Autoregulation of RCO by Low-Affinity Binding Modulates Cytokinin Action and Shapes Leaf Diversity

Mechanisms through which the evolution of gene regulation causes morphological diversity are largely unclear. The tremendous shape variation among plant leaves offers attractive opportunities to address this question. In cruciferous plants, the REDUCED COMPLEXITY (RCO) homeodomain protein evolved via gene duplication and acquired a novel expression domain that contributed to leaf shape diversity. However, the molecular pathways through which RCO regulates leaf growth are unknown. A key question is to identify genome-wide transcriptional targets of RCO and the DNA sequences to which RCO binds. We investigate this question using Cardamine hirsuta, which has complex leaves, and its relative Arabidopsis thaliana, which evolved simple leaves through loss of RCO. We demonstrate that RCO directly regulates genes controlling homeostasis of the hormone cytokinin to repress growth at the leaf base. Elevating cytokinin signaling in the RCO expression domain is sufficient to both transform A. thaliana simple leaves into complex ones and partially bypass the requirement for RCO in C. hirsuta complex leaf development. We also identify RCO as its own target gene. RCO directly represses its own transcription via an array of low-affinity binding sites, which evolved after RCO duplicated from its progenitor sequence. This autorepression is required to limit RCO expression. Thus, evolution of low-affinity binding sites created a negative autoregulatory loop that facilitated leaf shape evolution by defining RCO expression and fine-tuning cytokinin activity. In summary, we identify a transcriptional mechanism through which conflicts between novelty and pleiotropy are resolved during evolution and lead to morphological differences between species. Hajheidari et al. identify target genes for the RCO homeodomain protein that drove leaf shape diversity. They show that RCO regulates growth via orchestrating homeostasis for the hormone cytokinin and that it also represses its own transcription via low-affinity binding sites. This autorepression helps delimit RCO expression and shape leaf form

The Physiology and Proteomics of Drought Tolerance in Maize: Early Stomatal Closure as a Cause of Lower Tolerance to Short-Term Dehydration?

Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance

The Arabidopsis RNA Polymerase II Carboxyl Terminal Domain (CTD) Phosphatase-Like1 (CPL1) is a biotic stress susceptibility gene

© 2018, The Author(s). Crop breeding for improved disease resistance may be achieved through the manipulation of host susceptibility genes. Previously we identified multiple Arabidopsis mutants known as enhanced stress response1 (esr1) that have defects in a KH-domain RNA-binding protein and conferred increased resistance to the root fungal pathogen Fusarium oxysporum. Here, screening the same mutagenized population we discovered two further enhanced stress response mutants that also conferred enhanced resistance to F. oxysporum. These mutants also have enhanced resistance to a leaf fungal pathogen (Alternaria brassicicola) and an aphid pest (Myzus persicae), but not to the bacterial leaf pathogen Pseudomonas syringae. The causal alleles in these mutants were found to have defects in the ESR1 interacting protein partner RNA Polymerase II Carboxyl Terminal Domain (CTD) Phosphatase-Like1 (CPL1) and subsequently given the allele symbols cpl1-7 and cpl1-8. These results define a new role for CPL1 as a pathogen and pest susceptibility gene. Global transcriptome analysis and oxidative stress assays showed these cpl1 mutants have increased tolerance to oxidative stress. In particular, components of biotic stress responsive pathways were enriched in cpl1 over wild-type up-regulated gene expression datasets including genes related to defence, heat shock proteins and oxidative stress/redox state processes

Metabolite profiling at the cellular and subcellular level reveals metabolites associated with salinity tolerance in sugar beet

Hossain MS, Persicke M, ElSayed AI, Kalinowski J, Dietz K-J. Metabolite profiling at the cellular and subcellular level reveals metabolites associated with salinity tolerance in sugar beet. Journal of Experimental Botany. 2017;68(21-22):5961-5976.Sugar beet is among the most salt-tolerant crops. This study aimed to investigate the metabolic adaptation of sugar beet to salt stress at the cellular and subcellular levels. Seedlings were grown hydroponically and subjected to stepwise increases in salt stress up to 300 mM NaCl. Highly enriched fractions of chloroplasts were obtained by nonaqueous fractionation using organic solvents. Total leaf metabolites and metabolites in chloroplasts were profiled at 3 h and 14 d after reaching the maximum salinity stress of 300 mM NaCl. Metabolite profiling by gas chromatography- mass spectrometry (GC-MS) resulted in the identification of a total of 83 metabolites in leaves and chloroplasts under control and stress conditions. There was a lower abundance of Calvin cycle metabolites under salinity whereas there was a higher abundance of oxidative pentose phosphate cycle metabolites such as 6-phosphogluconate. Accumulation of ribose-5-phosphate and ribulose-5-phosphate coincided with limitation of carbon fixation by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Increases in glycolate and serine levels indicated that photorespiratory metabolism was stimulated in salt-stressed sugar beet. Compatible solutes such as proline, mannitol, and putrescine accumulated mostly outside the chloroplasts. Within the chloroplast, putrescine had the highest relative level and probably assisted in the acclimation of sugar beet to high salinity stress. The results provide new information on the contribution of chloroplasts and the extra-chloroplast space to salinity tolerance via metabolic adjustment in sugar beet

