2,612 research outputs found
Sensing and signalling salt stress in plant roots
No full textHonghong Wu, Lana Shabala, Jayakumar Bose, Meixue Zhou, and Sergey Shabal
Potassium retention in leaf mesophyll as an element of salinity tissue tolerance in halophytes
No full textAvailable online 13 October 2016Abstract not availableWilliam J. Percey, Lana Shabala, Qi Wu, Nana Su, Michael C. Breadmore, Rosanne M. Guijt, Jayakumar Bose, Sergey Shabal
Salt stress sensing and early signalling events in plant roots: current knowledge and hypothesis
No full textAvailable online 14 October 2015Abstract not availableSergey Shabala, Honghong Wu, Jayakumar Bos
Application of non-invasive microelectrode flux measurements in plant Stress physiology
No full textNon-invasive microelectrode flux measurement (the MIFE™ technique) is a convenient tool to study membrane-transport processes in plants in situ. Over the last 20 years, many papers have been published elucidating the critical role of membrane-transport processes in response to a variety of abiotic and biotic stresses including salinity, osmotic stress, temperature extremes, acidity, oxygen deprivation, nutritional disorders, oxidative stress, and pathogens and elicitors. In this review, we summarize some of these findings and illustrate how the application of ion-selective microelectrodes may be combined with other techniques to address some fundamental issues related to mechanisms of plant nutrient acquisition and stress signaling and adaptation.Sergey Shabala and Jayakumar Bos
Fish gill damage by harmful microalgae newly explored by microelectrode ion flux estimation techniques
No full textAvailable online 28 September 2018Harmful algal blooms (HAB) are responsible for massive mortalities of wild and aquacultured fish due to noticeable gill damage, but the precise fish-killing mechanisms remain poorly understood. A non-invasive microelectrode ion flux estimation (MIFE) technique was successfully applied to assess changes in membrane-transport processes in a model fish gill cell line exposed to harmful microplankton. Net Ca2+, H+, K+ ion fluxes in the rainbow trout cell line RTgill-W1 were monitored before and after addition of lysed cells of this Paralytic Shellfish Toxins (PST) producer along with purified endocellular dinoflagellate PST. It was demonstrated that PST alone do not play a role in fish gill damage during A. catenella outbreaks as previously thought, but that other ichthyotoxic metabolites from lysed algal cells (i.e. lipid peroxidation products or other unknown metabolites) result in net K+ efflux from fish gill cells and thereby gill cell death.Jorge I. Mardones, Lana Shabala, Sergey Shabala, Juan José Dorantes-Aranda, Andreas Seger, Gustaaf M. Hallegraef
Time to Network: The Molecular Blueprint of the Circadian Timing System in Plants
No full textDanisman S, Mateos JL, Staiger D. Time to Network: The Molecular Blueprint of the Circadian Timing System in Plants. In: Mancuso S, Shabala S, eds. Rhythms in Plants. Cham: Springer International Publishing; 2015: 257-278
Difference in root K(+) retention ability and reduced sensitivity of K(+)-permeable channels to reactive oxygen species confer differential salt tolerance in three Brassica species
No full textAdvance Access publication 23 June 2016Brassica species are known to possess significant inter and intraspecies variability in salinity stress tolerance, but the cell-specific mechanisms conferring this difference remain elusive. In this work, the role and relative contribution of several key plasma membrane transporters to salinity stress tolerance were evaluated in three Brassica species (B. napus, B. juncea, and B. oleracea) using a range of electrophysiological assays. Initial root growth assay and viability staining revealed that B. napus was most tolerant amongst the three species, followed by B. juncea and B. oleracea At the mechanistic level, this difference was conferred by at least three complementary physiological mechanisms: (i) higher Na⁺ extrusion ability from roots resulting from increased expression and activity of plasma membrane SOS1-like Na⁺/H⁺exchangers; (ii) better root K⁺ retention ability resulting from stress-inducible activation of H⁺-ATPase and ability to maintain more negative membrane potential under saline conditions; and (iii) reduced sensitivity of B. napus root K⁺-permeable channels to reactive oxygen species (ROS). The last two mechanisms played the dominant role and conferred most of the differential salt sensitivity between species. Brassica napus plants were also more efficient in preventing the stress-induced increase in GORK transcript levels and up-regulation of expression of AKT1, HAK5, and HKT1 transporter genes. Taken together, our data provide the mechanistic explanation for differential salt stress sensitivity amongst these species and shed light on transcriptional and post-translational regulation of key ion transport systems involved in the maintenance of the root plasma membrane potential and cytosolic K/Na ratio as a key attribute for salt tolerance in Brassica species.Koushik Chakraborty, Jayakumar Bose, Lana Shabala and Sergey Shabal
Calcium sensor kinase activates potassium uptake systems in gland cells of Venus flytraps
No full textThe Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K+ uptake system in the Venus flytrap. In search of K+ transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K+-transporter genes into Xenopus oocytes, however, both putative K+ transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K+ transporter 1 (AKT1), we coexpressed the putative K+ transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K+ uptake. DmKT1 was found to be a K+-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around -120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K+, reducing its concentration from millimolar levels down to trace levels
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