higher chemical defence signals and lower electrophysiological reactions in susceptible compared to tolerant barley genotypes
- 1Institute of Genereal Botany and Plant Physiology, Friedrich Schiller Universität Jena, Germany
- 2Biochemistry, Max Planck Institute for Chemical Ecology (MPG), Germany
- 3Elms College, United States
- 4Federal Research Centre for Cultivated Plants, Julius Kühn-Institut, Germany
Barley yellow dwarf virus (BYDV) is a phloem limited virus that is persistently transmitted by aphids. Due to huge yield losses in agriculture, the virus is of high economic relevance. Since the control of the virus itself is not possible, tolerant barley genotypes are considered as the most effective approach to avoid yield losses. Although several genes and quantitative trait loci are known and used in barley breeding for virus tolerance, little is known about molecular and physiological backgrounds of this trait. Therefore, we compared the anatomy and early defence responses of a virus susceptible to those of a virus-tolerant cultivar.
One of the very early defence responses is the transmission of electrophysiological reactions. Electrophysiological reactions to BYDV infection might differ between susceptible and tolerant cultivars, since BYDV causes disintegration of sieve elements in susceptible cultivars. The structure of vascular bundles, xylem vessels and sieve elements was examined using microscopy. All three were significantly decreased in size in infected susceptible plants where the virus causes disintegration of sieve elements. This could be associated with an uncontrolled ion exchange between the sieve-element lumen and apoplast. Further, a potential reduced electrophysiological isolation would negatively affect the propagation of electrophysiological reactions. To test the influence of BYDV infection on electrophysiological reactions, electropotential waves (EPWs) induced by leaf-tip burning were recorded using aphids as bioelectrodes. EPWs in infected susceptible plants disappeared already after 10 cm in contrast to those in healthy susceptible or infected tolerant or healthy tolerant plants. Another early plant defence reaction is an increase in reactive oxygen species (ROS). Using a fluorescent dye, we found a significant increase in ROS content in infected susceptible plants but not in infected tolerant plants. Similar results were found for the phytohormones abscisic acid and three jasmonates. Salicylic acid levels were generally higher after BYDV infection compared to uninfected plants. Heat stimulation caused an increase in jasmonates. By shedding light on the plant defence mechanisms against BYDV, this study, provides further knowledge for breeding viral tolerant plants.
Keywords: Barley yellow dwarf virus, electrical penetration graph, Electropotential waves, Phloem, phytohormones, Reactive Oxygen Species, sieve element, Xylem
Received: 06 Oct 2017;
Accepted: 25 Jan 2018.
Edited by:Vicenta Salvador Recatala, Ronin Institute, United States
Reviewed by:Stefanie Wienkoop, University of Vienna, Austria
Michael R. Thorpe, Australian National University, Australia
Copyright: © 2018 Paulmann, Kunert, Zimmermann, Theis, Ludwig, Meichsner, Oelmüller, Gershenzon, Habekuß, Ordon, Furch and Will. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Alexandra C. Furch, Friedrich Schiller Universität Jena, Institute of Genereal Botany and Plant Physiology, Dornburger Strasse 159, Jena, 07743, Germany, Alexandra.Furch@uni-jena.de