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The present study aims to investigate the differences in leaf pigment content and the photosynthetic characteristics under natural and low light intensities between the Chinese native Physocarpus amurensis Maxim and the imported Physocarpus opulifolius “Diabolo” from North America. We aim to discuss the responses and the adaptive mechanism of these two cultivars of Physocarpus to a low light environment. The results show that the specific leaf area (SLA) and the chlorophyll content were significantly increased in the leaves of both Physocarpus cultivars in response to a low light intensity, and the SLA and chlorophyll content were higher in the leaves of low light-treated P. opulifolius “Diabolo” compared with the leaves of low light-treated P. amurensis Maxim . Moreover, the content of anthocyanin was markedly reduced in the leaves of P. opulifolius “Diabolo” under low light intensity, which allowed for a greater capacity of photon capture under the low light condition. Under natural light, the photosynthetic carbon assimilation capacity was greater in the leaves of P. amurensis Maxim compared with the leaves of P. opulifolius “Diabolo” that were rich with anthocyanin. However, in response to low light, AQY, P max , LCP and LSP decreased to a lesser extent in the leaves of P. opulifolius “Diabolo” compared with the leaves of P. amurensis Maxim . These results suggest that P. opulifolius “Diabolo” exhibits a greater ability in adaption to low light, and it is probably related to the relatively higher chlorophyll content and the smaller SLA in the leaves of P. opulifolius “Diabolo.” In addition, the low light intensity resulted in a reduced photochemical activity of photosystem (PS) II in the leaves of both Physocarpus , as evidenced by increased values of the relative variable fluorescence at point J and point I on the OJIP curve. This result suggests that the electron acceptor in PS II was the major responsive site to the low light stress in the leaves of both Physocarpus cultivars, and that the low light intensity significantly inhibited electron transfer on the acceptor side of PS II and reduced the activity of the oxygen-evolving complex (OEC) in the leaves of both Physocarpus cultivars. The PS II function in P. opulifolius “Diabolo” was higher than that in P. amurensis Maxim in response to low light. Under low light, the composition of photosynthetic pigments was altered in the leaves of P. opulifolius “Diabolo” in order to maintain a relatively high activity of primary photochemical reactions, and this is the basis of the greater photosynthetic carbon assimilation capacity and one of the main reasons for the better shade-tolerance in P. opulifolius “Diabolo.”

This paper selected clonal cutting seedlings from the F1 hybrid varieties of Physocarpus amurensis Maxim (♀) × P. opulifolius “Diabolo” (♂) as research material to study the response of the photosynthetic gas exchange parameters and chlorophyll fluorescence parameters of P. amurensis hybrids and their parental leaves to NaCl stress (with concentrations of 0, 50, 100, and 200 mmol⋅L-1). The results showed that under salt stress, the stomatal conductance ( G s), transpiration rate ( T r), and net photosynthetic rate ( P n) of the three kinds of P. amurensis all significantly decreased. When the NaCl concentration was below 100 mmol⋅L-1, the intercellular CO2 concentration ( C i) of leaves of the three samples declined with the increase of salt concentration; however, when the concentration increased to 200 mmol⋅L-1, C i did not decrease significantly, especially when the C i of P. opulifolius “Diabolo” presented a slight increase. This indicated that the decline of photosynthetic carbon assimilation capacity induced by salt stress was the consequence of interaction between stomatal factors and non-stomatal factors, and the stomatal factors played an important role when the salt concentration was below 200 mmol⋅L-1. Compared with P. amurensis , the photosynthetic gas exchange capability of P. opulifolius “Diabolo” leaves was more sensitive to salt stress, and the limitation of non-stomatal factors was relatively evident. However, the photosynthetic capacity of hybrid P. amurensis leaves with the desired purple color was improved compared with P. amurensis . Under salt stress, the PSII activity of the three kinds of P. amurensis leaves declined, the electron transfer was inhibited, and obvious signs of photoinhibition were present. The PSII activity of P. opulifolius “Diabolo” leaves was more sensitive to salt stress than that in P. amurensis . Under salt stress, the NPQ of P. opulifolius “Diabolo” leaves decreased greatly, while under high salt concentrations the degree of photoinhibition in P. amurensis and hybrid P. amurensis were reduced due to a relatively high NPQ. With the increase of salt concentration, the V k of P. amurensis and hybrid P. amurensis leaves presented a decreasing trend. However, the V k of P. opulifolius “Diabolo” leaves increased slightly. This suggested that the effects of salt stress on the oxygen-evolving complex (OEC) of the three P. amurensis sample types were relatively limited and only the OEC of P.s opulifolius “Diabolo” leaves were slightly sensitive to salt stress. The V J of all leaves from the three P. amurensis types increased under salt stress, and the V J increased significantly when the salt concentration increased to 200 mmol⋅L-1, indicating that salt stress obviously impeded the electron transfer chain from QA to QB on the PSII receptor side. Moreover, high salt concentrations caused thylakoid membrane dissociation. The electron transfer and degree of damage to the thylakoid membrane of P. opulifolius “Diabolo” leaves were obviously higher than that of P. amurensis . However, the electron transfer capacity on the PSII receptor side as well as the degree of damage of the thylakoid membrane of hybrid P. amurensis leaves was obviously lower than those of P. opulifolius “Diabolo.” The salt tolerance of photosynthetic functions of hybrid P. amurensis (♀) × P. opulifolius “Diabolo” (♂) leaves was improved compared with that of parental P. opulifolius “Diabolo,” and the hybrid shows obvious hybrid vigor for photosynthesis.

