In recent decades, climate change has led to more frequent and severe drought events, causing serious consequences such as increased forest mortality and significant crop yield losses.... Show moreIn recent decades, climate change has led to more frequent and severe drought events, causing serious consequences such as increased forest mortality and significant crop yield losses. Understanding how drought affects plants, especially economically important herbaceous species, is crucial for predicting and developing drought-resistant crops. To address this issue, this study analyzed a comprehensive dataset of anatomical and hydraulic traits in different genotypes of Arabidopsis thaliana and tomato, including both wild-type and transgenic mutants. The study also investigated the expression of four well-known drought marker genes associated with ABA-dependent and ABA-independent pathways and the impact of overexpressing the JUNGBRUNNEN1 (JUB1) gene on drought response. The findings revealed that each genotype had a unique set of traits to cope with drought, which could be categorized into two response strategies. One group enhanced their drought resistance through traits like a more negative stem P50, thicker intervessel pit membranes, a more lignified inflorescence stem, and a gradual reduction of the low initial stomatal conductance during drought. This strategy enabled them to maintain a relatively high and stable leaf water potential (Ψl). The second group, represented by JUB1 overexpression genotypes, relied primarily on maintaining a high Ψl which is possibly due to osmoprotectant accumulation in leaves, while the other traits have not been recorded. Overall, this research demonstrated the adaptive capabilities of herbaceous plants to drought conditions, highlighting the intraspecific variation in drought responses that underscores the need for a detailed assessment of drought-responsive traits to improve crop yield in a warming world. Show less
This thesis describes how different colours of light affect various aspects of the growth and development of Arabidopsis and tomato plants. In the first chapter, we review the current knowledge of... Show moreThis thesis describes how different colours of light affect various aspects of the growth and development of Arabidopsis and tomato plants. In the first chapter, we review the current knowledge of light receptors and different light-regulated processes. In the second chapter we investigated the effect of direct illumination of roots. In the third chapter we presented an overview of the phenotypes that arise when plants are grown in white, red or blue light. In the fourth and fifth chapter we further investigate the stem and flowering phenotypes that were observed in the different light conditions. Altogether we show that red and blue light often act antagonistically, and that some light-regulated processes may be species- or age-specific. Show less
We showed that constitutive and inducible chemical and morphological defenses against Western flower thrips differ between tomato and chrysanthemum plants. Furthermore, we demonstrated that both... Show moreWe showed that constitutive and inducible chemical and morphological defenses against Western flower thrips differ between tomato and chrysanthemum plants. Furthermore, we demonstrated that both plant species respond differently to bacteria-derived defense elicitors, such as the phytotoxin coronatine. This highlights the plant species-specificity of these interactions and the possible limitation for the use of pathogen-associated molecular patterns to enhance the plant immune system. This study thus provides knowledge and novel strategies for Western flower thrips control. Yet, further comprehensive work is needed to evaluate the influence of these induction strategies on plant fitness. Show less
