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Tensor network states, and in particular projected entangled pair states (PEPS) have been a strong ansatz for the variational study of complicated quantum many-body systems, thanks to their built-in entanglement entropy area law. In this work, we use a special kind of PEPS-gauged Gaussian fermionic PEPS (GGFPEPS)-to find the ground state of 2 thorn 1 dimensional pure Z2 lattice gauge theories for a wide range of coupling constants. We do so by combining PEPS methods with Monte-Carlo computations, allowing for efficient contraction of the PEPS and computation of correlation functions. Previously, such numerical computations involved the calculation of the Pfaffian of a matrix scaling with the system size, forming a severe bottleneck; in this work we show how to overcome this problem. This paves the way for applying the method we propose and benchmark here to other gauge groups, higher dimensions, and models with fermionic matter, in an efficient, sign-problem-free way.

ABA produced in the fig fruit triggers ethylene production in the inflorescence and induces non-climacteric ripening in the receptacle tissue., The common fig bears a unique closed inflorescence structure, the syconium, composed of small individual drupelets that develop from the ovaries, which are enclosed in a succulent receptacle of vegetative origin. The fig ripening process is traditionally classified as climacteric; however, recent studies have suggested that distinct mechanisms exist in its reproductive and non-reproductive parts. We analysed ABA and ethylene production, and expression of ABA-metabolism, ethylene-biosynthesis, MADS-box, NAC, and ethylene response-factor genes in inflorescences and receptacles of on-tree fruit treated with ABA, ethephon, fluridone, and nordihydroguaiaretic acid (NDGA). Exogenous ABA and ethephon accelerated fruit ripening and softening, whereas fluridone and NDGA had the opposite effect, delaying endogenous ABA and ethylene production compared to controls. Expression of the ABA-biosynthesis genes FcNCED2 and FcABA2, ethylene-biosynthesis genes FcACS4, FcACOL, and FcACO2, FcMADS8, 14, 15, FcNAC1, 2, 5, and FcERF9006 was up-regulated by exogenous ABA and ethephon. NDGA down-regulated FcNCED2 and FcABA2, whereas fluridone down-regulated FcABA2; both down-regulated the ethylene-related genes. These results demonstrate the key role of ABA in regulation of ripening by promoting ethylene production, as in the climacteric model plant tomato, especially in the inflorescence. However, increasing accumulation of endogenous ABA until full ripeness and significantly low expression of ethylene-biosynthesis genes in the receptacle suggests non-climacteric, ABA-dependent ripening in the vegetative-originated succulent receptacle part of the fruit.

Carotenoids have various roles in plant physiology. Plant carotenoids are synthesized in plastids and are highly abundant in the chromoplasts of ripening fleshy fruits. Considerable research efforts have been devoted to elucidating mechanisms that regulate carotenoid biosynthesis, yet, little is known about the mechanism that triggers storage capacity, mainly through chromoplast differentiation. The Orange gene (OR) product stabilizes phytoene synthase protein (PSY) and triggers chromoplast differentiation. OR underlies carotenoid accumulation in orange cauliflower and melon. The OR’s ‘golden SNP’, found in melon, alters the highly evolutionary conserved Arginine108 to Histidine and controls β-carotene accumulation in melon fruit, in a mechanism yet to be elucidated. We have recently shown that similar carotenogenic metabolic flux is active in non-orange and orange melon fruit. This flux probably leads to carotenoid turnover but known carotenoid turnover products are not detected in non-orange fruit. Arrest of this metabolic flux, using chemical inhibitors or mutations, induces carotenoid accumulation and biogenesis of chromoplasts, regardless of the allelic state of OR. We suggest that the ‘golden SNP’ induces β-carotene accumulation probably by negatively affecting the capacity to synthesize downstream compounds. The accumulation of carotenoids induces chromoplast biogenesis through a metabolite-induced mechanism. Carotenogenic turnover flux can occur in non-photosynthetic tissues, which do not accumulate carotenoids. Arrest of this flux by the ‘golden SNP’ or other flux-arrest mutations is a potential tool for the biofortification of agricultural products with carotenoids.