Ninebark is a very popular ornamental shrub. Micropropagation is an efficient method for mass production of uniform plant material. This study was designed to develop and optimize conditions at all phases of ninebark micropropagation. For the multiplication stage, the Murashige and Skoog (MS) medium at full concentration and pH 5.8 was chosen as the basal medium. Sorbitol proved a more effective carbohydrate source than fructose, with no adverse effects on shoot vitrification or the medium itself. The best shoot production, both in number and length, was on the medium enriched with 2 and 3 mg·L⁻¹ zeatin. High numbers of shoots were also obtained in treatments with 1 mg·L⁻¹ 6-benzyladenine (BA) or 2 mg·L⁻¹ meta-Topolin (mT) in the basal medium. BA was the most cost-effective cytokinin. There was a positive effect of the gibberellic acid on proliferation: the highest shoot number per explant was produced in the presence of 1 mg·L⁻¹ GA₃. No effect of the culture age (up to 20 subcultures) on the percentage of regenerating expiants was evident, and the highest numbers of shoots were obtained between passages 10 and 17. For rooting, the MS medium at half strength was used. The best rooting was at 1 mg·L⁻¹ IBA. Spraying the in vitro rooted cuttings with abscisic acid (ABA) favored plant acclimation to the ex vitro conditions. Ex vitro rooting, including the treatments with IBA and ABA, shortened the production time by approximately one third.

Ninebark (Physocarpus opulifolius) is an attractive ornamental shrub with poor rooting characteristics in some cultivars, which is a limiting factor in commercial production This study was designed to optimize rooting conditions of ninebark cuttings and to observe the effect of exogenous auxin IBA on some morpho-anatomical and biochemical changes associated with rhizogenesis in the in vitro conditions. Both auxins under study: the indole-3-butyric acid (IBA) and 1-naphthalene acetic acid (NAA) gave comparable effects but the combination of ½ MS + 1 mg·L−1 IBA was the most cost effective for all rooting parameters. Anatomical changes at the cuttings’ bases during root formation were typical for woody plants and they were accelerated by auxin in the culture medium. High levels of the endogenous indole acid and hydrogen peroxide were temporarily associated with intensive cell divisions in cuttings, and the polyphenolic acid contents kept increasing during rooting above the initial levels and those in controls.Key messageResults of this work show that micropropagation may be the answer to growing demand for ninebark stocks. Anatomical changes occurring at the bases of stem cuttings during root formation in vitro are typical for woody plants. Auxin in the rooting medium accelerated individual phases of rhizogenesis making it shorter and more efficient. High levels of the endogenous indole acid and hydrogen peroxide were transiently associated with intensive cell divisions in cuttings. In auxin-treated cuttings, the polyphenolic acid contents increased during rooting above the initial levels and those in non-treated cuttings.

