Ascospore release and survival in Sclerotinia sclerotiorum

The release and survival of ascospores of a UK Sclerotinia sclerotiorum isolate were studied. Apothecia placed in a spore clock apparatus with different lighting regimes at 15 °C released ascospores continuously with an increasing rate for the duration of experiments (72–84 h). Spore release was not confined to light or dark periods in alternating regimes and occurred in continuous dark or light. Ascospores were released in both saturated air (90–95% rh) and at 65–75% rh. High temperature and rh were detrimental to ascospore survival but spore viability was maintained for longer periods than previously reported. The significance of these results in relation to disease control is discussed

A dual function of SnRK2 kinases in the regulation of SnRK1 and plant growth

[EN] Adverse environmental conditions trigger responses in plants that promote stress tolerance and survival at the expense of growth(1). However, little is known of how stress signalling pathways interact with each other and with growth regulatory components to balance growth and stress responses. Here, we show that plant growth is largely regulated by the interplay between the evolutionarily conserved energy-sensing SNF1-related protein kinase 1 (SnRK1) protein kinase and the abscisic acid (ABA) phytohormone pathway. While SnRK2 kinases are main drivers of ABA-triggered stress responses, we uncover an unexpected growth-promoting function of these kinases in the absence of ABA as repressors of SnRK1. Sequestration of SnRK1 by SnRK2-containing complexes inhibits SnRK1 signalling, thereby allowing target of rapamycin (TOR) activity and growth under optimal conditions. On the other hand, these complexes are essential for releasing and activating SnRK1 in response to ABA, leading to the inhibition of TOR and growth under stress. This dual regulation of SnRK1 by SnRK2 kinases couples growth control with environmental factors typical for the terrestrial habitat and is likely to have been critical for the water-to-land transition of plants.We thank J.-K. Zhu for the snrk2 mutants, M. Bennett for the SnRK2.2-GFP line, C. Koncz for the SnRK1-GFP line, X. Li for the SnRK2.3-FLAG OE line, J. Schroeder for the GFP-His-FLAG and SnRK2.6-His-FLAG OE lines, C. Mackintosh for the TPS5 antibody and the Nottingham Arabidopsis stock centre for T-DNA mutant seeds. The IGC Plant Facility (Vera Nunes) is thanked for excellent plant care. This work was supported by Fundacao para a Ciencia e a Tecnologia through the R&D Units UIDB/04551/2020 (GREEN-IT-Bioresources for Sustainability) and UID/MAR/04292/2019, FCT project nos. PTDC/BIA-PLA/7143/2014, LISBOA-01-0145-FEDER-028128 and PTDC/BIA-BID/32347/2017, and FCT fellowships/contract nos. SFRH/BD/122736/2016 (M.A.), SFRH/BPD/109336/2015 (A.C.), PD/BD/150239/2019 (D.R.B.), and IF/00804/2013 (E.B.G.). Work in P.L.R.'s laboratory was funded by MCIU grant no. BIO2017-82503-R. C.M. thanks the LabEx Paris Saclay Plant Sciences-SPS (ANR-10-LABX-040-SPS) for support. B.B.P. was funded by Programa VALi+d GVA APOSTD/2017/039. This project has received funding from the European Union Horizon 2020 research and innovation programme (grant agreement no. 867426-ABA-GrowthBalance-H2020-WF-2018-2020/H2020-WF-01-2018, awarded to B.B.P.). This work is dedicated to the memory of our beloved friend and colleague Americo Rodrigues.Belda-Palazón, B.; Adamo, M.; Valerio, C.; Ferreira, LJ.; Confraria, A.; Reis-Barata, D.; Rodrigues, A.... (2020). A dual function of SnRK2 kinases in the regulation of SnRK1 and plant growth. 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Plant-Type Trehalose Synthetic Pathway in Cryptosporidium and Some Other Apicomplexans