Gauge theories, through the local symmetry which is in their core, exhibit many local constraints, that must be taken care of and addressed in any calculation. In the Hamiltonian picture this is phrased through the Gauss laws, local constraints that restrict the physical Hilbert space and relate the matter and gauge degrees of freedom. In this work, we present a way that uses all the Gauss laws in lattice gauge theories with staggered fermions for completely removing the matter degrees of freedom, at the cost of locally extending the interaction range, breaking the symmetry and introducing new local constraints, due to the finiteness of the original local matter spaces.

Expression of 13 genes encoding chlorophyll biosynthesis and degradation was evaluated. Chlorophyll degradation was differentially regulated in pollinated and parthenocarpic fig fruits, leading to earlier chlorophyll degradation in parthenocarpic fruits. Varieties of the common fig typically yield a commercial summer crop that requires no pollination, although it can be pollinated. Fig fruit pollination results in larger fruit size, greener skin and darker interior inflorescence color, and slows the ripening process compared to non-pollinated fruits. We evaluated the effect of pollination on chlorophyll content and levels of transcripts encoding enzymes of the chlorophyll metabolism in fruits of the common fig ‘Brown Turkey’. We cloned and evaluated the expression of 13 different genes. All 13 genes showed high expression in the fruit skin, inflorescences and leaves, but extremely low expression in roots. Pollination delayed chlorophyll breakdown in the ripening fruit skin and inflorescences. This was correlated with the expression of genes encoding enzymes in the chlorophyll biosynthesis and degradation pathways. Expression of pheophorbide a oxygenase (PAO) was strongly negatively correlated with chlorophyll levels during ripening in pollinated fruits; along with its high expression levels in yellow leaves, this supports a pivotal role for PAO in chlorophyll degradation in figs. Normalizing expression levels of all chlorophyll metabolism genes in the pollinated and parthenocarpic fruit skin and inflorescences showed three synthesis (FcGluTR1, FcGluTR2 and FcCLS1) and three degradation (FcCLH1, FcCLH2 and FcRCCR1) genes with different temporal expression in the pollinated vs. parthenocarpic fruit skin and inflorescences. FcCAO also showed different expressions in the parthenocarpic fruit skin. Thus, chlorophyll degradation is differentially regulated in the pollinated and parthenocarpic fruit skin and inflorescences, leading to earlier and more sustained chlorophyll degradation in the parthenocarpic fruit.

Development and ripening processes differ in pollinated and parthenocarpic fruit. While the facultative parthenocarpic common-type fig fruit serves as a receptacle for flower development, it becomes fleshy by either pollination or through a parthenocarpic process. Here we studied the effect of pollination on common-type fig fruit development and ripening characteristics compared to the parthenocarpic fruit under otherwise identical conditions. The effects of pollination on fruit development were investigated on the tree and in storage. Pollinated fruit showed altered developmental processes. Ripened pollinated fruit were round, in contrast to the pear-like shape of the parthenocarpic fruit. The pollinated fruit also had a larger diameter and weight and improved firmness compared to the parthenocarpic fruit. At harvest, the pollinated fruit exhibited more commercially desirable physical and taste characteristics, with advanced fertile nutlets compared to the sterile undeveloped non-bearing nutlets of the parthenocarpic fruit. During storage, senescence and spoilage of the pollinated fruit were slower than in parthenocarpic fruit, as manifested by firmness, internal texture, weight, size, shriveling, and decay. Thus, pollination of the common-type fig cultivar Brown Turkey delayed senescence and extended the shelf life of its fruit. The external and internal morphological differences throughout post-pollination development make common-type fig an excellent research tool for studies of physiological and molecular aspects of pollination.

