Zendonadi dos Santos, Nícolas: High-Throughput Phenotyping of Photosynthesis Traits in Durum Wheat Under Drought Stress Using Light-Induced Fluorescence Transients. - Bonn, 2022. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-65991
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-65991,
author = {{Nícolas Zendonadi dos Santos}},
title = {High-Throughput Phenotyping of Photosynthesis Traits in Durum Wheat Under Drought Stress Using Light-Induced Fluorescence Transients},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2022,
month = mar,

note = {Agriculture in the twenty-first century faces the double challenge of feeding a growing population in a changing climate. Food security will increasingly rely on the active release of stable high-yielding cultivars with improved resilience to water shortages, particularly for vulnerable drought-prone environments. Therefore, developing new techniques and approaches to improve the efficiency and precision of crop breeding for drought tolerance is essential. Conventional plant phenotyping methods for assessing plant responses to water-limiting conditions, and supporting selective breeding, are usually laborious, time-consuming, and costly. More recently, cost-effective high-throughput phenotyping platforms (HTPPs) have emerged, enabling rapid and accurate phenotypic characterisation of large populations in either controlled or field conditions. HTPPs deploy sensors to non-invasively and non-destructively identify, quantify, and record relevant plant traits. An integrative signal, such as photosynthesis, may serve as a robust selection parameter for crop performance. Chlorophyll fluorescence (ChlF) is an inexpensive, fast, and non-invasive technique for probing photosynthesis and, therefore, for monitoring plant physiological status. Although proposed as a method for drought tolerance screening, ChlF has not yet been fully adopted in physiological breeding, mainly due to limitations in high-throughput phenotyping capabilities. Most of the prior research has relied on the pulse-amplitude modulation (PAM) fluorometry, which typically requires a saturating flash in very close proximity, done mainly by clamping on leaves, limiting its throughput. In this context, the Light-Induced Fluorescence Transient (LIFT) sensor arose as an alternative for acquiring high-throughput ChlF-based traits. The LIFT fluorometer actively monitors ChlF within milliseconds using subsaturating excitation flashlets instead of the saturating pulse. Also, this pump-and-probe method works at a distance, bridging the gap between leaf and canopy levels. LIFT-measured ChlF has proved to provide not only PAM-analogous photosynthetic parameters but also measures the downstream electron transport rates from the primary quinone acceptor (QA) to the plastoquinone (PQ) pool, and ultimately, towards the photosystem (PS) I. Nevertheless, little knowledge is available on the overall responses of LIFT-measured ChlF traits in field-grown crops under drought and their native genetic variability, aiding physiological crop breeding towards drought tolerance. To this end, the LIFT instrument was mounted on a manually pushed cart to measure ChlF across time in a large panel of durum wheat genotypes (> 220 elite accessions) subjected to progressive drought in replicated field trials over two growing seasons in Maricopa, Arizona, USA. Secondly, the LIFT sensor was combined with an existing automated HTPP for simultaneous and continuous monitoring of water relations in the soil-plant-atmosphere continuum of wheat plants growing in semi-controlled conditions. The photosynthetic performance was measured at the canopy level by means of the operating efficiency of PSII (Fq'⁄Fm') and the kinetics of electron transport from QA to PQ pool and from PQ pool to PSI measure by reoxidation rates, Fr1' and Fr2', respectively. Short- and long-term changes in ChlF traits were found in response to soil water availability and interactions with weather fluctuations, namely photosynthetic photon flux density (PPFD) and vapour pressure deficit (VPD). At an unprecedented scale, this high-throughput approach for phenotyping ChlF traits integrated with a high-resolution recording of the environment allowed for estimation of genetic effects over time and shed light on the diurnal dynamics of the photosynthetic apparatus, facilitating the ability to dissect complex physiological traits in fluctuating growing conditions.},
url = {https://hdl.handle.net/20.500.11811/9703}

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