381023 research outputs found
Sort by
Drought resistance in soybean : a genome-wide association approach
No full textSoybean [Glycine max (L.) Merr.] is the fourth leading crop worldwide and the most grown high-value grain legume as an important source of oil and protein for food, feed and industrial applications. Soybean is cultivated mainly in tropical, sub-tropical and temperate regions in a wide latitudinal range. The rising global demand has driven an increase in the cultivated area, and between 1971 and 2020, the total soybean acreage increased from 28 to 128 million hectares. The current soybean acreage of 5.5 million hectares in Europe, representing a mere 3.4% of the world soybean production, can meet only 34% of the current European needs. To meet the increasing European demand and to reduce the dependency on import, it is crucial to expand the area cultivated with soybean in Europe. This requires the deployment of adapted varieties through breeding and the development of cultivation practices tailored to European conditions, considering current and future scenarios. Historical records of climate data and future projections highlight an increased frequency and severity of drought spells in Europe. Therefore, the period between seedling emergence and reproductive development in soybean, can coincide with the occurrence of drought spells in many European regions. As drought at critical developmental moments can have a large negative impact on yield, breeding drought resistant soybean varieties, adapted to European growth conditions is urgently needed.
The main goal of this PhD thesis was to decipher the genetic control of drought resistance in soybean following a genome-wide association mapping approach (GWAS). This allowed us to get in-depth understanding of the genetic architecture of phenotypic traits related to drought resistance in soybean, which can be exploited by European breeders.
This study was based on a collection of soybean genotypes of particular significance for Europe, assembled in the context of the EU-H2020 project EUCLEG (the EUCLEG collection). First we analyzed the genetic diversity within the EUCLEG collection and characterized selective sweeps through a genome-wide diversity scan using Chinese soybean collections as reference (Chapter 2). As expected, we found a lower level of genetic diversity in the EUCLEG collection than in the Chinese collections. Substructuration in five groups, largely corresponding to geographical origin, dit not reflect the classification into maturity groups. A total of 23 selective sweep regions distributed over 12 chromosomes were identified, several of which were related to domestication and improvement traits including seed protein and oil content, phenology, nitrogen fixation, yield components, disease resistance and quality. Absence of signatures of selection for a substantial number of QTLs related to yield, protein content, oil content and phenological traits in the EUCLEG collection suggests the presence of substantial genetic diversity for these traits. Taken together, the results obtained demonstrate that the available genetic diversity in the EUCLEG collection can be further exploited for research and breeding purposes.
In a second step, we investigated the response to drought stress of the EUCLEG collection during two growing seasons (2018 and 2019) under semi-controlled conditions, using rain-out shelters in combination with remote sensing phenotyping tools (Chapter 3). Drought applied at the reproductive stage brought diverse responses. A ‘long duration drought treatment’ (for 6–7 weeks) in 2019 (LDS) caused a much stronger response as compared to the ‘short duration drought treatment’ (for 3–4 weeks) in 2018 (SDS). Main responses were an average reduction of 11–29% in maximum canopy height, an average reduction of 22% in maximum absolute growth rate and an acceleration of the rate of senescence by 26–110%. When a short period of drought was applied (2018) the earlier cessation of flower and pod formation allowed a less pronounced reduction of yield-related traits. A longer duration of the drought stress treatment (2019) brought a different response, and accessions that displayed a strong reduction in canopy height (cessation of growth) were also the most affected for yield-related traits. These results suggest that under the conditions associated with a short period of drought stress, drought resistance criteria can be based on yield-related traits, while resistance to long drought stress can be improved by selecting for genotypes that are able to maintain growth.
