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An illustrated gardener's guide to transgenic Arabidopsis field experiments
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).ORCID iD: 0000-0002-7906-6891
2008 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 180, no 2, 545-555 p.Article in journal (Refereed) Published
Abstract [en]

Field studies with transgenic Arabidopsislines have been performed over 8 yr, to better understand the influence that certain genes have on plant performance. Many (if not most) plant phenotypes cannot be observed under the near constant, low-stress conditions in growth chambers, making field experiments necessary. However, there are challenges in performing such experiments: permission must be obtained and regulations obeyed, the profound influence of uncontrollable biotic and abiotic factors has to be considered, and experimental design has to be strictly controlled.

The aim here is to provide inspiration and guidelines for researchers who are not used to setting up such experiments, allowing others to learn from our mistakes. This is believed to be the first example of a ‘manual’ for field experiments with transgenic Arabidopsisplants. Many of the challenges encountered are common for all field experiments, and many researchers from ecological backgrounds are skilled in such methods. There is huge potential in combining the detailed mechanistic understanding of molecular biologists with ecologists’ expertise in examining plant performance under field conditions, and it is suggested that more interdisciplinary collaborations will open up new scientific avenues to aid analyses of the roles of genetic and physiological variation in natural systems.

Place, publisher, year, edition, pages
2008. Vol. 180, no 2, 545-555 p.
Keyword [en]
Arabidopsis thaliana, field experiments, fitness, herbivory, transgenic lines, variation
National Category
Botany
Research subject
Physiological Botany
Identifiers
URN: urn:nbn:se:umu:diva-3208DOI: 10.1111/j.1469-8137.2008.02591.xPubMedID: 18721164OAI: oai:DiVA.org:umu-3208DiVA: diva2:141709
Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Light, stress and herbivory: from photoprotection to trophic interactions using Arabidopsis thaliana as a model organism
Open this publication in new window or tab >>Light, stress and herbivory: from photoprotection to trophic interactions using Arabidopsis thaliana as a model organism
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Photosynthesis is the most important process for nearly all life on earth. Photosynthetic organisms capture and transfer light energy from the sun into chemical energy which in turn provides a resource base for heterotrophic organisms. Natural light regimes are irregular and vary over magnitudes. At a certain light intensity, metabolic processes cannot keep up with the electron flow produced by the primary photoreactions, and thus reactive oxygen species (ROS) are produced. ROS are highly reactive and can damage the photosynthesis apparatus and hence plants have evolved several photoprotection mechanisms to avoid the formation of ROS.

The aim of this thesis was to examine the ecological effects of variations in photoprotection in plants. In particular I wanted to study the effect on fitness and the interaction with herbivorous insects of plants with different ability in photoprotection. To study this I used wild-type and transgenic Arabidopsis thaliana plants and grew them under natural conditions in field experiments in our botanical garden in Umeå, northern Sweden. For the investigation of the plant-insect interaction, a specialist on Brassicaceae (Plutella xylostella – diamondback moth) and a generalist herbivore (Spodoptera littoralis - Egyptian cotton worm) were used.

Plants that are genetically deficient in one of the photoprotection mechanisms showed reduced fitness under natural conditions. I could thus show that feedback de-excitation (FDE) is the most important photoprotection mechanism, because a lack of FDE showed the highest reduction in fitness. The comparison of field grown wild-type with FDE mutant plants, using molecular biology methods, revealed large changes in gene transcription and metabolic composition. In particular, the jasmonate pathway was upregulated in light stressed plants, especially in plants lacking FDE. Jasmonate in turn is known to be a chemical compound which induces herbivore resistance genes and other stress responses. Specialist and generalist insect herbivores responded differently in feeding (dual-choice and no-choice) and oviposition experiments with field grown plants that differed in FDE. Female diamondback moths were attracted by induced defense compounds whereas the larvae avoided these plants in feeding experiments. Generalist larvae preferred, and showed a higher survival rate, on less light-stressed plants compared to more light-stressed plants.

Combining molecular biology with ecological experiments is a challenging task. To summarize my experiences, I have produced a guide for experiments on transgenic plants in common gardens. In future investigations it is important to examine natural variations in photoprotection to elucidate selection pressures on specific genes.

