Impact of Sulphur Dioxide Deposition on Medicinal Plants' Growth and Production of Active Constituents
Azamal Husen in Environmental Pollution and Medicinal Plants, 2022
Necrotic streaks appear on parallel-veined plants between the veins near the leaf tip and extending toward the base with an increase in severity of injury. Conifers’ needle tips show injury in the form of browning that extends toward the base with an increase in severity of injury. High levels of SO2 exposure result in a dark lining on the brown necrotic part of the needle. Broadleaf plants in response to acute SO2 exposure suffer marginal injury (Legge and Krupa 2002). It was observed that new leaves are more sensitive than older leaves to SO2 (Horsman and Wellburn 1977). Most of the plants’ leaf susceptible region impacted by SO2 became flaccid and subsequently dried in most plant leaves (Taylor 1973). Brown leaf spots are chronic injury expressed from leaf margins, causing a decline in leaf area and plant yield (Kropff 1991). Acute injury symptoms emerge at the tip of leaves, causing necrotic and chlorotic streaks with irregular reddish pigmentation in monocot plants (Rai et al. 2011).
Potential of Mycochemicals in the Prevention and Control of Microbial Diseases
Mahendra Rai, Chistiane M. Feitosa in Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
While useful as microorganisms, they are also the causative agents of wide range of infectious diseases of humans and domestic animals. The human race and microbial entities have been involved in the war of survival from time immemorial. Microbes have shown incredible ability to adapt, re-adapt, survive and challenge human ingenuity in the last two to three decades (Fonkwo 2008). Hence, pathogens constantly change their genetic make-up, which normally results to ineffectiveness of vaccines and other chemotherapeutic agents used in fighting pathogenic microorganisms and microorganisms responsible for the spoilage of foods. This genetic flexibility allows many infectious agents to mutate or evolve into more deadly strains against which humans have little or no resistance against (Fonkwo 2008). Diseases such as plague, tuberculosis, anthrax and gonorrhea are caused by bacteria. Protozoa cause diseases including malaria, sleeping sickness, dysentery and toxoplasmosis. Microscopic fungi cause diseases such as ringworm, candidiasis and histoplasmosis. Pathogenic viruses cause diseases such as influenza, yellow fever and AIDs. The noxious effects of microorganisms are not limited to animals alone as they are also important pathogens responsible for various diseases of crop plants. Plant and crop diseases such as maize leaf rust, wheat stem rust, powdery mildew, leaf spot, and crown gall, and so on are caused by microbial pathogens in crops and plants. The great Irish famine of the 1840s as a result of potato blight was caused by a fungal plant pathogen, Oomycete, Phytophthora infestans (Kinealy 1994).
Antifungal Activity of Seaweeds and their Extracts
Leonel Pereira in Therapeutic and Nutritional Uses of Algae, 2018
Colletotrichum spp. causes anthracnose diseases in many economically important crops worldwide. The classification of species within this genus traditionally has been based on conidial shape and size, presence of sclerotia, appressoria production, and, often, on host origin. C. orbiculare causes anthracnose and fruit rot. Leaf spots are often large (> 10 mm in diameter) and pale brown to grey with distinct margins. Lesions on fruit appear as brownish discolorations, often growing to 20-30 mm in diameter, which become sunken, wrinkled, and dark, with concentric rings of conidiomata (Liu et al. 2007).
Genetics and optical coherence tomography features in a child with an achromatic retinal patch
Published in Ophthalmic Genetics, 2022
Noy Ashkenazy, Nicolas A. Yannuzzi, Audina M. Berrocal
The diameter of an achromatic retinal patch is generally under 1.5 mm (2,10,11), as shown in the case herein. However, a “giant” achromatic retinal patch with suspected similarities to a cutaneous ash-leaf spot has been described by Andrews et al. (10). The same authors also reported the enhanced-depth imaging (EDI) OCT features of an achromatic retinal patch with outer retinal and RPE loss, as well as increased choriocapillaris hyper-reflectivity (10). The current body of literature lacks information on the OCT features of typical achromatic retinal patches. We illustrate a focal elevation of the outer retina with disruption of the ellipsoid zone just above the RPE (Figure 1b). These OCT findings have not been previously described.
Antimicrobial activities of Trichoderma atroviride against common bean seed-borne Macrophomina phaseolina and Rhizoctonia solani
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Naglaa M. El-Benawy, Gamal M. Abdel-Fattah, Khalid M. Ghoneem, Yasser M. Shabana
Common bean is subjected to various types of diseases mainly by fungi which cause 80–100% yield loss [6]. Fungi cause the majority of infectious diseases of common bean including the angular leaf spot caused by Phaeoisariopsis griseola, leaf rust caused by Uromyces appendiculatus, anthracnose caused by Colletotrichum lindemuthianum, white mold caused by Sclerotinia sclerotiorum, root rot caused by Fusarium spp., damping-off caused by Rhizoctonia solani, and charcoal rot caused by Macrophomina phaseolina [7]. When they are seed-borne, up to 53% yield losses were reported [8].
Development and characterization of gamma ray and EMS induced mutants for powdery mildew resistance in blackgram
Published in International Journal of Radiation Biology, 2023
Murugesan Tamilzharasi, Dharmalingam Kumaresan, Venkatesan Thiruvengadam, Jegadeesan Souframanien, T. K. S. Latha, N. Manikanda Boopathi, Palaniappan Jayamani
The recognition of pathogens by plants will produce an excess of reactive oxygen species (ROS) due to oxidative stress. Pathogen-induced ROS functions as a signaling molecule that actively stimulates signal cascade pathways and triggers basal resistance (jasmonic acid, salicylic acid, abscisic acid, and auxins pathway) in host plants (Zechmann 2020). Meanwhile, ROS homeostasis should be maintained in the cell; otherwise, this would lead to oxidative stress. Inherently antioxidant pathways are triggered concurrently to the activation of the defense-related gene to counteract this. Increased levels of enzymatic antioxidants such as PPO (polyphenol oxidase), SOD (superoxide dismutase), and CAT (catalase) play a key role in scavenging harmful free radicals to maintain an intracellular oxidative condition of the host (Oliveira et al. 2012; Kumar et al. 2013). In the present study, a significant increase of SOD, CAT, POX, and PPO was observed in resistant mutants and resistant check than in susceptible genotypes which indicates that the resistant mutants can rapidly detoxify radicals formed during pathogen attacks (Hameed et al. 2017; Datta and Lal 2018). In the case of susceptible lines, it was not possible to sustain an optimum level of ROS in the powdery mildew susceptible lines even by the use of antioxidants generated by the host. The reduced capacity to scavenge ROS with a tremendous increase in ROS levels leads to susceptibility (Hafez and Gharib 2016; Waghmare and Nasreen 2019). It could cause DNA and membrane damage to the host, which eventually leads to the death of the host plant. Mohapatra (2016) reported similar findings earlier in pea for powdery mildew, Maurya et al. (2018) in mungbean for Cercospora leaf spot and Chakraborty and Basak (2018) in blackgram for Mungbean Yellow Mosaic Virus (MYMV).
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