In Vitro Propagation of Aconitum chasmanthum Stapf Ex Holmes: An Endemic and Critically Endangered Plant Species of the Western Himalaya

Aconitum chasmanthum Stapf ex Holmes, a highly valued medicinal plant, is a critically endangered plant species with restricted global distribution. Because there is no published report on the in vitro micropropagation of A. chasmanthum, the present study was undertaken to contribute to the development of an efficient micropropagation protocol for its conservation. Seeds collected from the wild showed enhanced germination after being given a chilling treatment (−4 °C and −20 °C) for different durations (10, 20, 30 and 40 days). Seeds given a chilling treatment of −4 °C for 10 days showed enhanced germination rates of 47.59 ± 0.53% with a mean germination time of 10.78 ± 0.21 days compared to seeds kept at room temperature when grown in an MS basal medium. Nodes, leaves and stems, taken from 20–40-day-old seedlings, were used as an explant for micropropagation. An MS medium supplemented with different concentrations of cytokinins (BAP, Kn), auxins (2,4-D, NAA), and an additive adenine sulphate were tested for callusing, direct shoot regeneration and rooting. Only nodal explants responded and showed direct multiple shoot regeneration with 7 ± 0.36 shoots with an elongation of 5.51 ± 0.26 cm in the MS medium supplemented with BAP 0.5 mg/L, and with a response time (RT) of 10.41 ± 0.51 days and a percentage culture response of 77.77 ± 2.77%. Rhizome formation was observed after 8 weeks, with the highest culture response of 36.66 ± 3.33% in the MS basal media with an RT of 43.75 ± 0.50 days. These rhizomes showed a 60% germination rate within 2 weeks and developed into plantlets. The present in vitro regeneration protocol could be used for the large-scale propagation and conservation of A. chasmanthum.

The Effects of Ozone on Visual Attraction Traits of Erodium paularense (Geraniaceae) Flowers: Modelled Perception by Insect Pollinators

Ozone (O3) effects on the visual attraction traits (color, perception and area) of petals are described for Erodium paularense, an endangered plant species. Plants were exposed to three O3 treatments: charcoal-filtered air (CFA), ambient (NFA) and ambient + 40 nL L−1 O3 (FU+) in open-top chambers. Changes in color were measured by spectral reflectance, from which the anthocyanin reflectance index (ARI) was calculated. Petal spectral reflectance was mapped onto color spaces of bees, flies and butterflies for studying color changes as perceived by different pollinator guilds. Ozone-induced increases in petal reflectance and a rise in ARI under NFA were observed. Ambient O3 levels also induced a partial change in the color perception of flies, with the number of petals seen as blue increasing to 53% compared to only 24% in CFA. Butterflies also showed the ability to partially perceive petal color changes, differentiating some CFA petals from NFA and FU+ petals through changes in the excitation of the UV photoreceptor. Importantly, O3 reduced petal area by 19.8 and 25% in NFA and FU+ relative to CFA, respectively. In sensitive species O3 may affect visual attraction traits important for pollination, and spectral reflectance is proposed as a novel method for studying O3 effects on flower color.

Light Deficiency Inhibits Growth by Affecting Photosynthesis Efficiency as well as JA and Ethylene Signaling in Endangered Plant Magnolia sinostellata

The endangered plant Magnolia sinostellata largely grows in the understory of forest and suffers light deficiency stress. It is generally recognized that the interaction between plant development and growth environment is intricate; however, the underlying molecular regulatory pathways by which light deficiency induced growth inhibition remain obscure. To understand the physiological and molecular mechanisms of plant response to shading caused light deficiency, we performed photosynthesis efficiency analysis and comparative transcriptome analysis in M. sinostellata leaves, which were subjected to shading treatments of different durations. Most of the parameters relevant to the photosynthesis systems were altered as the result of light deficiency treatment, which was also confirmed by the transcriptome analysis. Gene Ontology and KEGG pathway enrichment analyses illustrated that most of differential expression genes (DEGs) were enriched in photosynthesis-related pathways. Light deficiency may have accelerated leaf abscission by impacting the photosynthesis efficiency and hormone signaling. Further, shading could repress the expression of stress responsive transcription factors and R-genes, which confer disease resistance. This study provides valuable insight into light deficiency-induced molecular regulatory pathways in M. sinostellata and offers a theoretical basis for conservation and cultivation improvements of Magnolia and other endangered woody plants.

Rare and Endangered Plant Leaf Identification Method Based on Transfer Learning and Knowledge Distillation

Considering the limited sample size of rare and endangered plant leaves and the issue that leaf identification is mainly conducted using mobile smart devices and other technology with low computing power, this paper proposes a rare and endangered plant leaf identification method based on transfer learning and knowledge distillation. Following the expansion of data sets containing rare and endangered plant leaves, the last fully connected layer was replaced with trained Alexnet, VGG16, GoogLeNet, and ResNet models to conduct transfer learning, and realized a relatively high success rate in identifying images of these species. Then, knowledge distillation was utilized to transfer Alexnet, VGG16, GoogLeNet, and ResNet models into a lightweight model. The experiment results indicate that, compared with other methods, the lightweight rare and endangered plant identification model trained with the methods described in this paper was not only more accurate but also less complex than its alternatives.

Plant-arthropod interactions of an endangered California lupine

The reintroduction of endangered plant species is an essential conservation tool. Reintroductions can fail to create resilient, self-sustaining populations due to a poor understanding of environmental factors that limit or promote plant success. Biotic factors, specifically plant-arthropod interactions, have been shown to affect the establishment of endangered plant populations. Lupinus nipomensis (Nipomo Mesa lupine) is a state of California (California Rare Plant Rank: 1B.1) and federally (65 FR 14888) endangered endemic plant with only one extant population located along the central California coast. How arthropods positively or negatively interact with L. nipomensis is not well known and more information could aid conservation efforts. We conducted arthropod surveys of the entire L. nipomensis extant population in spring 2017. Observed arthropods present on L. nipomensis included 17 families, with a majority of individuals belonging to Thripidae. We did not detect any obvious pollinators of L. nipomensis, providing support for previous studies suggesting this lupine is capable of self-pollinating, and observed several arthropod genera that could potentially impact the reproductive success of L. nipomensis via incidental pollination or plant predation.

Aconitum heterophyllum Wall. ex Royle; an endemic, highly medicinal and critically endangered plant species of Northwestern Himalaya in peril

: Aconitum heterophyllum is a precious endemic medicinal plant of Northwestern Himalaya. It possesses a number of curative effects and is accounted for having diuretic, hepatoprotective, antipyretic, analgesic, antioxidant, alexipharmic, anodyne, anti-atrabilious, expectorant, immunostimulant, febrifuge, anthelminthic, anti- cancerous, anti-diarrhoeal, anti-emetic, anti-inflammatory, anti-flatulent, anti-periodic, anti-phlegmatic, anti-diabetic, antifungal, antimicrobial, antiviral and carminative properties. Further, it is an important ingredient of many Ayurvedic formulations. Its pharmacological potential may be attributed to of the presence of many biologically active phytochemicals like aconitine, mesaconitine, acetylaconitine, heterophylline A, and heterophylline B. Owing to its high therapeutic uses and market value, the plant is being exploited for its tubers from the wild. Further, there are some reproductive constraints due to which the population of the plant in the wild is waning at a rapid rate. Due to these factors, Aconitum heterophyllum has been categorized as critically endangered; demanding focused conservation strategies and cultivation efforts.