Biocontrol Potential of Endophytic Actinobacteria against Fusarium solani, the Causal Agent of Sudden Decline Syndrome on Date Palm in the UAE

Thirty-one endophytic streptomycete and non-streptomycete actinobacteria were isolated from healthy date palm root tissues. In vitro screening revealed that the antifungal action of isolate #16 was associated with the production of cell-wall degrading enzymes, whereas with diffusible antifungal metabolites in isolate #28, albeit their production of volatile antifungal compounds. According to the 16S rRNA gene sequencing, isolates #16 and #28 were identified as Streptomyces polychromogenes UAE2 (Sp; GenBank Accession #: OK560620) and Streptomyces coeruleoprunus UAE1 (Sc; OK560621), respectively. The two antagonists were recovered from root tissues until 12 weeks after inoculation, efficiently colonized root cortex and xylem vessels, indicating that the date palm roots are a suitable habitat for these endophytic isolates. At the end of the greenhouse experiments, the development of sudden decline syndrome (SDS) was markedly suppressed by 53% with the application of Sp and 86% with Sc, confirming their potential in disease management. Results showed that the estimated disease severity indices in diseased seedlings were significantly (p < 0.05) reduced from 4.75 (scale of 5) to 2.25 or 0.67 by either Sp or Sc, respectively. In addition, conidial numbers of the pathogen significantly (p < 0.05) dropped by 38% and 76% with Sp and Sc, respectively, compared to infected seedlings with F. solani (control). Thus, the suppression of disease symptoms was superior in seedlings pre-inoculated with S. coeruleoprunus, indicating that the diffusible antifungal metabolites were responsible for F. solani retardation in these plants. This is the first report of actinobacteria naturally existing in date palm tissues acting as microbial antagonists against SDS on date palm.

Can Plant Materials Be Valuable in the Treatment of Periodontal Diseases? Practical Review

Periodontal diseases are one of the most significant challenges in dental health. It is estimated that only a few percent of the worldwide population have entirely healthy teeth, and according to WHO, oral diseases may affect up to 3.5 billion people worldwide. One of the most serious oral diseases is periodontitis, an inflammatory disease affecting periodontal tissues, caused by pathogenic bacteria and environmental factors such as the ageing population, abuse of tobacco products, and lack of adequate oral hygiene due low public awareness. Plant materials are widely and successfully used in the management of many conditions, including periodontitis. Plant materials for periodontitis exhibit antibacterial, anti-inflammatory, antioxidant activities and affect the periodontium structure. Numerous studies demonstrate the advantages of phytotherapy for periodontitis relief and indicate the usefulness of Baikal skullcap root, Pomegranate fruit peel and root cortex, Tea leaves, Chamomile flowers, Magnolia bark, Blackberry leaves and fruits, Cranberry fruits and Lippia sidoides essential oil. This review aims to analyze the use and applicability of selected plant materials in periodontitis management since it is of paramount importance to evaluate the evidence of the traditionally used plant materials in light of continuously growing interest in phytotherapy and its adjuvant role in the treatment of periodontitis.

Mechanism of kinetin-induced death of Vicia faba ssp. minor root cortex cells

Cell death (CD) may be induced by endogenous or exogenous factors and contributes to all the steps of plant development. This paper presents results related to the mechanism of CD regulation induced by kinetin (Kin) in the root cortex of Vicia faba ssp. minor. To explain the process, 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55), adenine (Ad), 5′-amine-5′-deoxyadenosine (Ado) and N-(2-chloro-4-piridylo)-N′-phenylurea (CPPU) were applied to (i) block cytokinin receptors (CKs) and inhibit the activities of enzymes of CK metabolism, i.e., (ii) phosphoribosyltransferase, (iii) kinases, and (iv) oxidases, respectively. Moreover, ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), lanthanum chloride (LaCl3), ruthenium red (RRed) and cyclosporine A (CS-A) were applied to (i) chelate extracellular calcium ions (Ca2+) as well as blocks of (ii) plasma-, (iii) endoplasmic reticulum- (ER) membrane Ca2+ ion channels and (iv) mitochondria- (MIT) Ca2+ ions release by permeability transition por (PTP), respectively. The measured physiological effectiveness of these factors was the number of living and dying cortex cells estimated with orange acridine (OA) and ethidium bromide (EB), the amounts of cytosolic Ca2+ ions with chlortetracycline (CTC) staining and the intensity of chromatin and Ca2+-CTC complex fluorescence, respectively. Moreover, the role of sorafenib, an inhibitor of RAF kinase, on the vitality of cortex cells and ethylene levels as well as the activities of RAF-like kinase and MEK2 with Syntide-2 and Mek2 as substrates were studied. The results clarified the previously presented suggestion that Kin is converted to appropriate ribotides (5′-monophosphate ribonucleotides), which cooperate with the ethylene and Ca2+ ion signalling pathways to transduce the signal of kinetin-programmed cell death (Kin-PCD). Based on the present and previously published results related to Kin-PCD, the crosstalk between ethylene and MAP kinase signalling, as well as inhibitors of CK receptors and enzymes of their metabolism, is proposed.