Taxonomic circumscription is a critical prerequisite for ecological, taxonomic, and systematics research but can be complicated by undetected patterns in morphological variation. Cryptic variation has long confounded the taxonomy of Physocarpus (Cambess.) Raf., with conflicting circumscriptions especially prevalent in the Physocarpus opulifolius (L.) Maxim. complex, which comprises P. opulifolius sensu stricto and Physocarpus intermedius (Rydb.) C.K.Schneid. Here, we assess variation for carpel and follicle pubescence, a key diagnostic character for the P. opulifolius s.l. complex. Data were collected from 748 herbarium accessions obtained from across the range of this complex in North America. We then assessed the statistical and geographic distribution of this variation. As suggested by Rydberg and others, follicle pubescence is bimodally distributed and exhibits a strong geographic signal. An eastern, glabrous (or nearly so) form occurs in temperate forests from the St. Lawrence River valley of Quebec west to the Upper Great Lakes region and south to the southern Appalachians (i.e., P. opulifolius s.s.), while a more western, densely pubescent form occurs from the Interior Highlands north to the Driftless Area, with disjunct populations in the Southeastern Plains of Alabama, Sand Hills of Nebraska, Black Hills of South Dakota, Front Range of Colorado, and Sierra Madre Oriental of northeastern Mexico (i.e., P. intermedius). We conclude that taxonomic recognition is warranted based on variation in follicle pubescence, which also has implications for downstream research (e.g., floristics, phylogenetics, and ecological niche modeling).

There are currently no drugs known to rescue the function of Kv1.1 voltage-gated potassium channels carrying loss-of-function sequence variants underlying the inherited movement disorder, Episodic Ataxia 1 (EA1). The Kwakwaka’wakw First Nations of the Pacific Northwest Coast used Fucus gardneri (bladderwrack kelp), Physocarpus capitatus (Pacific ninebark) and Urtica dioica (common nettle) to treat locomotor ataxia. Here, we show that extracts of these plants enhance wild-type Kv1.1 current, especially at subthreshold potentials. Screening of their constituents revealed that gallic acid and tannic acid similarly augment wild-type Kv1.1 current, with submicromolar potency. Crucially, the extracts and their constituents also enhance activity of Kv1.1 channels containing EA1-linked sequence variants. Molecular dynamics simulations reveal that gallic acid augments Kv1.1 activity via a small-molecule binding site in the extracellular S1-S2 linker. Thus, traditional Native American ataxia treatments utilize a molecular mechanistic foundation that can inform small-molecule approaches to therapeutically correcting EA1 and potentially other Kv1.1-linked channelopathies. Drugs that rescue function of episodic ataxia 1 (EA1) mutant potassium channels are lacking. Here, Manville et al identify and describe the molecular basis for Native American botanical ataxia remedies that directly rescue EA1 mutant channels.

A phylogeny of the tribe Neillieae (Rosaceae), which comprises Neillia, Stephanandra, and Physocarpus, was reconstructed based on nucleotide sequences of several regions of cpDNA, the ITS and ETS regions of rDNA, and the second intron of LEAFY, to elucidate relationships among genera and species in Neillieae and to assess the historical biogeography of the tribe. Phylogenetic analyses indicated that Physocarpus and Neillia-Stephanandra were strongly supported as monophyletic and suggested that Stephanandra may have originated by hybridization between two lineages of NEILLIA: Dispersal-vicariance analyses suggested that the most recent common ancestor of Neillieae may have occupied eastern Asia and western North America and that Physocarpus and Neillia-Stephanandra may have been split by an intercontinental vicariance event in the early Miocene. The biogeographic analyses also suggested that species of Neillia and Stephanandra diversified in eastern Asia, whereas in Physocarpus one dispersal event from western North America to eastern Asia occurred. Two divergent types of LEAFY sequences were found in the eastern North American species, P. opulifolius, but only one type was present in each plant. The two types of sequences may represent homeologous genes that originated by hybridization between P. capitatus and P. monogynus, both western North American species.

