The role of mucilage envelope in the endozoochory of selected plant taxa

Application of Recurrence Plot Analysis to Examine Dynamics of Biological Molecules on the Example of Aggregation of Seed Mucilage Components

The goal of the research is to describe the aggregation process inside the mucilage produced by plant seeds using molecular dynamics (MD) combined with time series algorithmic analysis based on the recurrence plots. The studied biological molecules model is seed mucilage composed of three main polysaccharides, i.e. pectins, hemicellulose, and cellulose. The modeling of biological molecules is based on the assumption that a classical-quantum passage underlies the aggregation process in the mucilage, resulting from non-covalent interactions, as they affect the macroscopic properties of the system. The applied recurrence plot approach is an important tool for time series analysis and data mining dedicated to analyzing time series data originating from complex, chaotic systems. In the current research, we demonstrated that advanced algorithmic analysis of seed mucilage data can reveal some features of the dynamics of the system, namely temperature-dependent regions with different dynamics of increments of a number of hydrogen bonds and regions of stable oscillation of increments of a number of hydrophobic-polar interactions. Henceforth, we pave the path for automatic data-mining methods for the analysis of biological molecules with the intermediate step of the application of recurrence plot analysis, as the generalization of recurrence plot applications to other (biological molecules) datasets is straightforward.

Adhesive properties of Aphrophoridae spittlebug foam

Aphrophora alni spittlebug nymphs produce a wet foam from anal excrement fluid, covering and protecting themselves against numerous impacts. Foam fluid contact angles on normal (26°) and silanized glass (37°) suggest that the foam wets various substrates, including plant and arthropod surfaces. The pull-off force depends on the hydration state and is higher the more dry the fluid. Because the foam desiccates as fast as water, predators once captured struggle to free from drying foam, becoming stickier. The present study confirms that adhesion is one of the numerous foam characteristics resulting in multifunctional effects, which promote spittlebugs' survival and render the foam a smart, biocompatible material of biological, biomimetic and biomedical interest. The sustainable 'reuse' of large amounts of excrement for foam production and protection of the thin nymph integument suggests energetic and evolutionary advantages. Probably, that is why foam nests have evolved in different groups of organisms, such as spittlebugs, frogs and fish.

Convergent Evolution of Adhesive Properties in Leaf Insect Eggs and Plant Seeds: Cross-Kingdom Bioinspiration

Plants and animals are often used as a source for inspiration in biomimetic engineering. However, stronger engagement of biologists is often required in the field of biomimetics. The actual strength of using biological systems as a source of inspiration for human problem solving does not lie in a perfect copy of a single system but in the extraction of core principles from similarly functioning systems that have convergently solved the same problem in their evolution. Adhesive systems are an example of such convergent traits that independently evolved in different organisms. We herein compare two analogous adhesive systems, one from plants seeds and one from insect eggs, to test their properties and functional principles for differences and similarities in order to evaluate the input that can be potentially used for biomimetics. Although strikingly similar, the eggs of the leaf insect Phyllium philippinicum and the seeds of the ivy gourd Coccinia grandis make use of different surface structures for the generation of adhesion. Both employ a water-soluble glue that is spread on the surface via reinforcing fibrous surface structures, but the morphology of these structures is different. In addition to microscopic analysis of the two adhesive systems, we mechanically measured the actual adhesion generated by both systems to quantitatively compare their functional differences on various standardized substrates. We found that seeds can generate much stronger adhesion in some cases but overall provided less reliable adherence in comparison to eggs. Furthermore, eggs performed better regarding repetitive attachment. The similarities of these systems, and their differences resulting from their different purposes and different structural/chemical features, can be informative for engineers working on technical adhesive systems.

Underlying Biochemical and Molecular Mechanisms for Seed Germination

With the burgeoning population of the world, the successful germination of seeds to achieve maximum crop production is very important. Seed germination is a precise balance of phytohormones, light, and temperature that induces endosperm decay. Abscisic acid and gibberellins—mainly with auxins, ethylene, and jasmonic and salicylic acid through interdependent molecular pathways—lead to the rupture of the seed testa, after which the radicle protrudes out and the endosperm provides nutrients according to its growing energy demand. The incident light wavelength and low and supra-optimal temperature modulates phytohormone signaling pathways that induce the synthesis of ROS, which results in the maintenance of seed dormancy and germination. In this review, we have summarized in detail the biochemical and molecular processes occurring in the seed that lead to the germination of the seed. Moreover, an accurate explanation in chronological order of how phytohormones inside the seed act in accordance with the temperature and light signals from outside to degenerate the seed testa for the thriving seed’s germination has also been discussed.

Anchorage by seed mucilage prevents seed dislodgement in high surface flow: a mechanistic investigation

BACKGROUND AND AIMS

Seed mucilage is a common and highly diverse trait shared among thousands of angiosperm species. While it has long been recognized that mucilage allows seeds to anchor to substrates (antitelechory), resisting abiotic and biotic dislodgement, we still lack a mechanistic understanding of this process.

METHODS

We propose a mechanistic model of how mucilage affects substrate anchorage and fluid resistance, ultimately contributing to dislodgement resistance. To test this model, we subjected mucilaginous seeds of 52 species, varying in eight measured seed traits, to 7 d of continuous water flow at a range of dislodgement potentials.