Annual and perennial plants represent two different evolutionary strategies based on differential synchronization of their reproductive development. The mobile signal protein FLOWERING LOCUS T (FT) plays a central role in mediating the onset of reproduction in both plant types. Two novel FT-like genes from pear (Pyrus communis)-PcFT1 and PcFT2-were isolated, and their expression profiles were determined for one annual cycle. The effects of PcFT2 on flowering were investigated in annual (tobacco) and perennial (apple) plants by means of grafting and generating transgenic plants. Long-distance graft transmission of PcFT2 in both annual and perennial plants was confirmed using a 35S::PcFT2-YFP construct. Ectopic overexpression of PcFT2 caused early flowering in tobacco but not in apple. Transgenic apples were less sensitive to short-day-induced dormancy, and this phenotype was also observed in wild-type apples grafted onto the transgenic plants. Comparison of PcFT2 protein structure to the paralogous FT proteins from apple and pear showed alterations that could influence protein structure and thus the florigen-activation complex. PcFT2 protein seems to function by promoting flowering as all other FT proteins in the annual plant tobacco while in the perennial plant apple PcFT2 does not promote flowering but delays senescence. This observation may hint to a modified function of FT2 in perennial plants.

Highlight The ambiguous ripening nature of fig fruits contradicts the climacteric definition. One ethylene-responsive factor gene is potentially the ethylene-synthesis regulator responsible for the non-climacteric auto-inhibition of ethylene production in fig., The traditional definition of climacteric and non-climacteric fruits has been put into question. A significant example of this paradox is the climacteric fig fruit. Surprisingly, ripening-related ethylene production increases following pre- or postharvest 1-methylcyclopropene (1-MCP) application in an unexpected auto-inhibitory manner. In this study, ethylene production and the expression of potential ripening-regulator, ethylene-synthesis, and signal-transduction genes are characterized in figs ripening on the tree and following preharvest 1-MCP application. Fig ripening-related gene expression was similar to that in tomato and apple during ripening on the tree, but only in the fig inflorescence–drupelet section. Because the pattern in the receptacle is different for most of the genes, the fig drupelets developed inside the syconium are proposed to function as parthenocarpic true fruit, regulating ripening processes for the whole accessory fruit. Transcription of a potential ripening regulator, FcMADS8, increased during ripening on the tree and was inhibited following 1-MCP treatment. Expression patterns of the ethylene-synthesis genes FcACS2, FcACS4, and FcACO3 could be related to the auto-inhibition reaction of ethylene production in 1-MCP-treated fruit. Along with FcMADS8 suppression, gene expression analysis revealed upregulation of FcEBF1, and downregulation of FcEIL3 and several FcERFs by 1-MCP treatment. This corresponded with the high storability of the treated fruit. One FcERF was overexpressed in the 1-MCP-treated fruit, and did not share the increasing pattern of most FcERFs in the tree-ripened fig. This demonstrates the potential of this downstream ethylene-signal-transduction component as an ethylene-synthesis regulator, responsible for the non-climacteric auto-inhibition of ethylene production in fig.

The Ficus carica L. (Moraceae) tree belongs to one of the largest genera of angiosperms and bears a unique closed inflorescence structure. Ripe fresh figs are highly perishable and require delicate postharvest handling. Studying the pathways that lead to fig ripening may provide additional ways of extending their storage life. We selected four developmental stages of fig fruit for transcriptome sequencing and analysis to identify the major active metabolic pathways and transcription factors during fig fruit ripening. We found 12,751 unigenes, 93 % of which were homologous to at least one nonredundant database sequence, and 46,927 singletons, 39 % with a matching sequence from the nonredundant database. Differential activity related to photosynthesis, anthocyanin and volatile metabolism, cell wall and wax metabolism, cell expansion, transcription, DNA metabolism and organization was traced. In addition, ethylene-synthesis genes were identified. Finally, 516 unigenes encoding transcription factors were found which were active in the regulation of early and late ripening processes. Focusing on eight FcMADS-box transcription factors revealed three genes encoding members of the AGL2 (SEP) subfamily, which is closely associated with ripening regulation. This study provides expressed-gene dataset for multiple developmental stages of fig fruit (F. carica), and analysis directed to ripening metabolism, control, and regulation. It provides a potential platform for further studies of this unique plant family and contributes to ripening process research in nonmodel systems.

