ORCID Profile
0000-0003-1762-3709
Current Organisation
Norwegian University of Life Sciences
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Publisher: MDPI AG
Date: 20-10-2017
DOI: 10.3390/IJMS18102086
Publisher: MDPI AG
Date: 20-02-2019
DOI: 10.3390/IJMS20040923
Abstract: Date palm orchards suffer from serious diseases, including sudden decline syndrome (SDS). External symptoms were characterized by whitening on one side of the rachis, progressing from the base to the apex of the leaf until the whole leaf dies while the internal disease symptoms included reddish roots and highly colored vascular bundles causing wilting and death of the tree. Although three Fusarium spp. (F. oxysporum, F. proliferatum and F. solani) were isolated from diseased root s les, the fungal pathogen F. solani was associated with SDS on date palm in the United Arab Emirates (UAE). Fusarium spp. were identified based on their cultural and morphological characteristics. The internal transcribed spacer regions and large subunit of the ribosomal RNA (ITS/LSU rRNA) gene complex of the pathogens was further sequenced. Pathogenicity assays and disease severity indices confirm the main causal agent of SDS on date palm in the UAE is F. solani. Application of Cidely® Top (difenoconazole and cyflufenamid) significantly inhibited the fungal mycelial growth in vitro and reduced SDS development on date palm seedlings pre-inoculated with F. solani under greenhouse conditions. This is the first report confirming that the chemical fungicide Cidely® Top is strongly effective against SDS on date palm.
Publisher: Scientific Societies
Date: 12-2016
DOI: 10.1094/PDIS-05-16-0645-RE
Abstract: Date palm (Phoenix dactylifera L.) is one of the most important plants grown for its edible fruit. Palm diseases are among the major factors affecting its growth and productivity. In the United Arab Emirates (UAE), the causal agent of black scorch on date palm was found to be Thielaviopsis punctulata. The pathogen was isolated from all tissues of diseased trees affected by the virulent T. punctulata. Depending on the severity of the infection, symptoms included tissue necrosis, wilting, neck bending, death of terminal buds, and eventual plant mortality. This fungus, which was consistently isolated on potato dextrose agar from infected tissues, produced two types of conidia: the thick-walled aleuroconidia (chlamydospores) and phialoconidia (endoconidia). In addition, all target regions of 5.8S ribosomal RNA, 28S ribosomal DNA, β-tubulin, and transcription elongation factor 1-α genes of the pathogen were lified using polymerase chain reaction. We also found that the fungicide Score inhibited the mycelial growth of T. punctulata both in vitro and in vivo. Altogether, the morphology of the fruiting structures, pathogenicity tests, and molecular identification confirmed that the causal agent of symptomatic tissues is T. punctulata. This is the first report of the black scorch disease and the fungus T. punctulata on date palm in the UAE.
Publisher: Frontiers Media SA
Date: 31-07-2017
Publisher: MDPI AG
Date: 04-02-2020
DOI: 10.3390/IJMS21031033
Abstract: In the United Arab Emirates (UAE), royal poinciana (Delonix regia) trees suffer from stem canker disease. Symptoms of stem canker can be characterized by branch and leaf dryness, bark lesions, discoloration of xylem tissues, longitudinal wood necrosis and extensive gumming. General dieback signs were also observed leading to complete defoliation of leaves and ultimately death of trees in advanced stages. The fungus, Neoscytalidium dimidiatum DSM 109897, was consistently recovered from diseased royal poinciana tissues this was confirmed by the molecular, structural and morphological studies. Phylogenetic analyses of the translation elongation factor 1-a (TEF1-α) of N. dimidiatum from the UAE with reference specimens of Botryosphaeriaceae family validated the identity of the pathogen. To manage the disease, the chemical fungicides, Protifert®, Cidely® Top and Amistrar® Top, significantly inhibited mycelial growth and reduced conidial numbers of N. dimidiatum in laboratory and greenhouse experiments. The described “apple bioassay” is an innovative approach that can be useful when performing fungicide treatment studies. Under field conditions, Cidely® Top proved to be the most effective fungicide against N. dimidiatum among all tested treatments. Our data suggest that the causal agent of stem canker disease on royal poinciana in the UAE is N. dimidiatum.
Publisher: Springer Science and Business Media LLC
Date: 18-11-2019
DOI: 10.1038/S41598-019-53694-1
Abstract: In this study, we aimed to identify common genetic components during stress response responsible for crosstalk among stresses, and to determine the role of differentially expressed genes in Arabidopsis - Botrytis cinerea interaction. Of 1,554 B. cinerea up-regulated genes, 24%, 1.4% and 14% were induced by biotic, abiotic and hormonal treatments, respectively. About 18%, 2.5% and 22% of B. cinerea down-regulated genes were also repressed by the same stress groups. Our transcriptomic analysis indicates that plant responses to all tested stresses can be mediated by commonly regulated genes and protein-protein interaction network confirms the cross-interaction between proteins regulated by these genes. Upon challenges to in idual or multiple stress(es), accumulation of signaling molecules (e.g. hormones) plays a major role in the activation of downstream defense responses. In silico gene analyses enabled us to assess the involvement of RAP2.4 (related to AP2.4) in plant immunity. Arabidopsis RAP2.4 was repressed by B. cinerea , and its mutants enhanced resistance to the same pathogen. To the best of our knowledge, this is the first report demonstrating the role of RAP2.4 in plant defense against B. cinerea . This research can provide a basis for breeding programs to increase tolerance and improve yield performance in crops.
Publisher: Frontiers Media SA
Date: 24-07-2019
No related grants have been discovered for Arjun Sham Valiyaveettil Shamgopal.