Revealing on hydrogen sulfide and nitric oxide signals co-ordination for plant growth under stress conditions

In the recent times, plants are facing certain types of environmental stresses, which give rise to formation of reactive oxygen species (ROS) such as hydroxyl radicals, hydrogen peroxides, superoxide anions and so on. These are required by the plants at low concentrations for signal transduction and at high concentrations, they repress plant root growth. Apart from the ROS activities, hydrogen sulfide (H₂S) and nitric oxide (NO) have major contributions in regulating growth and developmental processes in plants, as they also play key roles as signaling molecules and act as chief plant immune defense mechanisms against various biotic as well as abiotic stresses. H₂S and NO are the two pivotal gaseous messengers involved in growth, germination and improved tolerance in plants under stressed and non-stress conditions. H₂S and NO mediate cell signaling in plants as a response to several abiotic stresses like temperature, heavy metal exposure, water and salinity. They alter gene expression levels to induce the synthesis of antioxidant enzymes, osmolytes and also trigger their interactions with each other. However, research has been limited to only cross adaptations and signal transductions. Understanding the change and mechanism of H₂S and NO mediated cell signaling will broaden our knowledge on the various biochemical changes that occur in plant cells related to different stresses. A clear understanding of these molecules in various environmental stresses would help to confer biotechnological applications to protect plants against abiotic stresses and to improve crop productivity.     

Properties,production, and applications of camelid single-domain antibody fragments

Camelids produce functional antibodies devoid of light chains of which the single N-terminal domain is fully capable of antigen binding. These single-domain antibody fragments (VHHs or Nanobodies) have several advantages for biotechnological applications. They are well expressed in microorganisms and have a high stability and solubility. Furthermore, they are well suited for construction of larger molecules and selection systems such as phage, yeast, or ribosome display. This minireview offers an overview of (1) their properties as compared to conventional antibodies, (2) their production in microorganisms, with a focus on yeasts, and (3) their therapeutic applications.     

Biology and biotechnology of Trichoderma

Fungi of the genus Trichoderma are soilborne, green-spored ascomycetes that can be found all over the world. They have been studied with respect to various characteristics and applications and are known as successful colonizers of their habitats, efficiently fighting their competitors. Once established, they launch their potent degradative machinery for decomposition of the often heterogeneous substrate at hand. Therefore, distribution and phylogeny, defense mechanisms, beneficial as well as deleterious interaction with hosts, enzyme production and secretion, sexual development, and response to environmental conditions such as nutrients and light have been studied in great detail with many species of this genus, thus rendering Trichoderma one of the best studied fungi with the genome of three species currently available. Efficient biocontrol strains of the genus are being developed as promising biological fungicides, and their weaponry for this function also includes secondary metabolites with potential applications as novel antibiotics. The cellulases produced by Trichoderma reesei, the biotechnological workhorse of the genus, are important industrial products, especially with respect to production of second generation biofuels from cellulosic waste. Genetic engineering not only led to significant improvements in industrial processes but also to intriguing insights into the biology of these fungi and is now complemented by the availability of a sexual cycle in T. reesei/Hypocrea jecorina, which significantly facilitates both industrial and basic research. This review aims to give a broad overview on the qualities and versatility of the best studied Trichoderma species and to highlight intriguing findings as well as promising applications.     

Phycobiliproteins from cyanobacteria: Chemistry and biotechnological applications

Phycobiliproteins are a group of water soluble proteins with an associated chromophore, responsible for the light-harvesting in cyanobacteria. They are divided in four main types: phycoerythrin, phycocyanin, phycoerythrocyanin and allophycocyanin, and they are characterized according to their structure and light quality absorption. Phycobiliproteins from cyanobacteria have been described as potential bioactive compounds, and recognized as high-valued natural products for biotechnological applications. Moreover, phycobiliproteins have been associated to antioxidant, anticancer and anti-inflammatory capacities among others. Thus, in order to produce phycobiliproteins from cyanobacteria for industrial application, it is necessary to optimize the whole bioprocess, including the processing parameters (such as light, nitrogen and carbon source, pH, temperature and salinity) that affects the growth and phycobiliprotein accumulation, as well as the optimization of phycobiliproteins extraction and purification. The aim of this review is to give an overview of phycobiliproteins not only in terms of their chemistry, but also in terms of their biotechnological applicability and the advances and challenges in the production of such compounds.     

