Litter and soil biodiversity jointly drive ecosystem functions

The decomposition of litter and the supply of nutrients into and from the soil are two fundamental processes through which the above- and belowground world interact. Microbial biodiversity, and especially that of decomposers, plays a key role in these processes by helping litter decomposition. Yet the relative contribution of litter diversity and soil biodiversity in supporting multiple ecosystem services remains virtually unknown. Here we conducted a mesocosm experiment where leaf litter and soil biodiversity were manipulated to investigate their influence on plant productivity, litter decomposition, soil respiration, and enzymatic activity in the littersphere. We showed that both leaf litter diversity and soil microbial diversity (richness and community composition) independently contributed to explain multiple ecosystem functions. Fungal saprobes community composition was especially important for supporting ecosystem multifunctionality (EMF), plant production, litter decomposition, and activity of soil phosphatase when compared with bacteria or other fungal functional groups and litter species richness. Moreover, leaf litter diversity and soil microbial diversity exerted previously undescribed and significantly interactive effects on EMF and multiple individual ecosystem functions, such as litter decomposition and plant production. Together, our work provides experimental evidence supporting the independent and interactive roles of litter and belowground soil biodiversity to maintain ecosystem functions and multiple services.

Stiffness Evaluation of Laboratory and Plant Produced Foamed Bitumen Warm Asphalt Mixtures with Fiber Reinforcement and Bio-Flux Additive

The present paper investigates the viscoelastic stress-strain responses of laboratory and plant produced warm mix asphalt mixtures containing basalt fiber dispersed reinforcement. The investigated processes and mixture components were evaluated for their efficacy in producing highly performing asphalt mixtures with decreased mixing and compaction temperatures. Surface course asphalt concrete (AC-S 11 mm) and high modulus asphalt concrete (HMAC 22 mm) conventionally and using a warm mix asphalt technique with foamed bitumen and a bio-derived fluxing additive. The warm mixtures included lowered production temperature (by 10 °C) and lowered compaction temperatures (by 15 °C and 30 °C). The complex stiffness moduli of the mixtures were assessed under cyclic loading tests at combinations of four temperatures and five loading frequencies. It was found that the warm produced mixtures were characterized by lower dynamic moduli than the reference mixtures in the whole spectrum of loading conditions, however, the mixtures compacted at the 30 °C lower temperature performed better than the mixtures compacted at 15 °C lower temperature, specifically when highest testing temperatures are considered. The differences in the performance of plant and laboratory produced mixtures were ascertained to be nonsignificant. It was concluded that the differences in stiffness of hot mix and warm mixtures can be attributed to the inherent properties of foamed bitumen mixtures and that these differences should shrink in time.

Plants as Biofactories for Therapeutic Proteins and Antiviral Compounds to Combat COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had a profound impact on the world's health and economy. Although the end of the pandemic may come in 2023, it is generally believed that the virus will not be completely eradicated. Most likely, the disease will become an endemicity. The rapid development of vaccines of different types (mRNA, subunit protein, inactivated virus, etc.) and some other antiviral drugs (Remdesivir, Olumiant, Paxlovid, etc.) has provided effectiveness in reducing COVID-19's impact worldwide. However, the circulating SARS-CoV-2 virus has been constantly mutating with the emergence of multiple variants, which makes control of COVID-19 difficult. There is still a pressing need for developing more effective antiviral drugs to fight against the disease. Plants have provided a promising production platform for both bioactive chemical compounds (small molecules) and recombinant therapeutics (big molecules). Plants naturally produce a diverse range of bioactive compounds as secondary metabolites, such as alkaloids, terpenoids/terpenes and polyphenols, which are a rich source of countless antiviral compounds. Plants can also be genetically engineered to produce valuable recombinant therapeutics. This molecular farming in plants has an unprecedented opportunity for developing vaccines, antibodies, and other biologics for pandemic diseases because of its potential advantages, such as low cost, safety, and high production volume. This review summarizes the latest advancements in plant-derived drugs used to combat COVID-19 and discusses the prospects and challenges of the plant-based production platform for antiviral agents.

