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• Hydrogen sulphide (H₂S) has been proposed as the third gasotransmitter. In animal cells, H₂S has been implicated in several physiological processes. H₂S is endogenously synthesized in both animals and plants by enzymes with l‐Cys desulphydrase activity in the conversion of l‐Cys to H₂S, pyruvate and ammonia. • The participation of H₂S in both stomatal movement regulation and abscisic acid (ABA)‐dependent induction of stomatal closure was studied in epidermal strips of three plant species (Vicia faba, Arabidopsis thaliana and Impatiens walleriana). The effect of H₂S on stomatal movement was contrasted with leaf relative water content (RWC) measurements of whole plants subjected to water stress. • In this work we report that exogenous H₂S induces stomatal closure and this effect is impaired by the ATP‐binding cassette (ABC) transporter inhibitor glibenclamide; scavenging H₂S or inhibition of the enzyme responsible for endogenous H₂S synthesis partially blocks ABA‐dependent stomatal closure; and H₂S treatment increases RWC and protects plants against drought stress. • Our results indicate that H₂S induces stomatal closure and participates in ABA‐dependent signalling, possibly through the regulation of ABC transporters in guard cells.

The effect of the habitat conditions on the pollen features of invasive species has not been studied so far, and may affect the quality of their generative reproduction and contribute to the development of more effective methods of their control. Three species invasive in Europe and Poland were selected for the study - Impatiens parviflora DC., Impatiens glandulifera Royle and Impatiens capensis Meerb. The morphology and intraspecific variability of pollen grains in three Impatiens species growing under different habitat conditions were examined. Specimens were sampled from 198 sites throughout Poland, covering 10 ecologically distinct habitat types. In total, 5940 pollen grains were analysed in respect to the length of the polar axis (P), equatorial diameter (E), exine thickness (Exp), P/E, Exp/P ratios, and exine ornamentation and ectocolpi arrangement. Our research showed that the three studied species can be distinguished based on their palynomorphology. The most important traits were: exine ornamentation and ectocolpi arrangement, pollen size (P, E) and exine thickness (Exp). A relationship between the habitat conditions prevailing in the analysed habitats and the pollen grain characteristics was found, especially in I. glandulifera . In this species pollen size (P, E) increases in the optimal habitat conditions such as edges of reservoirs and watercourses, and decreases in the suboptimal habitat conditions such as anthropogenic habitats. A similar pattern is observed in I. parviflora , where optimal habitats such as mesic mixed coniferous forest favour larger pollen grains, whereas suboptimal habitats like swamp forest are associated with reduced pollen size. In I. capensis , optimal conditions also correspond to edges of watercourses, while suboptimal conditions include swamp forest. Additionally, exine thickness (Exp) may represent an adaptive trait, reflecting plant response to growth and development in unfavorable environments.

Impatiens spp. are well-known ornamental and medicinal plants that are widely distributed in the highlands and mountains of southwestern China. This area is one of the hotspots for the distribution of Impatiens species, with typical karst landforms and abundant wild resources. Many of these species are endemic to a narrow distribution area, but their classification and relationships are relatively unclear because of insufficient field investigations, diverse morphological characteristics and lack of molecular information. In this study, chloroplast genome analysis of 13 species (including 2 synonyms) in karst habitats was conducted to study their characteristics and phylogenetic relationships. The results revealed that these chloroplast genomes all had double-stranded tetrad structures ranging in length from 151,284 bp to 152,421 bp, including a total of 113 genes, including 80 protein-coding genes, 29 transfer RNAs, and 4 ribosomal RNAs. SSRs mainly consist of A/T repeats and AT/AT repeats, while INEs mainly consist of positive repeats and palindromic repeats. The frequency of codon usage was essentially the same, with a total of 31 high-frequency codons detected, the vast majority ending in A/U. Five mutation hotspots were detected: rps16-trnQ-UUG , ndhF , ccsA - ndhD , ycf1 , and trnN-GUU , among which ycf1 had the highest Pi value and the greatest potential as a DNA barcode marker. Our phylogenetic tree shows that all 13 species belong to Section Impatiens . And supported the classification of I. reptans and I. rhombifolia should as synonyms (BS = 100/PP = 1.00). This study comprehensively analyzed the cp genomes of different taxa, sheds light on the taxonomic intricacies of Impatiens species, provide valuable information into its phylogenetic and taxonomy.

