Gene regulation in response to drought in the plant genera Panicum and Quercus

Droughts impair plant growth, limit global net primary production and are predicted to increase in the course of climate change. Knowledge of the plant drought response on a molecular level can facilitate the selection of drought resistant genotypes and genetic engineering and thereby can help to implement strategies, such as assisted migration projects or crop improvement, in order to preserve natural and agricultural vegetation against droughts. Studies on gene expression under drought stress were conducted in three species each of the genera Quercus and Panicum, to shed light on the molecular drought response in these species and identify drought responsive genes as a basis for technical applications. In the genus Quercus, gene expression studies were conducted in the three major European forest trees Q. ilex, Q. pubescens and Q. robur, for which a distributional shift caused by climate change is predicted for the 21st century. RNA-Seq experiments were conducted in the three Quercus species for the first time, ortholog groups were assigned and unregulated genes, as well as drought responsive genes, were identified (Madritsch et al. 2019). For a set of the unregulated genes, a stable expression over the course of long-term drought periods was evaluated in order to enable an application as reference genes for normalizing qRT-PCR experiments (Kotrade 2019a). The reference genes were used in subsequent experiments to generate gene expression profiles over the course of a two-year drought experiment with consecutive drought periods for a set of twelve drought responsive genes and revealed a highly variable gene regulation under long-term drought stress in the Quercus species (Kotrade et al. 2019b). In the genus Panicum, the gene expression in response to drought was examined in the two wild crop species, P. laetum and P. turgidum, and in the less drought tolerant species P. bisulcatum via RNA-Seq experiments (Kotrade et al. 2020 (in revision). The transcriptomes of the species were sequenced for the first time, ortholog groups were assigned and the gene regulation was compared across the species. The common grounds of the drought response in Panicum were determined by identifying similarities across the species, while the identification of differences between the species led to genes that might contribute to the higher drought tolerance of P. laetum and P. turgidum A comparison across the two genera showed large differences in the gene regulation upon drought. This might be largely explained by different experimental setups that resulted in different drought conditions in the genera, such as drought intensity, drought duration and velocity of drought development. The sequence information and the drought responsive genes identified in the Quercus and Panicum species can be used to develop marker assays for marker-assisted selection. The genes that putatively contribute to the higher drought tolerance of the two wild crop Panicum species should be considered as candidate targets in genetic engineering studies. Marker-assisted selection and genetic engineering can be applied, for example, in assisted migration projects to support natural vegetation in the course of climate change or to breed more drought tolerant crop strains to mitigate crop failure rates caused by droughts

Transepidermal oxygen flux during arterial occlusion using ratiometric luminescence imaging

BACKGROUND: A physiological oxygen transport through a circulatory and microcirculatory system is essential for execution of cellular functions. Several pathological conditions e.g. infections, ischemia, cancer, diabetes, hypertension or chronic wounds show a change of oxygen distribution and oxygen tension in cellular microenvironment. Additionally complex operative procedures in order to reconstruct tissue defects require a reliable monitoring of microcirculation. OBJECTIVE: Target of this study was to evaluate skin oxygenation during an ischemia-reperfusion experiment using transepidermal oxygen flux imaging. METHODS: Twelve patients at the Department of Plastic and Reconstructive surgery of the University hospital of Regensburg underwent to elective hand operations. During the operation a tourniquet is standardly set on the upper arm to create ischemia in order to facilitate the operative procedure. Measurements were performed at the different time intervals: in rest, under ischemia and after reperfusion. RESULTS: The transepidermal oxygen flux increased during the ischemic condition compared to normal condition and decreased to a lower value during reperfusion (rest: 0.043 +/- 0.007, ischemia: 0.063 +/- 0.014, reperfusion: 0.030 +/- 0.028). CONCULSION: Transepidermal oxygen flux imaging by ratiometric luminescence imaging seems to be a reliable tool to assess skin oxygenation. However dynamic changes seem to be more informative than absolute thresholds. Further investigations are necessary to prove these promising results

Elucidating Drought Stress Tolerance in European Oaks Through Cross-Species Transcriptomics

The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European forests. As a result, forests are expected to shift their distribution patterns toward north-east, which may lead to a dramatic loss in value of European forest land. Consequently, unraveling key processes that underlie drought stress tolerance is not only of great scientific but also of utmost economic importance for forests to withstand future heat and drought wave scenarios. To reveal drought stress-related molecular patterns we applied cross-species comparative transcriptomics of three major European oak species: the less tolerant deciduous pedunculate oak (Quercus robur), the deciduous but quite tolerant pubescent oak (Q. pubescens), and the very tolerant evergreen holm oak (Q. ilex). We found 415, 79, and 222 differentially expressed genes during drought stress in Q. robur, Q. pubescens, and Q. ilex, respectively, indicating species-specific response mechanisms. Further, by comparative orthologous gene family analysis, 517 orthologous genes could be characterized that may play an important role in drought stress adaptation on the genus level. New regulatory candidate pathways and genes in the context of drought stress response were identified, highlighting the importance of the antioxidant capacity, the mitochondrial respiration machinery, the lignification of the water transport system, and the suppression of drought-induced senescence – providing a valuable knowledge base that could be integrated in breeding programs in the face of climate change