Generation of unequal nuclear genotype proportions in Rhizophagus irregularis progeny causes allelic imbalance in gene transcription

Arbuscular mycorrhizal fungi (AMF) form mutualisms with most plant species. The model AMF Rhizophagus irregularis is common in many ecosystems and naturally forms homokaryons and dikaryons. Quantitative variation in allele frequencies in clonally dikaryon offspring suggests they disproportionately inherit two distinct nuclear genotypes from their parent. This is interesting, because such progeny strongly and differentially affect plant growth. Neither the frequency and magnitude of this occurrence nor its effect on gene transcription are known. Using reduced representation genome sequencing, transcriptomics, and quantitative analysis tools, we show that progeny of homokaryons and dikaryons are qualitatively genetically identical to the parent. However, dikaryon progeny differ quantitatively due to unequal inheritance of nuclear genotypes. Allele frequencies of actively transcribed biallelic genes resembled the frequencies of the two nuclear genotypes. More biallelic genes showed transcription of both alleles than monoallelic transcription, but biallelic transcription was less likely with greater allelic divergence. Monoallelic transcription levels of biallelic genes were reduced compared with biallelic gene transcription, a finding consistent with genomic conflict. Given that genetic variation in R. irregularis is associated with plant growth, our results establish quantitative genetic variation as a future consideration when selecting AMF lines to improve plant production.

Development of Cold Plasma Technologies for Surface Decontamination of Seed Fungal Pathogens: Present Status and Perspectives

In view of the ever-growing human population and global environmental crisis, new technologies are emerging in all fields of our life. In the last two decades, the development of cold plasma (CP) technology has offered a promising and environmentally friendly solution for addressing global food security problems. Besides many positive effects, such as promoting seed germination, plant growth, and development, CP can also serve as a surface sterilizing agent. It can be considered a method for decontamination of microorganisms on the seed surface alternative to the traditional use of fungicides. This review covers basics of CP technology and its application in seed decontamination. As this is a relatively young field of research, the data are scarce and hard to compare due to various plasma setups and parameters. On the other hand, the rapidly growing research field offers opportunities for novel findings and applications.

Unaltered soil microbial community composition, but decreased metabolic activity in a semiarid grassland after two years of passive experimental warming

Soil microbial communities regulate soil carbon feedbacks to climate warming through microbial respiration (i.e., metabolic rate). A thorough understanding of the responses of composition, biomass, and metabolic rate of soil microbial community to warming is crucial to predict soil carbon stocks in a future warmer climate. Therefore, we conducted a field manipulative experiment in a semiarid grassland on the Loess Plateau of China to evaluate the responses of the soil microbial community to increased temperature from April 2015 to December 2017. Soil temperature was 2.0°C higher relative to the ambient when open-top chambers (OTCs) were used. Warming did not affect microbial biomass or the composition of microbial functional groups. However, warming significantly decreased microbial respiration, directly resulting from soil pH decrease driven by the comediation of aboveground biomass increase, inorganic nitrogen increase, and moisture decrease. These findings highlight that the soil microbial community structure of semiarid grasslands resisted the short-term warming by 2°C, although its metabolic rate declined.

UVA Radiation Is Beneficial for Yield and Quality of Indoor Cultivated Lettuce

Understanding the wavelength dependence of plant responses is essential for optimizing production and quality of indoor plant cultivation. UVA is the main component of solar UV radiation, but its role on plant growth is poorly understood. Here, two experiments were conducted to examine whether UVA supplementation is beneficial for indoor plant cultivation. Lettuce (Lactuca sativa L. cv. "Klee") was grown under mixed blue, red, and far-red light with photon flux density of 237 μmol m-2 s-1 in the growth room; photoperiod was 16 h. In the first experiment, three UVA intensities with peak wavelengths at 365 nm were used: 10 (UVA-10), 20 (UVA-20), and 30 (UVA-30) μmol m-2 s-1, respectively. In the second experiment, 10 μmol m-2 s-1 UVA radiation were given for 5 (UVA-5d), 10 (UVA-10d), and 15 (UVA-15d) days before harvest on day 15, respectively. Compared with control (no UVA), shoot dry weight was increased by 27%, 29%, and 15% in the UVA-10, UVA-20, and UVA-30 treatments, respectively, which correlated with 31% (UVA-10), 32% (UVA-20), and 14% (UVA-30) larger leaf area. Shoot dry weight under the treatments of UVA-5d, UVA-10d, and UVA-15d was increased by 18%, 32%, and 30%, respectively, and leaf area was increased by 15%-26%. For both experiments, UVA radiation substantially enhanced secondary metabolites accumulation, e.g. anthocyanin and ascorbic acid contents were increased by 17%-49% and 47%-80%, respectively. Moreover, plants grown under the UVA-30 treatment were stressed, as indicated by lipid peroxidation and lower maximum quantum efficiency of photosystem II photochemistry (Fv/Fm). We conclude that UVA supplementation not only stimulates biomass production in controlled environments, but also enhances secondary metabolite accumulation.