Metabolic and functional diversity of saponins,biosynthetic intermediates and semi-synthetic derivatives

Abstract

Saponins are widely distributed plant natural products with vast structural and functional diversity. They are typically composed of a hydrophobic aglycone, which is extensively decorated with functional groups prior to the addition of hydrophilic sugar moieties, to result in surface-active amphipathic compounds. The saponins are broadly classified as triterpenoids, steroids or steroidal glycoalkaloids, based on the aglycone structure from which they are derived. The saponins and their biosynthetic intermediates display a variety of biological activities of interest to the pharmaceutical, cosmetic and food sectors. Although their relevance in industrial applications has long been recognized, their role in plants is underexplored. Recent research on modulating native pathway flux in saponin biosynthesis has demonstrated the roles of saponins and their biosynthetic intermediates in plant growth and development. Here, we review the literature on the effects of these molecules on plant physiology, which collectively implicate them in plant primary processes. The industrial uses and potential of saponins are discussed with respect to structure and activity, highlighting the undoubted value of these molecules as therapeutics.     

B chromosomes in plants

Abstract

B chromosomes (Bs) can be described as “selfish chromosomes”, a term that has been used for the repetitive DNA which comprises the bulk of the genome in large genome species, except that Bs have a life of their own as independent chromosomes. They can accumulate in number by various processes of mitotic or meiotic drive, especially in the gametophyte phase of the life cycle of flowering plants. This parasitic property of drive ensures their survival and spread in natural populations, even against a gradient of harmful effects on the host plant phenotype. B chromosomes are inhabitants of the nucleus and they are subject to control by “genes” in the A chromosome (As) complement. This interaction with the As, together with the balance between drive and harmful effects makes a dynamic system in the life of a Bs. In this review, we concentrate mainly on recent developments in the Bs of rye and maize, two of the species currently receiving most attention. We focus on their population dynamics and on the molecular basis of their structural organisation and mechanisms of drive, as well as on their mode of origin and potential applications in plant biotechnology.     

Comparative biochemical and structural characterizations of fungal polygalacturonases

Endo- and exo-polygalacturonases produced by various fungi are involved in the degradation of pectic substances. They have found a wide range of applications in the food and textile industries. Several phyto-pathogenic fungi secrete polygalacturonases and they act as virulence factors during plant pathogenesis. The comparison of biochemical properties of different fungal polygalacturonases, their mechanism of actions, structural aspects and interactions with inhibitors/proteins could be used as a possible strategy for the fungal-crop disease management. This review focuses on fungal polygalacturonases, including their regulation, comparative biochemical and structural characterizations and their interactions with inhibitors.     

The stem cell—Chromatin connection

Stem cells self-renew and give rise to all differentiated cell types of the adult body. They are classified as toti-, pluri- or multi-potent based on the number of different cell types they can give rise to. Recently it has become apparent that chromatin regulation plays a critical role in determining the fate of stem cells and their descendants. In this review we will discuss the role of chromatin regulators in maintenance of stem cells and their ability to give rise to differentiating cells in both the animal and plant kingdom. We will highlight similarities and differences in chromatin-mediated control of stem cell fate in plants and animals. We will consider possible reasons why chromatin regulators play a central role in pluripotency in both kingdoms given that multicellularity evolved independently in each.     

MEDDB: a medicinal plant database developed with the information gathered from tribal people in and around Madurai, Tamil Nadu

Tribal peoples are endowed with enriched traditional wisdom to use available nature resources around them. They are well versed in the usage of plant for treating various diseases. They have used powder or extract or paste form of the plant parts such as root, shoot, whole plant, fruits and leaves etc. The recipe known by the tribal people was passed on only to their family members and community through mouth to mouth practice. Hence, the knowledge is confined to particular people alone. It is always expedient to store information in the database, so that it will be accessible by everyone from everywhere. To achieve this, MEDDB has been developed, which stores the details of 110 plant species that are commonly used by tribes for fever, asthma, cold, cough, diabetes, diarrhea, dysentery, eye infections, stomach ache, wounds and snake bite. The details of each plant were collected from the literature and through web search to give comprehensive and exhaustive information. Each plant entry is compiled under the subheadings viz., common name, classification, physical characteristics, medicinal uses, active constituents, and references.     

