Frimpong, Felix: Proline mediated drought tolerance of selected barley (Hordeum vulgare L.) introgression lines and characterization of in vivo spike development. - Bonn, 2022. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc:
author = {{Felix Frimpong}},
title = {Proline mediated drought tolerance of selected barley (Hordeum vulgare L.) introgression lines and characterization of in vivo spike development},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2022,
month = aug,

note = {The potential yield of barley is likely to decrease in the future due to the prevalence of drought stress in many world regions. In our study, drought stress affected phenology, biomass and other growth traits, and seed yield-related traits. We observed that drought stress in barley causes alterations in critical physiological parameters, including leaf water status, net CO2 assimilation rate, stomatal conductance, transpiration rate, water use efficiency, floret fertility, and seed filling. The drought in our study generally decreased our barley types’ shoot and root growth by at least 70%.
Different barley introgressions and elite varieties of varying genetic makeup were investigated under well-watered and water stress treatments. The mechanistic responses of these lines to water stress, specifically, how they accumulate proline in their shoots and roots relating to stress tolerance, were analyzed and discussed. We found that a wild allele of Pyrroline-5-carboxylate synthase1 (P5cs1) led to proline accumulation in the spikes and leaves of barley introgression lines, contributing to improved performance under reduced water availability. We found that water stress applied at the seedling stage induces increased shoot and root proline accumulation in a more homogenous near-isogenic barley line NIL 143, which harbour the wild allele at the P5cs1 locus, and that this effect was associated with increased lateral root growth. We conclude that proline, functioning as an osmoprotectant, promotes drought tolerance mainly by helping maintain whole-plant water status. Our results suggest that proline accumulation at the reproductive stage contributes to the maintenance of grain formation under water shortage (Frimpong et al., 2021a). Increased shoot and root proline accumulation in the NIL 143 barley was associated with increased lateral root growth. Future studies on the P5cs1-introgressions should focus on validating presented physiological variation in field conditions and the effect of elevated proline on grain quality traits. We recommend further studies to explore the variations in root-shoot growth observed for NIL 143 in the field to test their performance under a water-limited environment. In addition, further studies will be required to explore how proline accumulation promotes barley root water uptake under water stress.
Furthermore, we explored the use of MRI to visualize barley grain development as a tool to detect internal florets, seed initiation and seed abortion, seed structures, spike architecture, and temporal growth of the grain on intact spikes of two-row spring barley genotypes. We found that MRI visualized differential genotypic seed initiation, seed growth and development, or abortion. MRI highlighted genotypic variations in a-synchronicity of floret initiation, seed set, and filling along the different spike axis. Also, MRI distinguished barley spike morphology and seed abortion as affected by water stress treatment compared to well-watered plants in our barley types. We recommend that future MRI studies of the spike could integrate algorithmic tools, and machine learning models to explore different functional seed traits and physiological behaviour beyond our photographing. Finally, using six multiplexed NMR sensors, we monitored and quantified non-destructively the dynamics of seed loading in terms of fresh weight, water and dry matter content during barley grain filling. Based on the acquired non-invasive data, peak seed filling rate, the diurnal rate of change in accumulation rate (fresh weight, dry matter content and water influx), and the variations in genotypes on live barley spikes were determined and discussed. We found that the grain yield of all our barley genotypes from our destructive harvest was consistent with the non-destructive multiplexed NMR sensor measurements.},

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