Plant protection means used in organic farming throughout the European Union

Following the obligatory implementation of integrated pest management in the European Union (EU), the plant protection means suitable for application in organic agriculture attracted the attention of quite a wide group of potential users. In spite of the common rules of organic production, as well as the uniform principles of placing plant protection products on the market, the availability of products that can be legally used in organic crop protection differs significantly among the Member States. There is a uniform list of 10 basic substances that can be used in the protection of organic crops throughout the entire EU. Twelve Member States have official registers of plant protection products for use in organic agriculture, and the total number of qualified products per country varies from 11 in Lithuania to 576 in Italy. Some products that improve plant vigour or resistance and may be of use in protection of organic crops are placed on the market as biostimulants. They fall under the law that governs fertilisers and the systems of their registration vary widely among the Member States. In addition, there exist a number of products that have been legally introduced onto the markets of some Member States without registration as a consequence of a loophole in the law. The use of unregistered products in organic agriculture raises some doubts, but currently it seems that there is no legal basis on which to explicitly prohibit the practice. © 2017 Society of Chemical Industry.

Arbuscular Mycorrhizas: A Promising Component of Plant Production Systems Provided Favorable Conditions for Their Growth

Arbuscular mycorrhizal (AM) fungi have become an attractive target as biostimulants in agriculture due to their known contributions to plant nutrient uptake and abiotic stress tolerance. However, inoculation with AM fungi can result in depressed, unchanged, or stimulated plant growth, which limits security of application in crop production systems. Crop production comprises high diversity and variability in atmospheric conditions, substrates, plant species, and more. In this review, we emphasize that we need integrative approaches for studying mycorrhizal symbioses in order to increase the predictability of growth outcomes and security of implementation of AM fungi into crop production. We briefly review known mechanisms of AM on nutrient uptake and drought tolerance of plants, on soil structure and soil hydraulic properties. We carve out that an important factor for both nutrient availability and drought tolerance is yet not well understood; the AM effects on soil hydraulic properties. We gave special emphasis to circular references between atmospheric conditions, soil hydraulic properties and plant nutrient and water uptake. We stress that interdisciplinary approaches are needed that account for a variability of atmospheric conditions and, how this would match to mycorrhizal functions and demands in a way that increased plant nutrient and water uptake can be effectively used for physiological processes and ultimately growth. Only with integrated analyses under a wide range of growing conditions, we will be able to make profound decisions whether or not to use AM in particular crop production systems or can adjust culture conditions in ways that AM plants thrive.

Potential use and perspectives of nitric oxide donors in agriculture

Nitric oxide (NO) has emerged in the last 30 years as a key molecule involved in many physiological processes in plants, animals and bacteria. Current research has shown that NO can be delivered via donor molecules. In such cases, the NO release rate is dependent on the chemical structure of the donor itself and on the chemical environment. Despite NO's powerful signaling effect in plants and animals, the application of NO donors in agriculture is currently not implemented and research remains mainly at the experimental level. Technological development in the field of NO donors is rapidly expanding in scope to include controlling seed germination, plant development, ripening and increasing shelf-life of produce. Potential applications in animal production have also been identified. This concise review focuses on the use of donors that have shown potential biotechnological applications in agriculture. Insights are provided into (i) the role of donors in plant production, (ii) the potential use of donors in animal production and (iii) future approaches to explore the use and applications of donors for the benefit of agriculture. © 2016 Society of Chemical Industry.