In a last step, we combined genotypic (Chapter 2) and phenotypic information (Chapter 3) to perform a GWAS analysis (Chapter 4). This analysis revealed 17 and 22 significant marker-trait associations, in the SDS and LDS experiments, respectively. Based on these marker-trait associations a total of 12 (SDS) and 16 (LDS) genes of particular relevance for drought stress responses including stomatal movement, root formation, photosynthesis, ABA signaling, cellular protection and cellular repair mechanisms, were identified. Furthermore, several previously known QTLs for drought resistance traits such as WUE, chlorophyll content and photosynthesis, co-localized with the significantly associated SNPs, confirming their role in drought resistance mechanisms in soybean. The genomic regions identified in this study are of great value for the implementation of genomics-assisted selection for drought resistance in soybean. Given the complexity of drought resistance in soybean, using marker-based approaches can enable a stronger genetic gain, compared to phenotypic selection
Liquid biopsies for integrated cancer (differential) diagnosis : from whole-genome to targeted and from genomics to epigenomics
No full text
Sexual and reproductive health communication within families : development and evaluation of an intervention to improve caregiver and young adolescent sexual and reproductive health communication using participatory research approaches in Southwestern Uganda
No full textGreek formulae in Coptic legal documents (7th-8th c.) : graphemic and linguistic adaptation vs. alternation
No full textThe paper investigates motivations behind linguistic and paleographic variation of Greek formulaic speech in the opening, body, and closing of Coptic legal documents. The primary corpus consists of late-seventh- and eighth-century legal deeds with Greek formulaic expressions from the area of Djeme, which is well-documented and allows diachronic observations on inter- and intra-writer variation. Documents mainly from the Hermopolite nome, dating to the same two centuries, and including a specific formulaic phrase, ⲕⲁⲑⲁⲣⲱⲥ ⲕⲁⲓ ⲁⲡⲟⲕⲣⲟⲧⲱⲥ (καθαρῶς καὶ ἀποκρότως), are examined as a second comparative corpus. It is found that, although Theban scribes start using a second writing style and occasionally improved language for their opening and closing formulae from the 720s, formulaic expressions in the body of Coptic documents are still written in the primary “Coptic” style of the document, and in poorly formed Greek, even in later decades; the same pattern is observed in the second corpus. These differences were motivated by practical/textual considerations, such as layout, framing, and highlighting important information. Using language and script contact theories, (socio-)linguistic factors (e.g. stylistic elevation, perceiving or portraying formulae as code-switches or borrowings) also prove relevant. The study shows that, following the Islamic rule of Egypt, the Greek inherited from earlier deeds has started degenerating into brief, mechanical switches with a largely symbolic role, which are expressed visually against a background of rapidly developing legal Coptic
Capturing life as it is lived : studying work events using an expanded taxonomy
No full textOrganizational psychologists have long been interested in the daily dynamics within a workday (Basch & Fisher, 1998; Weiss & Cropanzano, 1996). To explain these dynamics, they proposed that concise situations at work, so-called work events, add variety to the work routine and thus cause daily variability in affective reactions and organizational behavior. The role of work events in organizational behavior was discussed in two theories. The first theory, affective event theory (Weiss & Beal, 2005; Weiss & Cropanzano, 1996), argued that work events get evaluated as positive or negative and that these affective events explain variability in emotions and organizational behavior. Affective events became particularly popular to explain daily changes in emotions and affective well-being at work (Basch & Fisher, 1998; Gross et al., 2011; Kuba & Scheibe, 2017; Ohly & Schmitt, 2015). The second theory, event system theory (Morgeson et al., 2015), proposed subjective event features that describe how strongly an event affects organizational behavior. Event strength dimensions now contribute to research in the broader field of organizational behavior and development (Beeler et al., 2017; Chen et al., 2021; Morgeson & Derue, 2006).
Event affectivity and event strength dimensions were theoretically well embedded but measuring these dimensions simultaneously remained difficult. Personality psychologists, however, recently developed new taxonomies to describe general life situations using data-driven bottom-up approaches (Oreg et al., 2020; Parrigon et al., 2017; Rauthmann et al., 2014; Ziegler et al., 2019). Parrigon et al. (2017), for instance, applied the lexical approach (Allport & Odbert, 1936) and extracted adjectives from movie subtitles to describe situations. From these adjectives, they derived seven dimensions that capture the subjective experience of work events—Complexity, Adversity, Positive valence, Typicality, Importance, humOr, and Negative valence (short: CAPTION). In this dissertation, we introduced the newly developed CAPTION situation taxonomy as a measure for daily work event dimensions.
