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Effective, long-range, and self-propelled water elevation and transport are important in industrial, medical, and agricultural applications. Although research has grown rapidly, existing methods for water film elevation are still limited. Scaling up for practical applications in an energy-efficient way remains a challenge. Inspired by the continuous water cross-boundary transport on the peristome surface of Nepenthes alata, here we demonstrate the use of peristome-mimetic structures for controlled water elevation by bending biomimetic plates into tubes. The fabricated structures have unique advantages beyond those of natural pitcher plants: bulk water diode transport behavior is achieved with a high-speed passing state (several centimeters per second on a milliliter scale) and a gating state as a result of the synergistic effect between peristome-mimetic structures and tube curvature without external energy input. Significantly, on further bending the peristome-mimetic tube into a “candy cane”-shaped pipe, a self-siphon with liquid diode behavior is achieved. Such a transport mechanism should inspire the design of next generation water transport devices.

Carnivorous plants of the genus Nepenthes have evolved passive pitcher traps for prey capture. In this study, we investigated the ability of chemical signals from a prey (chitin, protein, and ammonium) to induce transcription and synthesis of digestive enzymes in Nepenthes×Mixta. We used real-time PCR and specific antibodies generated against the aspartic proteases nepenthesins, and type III and type IV chitinases to investigate the induction of digestive enzyme synthesis in response to different chemical stimuli from the prey. Transcription of nepenthesins was strongly induced by ammonium, protein and live prey; chitin induced transcription only very slightly. This is in accordance with the amount of released enzyme and proteolytic activity in the digestive fluid. Although transcription of type III chitinase was induced by all investigated stimuli, a significant accumulation of the enzyme in the digestive fluid was found mainly after protein and live prey addition. Protein and live prey were also the best inducers for accumulation of type IV chitinase in the digestive fluid. Although ammonium strongly induced transcription of all investigated genes probably through membrane depolarization, strong acidification of the digestive fluid affected stability and abundance of both chitinases in the digestive fluid. The study showed that the proteins are universal inductors of enzyme activities in carnivorous pitcher plants best mimicking the presence of insect prey. This is not surprising, because proteins are a much valuable source of nitrogen, superior to chitin. Extensive vesicular activity was observed in prey-activated glands.

A three-year field monoculture trial of Radix pseudostellariae and complementary laboratory studies were conducted to further elucidate the underlying mechanism responsible for significant decreases in the biomass yield and quality of R. pseudostellariae under continuous monoculture regimes. HPLC analysis indicated that continuous monoculture soil was rich in organic acids, which had cumulative effects over time. Further analysis suggested that the application of a mixture of organic acids significantly promoted growth of pathogenic fungi, and increased the expression of chemotaxis-related gene ( che A) and biofilm formation of the specific pathogenic Kosakonia sacchari . However, opposite reactions were observed in the case of Bacillus megaterium and Bacillus pumilus . Concurrently, the present results revealed that the mixed organic acids stimulated the production of toxins, as well as H 2 O 2 in the pathogenic fungi. Furthermore, the presence of organic acids reflecting environmental conditions under monocropping had negative effects on the expression of the biocontrol-related genes, which resulted in attenuated antagonistic activities of plant growth-promoting rhizobacteria (PGPR) to suppress mycelial growth of the pathogenic fungi. These results help to unveil the mechanisms associated with how accumulated organic acids differentially mediate deterioration of soil microbial composition and structure in monocropping system.

Carnivorous plants capture and digest insects for nutrients, allowing them to survive in soil deprived of nitrogenous nutrients. Plants from the genus Nepenthes produce unique pitchers containing secretory glands, which secrete enzymes into the digestive fluid. We performed RNA-seq analysis on the pitcher tissues and liquid chromatography-tandem mass spectrometry (LC–MS/MS) analysis on the pitcher fluids of Nepenthes × ventrata to study protein expression in this carnivory organ during early days of pitcher opening. This transcriptome provides a sequence database for pitcher fluid protein identification. A total of 32 proteins of diverse functions were successfully identified in which 19 proteins can be quantified based on label-free quantitative proteomics (SWATH-MS) analysis while 16 proteins were not reported previously. Our findings show that certain proteins in the pitcher fluid were continuously secreted or replenished after pitcher opening, even without any prey or chitin induction. We also discovered a new aspartic proteinase, Nep6, secreted into pitcher fluid. This is the first SWATH-MS analysis of protein expression in Nepenthes pitcher fluid using a species-specific reference transcriptome. Taken together, our study using a gel-free shotgun proteomics informed by transcriptomics (PIT) approach showed the dynamics of endogenous protein secretion in the digestive organ of N. × ventrata and provides insights on protein regulation during early pitcher opening prior to prey capture.

