Browsing by Subject "ABA"

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  • Ayvaz, Muavviz; Guven, Avni; Fagerstedt, Kurt Valter (2015)
    Potato crop production in Turkey ranks on the thirteenth place in the world. Toxicity is a problematic issue for some parts of the Turkish soils. Hence, it is very important to clarify the physiological responses of plants to toxic mineral stress. In this study, two different potato cultivars - Solanum tuberosum cv. Resy and Solanum tuberosum cv. Agria - were used as a study material. Excess boron was applied in two different concentrations (5 mmol/L and 12.5 mmol/L) 32 days after planting the tubers. Plants were harvested at the end of 15 days of excess boron application. Chlorophyll fluorescence (Fv/Fm) was measured. Shoot height and shoot-root fresh weight contents were determined. Analyses were carried out for the contents of the endogenous hormones indole-3-acetic acid (IAA) and abscisic acid (ABA) by using gas chromatography-mass spectrophotometry (GS-MS). According to the obtained data, plants' shoot height did not change, whereas the shoot's fresh weight decreased significantly with increasing of the boron concentrations in cv Resy, by applying 12.5 mmol/L boron. With 12.5 mmol/L boron, the photosynthesis was negatively affected in both cultivars. Boron application led to increased endogenous IAA and ABA content in both cultivars. As a result, cv. Resy showed more resistance to excess boron. Findings on the hormone metabolism and chlorophyll fluorescence in different cultivars will shed a light on understanding the physiological response to excess mineral stress.
  • Deger, Aysin Guzel; Scherzer, Sönke; Nuhkat, Maris; Kedzierska, Justyna; Kollist, Hannes; Brosche, Mikael; Unyayar, Serpil; Boudsocq, Marie; Hedrich, Rainer; Roelfsema, M. Rob G. (2015)
    During infection plants recognize microbe-associated molecular patterns (MAMPs), and this leads to stomatal closure. This study analyzes the molecular mechanisms underlying this MAMP response and its interrelation with ABA signaling. Stomata in intact Arabidopsis thaliana plants were stimulated with the bacterial MAMP flg22, or the stress hormone ABA, by using the noninvasive nanoinfusion technique. Intracellular double-barreled microelectrodes were applied to measure the activity of plasma membrane ion channels. Flg22 induced rapid stomatal closure and stimulated the SLAC1 and SLAH3 anion channels in guard cells. Loss of both channels resulted in cells that lacked flg22-induced anion channel activity and stomata that did not close in response to flg22 or ABA. Rapid flg22-dependent stomatal closure was impaired in plants that were flagellin receptor (FLS2)-deficient, as well as in the ost1-2 (Open Stomata 1) mutant, which lacks a key ABA-signaling protein kinase. By contrast, stomata of the ABA protein phosphatase mutant abi1-1 (ABscisic acid Insensitive 1) remained flg22-responsive. These data suggest that the initial steps in flg22 and ABA signaling are different, but that the pathways merge at the level of OST1 and lead to activation of SLAC1 and SLAH3 anion channels.
  • Pavicic, M.; Wang, F.; Mouhu, K.; Himanen, K. (2019)
    Seed quality is an important factor for seedling vigour as well as adult plant resilience. The key quality attributes are related to physical characteristics, physiological performance, genetic background and health status of the seeds. Many ways to address seed quality attributes have been developed and recently many of them have featured automated high throughput methods. In our study, we addressed two of the seed quality attributes, namely physiological performance and genetic background by analysing germination rates in our mutant collection. These mutants represent ubiquitin E3 ligases that transcriptionally respond to abscisic acid (ABA). This plant hormone is an important regulator of germination and seedling establishment. To facilitate in vitro germination screens of large seed collections a high throughput image-based assay was developed. As a read out of the germination on ABA treatment the cotyledon emergence was detected with top view chlorophyll fluorescence camera. By applying the ABA treatment during germination, RING-type ubiquitin E3 ligase mutants were identified, showing either resistant or sensitive responses to ABA. In conclusion, a scalable high throughput screen for in vitro germination assay was established that allowed fast screening of tens of mutants in a hormone supplemented media.
  • Ehonen, Sanna; Yarmolinsky, Dmitry; Kollist, Hannes; Kangasjärvi, Jaakko (2019)
    Significance: Stomata sense the intercellular carbon dioxide (CO2) concentration (C-i) and water availability under changing environmental conditions and adjust their apertures to maintain optimal cellular conditions for photosynthesis. Stomatal movements are regulated by a complex network of signaling cascades where reactive oxygen species (ROS) play a key role as signaling molecules. Recent Advances: Recent research has uncovered several new signaling components involved in CO2- and abscisic acid-triggered guard cell signaling pathways. In addition, we are beginning to understand the complex interactions between different signaling pathways. Critical Issues: Plants close their stomata in reaction to stress conditions, such as drought, and the subsequent decrease in C-i leads to ROS production through photorespiration and over-reduction of the chloroplast electron transport chain. This reduces plant growth and thus drought may cause severe yield losses for agriculture especially in arid areas. Future Directions: The focus of future research should be drawn toward understanding the interplay between various signaling pathways and how ROS, redox, and hormonal balance changes in space and time. Translating this knowledge from model species to crop plants will help in the development of new drought-resistant crop species with high yields. Antioxid. Redox Signal. 00, 000-000.
  • Piisilä, Maria; Keceli, Mehmet A.; Brader, Günter; Jakobson, Liina; Joesaar, Indrek; Sipari, Nina; Kollist, Hannes; Palva, E. Tapio; Kariola, Tarja (2015)
  • Qian, Hui; Dong, Ai-Mei; Roitto, Marja; Xiang, Di-Ying; Zhang, Gang; Repo, Tapani; Wang, Ai-Fang (2021)
    Background and Objectives: More frequent and severe droughts are occurring due to climate change in northern China. In addition to intensity and duration, the timing of droughts may be decisive for its impacts on tree growth, mortality, and the whole forest ecosystem. The aim of this study was to compare the effect of drought occurring in the early- and mid-growing season on the growth and physiology of Mongolian pine (Pinus sylvestris var. mongolica Litv.) saplings. Materials and Methods: Four-year-old container saplings that were about to sprout were exposed to three treatments: (i) regular irrigation throughout the growing season (CTRL), (ii) no irrigation in the early growing season (weeks 1-5) followed by regular irrigation (EGD), (iii) no irrigation in the mid growing season (weeks 5-10), and regular irrigation in the early and late growing season (MGD). We measured the root and shoot growth, sapling mortality, and the physiological changes in the roots and needles periodically. Results: Drought in the mid growing season was more harmful than in the early growing season in terms of chlorophyll fluorescence, electrolyte leakage of needles, needle length, stem diameter increment, and sapling mortality. The high mortality in the mid growing season might be attributed to the joint effect of drought and high temperature. Drought in the early growing season decreased root growth, and the starch and soluble sugars in roots as much as the drought in the mid growing season. Abscisic acid concentration increased in fine roots, but decreased in old needles after drought. Conclusions: Special attention should be paid on forest sites susceptible to drought during afforestation in the face of ongoing climate change.