KEY RESULTS

Supporting our model, mucilage mass increased the force necessary to dislodge both dry and wet seeds; our measurement of the dislodgement force of dry mucilage explained time to dislodgement well. The effect size was remarkably large; increasing the standardized mucilage mass by 1 s.d. resulted in a 280-fold increase in the time to dislodgement. Fluid resistance was largely dependent on the speed of water flow and the seed's modified drag coefficient, but not seed traits. Neither mucilage expansion speed nor mucilage decay rate explained dislodgement potential well.

CONCLUSIONS

Our results suggest that the degree of anchorage to a substrate, measured with a simple dislodgement force assay, is highly predictive of mucilaginous seed retention in highly erosive environments. In contrast, we found that other seed and mucilage traits are of lesser importance to anchorage.

Seed Mucilage Promotes Dispersal of Plantago asiatica Seeds by Facilitating Attachment to Shoes

Understanding the mechanisms underlying seed dispersal is a fundamental issue in plant ecology and vegetation management. Several species demonstrate myxospermy, a phenomenon where the seeds form mucilage after absorbing water. Mucilage is thought to act as a glue, enabling seeds to attach to the external surfaces of dispersing agents. However, there have been no quantitative investigations of the efficacy of this function of seed mucilage. We performed a trampling and walking experiment to investigate the seed dispersal of a perennial herb, Asian plantain (Plantago asiatica L.), which forms polysaccharide mucilage upon hydration. Our experiment showed that: (1) after trampling, more seeds of P. asiatica attached to shoes in wet conditions (after rainfall), in which seed mucilage was created, than in dry conditions (no rainfall); and (2) after walking for 1000 m, more seeds remained attached to shoes in wet conditions than in dry conditions. Our results indicate that mucilage promotes the adherence of seeds to the surface of vectors. We therefore provide the first empirical evidence that seed mucilage facilitates epizoochory and human-mediated dispersal.

Solutions in microbiome engineering: prioritizing barriers to organism establishment

Microbiome engineering is increasingly being employed as a solution to challenges in health, agriculture, and climate. Often manipulation involves inoculation of new microbes designed to improve function into a preexisting microbial community. Despite, increased efforts in microbiome engineering inoculants frequently fail to establish and/or confer long-lasting modifications on ecosystem function. We posit that one underlying cause of these shortfalls is the failure to consider barriers to organism establishment. This is a key challenge and focus of macroecology research, specifically invasion biology and restoration ecology. We adopt a framework from invasion biology that summarizes establishment barriers in three categories: (1) propagule pressure, (2) environmental filtering, and (3) biotic interactions factors. We suggest that biotic interactions is the most neglected factor in microbiome engineering research, and we recommend a number of actions to accelerate engineering solutions.

Seed Mucilage: Biological Functions and Potential Applications in Biotechnology

In plants, the diaspore (seed dispersal unit) may include a seed coat and/or pericarp to protect the embryo and assist in dispersion. In many species, the seed coat and/or pericarp secrete a gelatinous mixture of cell wall polysaccharides known as mucilage. In several species, mucilage synthesis, secretion and modification have been studied extensively as model systems for the investigation of plant cell wall structure and function. Despite this, efforts toward understanding the role of mucilage have received less attention. Mucilage has been hypothesized to impact seed dispersal through interaction with soil, protecting the seed in the gut following ingestion by animals or affecting the ability of seeds to sink or float in water. Mucilage has been found to influence seed germination and seedling establishment, most often during abiotic stress, probably by maintaining seed hydration when water is scarce. Finally, mucilage has been documented to mediate interactions with various organisms. Advances in transgenic technology should enable the genetic modification of mucilage structure and function in crop plants. Cells synthesizing mucilage may also be a suitable platform for creating custom polysaccharides or proteins with industrial applications. Thus, in the near future, it is likely that research on seed mucilage will expand well beyond the current focus. Here we summarize our understanding of the biological functions of mucilage and provide an outlook on the future of mucilage research.

The Renaissance of Plant Mucilage in Health Promotion and Industrial Applications: A Review

Plant mucilage is a renewable and cost-effective source of plant-based compounds that are biologically active, biodegradable, biocompatible, nontoxic, and environmentally friendly. Until recently, plant mucilage has been of interest mostly for technological purposes. This review examined both its traditional uses and potential modern applications in a new generation of health-promoting foods, as well as in cosmetics and biomaterials. We explored the nutritional, phytochemical, and pharmacological richness of plant mucilage, with a particular focus on its biological activity. We also highlighted areas where more research is needed in order to understand the full commercial potential of plant mucilage.

Plantago media L.-Explored and Potential Applications of an Underutilized Plant

The search of valuable natural compounds should be directed towards alternative vegetal resources, and to the re-discovery of underutilized plants. Belonging to the Plantaginaceae family, the hoary plantain (Plantago media L.) represents one of the lesser studied species from the Plantago genus. The literature study revealed the under-utilization of the hoary plantain, a surprising aspect, considering its widespread. If the composition of Plantago media L. is rather well established, its applications are not nearly studied as for other Plantago species. The goal of the present paper is to summarize the findings regarding the applications of P. media, and, having as starting point the applications of related species, to propose new emerging areas of research, such as the biomedical applications validation through in vivo assays, and the evaluation of its potential towards industrial applications (i.e., development of food or personal care products), pisciculture or zootechny, phytoremediation and other environmental protection applications, or in the nanotechnology area (materials phytosynthesis). The present work constitutes not only a brief presentation of this plant's present and potential applications, but also an invitation to research groups world-wide to explore the available vegetal resources.