An evaluation for the medium-term storage and viability of root cortex tissues stained with blue ink in the assessment of arbuscular mycorrhizal fungi

Sheaffer blue ink is an effective method to stain arbuscular mycorrhizal (AM) fungi in a variety of plant species. It has, however, received criticism for its potential rapid degradation and short-term viability. The long and medium term storage and viability of stained samples has not, to date, been described for this particular staining method. This short communication reports on the viability of 730 samples stained with Sheaffer blue ink stored for the duration of 4 years in microscope slide boxes out of direct sunlight. There was no significant difference in micrograph image quality and presence of stain between years as indicated by the number of AM fungal structures quantified. In conclusion Sheaffer blue ink stain does not deteriorate in the medium term.

Phosphate fertilization regulates arbuscular mycorrhizal symbiosis in roots of soybean (Glycine max L.) cultivars in a humid tropical soil

<p>The effect of phosphate fertilization on arbuscular mycorhizal symbiosis and grain yields of soybean cultivars was investigated on P deficient soil. A two-year field study (2017-2018) consisting of two soybean cultivars (TGx 1448-2E and TGx 1440-1E) and three phosphate rates [0, 20 and 40 kg P₂O₅ ha^-1) was laid out in a randomized complete block design with three replications. The results showed that P fertilization significantly (<em>p</em> &lt; 0.001) reduced AMF root colonization of both cultivars in the two cropping years. The arbuscular, vesicular, internal hyphae and total colonization in the root cortex of the soybean cultivars were significantly (<em>p</em> &lt; 0.001) reduced with high P (40 kg) application. However, moderate P (20 kg) promote AMF symbiosis in roots of ‘TG x 1448-2E‘. Dry mass (root and shoot), P uptake and grain yield of the soybean cultivars were significantly (<em>p</em> &lt; 0.001) increased with increasing P ferilization. There was a strong linear relationships between root colonization and total dry matter mass (r = 0.81), P uptake (r = 0.81) and grain yield (r = 0.85). Thus, it could be concluded that moderate P fertilizer application is needed to promote mycorrhizal symbiosis in soybean and sustainable crop production in humid tropical soil.</p>

The microorganism-plant system for remediation of soil exposed to coal mining

Introduction. Coal mining causes a radical transformation of the soil cover. Research is required into modern methods and complementary technologies for monitoring technogenic landscapes and their remediation. Our study aimed to assess soil and rhizosphere microorganisms and their potential uses for the remediation of technogenic soils in Russian coal regions. Study objects and methods. We reviewed scientific articles published over the past five years, as well as those cited in Scopus and Web of Science. Results and discussion. Areas lying in the vicinity of coal mines and coal transportation lines are exposed to heavy metal contamination. We studied the application of soil remediation technologies that use sorbents from environmentally friendly natural materials as immobilizers of toxic elements and compounds. Mycorrhizal symbionts are used for soil decontamination, such as arbuscular mycorrhiza with characteristic morphological structures in root cortex cells and some mycotallia in the form of arbuscules or vesicles. Highly important are Gram-negative proteobacteria (Agrobacterium, Azospirillum, Azotobacter, Burkholderia, Bradyrizobium, Enterobacter, Pseudomonas, Klebsiella, Rizobium), Gram-positive bacteria (Bacillus, Brevibacillus, Paenibacillus), and Grampositive actinomycetes (Rhodococcus, Streptomyces, Arhtrobacter). They produce phytohormones, vitamins, and bioactive substances, stimulating plant growth. Also, they reduce the phytopathogenicity of dangerous diseases and harmfulness of insects. Finally, they increase the soil’s tolerance to salinity, drought, and oxidative stress. Mycorrhizal chains enable the transport and exchange of various substances, including mineral forms of nitrogen, phosphorus, and organic forms of C3 and C4 plants. Microorganisms contribute to the removal of toxic elements by absorbing, precipitating or accumulating them both inside the cells and in the extracellular space. Conclusion. Our review of scientific literature identified the sources of pollution of natural, agrogenic, and technogenic landscapes. We revealed the effects of toxic pollutants on the state and functioning of living systems: plants, animals, and microorganisms. Finally, we gave examples of modern methods used to remediate degraded landscapes and reclaim disturbed lands, including the latest technologies based on the integration of plants and microorganisms.

Spatial differences in stoichiometry of EGR phosphatase and Microtubule-Associated Stress Protein 1 control root meristem activity during drought stress.