Chapter 1 of this dissertation introduces the field of work event research and outlines the research objectives of this dissertation. After establishing the CAPTION taxonomy for work events, we showed that additional work event dimensions assessed in the CAPTION framework explain incremental validity in affective well-being outcomes beyond the traditional affective positive/negative event approach (e.g., Basch & Fisher, 1998; Ilies et al., 2011; Ohly & Schmitt, 2015). We then studied personality, objective event features, and the social context at work as potential antecedents of the subjective work event experiences.
In Chapter 2, we adjusted the CAPTION framework for work events and showed that measuring work event dimensions next to event positivity and negativity adds to explaining affective well-being during and after work. We first theoretically aligned the affective dimensions rooting in the affective event theory (positivity, negativity) and the event strength dimensions proposed in the event system theory (disruption, criticality, novelty) with dimensions of the newly developed CAPTION situation framework. We then adopted the CAPTION taxonomy for work events and tested the seven-dimensional structure in work events at the person-, day-, and event-level. In Study 1, the seven-dimensional CAPTION framework explained incremental variability in affective reactions at the end of the workday beyond the traditional positive/negative event approach; in Study 2, the seven-dimensional CAPTION framework explained incremental validity in emotional reactions during the workday beyond the traditional positive/negative event approach. Based on these findings, we can encourage future research to apply the CAPTION framework to study work events and daily dynamics at work.
Next, we were interested in potential antecedents of work event experiences. Researchers have argued that both, the person and the situation, independently contribute to behavioral reactions of people to a situation (Lewin, 1951). Drawing from this idea, we suggest that person features, as well as objective event features, also both contribute to subjective event experiences. In Chapter 3, we studied the role of personality in the experience of daily work events. We showed that personality traits, as well as personality strength, predict variability in subjective work event experiences. Building on traditional theories on personality traits (Allport, 1961; McCrae & Costa, 1991), we suggested that specific personality traits will explain variability in daily event experiences. We further drew from personality strength theory (Dalal et al., 2015) and tested whether personality strength (an additional trait that describes how variable a person is within their personality expression) additionally explains variability in daily event experiences. To that end, we introduced the item-response-based Trait-Variability-Tree-Model (TVTM; Lang et al., 2019) as a new statistical approach towards personality strength. Using the TVTM, we separated personality traits from personality strength in a one-shot personality survey. Trait neuroticism increased variability in work event experiences while trait conscientiousness decreased variability in daily event experiences. Personality strength explained variability in work event experiences beyond these traits so that strong personalities showed less variability in event experiences. These findings expand earlier theories on personality traits. First, personality traits explain variability in situation experiences and support personality strength theory. Second, personality strength decreases variability in situation experiences.
In Chapter 4, we studied whether objective event features of work events and the higher-level work context explain work event experiences. The objective features of work events can be described as who did what, where, when, and why? (Johns, 2006). The social component (who?) has been suggested as the most relevant objective feature of situations (Reis et al., 2000). To test this idea, we compared employees’ social work events with their non-social work events and found that social events were experienced as more positive, more humorous, less adverse, and more complex than non-social events. Further, the social interaction partner was important for how work events were experienced. Especially events with leaders differed from other social events as they were more cognitively challenging (more important, more complex) and less humorous than other social work events.
Event system theory suggests that higher-level events or contexts affect lower-level events (Morgeson et al., 2015). When the COVID-19 pandemic started, employees were strongly encouraged to work from home and to keep social distance. These regulations changed the social work context for employees towards a more isolated work environment. Transition theories (Bliese et al., 2017; Schlossberg, 1981) suggest that employees adjust to changes in their larger environment and then may change their experiences. Building on these transition theories, we suggested that employees will adjust to their new social work context and experience social versus non-social work events differently. To test this idea, we compared the experiences of social and non-social work events of a group of employees before the COVID-19 pandemic with work events of a group of employees during the pandemic. Indeed, non-social work events during the pandemic were experienced as less adverse, less negative, and more important than before the pandemic. In line with transition theories, these findings suggest that participants adjusted to an altered social context. The findings further support event system theory in that higher-level transition events affect event experiences at a lower level.
Chapter 5 closes this dissertation by summarizing the results from the three empirical chapters and connecting their findings with the research objectives of the dissertation. This final chapter elaborates on the theoretical, methodological, and practical implications of this dissertation and discusses strengths, limitations, and future research direction resulting from this dissertation. The chapter closes with the main conclusions derived from this doctoral thesis