Shading and mechanical stress (MS) modulate plant architecture by inducing different developmental pathways. Shading results in increased stem elongation, often reducing whole-plant mechanical stability, while MS inhibits elongation, with a concomitant increase in stability. Here, we examined how these organ-level responses are related to patterns and processes at the cellular level by exposing Impatiens capensis to shading and MS. Shading led to the production of narrower cells along the vertical axis. By contrast, MS led to the production of fewer, smaller and broader cells. These responses to treatments were largely in line with genetic differences found among plants from open and closed canopy sites. Shading- and MS-induced plastic responses in cellular characteristics were negatively correlated: genotypes that were more responsive to shading were less responsive to MS and vice versa. This negative correlation, however, did not scale to mechanical and architectural traits. Our data show how environmental conditions elicit distinctly different associations between characteristics at the cellular level, plant morphology and biomechanics. The evolution of optimal response to different environmental cues may be limited by negative correlations of stress-induced responses at the cellular level.

Impatiens morsei is an annual or perennial flower that is a member of the Impatiens genus in the Balsaminaceae family, with pink flowers and dark purple spots on the vexil and wing petals, which is important for the study of new flower colors of Balsaminaceae. However, there has been no study on the flavonoid biosynthesis pathway and carotenoid biosynthesis pathway of I. morsei and the mechanism of its pigment formation is still unclear. Transcriptome sequencing of spotted and non-spotted regions was performed using the petals of I. morsei at full bloom as test material. The results showed that (1) After transcriptome sequencing, 39,917 unigene sequences and 39,110 differentially expressed genes were obtained, and the number of genes that are down-expressed was higher than genes that are up-expressed. (2) Three key genes in the flavonoid biosynthetic pathway, FLS , PAL , and CHS1 , were screened out. Additionally, two key genes in the carotenoid biosynthetic pathway, ABA1 and CCS , were identified. Furthermore, two regulatory genes, MSI4 and CPC, were also selected.and analyzed the spatiotemporal expression patterns of these seven genes. The results of this study lay a theoretical foundation for the study of the formation mechanism of floral spots in I. morsei .

Background The Impatiens plants are one of the world’s top three flower bed floriferous plants with important ornamental and horticultural values, vivid floral colors are more likely to attract pollinators, and one of the important ornamental traits of flowers. This study was conducted to determine whether the flower color of Impatiens can be altered after induction, with the aim of clarifying the molecular basis underlying its variation and to offer a vital reference for developing novel Impatiens varieties. Compared with diploids, the flower color of colchicine-induced Impatiens showed obvious changes, the flowers changed from pinkish purple to orange. Results Integrated metabolomics and transcriptomics were comprehensively utilized to reveal the metabolic pathways of anthocyanin biosynthesis in non-mutant purple flowers and mutant orange. The floral hue discrepancies between Ih -WT and Ih -MU in Impatiens hybrida ‘Solarscape’ exhibit marked variations in luminance (L*), the red-green axis (a*), the yellow-blue axis (b*), and color intensity (Chroma c*). Specifically, the L* value of Ih -WT is significantly higher than that of Ih -MU, and the a*, b*, and Chroma c* values of Ih -WT are significantly greater than those of Ih -MU. Metabolomics identified 93 differential metabolites, most of which were Cyanidin and Pelargonidin-like metabolites, and the accumulation of Cyanidin and Pelargonidin was the principal factor underlying the petal color transition to orange in I. hybrida ‘Solarscape’. Analysis of the transcriptome identified 1888 differentially expressed genes (DEGs), including key genes for anthocyanin synthesis ( IhC4H, IhUFGT, IhDFR, and IhANS ) and regulators ( Ih MYB308, Ih NAC56, and Ih MYC2) with high levels of expression of Ih -MU in orange flowers, indicating that they play a role in the regulation of anthocyanin biosynthesis. These genes may be pivotal for the biosynthesis of orange anthocyanins. Co-expression analysis of differentially expressed genes and the relative levels of differentially expressed anthocyanins revealed that each anthocyanin is strongly associated with multiple genes, indicating that the anthocyanin accumulation process is governed by multiple genes. The expression levels of these genes exhibited a statistically significant positive correlation with the relative concentrations of Pelargonidin-3-O-sophoroside, Cyanidin-3-O-(6-O-p-coumaroyl)-glucoside, and Cyanidin-3-O-sophoroside. Conclusions This study showed substantial alterations in color and anthocyanin synthesis in chemically mutagenized I. hybrida ‘Solarscape’ flowers, and these findings could provide some insight into the relationship between Impatiens and other flowers could offer a theoretical foundation for the breeding improvement of Impatiens and other flowers.

The importance of plant volatiles in mediating interactions between plant species is much debated. Here, we demonstrate that the parasitic plant Cuscuta pentagona (dodder) uses volatile cues for host location. Cuscuta pentagona seedlings exhibit directed growth toward nearby tomato plants (Lycopersicon esculentum) and toward extracted tomato-plant volatiles presented in the absence of other cues. Impatiens (Impatiens wallerana) and wheat plants (Triticum aestivum) also elicit directed growth. Moreover, seedlings can distinguish tomato and wheat volatiles and preferentially grow toward the former. Several individual compounds from tomato and wheat elicit directed growth by C. pentagona, whereas one compound from wheat is repellent. These findings provide compelling evidence that volatiles mediate important ecological interactions among plant species.