Screening salinity-tolerant plants is usually time intensive and only applicable to a limited number of salinity levels. A near-continuous gradient dosing (NCGD) system allows researchers to evaluate a large number of plants for salinity tolerance with multiple treatments, more flexibility, and reduced efforts of irrigation. Rose of sharon ( Hibiscus syriacus ), ninebark ( Physocarpus opulifolius ), and japanese spirea ( Spiraea japonica ) were irrigated using an NCGD system with eight electrical conductivity (EC) levels ranging from 0.9 to 6.5 dS·m –1 . At 11 weeks after irrigation was initiated, there were no significant differences among EC levels in terms of visual score, growth index [(Height + Width 1 + Width 2)/3], stem diameter, number of inflorescences, and shoot dry weight (DW) of rose of sharon. However, the root DW, relative chlorophyll content (SPAD), and net photosynthesis rate (P n ) of rose of sharon decreased linearly as EC levels increased. Ninebark and japanese spirea had increased foliar salt damage with increasing EC levels. The growth index, stem diameter, number of inflorescences, shoot and root DW, SPAD, and P n of ninebark decreased linearly as EC levels increased. The growth index and SPAD of japanese spirea decreased quadratically with increasing EC levels, but its stem diameter, number of inflorescences, shoot and root DW, and P n decreased linearly with increasing EC levels. The salinity threshold (50% loss of shoot DW) was 5.4 and 4.6 dS·m –1 , respectively, for ninebark and japanese spirea. We were not able to define the salinity threshold for rose of sharon in this study. However, rose of sharon was the most salinity-tolerant species among the three landscape plants.

Acclimation is the final phase of micropropagation and often decisive for its economic output. The aim of the experiments was to evaluate the effect of abscisic acid (ABA) and supplementary light on acclimation and leaf anatomy of the in vitro-rooted plants of ninebark (Physocarpus opulifolius L.). The initial material came from 8–10-week-old in vitro cultures on ½MS supplemented with 1 mg·L−1 IBA. After potting, plantlets were sprayed with ABA solutions or distilled water and were grown either under natural daylight or under supplemental sodium light at 230 μmol·m−2·s−1 between 2 and 9 p.m. All measurements and anatomical observations were done after eight weeks in the greenhouse. Supplementary lighting significantly increased the percentage of acclimatized plants, plant height and the internode number. Plant growth was also positively affected by 1 mg·L−1 ABA. During acclimation, the photosynthesis rate increased while the transpiration and stomatal conductance dropped. The assimilation pigment contents increased under supplemental lighting while ABA had no detectable effect. However, relative to water controls, ABA increased photosynthesis, reduced transpiration, and stomatal conductance in plants growing under both light conditions. Leaves from the in vitro plants were about two times thinner than those from plants growing in soil, with only a single layer of the palisade parenchyma, hence with lower proportion in relation to the spongy parenchyma. Supplementary light during acclimation increased leaf thickness but only in the water control while it decreased it in the ABA-treated plants. ABA increased the mesophyll thickness but only in plants growing under natural light. In conclusion, supplementary light and treatment with ABA enhance acclimation of micropropagated ninebark plants.

Taxonomic circumscription is a critical prerequisite for ecological, taxonomic, and systematics research but can be complicated by undetected patterns in morphological variation. Cryptic variation has long confounded the taxonomy of Physocarpus (Cambess.) Raf., with conflicting circumscriptions especially prevalent in the Physocarpus opulifolius (L.) Maxim. complex, which comprises P. opulifolius sensu stricto and Physocarpus intermedius (Rydb.) C.K.Schneid. Here, we assess variation for carpel and follicle pubescence, a key diagnostic character for the P. opulifolius s.l. complex. Data were collected from 748 herbarium accessions obtained from across the range of this complex in North America. We then assessed the statistical and geographic distribution of this variation. As suggested by Rydberg and others, follicle pubescence is bimodally distributed and exhibits a strong geographic signal. An eastern, glabrous (or nearly so) form occurs in temperate forests from the St. Lawrence River valley of Quebec west to the Upper Great Lakes region and south to the southern Appalachians (i.e., P. opulifolius s.s.), while a more western, densely pubescent form occurs from the Interior Highlands north to the Driftless Area, with disjunct populations in the Southeastern Plains of Alabama, Sand Hills of Nebraska, Black Hills of South Dakota, Front Range of Colorado, and Sierra Madre Oriental of northeastern Mexico (i.e., P. intermedius). We conclude that taxonomic recognition is warranted based on variation in follicle pubescence, which also has implications for downstream research (e.g., floristics, phylogenetics, and ecological niche modeling).