Earlier snowmelt and warming lead to earlier but not necessarily more plant growth

Climate change over the past ∼50 years has resulted in earlier occurrence of plant life-cycle events for many species. Across temperate, boreal and polar latitudes, earlier seasonal warming is considered the key mechanism leading to earlier leaf expansion and growth. Yet, in seasonally snow-covered ecosystems, the timing of spring plant growth may also be cued by snowmelt, which may occur earlier in a warmer climate. Multiple environmental cues protect plants from growing too early, but to understand how climate change will alter the timing and magnitude of plant growth, experiments need to independently manipulate temperature and snowmelt. Here, we demonstrate that altered seasonality through experimental warming and earlier snowmelt led to earlier plant growth, but the aboveground production response varied among plant functional groups. Earlier snowmelt without warming led to early leaf emergence, but often slowed the rate of leaf expansion and had limited effects on aboveground production. Experimental warming alone had small and inconsistent effects on aboveground phenology, while the effect of the combined treatment resembled that of early snowmelt alone. Experimental warming led to greater aboveground production among the graminoids, limited changes among deciduous shrubs and decreased production in one of the dominant evergreen shrubs. As a result, we predict that early onset of the growing season may favour early growing plant species, even those that do not shift the timing of leaf expansion.

Antibody Production in Plants and Green Algae

Monoclonal antibodies (mAbs) have a wide range of modern applications, including research, diagnostic, therapeutic, and industrial uses. Market demand for mAbs is high and continues to grow. Although mammalian systems, which currently dominate the biomanufacturing industry, produce effective and safe recombinant mAbs, they have a limited manufacturing capacity and high costs. Bacteria, yeast, and insect cell systems are highly scalable and cost effective but vary in their ability to produce appropriate posttranslationally modified mAbs. Plants and green algae are emerging as promising production platforms because of their time and cost efficiencies, scalability, lack of mammalian pathogens, and eukaryotic posttranslational protein modification machinery. So far, plant- and algae-derived mAbs have been produced predominantly as candidate therapeutics for infectious diseases and cancer. These candidates have been extensively evaluated in animal models, and some have shown efficacy in clinical trials. Here, we review ongoing efforts to advance the production of mAbs in plants and algae.

Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency

Leaf senescence in winter deciduous species signals the transition from the active to the dormant stage. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. Photoperiod and temperature are the main cues controlling leaf senescence in winter deciduous species, with water stress imposing an additional influence. Photoperiod exerts a strict control on leaf senescence at latitudes where winters are severe and temperature gains importance in the regulation as winters become less severe. On average, climatic warming will delay and drought will advance leaf senescence, but at varying degrees depending on the species. Warming and drought thus have opposite effects on the phenology of leaf senescence, and the impact of climate change will therefore depend on the relative importance of each factor in specific regions. Warming is not expected to have a strong impact on nutrient proficiency although a slower speed of leaf senescence induced by warming could facilitate a more efficient nutrient resorption. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. The overall effects of climate change on nutrient resorption will depend on the contrasting effects of warming and drought. Changes in nutrient resorption and proficiency will impact production in the following year, at least in early spring, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling, especially if the changes are consequence of water stress.

Plant-Based Vaccines as a Global Vaccination Approach: Current Perspectives

This chapter provides a perspective on the evolution of the field of plant-based vaccine from the limitations identified in initial developments as to how this biotechnological approach has become sophisticated via the development of new technologies and has gained industry interest. Perspectives for the field at both the basic research and the industrial level are emphasized. Perspectives considered of relevance in terms of basic research include (1) advancing the development of oral formulations, (2) expanding the modalities of expression of immunogens, (3) diversifying production platforms, particularly those performed under full containment, and (4) targeting a broader number of diseases. These goals are expected to multiply the expectations for benefits derived from plant-based vaccine-production technology. On the other hand, technology transfer and regulatory issues represent a critical hurdle to this technology becoming a reality. It is also critical to achieve social acceptance as well as implement initiatives for the exploitation of the technology for humanitarian purposes and for the benefit of poor countries. This overview predicts considerable potential for plant-based vaccines to positively impact the field of vaccinology in the near future.