Luminosity determination using Z boson production at the CMS experiment

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton–proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13 TeV . Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 20 pb-1 of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z bosons for the integrated luminosity measurement is performed. The uncertainty in the extrapolation between two data sets, recorded in 2017 at low and high instantaneous luminosity, is less than 0.5%. We show that the Z boson rate measurement constitutes a precise method, complementary to traditional methods, with the potential to improve the measurement of the integrated luminosity

Measurements of the branching fraction ratio B(ϕ→μ+μ−)/B(ϕ→e+e−)\cal{B}(\phi \to \mu^+\mu^-)/\cal{B}(\phi \to e^+e^-) with charm meson decays

Measurements of the branching fraction ratio ${\cal{B}(\phi \to \mu^+ \mu^-)/\cal{B}(\phi\to e^+e^-)}$ with ${D_{s}^{+} \to \pi^{+} \phi}$ and ${D^{+} \to \pi^{+} \phi}$ decays, denoted $R^{s}_{\phi \pi}$ and $R^{d}_{\phi \pi}$, are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4$\,\rm{fb}^{-1}$ of $pp$ collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the ${B^{+} \to K^{+} J/\psi(\to e^+e^-)}$ and ${B^{+} \to K^{+} J/\psi(\to \mu^+\mu^-)}$ decay modes. The combination of the results yields $$R_{\phi \pi} = 1.022 \pm 0.012 \,({\rm stat}) \, \pm 0.048 \,({\rm syst}).$$ The result is compatible with previous measurements of the $\phi \to \ell^{+}\ell^{-}$ branching fractions and predictions based on the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-038.html (LHCb public pages

Search for CP\textit{CP} violation in the phase space of D0→KS0K±π∓D^{0} \rightarrow K_{S}^{0} K^{\pm} \pi^{\mp} decays with the energy test

A search for $\textit{CP}$ violation in $D^{0} \rightarrow K_{S}^{0} K^{+} \pi^{-}$ and $D^{0} \rightarrow K_{S}^{0} K^{-} \pi^{+}$ decays is reported. The search is performed using an unbinned model-independent method known as the energy test that probes local $\textit{CP}$ violation in the phase space of the decays. The data analysed correspond to an integrated luminosity of $5.4~$fb$^{-1}$ collected in proton-proton collisions by the LHCb experiment at a centre-of-mass energy of $\sqrt{s}=13$~TeV, amounting to approximately 950000 and 620000 signal candidates for the $D^{0} \rightarrow K_{S}^{0} K^{-} \pi^{+}$ and $D^{0} \rightarrow K_{S}^{0} K^{+} \pi^{-}$ modes, respectively. The method is validated using $D^{0} \rightarrow K^{-} \pi^{+} \pi^{-} \pi^{+}$ and $D^{0} \rightarrow K_{S}^{0} \pi^{+} \pi^{-}$ decays, where $\textit{CP}$-violating effects are expected to be negligible, and using background-enhanced regions of the signal decays. The results are consistent with $\textit{CP}$ symmetry in both the $D^{0} \rightarrow K_{S}^{0} K^{-} \pi^{+}$ and the $D^{0} \rightarrow K_{S}^{0} K^{+} \pi^{-}$ decays, with $p$-values for the hypothesis of no $\textit{CP}$ violation of 70% and 66%, respectively.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-019.html (LHCb public pages

Observation of strangeness enhancement with charmed mesons in high-multiplicity pPbp\mathrm{Pb} collisions at sNN=8.16 \sqrt {s_{\mathrm{NN}}}=8.16\,TeV

The production of prompt $D^+_{s}$ and $D^+$ mesons is measured by the LHCb experiment in proton-lead ($p\mathrm{Pb}$) collisions in both the forward ($1.5<y^*<4.0$) and backward ($-5.0<y^*<-2.5$) rapidity regions at a nucleon-nucleon center-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=8.16\,$TeV. The nuclear modification factors of both $D^+_{s}$ and $D^+$ mesons are determined as a function of transverse momentum, $p_{\mathrm{T}}$, and rapidity. In addition, the $D^+_{s}$ to $D^+$ cross-section ratio is measured as a function of the charged particle multiplicity in the event. An enhanced $D^+_{s}$ to $D^+$ production in high-multiplicity events is observed for the whole measured $p_{\mathrm{T}}$ range, in particular at low $p_{\mathrm{T}}$ and backward rapidity, where the significance exceeds six standard deviations. This constitutes the first observation of strangeness enhancement in charm quark hadronization in high-multiplicity $p\mathrm{Pb}$ collisions. The results are also qualitatively consistent with the presence of quark coalescence as an additional charm quark hadronization mechanism in high-multiplicity proton-lead collisions.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-021.html (LHCb public pages