Place, publisher, year, edition, pages
Umeå: Ekologi, miljö och geovetenskap, 2008. 23 p.
Keyword
Arabidopsis thaliana, photoprotection, herbivory, light-stress, jasmonate, fitness, FDE, dual-choice
National Category
Biological Sciences
Identifiers
urn:nbn:se:umu:diva-1651 (URN)978-91-7264-643-1 (ISBN)
Public defence
2008-06-04, Lilla hörsalen, KBC-huset, Umeå University, 901 87 Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2009-06-22Bibliographically approved
2. Stress responses of Arabidopsis plants with a varying level of non-photochemical quenching
Open this publication in new window or tab >>Stress responses of Arabidopsis plants with a varying level of non-photochemical quenching
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Stressresponser i Arabidopsis med olika kapacitet för ”icke-fotokemisk" quenching
Abstract [en]

When light energy input exceeds the capacity for photosynthesis the plant need to dissipate the excess energy and this is done through non-photo-chemical quenching (NPQ). Photochemical quenching (photosynthesis), NPQ and fluorescence are three alternative faiths of excited chlorophylls. PsbS associates to photosystem II and is involved in NPQ.

The results presented in this thesis were generated on Arabidopsis plants and mainly based on wildtype Col-0 together with a mutant deficient in PsbS (npq4) and a transgene overexpressing PsbS (oePsbS). We connect light and herbivore stress and show that the level of PsbS influences the food preference of both a specialist (Plutella) and a generalist (Spodoptera) herbivore as well as oviposition of Plutella. Level of PsbS also affects both metabolomics and transcriptomics of the plant; up-regulation of genes in the jasmonic acid (JA) -pathway and amount of JA has been found in the npq4 plants after herbivory.

Since many experiments were performed in field we have also characterized the field plant and how it differs from the commonly used lab plant. We have also studied the natural variation of NPQ in Arabidopsis plants both in the field and the lab. The results show surprisingly no correlation.

Abstract [sv]

Överskottsenergi kan vara skadligt för en växts membran och fotosynteskomplex. Vid överskott av solenergi blir fotosystemen mättade och växten behöver därför ett sätt för att göra sig av med all överskottsenergi, detta kallas för ”icke-fotokemisk quenching” (NPQ). Fotokemisk quenching (fotosyntes), NPQ och fluoresens är tre alternativa vägar för exalterade klorofyller. PsbS är involverad i NPQ och associerar med fotosystem II.

De resultat som presenteras i denna avhandling kommer från studier av modellväxten Arabidopsis thaliana (Backtrav), i huvudsak gjorda på vildtypen i jämförelse med en mutant som saknar PsbS (npq4) och en transgen som överuttrycker PsbS (oePsbS). Vi har försökt att undersöka kopplingen mellan ljus- och herbivoristress och visar här att mängden PsbS påverkar både en specialist (Plutella) och en generalist (Spodoptera) insekt vid val av föda, samt Plutella även vid äggläggning. Växternas nivå av PsbS visade sig även påverka metabolomet och transkriptomet, och vi fann en uppreglering av gener i biosyntesen för jasmonat samt mer av själva hormonet jasmonat i npq4 växter efter herbivori.

Eftersom vi har gjort många av experimenten ute i fält har vi även karakteriserat en typisk Arabidopsis växt i fält samt hur denna skiljer sig från den vanligt använda lab-växten. Dessutom har vi även undersökt naturlig variation av NPQ av Arabidopsis både i fält och på lab och resultaten visar, till vår förvåning, att det inte går att finna någon korrelation mellan dessa.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, Institutionen för fysiologisk botanik, 2011. 54 p.
Keyword
Arabidopsis, NPQ, PsbS, photosynthesis, field experiment, metabolomics
National Category
Biological Sciences
Research subject
Physiological Botany; Molecular Biology
Identifiers
urn:nbn:se:umu:diva-48566 (URN)978-91-7459-314-3 (ISBN)
Public defence
2011-11-18, KBC-huset, KB3B1, Umeå Universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council
Available from: 2011-10-28 Created: 2011-10-24 Last updated: 2015-04-29Bibliographically approved

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