The trehalose synthetic pathway is present in bacteria, fungi, plants and invertebrate animals, but is absent in vertebrates. This disaccharide mainly functions as a stress protectant against desiccation, heat, cold and oxidation. Genes involved in trehalose synthesis have been observed in apicomplexan parasites, but little was known about these enzymes. Study on trehalose synthesis in apicomplexans would not only shed new light into the evolution of this pathway, but also provide data for exploring this pathway as novel drug target.We have observed the presence of the trehalose synthetic pathway in Cryptosporidium and other apicomplexans and alveolates. Two key enzymes (trehalose 6-phosphate synthase [T6PS; EC 2.4.1.15] and trehalose phosphatase [TPase; EC 3.1.3.12] are present as Class II bifunctional proteins (T6PS-TPase) in the majority of apicomplexans with the exception of Plasmodium species. The enzyme for synthesizing the precursor (UDP-glucose) is homologous to dual-substrate UDP-galactose/glucose pyrophosphorylases (UGGPases), rather than the "classic" UDP-glucose pyrophosphorylase (UGPase). Phylogenetic recontructions indicate that both T6PS-TPases and UGGPases in apicomplexans and other alveolates are evolutionarily affiliated with stramenopiles and plants. The expression level of T6PS-TPase in C. parvum is highly elevated in the late intracellular developmental stage prior to or during the production of oocysts, implying that trehalose may be important in oocysts as a protectant against environmental stresses. Finally, trehalose has been detected in C. parvum oocysts, thus confirming the trehalose synthetic activity in this parasite.A trehalose synthetic pathway is described in the majority of apicomplexan parasites including Cryptosporidium and the presence of trehalose was confirmed in the C. parvum oocyst. Key enzymes in the pathway (i.e., T6PS-TPase and UGGPase) are plant-type and absent in humans and animals, and may potentially serve as novel drug targets in the apicomplexans

Dominant culture and bullying : personal accounts of workers in Malaysia

Workplace bullying has been termed the cancer of the workplace; it is a widespread and often intractable problem. Internationally, a wealth of research has examined the prevalence of workplace bullying and its negative effects. This research base and the scientific definition of workplace bullying are, however, based on Western perspectives and supported by theories, models, and research studies conducted in Western cultures. The differences in cultural perspectives of Western and Eastern countries mean that workplace bullying may not be understood in the same way across different cultural groups, particularly when cultures differ along the Individualism-Collectivism dimension. Given that Malaysia is an Eastern country with a number of ethnic groups, a more comprehensive understanding of workplace bullying in the Malaysian context is important. Through a case study comprising in-depth qualitative interviews with 20 employees from different organisations in Malaysia, this chapter reveals six lay beliefs of workplace bullying and 19 lay beliefs about bullying behaviors. The study also found that the 12 bullying behaviors are work related while the other seven are personal-nature bullying behaviors. These results emphasize the influence of culture on how bullying is perceived within the Malaysian context, and the importance of understanding lay representations of workplace bullying from the Eastern context that apparent across nation. Based on the interviews, a general definition of workplace bullying from Malaysian employees' perspectives is presented and developed. The chapter concludes with implications for understanding bullying as an important psychosocial hazard at work and recommendations for future research and practice across the Asia Pacific region

Phosphorylation and 14-3-3 binding of Arabidopsis 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase

Fructose 2,6-bisphosphate (fru-2,6-P2) is a signalling metabolite that regulates photosynthetic carbon partitioning in plants. The content of fru-2,6-P2 in Arabidopsis leaves varied in response to photosynthetic activity with an abrupt decrease at the start of the photoperiod, gradual increase through the day, and modest decrease at the start of the dark period. In Arabidopsis suspension cells, fru-2,6-P2 content increased in response to an unknown signal upon transfer to fresh culture medium. This increase was blocked by either 2-deoxyglucose or the protein phosphatase inhibitor, calyculin A, and the effects of calyculin A were counteracted by the general protein kinase inhibitor K252a. The changes in fru-2,6-P2 at the start of dark period in leaves and in the cell experiments generally paralleled changes in nitrate reductase (NR) activity. NR is inhibited by protein phosphorylation and binding to 14-3-3 proteins, raising the question of whether fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase protein from Arabidopsis thaliana (AtF2KP), which both generates and hydrolyses fru-2,6-P2, is also regulated by phosphorylation and 14-3-3s. Consistent with this hypothesis, AtF2KP and NR from Arabidopsis cell extracts bound to a 14-3-3 column, and were eluted specifically by a synthetic 14-3-3-binding phosphopeptide (ARAApSAPA). 14-3-3s co-precipitated with recombinant glutathione S-transferase (GST)-AtF2KP that had been incubated with Arabidopsis cell extracts in the presence of Mg-ATP. 14-3-3s bound directly to GST-AtF2KP that had been phosphorylated on Ser220 (SLSASGpSFR) and Ser303 (RLVKSLpSASSF) by recombinant Arabidopsis calcium-dependent protein kinase isoform 3 (CPK3), or on Ser303 by rat liver mammalian AMP-activated protein kinase (AMPK; homologue of plant SNF-1 related protein kinases (SnRKs)) or an Arabidopsis cell extract. We have failed to find any direct effect of 14-3-3s on the F2KP activity in vitro to date. Nevertheless, our findings indicate the possibility that 14-3-3 binding to SnRK1-phosphorylated sites on NR and F2KP may regulate both nitrate assimilation and sucrose/starch partitioning in leaves

Regulation of multisite phosphorylation and 14-3-3 binding of AS160 in response to IGF-1, EGF, PMA and AICAR

AS160 (Akt substrate of 160 kDa) mediates insulin-stimulated GLUT4 (glucose transporter 4) translocation, but is widely expressed in insulin-insensitive tissues lacking GLUT4. Having isolated AS160 by 14-3-3-affinity chromatography, we found that binding of AS160 to 14-3-3 isoforms in HEK (human embryonic kidney)-293 cells was induced by IGF-1 (insulin-like growth factor-1), EGF (epidermal growth factor), PMA and, to a lesser extent, AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside). AS160-14-3-3 interactions were stabilized by chemical cross-linking and abolished by dephosphorylation. Eight residues on AS160 (Ser(318), Ser(341), Thr(568), Ser(570), Ser(588), Thr(642), Ser(666) and Ser(751)) were differentially phosphorylated in response to IGF-1, EGF, PMA and AICAR. The binding of 14-3-3 proteins to HA–AS160 (where HA is haemagglutinin) was markedly decreased by mutation of Thr(642) and abolished in a Thr642Ala/Ser341Ala double mutant. The AGC (protein kinase A/protein kinase G/protein kinase C-family) kinases RSK1 (p90 ribosomal S6 kinase 1), SGK1 (serum- and glucocorticoid-induced protein kinase 1) and PKB (protein kinase B) displayed distinct signatures of AS160 phosphorylation in vitro: all three kinases phosphorylated Ser(318), Ser(588) and Thr(642); RSK1 also phosphorylated Ser(341), Ser(751) and to a lesser extent Thr(568); and SGK1 phosphorylated Thr(568) and Ser(751). AMPK (AMP-activated protein kinase) preferentially phosphorylated Ser(588), with less phosphorylation of other sites. In cells, the IGF-1-stimulated phosphorylations, and certain EGF-stimulated phosphorylations, were inhibited by PI3K (phosphoinositide 3-kinase) inhibitors, whereas the RSK inhibitor BI-D1870 inhibited the PMA-induced phosphorylations. The expression of LKB1 in HeLa cells and the use of AICAR in HEK-293 cells promoted phosphorylation of Ser(588), but only weak Ser(341) and Thr(642) phosphorylations and binding to 14-3-3s. Paradoxically however, phenformin activated AMPK without promoting AS160 phosphorylation. The IGF-1-induced phosphorylation of the novel phosphorylated Ser(666)-Pro site was suppressed by AICAR, and by combined mutation of a TOS (mTOR signalling)-like sequence (FEMDI) and rapamycin. Thus, although AS160 is a common target of insulin, IGF-1, EGF, PMA and AICAR, these stimuli induce distinctive patterns of phosphorylation and 14-3-3 binding, mediated by at least four protein kinases