Inhibitors of topoisomerase II enzymes: a unique group of environmental mutagens and carcinogens

Many inhibitors of topoisomerase II enzymes are potent mutagens, leading to major chromosomal deletions, illegitimate recombination and aneuploidy. There is increasing evidence that they are also human carcinogens. However, their lack of chemical reactivity means that they may give weak or negative results in commonly used mutagenicity tests, or may give data with characteristics quite distinct from chemicals that alkylate DNA. They do not form DNA adducts and assays such as ³²P-postlabelling will not detect their presence in the body. They are generally not point mutagens and may fail to provide distinctive fingerprints in mutation spectra. These characteristics may be limiting a realistic evaluation of their role in human carcinogenesis using current methodologies.     

植物微生物组的功能及应用研究进展

健康的植物中生活着多种多样但分类学结构不同的微生物群落,它们在所有可接触到的植物组织中定殖.这些微生物群落赋予植物宿主健康优势,包括促进宿主植物生长、营养吸收、抗逆性和对病原菌的抵抗力等.植物菌群及其相互作用具有高度的多样性,多种因素决定着群落的组成和功能.虽然从19世纪开始植物菌群就被人们所认识,但对其功能及应用的相...     

Yeast killer toxins: from ecological significance to application

Killer toxins are proteins that are often glycosylated and bind to specific receptors on the surface of their target microorganism, which is then killed through a target-specific mode of action. The killer phenotype is widespread among yeast and about 100 yeast killer species have been described to date. The spectrum of action of the killer toxins they produce targets spoilage and pathogenic microorganisms. Thus, they have potential as natural antimicrobials in food and for biological control of plant pathogens, as well as therapeutic agents against animal and human infections. In spite of this wide range of possible applications, their exploitation on the industrial level is still in its infancy. Here, we initially briefly report on the biodiversity of killer toxins and the ecological significance of their production. Their actual and possible applications in the agro-food industry are discussed, together with recent advances in their heterologous production and the manipulation for development of peptide-based therapeutic agents.     

Ontologies in radiation oncology

Ontologies are a formal, computer-compatible method for representing scientific knowledge about a given domain. They provide a standardized vocabulary, taxonomy and set of relations between concepts. When formatted in a standard way, they can be read and reasoned upon by computers as well as by humans. At the 2019 International Conference on the Use of Computers in Radiation Therapy, there was a session devoted to ontologies in radiation therapy. This paper is a compilation of the material presented, and is meant as an introduction to the subject. This is done by means of a didactic introduction to the topic followed by a series of applications in radiation therapy. The goal of this article is to provide the medical physicist and related professionals with sufficient background that they can understand their construction as well as their practical uses.     

How aphid alarm pheromone can control aphids: a review

Aphids are the major pests of arable crops, mostly in temperate regions. They are monophagous as well as polyphagous. They inflict damage in brassica, potato, cotton, vegetable and fruit crops. They damage their host plant directly by feeding upon their phloem sap, or indirectly by transmitting pathogens to them. Their life cycle can be autoecious as well as heteroecious. Aphids use semiochemicals for various purposes, in gathering information from their environment and for communication among themselves. They protect themselves from predators and parasitoids by escape response which is arbitrated by use of alarm pheromone signalling. When alarm pheromone, (E)-ß-farnesene, is released, nearby aphids exhibit a variety of behaviours like moving away, running, dropping off the plant and even attacking the predator. Previous studies of integrated pest management strategies have been aimed at the usage of alarm pheromone. However, scientists require complete knowledge of aphid ecology as well as aphid interaction with its natural enemies to establish efficient and viable biological control. This review presents analysis of the existing aphid pest management methodologies and effectiveness of alarm pheromone on aphids and their natural enemies.     

