The influence of ultraviolet radiation on plant-insect interactions [Elektronische Ressource] / vorgelegt von Franziska Kuhlmann

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• Publié par: julius-maximilians-universitat_wurzburg
• Publié le: 01 janvier 2009
• Nombre de lectures: 27
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

The influence of ultraviolet radiation on
plant-insect interactions



Dissertation zur Erlangung
des naturwissenschaftlichen Doktorgrades
der Julius-Maximilians-Universität Würzburg


vorgelegt von
Franziska Kuhlmann
aus Pirna






Würzburg 2009




















Eingereicht am: ……………………………………………………..

Mitglieder der Promotionskommission
Vorsitzender: ……………………………………………………..
Erstgutachterin: Prof. Dr. Caroline Müller, Universität Bielefeld
Zweitgutachter: Prof. Dr. Markus Riederer, Universität Würzburg

Tag des Promotionskolloquiums: ……………………………………………………..
Promotionsurkunde ausgehändigt am:…………………………………………………….
Contents
1 Synopsis.................................................................................................................... 7
1.1 Sunlight and ultraviolet (UV) radiation – Plant responses to UV radiation ..... 7
1.2 UV radiation and insect feeding ..................................................................... 12
1.3 The characteristic secondary metabolites of Brassicaceae – Glucosinolates . 14
1.4 Glucosinolates and insect feeding................................................................... 15
1.5 Different feeding strategies of insects affect plant-insect-interactions
differently........................................................................................................ 17
1.6 Aims of the study............................................................................................ 19
1.7 Future prospects.............................................................................................. 22
1.8 References....................................................................................................... 24
2 Chapter I................................................................................................................ 33
Development-dependent effects of UV radiation exposure on broccoli plants and
interactions with herbivorous insects.......................................................................... 33
2.1 Introduction..................................................................................................... 35
2.2 Methods and materials .................................................................................... 37
2.3 Results............................................................................................................. 41
2.4 Discussion....................................................................................................... 48
2.5 Conclusion ...................................................................................................... 50
2.6 References....................................................................................................... 51
3 Chapter II .............................................................................................................. 57
Independent responses to ultraviolet radiation and herbivore attack in broccoli.. 57
3.1 Introduction..................................................................................................... 59
3.2 Material and methods...................................................................................... 61
3.3 Results............................................................................................................. 63
3.4 Discussion....................................................................................................... 68
3.5 References....................................................................................................... 71 4 Chapter III.............................................................................................................77
UV-B impact on aphid performance mediated by plant quality and plant changes
induced by aphids..........................................................................................................77
4.1 Introduction .....................................................................................................79
4.2 Materials and Methods ....................................................................................80
4.3 Results .............................................................................................................85
4.4 Discussion .......................................................................................................91
4.5 References .......................................................................................................94
5 Appendix ................................................................................................................99
5.1 Plant chemistry..............................................................................................100
5.2 Aphid proliferation........................................................................................105
5.3 References .....................................................................................................106
Summary ......................................................................................................................107
Zusammenfassung.......................................................................................................110
Publications, poster and oral presentations..............................................................114
Curriculum vitae .........................................................................................................115
Danksagung..................................................................................................................117
Erklärung.....................................................................................................................119
Synopsis
Abiotic and biotic environmental conditions determine development, physiology and
life history of plants. The phenotypic plasticity enables plants to respond, adjust and
acclimatise to a changing environment. Thereby plants are capable to react with short
and long term plastic morphological and chemical responses (Lichtenthaler, 1998;
Sultan, 2000). Consequently, specific signal perception and transduction mechanisms
need to be highly developed. UV induced changes in plants potentially influence the
next trophic levels such as herbivores and parasitoids and may have the ability to shift
plant-insect interactions.
1.1 Sunlight and ultraviolet (UV) radiation – Plant responses to UV
radiation
Plants need to capture sunlight (Fig. 1.1.1) for photosynthesis. Therefore sunlight is an
essential and unavoidable environmental factor in plants’ life. The most energetic
fraction of solar radiation reaching the biosphere is UV-B (280-315 nm) which is
primarily absorbed by the stratospheric ozone layer. Other factors affecting UV-B
radiation intensities on earth are the angle of sun rays, cloud cover, season, aerosols,
altitude, surface reflectance, shading and plant canopies (Madronich et al., 1998;
McKenzie et al., 2003; Paul and Gwynn-Jones, 2003; Jenkins and Brown, 2007).
Wavelengths reaching the biosphere
PAR
UV-C UV-B UV-A Blue Red Far-red
200 280 315 400 500 600 700 800 nm

Fig. 1.1.1 Fractions of sunlight that reach the earth’s surface are ultraviolet-B (UV-B, 280-315 nm),
ultraviolet-A (UV-A, 315-400 nm), photosynthetic active radiation (PAR; 400-700 nm) and infrared (700
nm-1 mm) radiation (Frohnmeyer and Staiger, 2003; Paul and Gwynn-Jones, 2003).
UV-B radiation can cause damage to DNA, proteins and lipids, generate reactive
oxygen species (ROS) and alter hormone levels. Therefore rather effective mechanisms
for UV-protection and repair, including accumulation of protective phenolic compounds
and activation of repairing enzymes like DNA photolyases as well as the free-radical
scavenging system have evolved (Rozema et al., 1997; Jansen et al., 1998; Frohnmeyer
and Staiger, 2003). The magnitude of stress for the individual plant might depend on the 8
ecological context of the species, on its developmental stage and on the level of
acclimation to and on the quantity of UV-B. In natural environments symptoms of UV-
damage are rare. Therefore plants must have a highly elaborate system of UV
perception and signal transduction that enables plants to adjust to their surrounding
radiation challenges, even though UV-B receptors still have not been identified yet
(Frohnmeyer and Staiger, 2003; Jenkins and Brown, 2007; Brown and Jenkins, 2008). It
is presumed that two fluence rate dependent non-specific (stress) and UV-B specific
(photomorphogenic) signalling pathways might exist (Frohnmeyer and Staiger, 2003;
Ulm and Nagy, 2005; Jenkins and Brown, 2007; Brown and Jenkins, 2008), whereas
UV-B specific responses do not result from DNA damage or stress (Brown and Jenkins,
2008; Safrany et al., 2008). The chalcone synthase is the key enzyme for the
biosynthesis of phenylpropanoids and is believed to be the terminal step of a UV-B
signalling pathway (Safrany et al., 2008).
UV-A radiation (315-400nm) is not absorbed by the ozone layer and is present at much
higher intensities in sunlight than UV-B radiation. UV-A can impact