To fuel their activities and rear their offspring, foraging bees must obtain a sufficient quality and quantity of nutritional resources from a diverse plant community. Pollen is the primary source of proteins and lipids for bees, and the concentrations of these nutrients in pollen can vary widely among host-plant species. Therefore we hypothesized that foraging decisions of bumble bees are driven by both the protein and lipid content of pollen. By successively reducing environmental and floral cues, we analyzed pollen-foraging preferences of Bombus impatiens in (i) host-plant species, (ii) pollen isolated from these host-plant species, and (iii) nutritionally modified single-source pollen diets encompassing a range of protein and lipid concentrations. In our semifield experiments, B. impatiens foragers exponentially increased their foraging rates of pollen from plant species with high protein: lipid (P:L) ratios; the most preferred plant species had the highest ratio (∼4.6:1). These preferences were confirmed in cage studies where, in pairwise comparisons in the absence of other floral cues, B. impatiens workers still preferred pollen with higher P:L ratios. Finally, when presented with nutritionally modified pollen, workers were most attracted to pollen with P:L ratios of 5:1 and 10:1, but increasing the protein or lipid concentration (while leaving ratios intact) reduced attraction. Thus, macronutritional ratios appear to be a primary factor driving bee pollen-foraging behavior and may explain observed patterns of host-plant visitation across the landscape. The nutritional quality of pollen resources should be taken into consideration when designing conservation habitats supporting bee populations.

Background and AimsInvasiveness of some alien plants is associated with their traits, plastic responses to environmental conditions and interpopulation differentiation. To obtain insights into the role of these processes in contributing to variation in performance, we compared congeneric species of Impatiens (Balsaminaceae) with different origin and invasion status that occur in central Europe.MethodsNative I. noli-tangere and three alien species (highly invasive I. glandulifera, less invasive I. parviflora and potentially invasive I. capensis) were studied and their responses to simulated canopy shading and different nutrient and moisture levels were determined in terms of survival and seedling traits.Key Results and ConclusionsImpatiens glandulifera produced high biomass in all the treatments and the control, exhibiting the ‘Jack-and-master’ strategy that makes it a strong competitor from germination onwards. The results suggest that plasticity and differentiation occurred in all the species tested and that along the continuum from plasticity to differentiation, the species at the plasticity end is the better invader. The most invasive species I. glandulifera appears to be highly plastic, whereas the other two less invasive species, I. parviflora and I. capensis, exhibited lower plasticity but rather strong population differentiation. The invasive Impatiens species were taller and exhibited higher plasticity and differentiation than native I. noli-tangere. This suggests that even within one genus, the relative importance of the phenomena contributing to invasiveness appears to be species'specific.

Background Impatiens is an important genus with rich species of garden plants, and its distribution is extremely extensive, which is reflected in its diverse ecological environment. However, the specific mechanisms of Impatiens ’ adaptation to various environments and the mechanism related to lignin remain unclear. Results Three representative Impatiens species, Impatiens chlorosepala (wet, low degree of lignification), Impatiens uliginosa (aquatic, moderate degree of lignification) and Impatiens rubrostriata (terrestrial, high degree of lignification), were selected and analyzed for their anatomical structures, lignin content and composition, and lignin-related gene expression. There are significant differences in anatomical parameters among the stems of three Impatiens species, and the anatomical structure is consistent with the determination results of lignin content. Furthermore, the thickness of the xylem and cell walls, as well as the ratio of cell wall thickness to stem diameter have a strong correlation with lignin content. The anatomical structure and degree of lignification in Impatiens can be attributed to the plant's growth environment, morphology, and growth rate. Our analysis of lignin-related genes revealed a negative correlation between the MYB4 gene and lignin content. The MYB4 gene may control the lignin synthesis in Impatiens by controlling the structural genes involved in the lignin synthesis pathway, such as HCT , C3H , and COMT . Nonetheless, the regulation pathway differs between species of Impatiens . Conclusions This study demonstrated consistency between the stem anatomy of Impatiens and the results obtained from lignin content and composition analyses. It is speculated that MYB4 negatively regulates the lignin synthesis in the stems of three Impatiens species by regulating the expression of structural genes, and its regulation mechanism appears to vary across different Impatiens species. This study analyses the variations among different Impatiens plants in diverse habitats, and can guide further molecular investigations of lignin biosynthesis in Impatiens .