In this study the substitutability of maize silage with Acutodesmus obliquus biomass was investigated. To do this, an existing large-scale biogas plant digesting maize silage and pig slurry was simulated at laboratory scale and run for 270 days at 38 °C. In different operation types 10% and 20% of maize silage VS were substituted with A. obliquus biomass VS. Additionally, reactors were fed with 20% ultrasonicated A. obliquus biomass. Differences in process stability could not be observed. The biogas production decreased at increased concentrations of microalgal biomass. A significant difference between untreated and ultrasonicated algal biomass (both 20%) could not be proven.However, the percentage decrease was lower than the percentage of maize silage VS substituted. Therefore it can be concluded that A. obliuus biomass is anaerobically degradable without any pretreatment., Proceedings of the 24th European Biomass Conference and Exhibition, 6-9 June 2016, Amsterdam, The Netherlands, pp. 619-621

Brunfelsia calycina flowers change colour from purple to white due to anthocyanin degradation, parallel to an increase in fragrance and petal size. Here it was tested whether the production of the fragrant benzenoids is dependent on induction of the shikimate pathway, or if they are formed from the anthocyanin degradation products. An extensive characterization of the events taking place in Brunfelsia flowers is presented. Anthocyanin characterization was performed using ultraperfomance liquid chromatography-quadrupole time of flight-tandem mass specrometry (UPLC-QTOF-MS/MS). Volatiles emitted were identified by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Accumulated proteins were identified by 2D gel electrophoresis. Transcription profiles were characterized by cross-species hybridization of Brunfelsia cDNAs to potato cDNA microarrays. Identification of accumulated metabolites was performed by UPLC-QTOF-MS non-targeted metabolite analysis. The results include characterization of the nine main anthocyanins in Brunfelsia flowers. In addition, 146 up-regulated genes, 19 volatiles, seven proteins, and 17 metabolites that increased during anthocyanin degradation were identified. A multilevel analysis suggests induction of the shikimate pathway. This pathway is the most probable source of the phenolic acids, which in turn are precursors of both the benzenoid and lignin production pathways. The knowledge obtained is valuable for future studies on degradation of anthocyanins, formation of volatiles, and the network of secondary metabolism in Brunfelsia and related species.

Tensor network states, and in particular projected entangled pair states (PEPS), suggest an innovative approach for the study of lattice gauge theories, both from a pure theoretic point of view, and as a tool for the analysis of the recent proposals for quantum simulations of lattice gauge theories. In this paper we present a framework for describing locally gauge invariant states on lattices using PEPS. The PEPS constructed hereby shall include both bosonic and fermionic states, suitable for all combinations of matter and gauge fields in lattice gauge theories defined by either finite or compact Lie groups., Updated version with a new section, an extended introduction and additional comments and references

Anaerobic digestion of microalgal biomass is one option for sustainable energy production. Therefore, several microalgae i.e. Chlorella vulgaris, C. emersonii and Acutodesmus obliquus were produced in a sleevebag photobioreactor system (maximum volume 800 L) and investigated in so-called biochemical methane potential tests (BMP). Different pre-treatments were selected in order to enhance methane (CH4) yields. A. obliquus was selected to screen for effective pretreatment methods: a combined milling and enzyme approach (+57%), ultrasonication (+53%) and milling (+51%) resulted in significantly higher CH4 yields. In the follow-up experiments, milling and ultrasonication were applied to cooled biomass of C. emersonii and A. obliquus. In both cases, ultrasonication led again to significantly higher CH4 yields (+41%) for A. obliquus and (+35%) for C. emersonii. In experiments with frozen biomass, highest CH4 yields were reached with freeze-thawed C. vulgaris biomass i.e. 406 Nm³ t-1 VSharvest. Freeze-thawed A. obliquus biomass yielded 337 Nm³ t-1 VSharvest, an increase of 47% if compared to unfrozen biomass i.e. 229 Nm³ t-1 VSharvest. Ultrasonication of frozen A. obliquus biomass increased CH4 yields for only 20% indicating that freeze-thawing strongly affects CH4 yields and provokes cell disruption by ice crystals. In addition, our work proposes that pretreatments seem to act strain-specific., Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 612-615