Clonal plants grow horizontally by producing multiple physiological individuals (ramets). We studied clonal growth in a homogeneous environment using a dynamic spatial model based on a stochastic cellular automaton. We investigated different growth forms from the aspect of ramet mortality. Non-steady-state and quasi-steady-state cases were defined, and we determined the number of steps suitable for making a reliable difference between these two types of cases. This given number of steps was used when testing for the proportion of quasi-steady-state cases in 1000 repetitions. We also tested the efficiency of occupation in these cases. Our expectation was that higher occupation would be associated with lower ramet mortality. The results only partially verified this hypothesis. Though with increasing ramet mortality, the average number of ramets tended to decrease, it was not the lowest ramet mortality that resulted in the highest occupation. Our results showed that very low ramet mortality was unfavourable for the plant, as the spreading front and the area behind this front were so packed that the plant was not able to return and recolonize the vacated sites in the central area. This resulted in a lower proportion of quasi-steady-state cases and lower occupation in these cases. Our results may contribute to a deeper understanding of clonal plant growth and its limiting factors.

Investigations of plant metabolism reveal how an enzyme variant with reduced feedback sensitivity may allow plants to switch their pigment palettes.

Background A structural phenomenon seen in certain lineages of angiosperms that has captivated many scholars including Charles Darwin is the evolution of plant carnivory. Evidently, these structural features collectively termed carnivorous syndrome, evolved to aid nutritional acquisition from attracted, captured and digested prey. We now understand why plant carnivory evolved but how carnivorous plants acquired these attributes remains a mystery. In an attempt to understand the evolution of Nepenthes pitcher and to shed more light on its role in prey digestion, we analyzed the transcriptome data of the highly specialized Nepenthes khasiana leaf comprising the leaf base lamina, tendril and the different parts/zones of the pitcher tube viz. digestive zone, waxy zone and lid. Results In total, we generated around 262 million high-quality Illumina reads. Reads were pooled, normalized and de novo assembled to generate a reference transcriptome of about 412,224 transcripts. We then estimated transcript abundance along the N. khasiana leaf by mapping individual reads from each part/zone to the reference transcriptome. Correlation-based hierarchical clustering analysis of 27,208 commonly expressed genes indicated functional relationship and similar cellular processes underlying the development of the leaf base and the pitcher, thereby implying that the Nepenthes pitcher is indeed a modified leaf. From a list of 2386 differentially expressed genes (DEGs), we identified transcripts encoding key enzymes involved in prey digestion and protection against pathogen attack, some of which are expressed at high levels in the digestive zone. Interestingly, many of these enzyme-encoding genes are also expressed in the unopened N. khasiana pitcher. Transcripts showing homology to both bacteria and fungi were also detected; and in the digestive zone, fungi are more predominant as compared to bacteria. Taking cues from histology and scanning electron microscopy (SEM) photomicrographs, we found altered expressions of key regulatory genes involved in leaf development. Of particular interest, the expression of class III HOMEODOMAIN-LEUCINE ZIPPER ( HD-ZIPIII ) and ARGONAUTE ( AGO ) genes were upregulated in the tendril. Conclusions Our findings suggest that N. khasiana pitchers employ a wide range of enzymes for prey digestion and plant defense, harbor microbes and probably evolved through altered expression of leaf polarity genes.