Elucidating drought stress tolerance in european oaks through cross-species transcriptomics

The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European forests. As a result, forests are expected to shift their distribution patterns toward north-east, which may lead to a dramatic loss in value of European forest land. Consequently, unraveling key processes that underlie drought stress tolerance is not only of great scientific but also of utmost economic importance for forests to withstand future heat and drought wave scenarios. To reveal drought stress-related molecular patterns we applied cross-species comparative transcriptomics of three major European oak species: the less tolerant deciduous pedunculate oak (Quercus robur), the deciduous but quite tolerant pubescent oak (Q. pubescens), and the very tolerant evergreen holm oak (Q. ilex). We found 415, 79, and 222 differentially expressed genes during drought stress in Q. robur, Q. pubescens, and Q. ilex, respectively, indicating species-specific response mechanisms. Further, by comparative orthologous gene family analysis, 517 orthologous genes could be characterized that may play an important role in drought stress adaptation on the genus level. New regulatory candidate pathways and genes in the context of drought stress response were identified, highlighting the importance of the antioxidant capacity, the mitochondrial respiration machinery, the lignification of the water transport system, and the suppression of drought-induced senescence - providing a valuable knowledge base that could be integrated in breeding programs in the face of climate change

Transepidermal oxygen flux measurement – First clinical application for postoperative wound monitoring

BACKGROUND: Measurement of skin oxygen is of great interest in diverse fields of medicine. Different pathologies, e.g. infection, ischemia cancer or chronic wounds show a characteristic oxygen distribution and skin oxygen tension. Additionally diverse operative procedures require a reliable postoperative monitoring in order to ensure success of the therapy. OBJECTIVE: Aim of this study was to assess transepidermal oxygen flux for postoperative wound monitoring after operative treatment of fractures close to the hip. METHODS: 22 patients underwent transepidermal oxygen flux measurement at the first postoperative day. Transepidermal oxygen flux measurement was performed using ratiometric luminescence imaging. Examination was conducted in close proximity to the operation wound. The corresponding area at the contralateral side served as reference. RESULTS: Oxygen flux in the operation area was higher (0.084 +/- 0.021) than the contralateral side (0.071 +/- 0.029). CONCLUSIONS: Transepidermal oxygen flux imaging by ratiometric luminescence imaging seems to be a reliable tool to assess postoperative wound healing. However further investigations in greater populations and under pathologic conditions have to be performed to prove these first results

Gisekia(Gisekiaceae):Phylogenetic relationships, biogeography, and ecophysiology of a poorly known C4lineage in the Caryophyllales

• Premise of the study: Gisekiaceae are a monogeneric family of the core Caryophyllales distributed in arid regions of Africa and Asia. The only widespread species of the genus, Gisekia pharnaceoides, performs C4 photosynthesis based on CO2 compensation point measurements. This study investigates the C4 syndrome and its evolution in Gisekia. The infrageneric relationships, distribution and bioclimatic preferences of Gisekia are also investigated. • Methods: Leaf gas exchange characteristics, activity of Rubisco and major C4 cycle enzymes, and ultrastructural characteristics of mesophyll and bundle sheath cells are studied for Gisekia pharnaceoides. δ13C values and leaf anatomy are analyzed for all species. A dated molecular phylogeny of 39 accessions representing all species of Gisekiaceae and 14 representatives of closely related core Caryophyllales families is generated using four cp markers and ITS. The precise current distribution and bioclimatic niche of Gisekia is assessed on the basis of 520 georeferenced specimen localities. • Key results: All traditionally recognized species of Gisekia are C4 plants with atriplicoid Kranz anatomy. Gisekia pharnaceoides uses the NAD-ME biochemical type. The molecular phylogeny demonstrated two East African clades nested within South African clades, demonstrating migration along the arid areas of eastern Africa during the Late Miocene/Pliocene Epochs. Most traditionally defined species are polyphyletic. • Conclusions: Gisekia represents an isolated C4 lineage within core Caryophyllales dating back to the Miocene Epoch and probably spread along the African arid corridor from a South African center of origin. The seven currently recognized species should be treated as one polymorphic species or species complex, Gisekia pharnaceoides agg