During moderate severity drought and low water potential (Ψw) stress, poorly understood signaling mechanisms restrict both meristem cell division and subsequent cell expansion. We found that the Clade E Growth-Regulating 2 (EGR2) protein phosphatase and Microtubule Associated Stress Protein 1 (MASP1) differed in their stoichiometry of expression across the root meristem and had opposing effects on root meristem activity at low Ψw. Ectopic MASP1 or EGR expression increased or decreased, respectively, root meristem size and root elongation during low Ψw stress. This, along with the ability of phosphomimic MASP1 to overcome EGR suppression of root meristem size and observation that ectopic EGR expression had no effect on unstressed plants, indicated that during low Ψw EGR activation and attenuation of MASP1 phosphorylation in their overlapping zone of expression determines root meristem size and activity. Ectopic EGR expression also decreased root cell size at low Ψw. Conversely, both the egr1-1egr2-1 and egr1-1egr2-1masp1-1 mutants had similarly increased root cell size; but, only egr1-1egr2-1 had increased cell division. These observations demonstrated that EGRs affect meristem activity via MASP1 but affect cell expansion via other mechanisms. Interestingly, EGR2 was highly expressed in the root cortex, a cell type important for growth regulation and environmental response.

A Peptide Encoding Gene MdCLE8 Regulates Lateral Root Development in Apple

Nitrogen is not only an essential nutrient for plant, but also an important signal molecule to integrate and regulate gene expression, metabolism and growth. Plant peptides are considered as a new hormone, and play an important regulatory role in plant growth and development. However, there are few researches on the co-regulation network between nitrogen and peptide hormones in plant. Here we identified an apple MdCLE8 gene, which encodes a putative peptide, induced by nitrogen deficiency in apple. Ectopic expression of MdCLE8 inhibited lateral root formation in Arabidopsis under nitrogen deficiency. Similarly, overexpression of MdCLE8 inhibited lateral root development in apple adventitious roots, and this inhibition was amplified under nitrogen deficiency treatment. Further studies showed that MdCLE8 may inhibit the expression of several key genes during lateral root emergence stage in Arabidopsis, thereby inhibiting the emergence of lateral root from root cortex cells. Collectively, our study not only broadened the gene regulatory network under the influence of nitrogen in apple, but also expanded the function of CLE peptide hormones in apple.

The anatomical, palynological and micromorphological aspects of three endemic Bellevalia species (Asparagaceae) in Turkey and their taxonomic importance

In the present research, anatomical, palynological and micromorphological characteristics of three endemic Bellevalia species (B. gracilis, B. malatyaensis and B. vuralii) for Turkey are carried out. This work reveals the descriptive characteristics of the examined species, and contribute to solving taxonomic problems. Anatomical studies were carried out on cross sections of root, scape and leaf. The metaxylem, the number of root cortex cells, and the number of cortex and sclerenchyma cells in the scape were found to be significant in terms of taxonomy. Pollen grains of all the examined species were monosulcate and heteropolar. In addition, seed and pollen surface ornamentation were photographed under SEM microscopy, which SEM micrographs showed that the exine sculpturing pattern is reticulate-perforate, and pollen muri walls of were different among the examined species. Conversely, seeds showed a general similarity of the surface among the studied species, all showing a reticulate faveolate ornamentation.

Variation of resistance response of orchids induced by Rhizoctonia against the infection of Odontoglossum ringspot virus (ORSV) based on percentage of disease development

Orchid is one of the largest groups of flowering plants that are in great demand by society. Besides, the various flowers with a long vase life, the price of orchids is also stable and affordable. Phalaenopsis and Dendrobium are the most popular types of orchids. To anticipate this, orchid cultivation needs to be improved. However, orchid cultivation is not always accompanied by the effort of disease prevention, particularly those caused by viruses. The virus that most infects orchids is the Odontoglossum ringspot virus (ORSV). Symptoms that appear on the leaves are chlorosis, mosaic with a pattern of lines, circles, and necrotic rings/rings. Control of viral infections can utilize organisms that are able to induce resistance, namely mycorrhizae. Mycorrhizae will penetrate into the root cortex tissue and provide nutrients for the orchid. Mycorrhizae that are quite often found are Rhizoctonia and are applied by induction to orchids. Induction was undertaken by planting orchids in Rhizoctonia inoculum until anatomically a peloton structure (solid coils) was formed on the orchid roots. The aim of this study was to study the response of orchid plants in the form of percentage incidence and intensity of the disease and the level of plant resistance to ORSV infection in Phalaenopsis amabilis and Dendrobium discolour which had been induced by Rhizoctonia. This research was conducted at the Laboratory of Botany, Biology, FMIPA, Universitas Lampung, using a factorial completely randomized design (CRD). Factor 1 was the type of orchid and factor 2 was mycorrhizal induction, virus inoculation, and a combination of both with 4 replications. The finding indicated that Phalaenopsis amabilis was more susceptible to ORSV infection than Dendrobium discolour based on a higher incidence and intensity of the disease. Mycorrhizal induction and virus inoculation (MAV) in Dendrobium discolour showed an increase of resistance response compared to Phalaenopsis amabilis.