Many phylogenomic studies based on transcriptomes have been limited to “single-copy” genes due to methodological challenges in homology and orthology inferences. Only a relatively small number of studies have explored analyses beyond reconstructing species relationships. We sampled 69 transcriptomes in the hyperdiverse plant clade Caryophyllales and 27 outgroups from annotated genomes across eudicots. Using a combined similarity- and phylogenetic tree-based approach, we recovered 10,960 homolog groups, where each was represented by at least eight ingroup taxa. By decomposing these homolog trees, and taking gene duplications into account, we obtained 17,273 ortholog groups, where each was represented by at least ten ingroup taxa. We reconstructed the species phylogeny using a 1,122-gene data set with a gene occupancy of 92.1%. From the homolog trees, we found that both synonymous and nonsynonymous substitution rates in herbaceous lineages are up to three times as fast as in their woody relatives. This is the first time such a pattern has been shown across thousands of nuclear genes with dense taxon sampling. We also pinpointed regions of the Caryophyllales tree that were characterized by relatively high frequencies of gene duplication, including three previously unrecognized whole-genome duplications. By further combining information from homolog tree topology and synonymous distance between paralog pairs, phylogenetic locations for 13 putative genome duplication events were identified. Genes that experienced the greatest gene family expansion were concentrated among those involved in signal transduction and oxidoreduction, including a cytochrome P450 gene that encodes a key enzyme in the betalain synthesis pathway. Our approach demonstrates a new approach for functional phylogenomic analysis in nonmodel species that is based on homolog groups in addition to inferred ortholog groups.

Although anthocyanins are widely distributed in higher plants, betalains have replaced anthocyanins in most species of the order Caryophyllales. The accumulation of flavonols in Caryophyllales plants implies that the late step of anthocyanin biosynthesis from dihydroflavonols to anthocyanins may be blocked in Caryophyllales. The isolation and characterization of functional dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS) from Caryophyllales plants has indicated a lack of anthocyanins due to suppression of DFR and ANS. In this study, we demonstrated that overexpression of DFR and ANS from Spinacia oleracea (SoDFR and SoANS, respectively) with PhAN9, which encodes glutathione S-transferase (required for anthocyanin sequestration) from Petunia induces ectopic anthocyanin accumulation in yellow tepals of the cactus Astrophytum myriostigma. A promoter assay of SoANS showed that the Arabidopsis MYB transcription factor PRODUCTION OF ANTHOCYANIN PIGMENT1 (PAP1) activated the SoANS promoter in Arabidopsis leaves. The overexpression of Arabidopsis transcription factors with PhAN9 also induced ectopic anthocyanin accumulation in yellow cactus tepals. PAP homologs from betalain-producing Caryophyllales did not activate the promoter of ANS. In-depth characterization of Caryophyllales PAPs and site-directed mutagenesis in the R2R3–MYB domains identified the amino acid residues affecting transactivation of Caryophyllales PAPs. The substitution of amino acid residues recovered the transactivation ability of Caryophyllales PAPs. Therefore, loss of function in MYB transcription factors may suppress expression of genes involved in the late stage of anthocyanin synthesis, resulting in a lack of anthocyanin in betalain-producing Caryophyllales plants.

Background Alkaloids, important secondary metabolites produced by plants, play a crucial role in responding to environmental stress. Heuchera micrantha , a well-known plant used in landscaping, has the ability to purify air, and absorb toxic and radioactive substances, showing strong environmental adaptability. However, there is still limited understanding of the accumulation characteristics and metabolic mechanism of alkaloids in H. micrantha . Results In this study, four distinct varieties of H. micrantha were used to investigate the accumulation and metabolic traits of alkaloids in its leaves. We conducted a combined analysis of the plant’s metabolome and transcriptome. Our analysis identified 44 alkaloids metabolites in the leaves of the four H. micrantha varieties, with 26 showing different levels of accumulation among the groups. The HT and JQ varieties exhibited higher accumulation of differential alkaloid metabolites compared to YH and HY. We annotated the differential alkaloid metabolites to 22 metabolic pathways, including several alkaloid metabolism. Transcriptome data revealed 5064 differentially expressed genes involved in these metabolic pathways. Multivariate analysis showed that four key metabolites (N-hydroxytryptamine, L-tyramine, tryptamine, and 2-phenylethylamine) and three candidate genes ( Cluster-15488.116815 , Cluster-15488.146268 , and Cluster-15488.173297 ) that merit further investigation. Conclusions This study provided preliminarily insight into the molecular mechanism of the biosynthesis of alkaloids in H. micrantha . However, further analysis is required to elucidate the specific regulatory mechanisms of the candidate gene involved in the synthesis of key alkaloid metabolites. In summary, our findings provide important information about how alkaloid metabolites build up and the metabolic pathways involved in H. micrantha varieties. This gives us a good starting point for future research on the regulation mechanism, and development, and utilization of alkaloids in H. micrantha .