Homology modeling of plant cytochrome P450s

Plant P450 monooxygenases represent the largest family of plant proteins and the largest collection of P450s available for comparative studies and biotechnological applications. They have been shown to catalyze a diverse array of difficult chemical reactions and have demonstrated potential to be used in pharmacological, agronomic and phytoremediative applications. Central to our use of these catalytically competent enzymes is the need to understand their interactions with substrates. Because most characterized plant P450s are membrane-bound proteins that are resistant to standard X-ray and NMR structure determinations, homology modeling represents a reliable and relatively rapid alternative method for analyzing structure-function relationships and predicting substrates for many P450s that are only now being characterized. These methods, which are being widely used in mammalian P450 structure-function studies, can allow plant biologists to define critical residues interacting with substrates and, in a directed fashion, alter the reactivities of individual monooxygenases. The homology modelings that have been done on a limited number of plant P450s and the site-directed mutations that validate them indicate that current modeling and substrate docking procedures are capable of providing structural explanations for sequence variants as well as for predicting functional characteristics of undefined P450s.     

Analysis of Brassinosteroids in Plants

Brassinosteroids (BRs) are the polyhydroxylated plant hormones sharing a common resemblance with animal steroids. They are active even at very low concentrations and are implicated for their pleiotropic involvement in diverse physiological processes and defense strategies during stress in plants. These compounds are well apparent in the plant kingdom with higher amounts in juvenile tissues. A total of 62 steroidal compounds have been identified so far. Keeping their significance in mind, researchers not only have worked extensively on their isolation, but also they were synthesizing their synthetic isomers. Different analytical techniques like HPLC, GC-MS, LC-MS/MS, UPLC-MS/MS, and bioassay-based methods have been used for their isolation, detection, and characterization from composite plant materials. Therefore, this review provides comprehensive information to the readers intending to isolate and characterize BRs, using either laborious techniques or modern-day more efficient methods.     

Production of Plant Bioactive Triterpenoid Saponins: Elicitation Strategies and Target Genes to Improve Yields

Triterpenoid saponins are a class of plant secondary metabolites with structure derived from the precursor oxidosqualene in which one or more sugar residues are added. They have a wide range of pharmacological applications, such as antiplatelet, hypocholesterolemic, antitumoral, anti-HIV, immunoadjuvant, anti-inflammatory, antibacterial, insecticide, fungicide and anti-leishmanial agents. Their accumulation in plant cells is stimulated in response to changes mediated by biotic and abiotic elicitors. The enhancement of saponin yields by methyl jasmonate in plants and cell cultures in several species indicates the involvement of these metabolites in plant defence mechanisms. The elucidation of their biosynthesis at the molecular level has advanced recently. Most studies to date have focused on the participation of early enzymes in the pathway, including oxidosqualene cyclase, squalene synthase and dammarenediol synthase, as well as in isolating and characterizing genes that encode β-amyrin synthase. Yields of bioactive saponins in various plant species and experimental systems have been successfully increased by treating cells and tissues with jasmonate or by exposing these to oxidative stress. These elicitation and molecular studies are consolidating a robust knowledge platform from which to launch the development of improved sources for commercial supply of bioactive saponins.     

Microbial and fungal protease inhibitors—current and potential applications

Proteolytic enzymes play essential metabolic and regulatory functions in many biological processes and also offer a wide range of biotechnological applications. Because of their essential roles, their proteolytic activity needs to be tightly regulated. Therefore, small molecules and proteins that inhibit proteases can be versatile tools in the fields of medicine, agriculture and biotechnology. In medicine, protease inhibitors can be used as diagnostic or therapeutic agents for viral, bacterial, fungal and parasitic diseases as well as for treating cancer and immunological, neurodegenerative and cardiovascular diseases. They can be involved in crop protection against plant pathogens and herbivorous pests as well as against abiotic stress such as drought. Furthermore, protease inhibitors are indispensable in protein purification procedures to prevent undesired proteolysis during heterologous expression or protein extraction. They are also valuable tools for simple and effective purification of proteases, using affinity chromatography. Because there are such a large number and diversity of proteases in prokaryotes, yeasts, filamentous fungi and mushrooms, we can expect them to be a rich source of protease inhibitors as well.