Pythium and Globisporangium species associated with cucumber rhizosphere causing damping-off and their effects on cucumber seed decay in Oman.

Autor: Al-Mahmooli IH; Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod, Muscat, 123, Oman. issah@squ.edu.om.; Faculty Organic Agricultural Sciences, Kassel University, Fachbereich 11-Fachgebiet Ökologischer Pflanzenschutz Nordbahnhofstraße1a, 37213, Witzenhausen, Germany. issah@squ.edu.om., Finckh MR; Faculty Organic Agricultural Sciences, Kassel University, Fachbereich 11-Fachgebiet Ökologischer Pflanzenschutz Nordbahnhofstraße1a, 37213, Witzenhausen, Germany., Velazhahan R; Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod, Muscat, 123, Oman., AlJabri AM; Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod, Muscat, 123, Oman., Šišić A; Faculty Organic Agricultural Sciences, Kassel University, Fachbereich 11-Fachgebiet Ökologischer Pflanzenschutz Nordbahnhofstraße1a, 37213, Witzenhausen, Germany., Hussain S; Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod, Muscat, 123, Oman., Abdel-Jalil R; Department of Chemistry, College of Science, Sultan Qaboos University, Al-Khod, Muscat, 123, Oman., Al-Sadi AM; Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod, Muscat, 123, Oman.
Jazyk: angličtina
Zdroj: Archives of microbiology [Arch Microbiol] 2024 Aug 10; Vol. 206 (9), pp. 374. Date of Electronic Publication: 2024 Aug 10.
DOI: 10.1007/s00203-024-04097-y
Abstrakt: Pythium sensu lato (s.l.) is a pathogenic oomycete. The present study was conducted to isolate and identify Pythium s.l. species associated with the rhizosphere and roots of greenhouse-growing cucumbers showing damping-off symptoms in 10 Omani governorates (provinces). A total of 166 isolates were recovered from 276 rhizosphere soil and root samples and were identified based on the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region and the cytochrome c oxidase subunit I (COX I) gene region. Pythium aphanidermatum, P. myriotylum, Globisporangium spinosum, Globisporangium sp.1 (isolates Kb003/PySyCu-1 and Kb004/PySyCu-2), and Globisporangium sp.2 (isolate Ib002R) were identified. Among these species, P. aphanidermatum was the most abundant species, represented by 143 isolates (86.1%), followed by G. spinosum with 18 isolates (10.8%), Globisporangium sp.1 and P. myriotylum each with 2 isolates (2.4%), and Globisporangium sp.2 with 1 isolate (0.6%). Pathogenicity tests were also conducted for 38 isolates, including P. aphanidermatum (25), P. myriotylum (2), Globisporangium sp.2 (1), G. spinosum (8), and Globisporangium sp.1 (2). Among the tested isolates, only Globisporangium sp.2 isolate was avirulent, and none of the seeds were rotted at the end of the treatment. However, the other species induced the symptoms of seed decay with the incidence ranged from 86.7 to 100%. Phylogenetic analyses were conducted based on 222 ITS and 53 COX I sequences, and confirmed morphological identification. In addition, the genetic diversity of 93 P. aphanidermatum isolates was assessed via the amplified fragment length polymorphism (AFLP) method. The analysis produced 93 genotypes and 449 polymorphic loci. Pythium aphanidermatum populations were found to have moderate levels of genetic diversity (H = 0.2) and a moderate Shannon information index (I = 0.3793). Analysis of molecular variance (F ST  = 0.1, P = 0.0) revealed a moderate level of genetic differentiation among P. aphanidermatum isolates between Oman governorates. The sensitivity of 15 P. aphanidermatum isolates was evaluated against hymexazol at different concentrations (10, 100, and 1000 ppm). The results revealed that P. aphanidermatum could grow well at concentrations of up to 100 ppm hymexazol. However, hymexazol at 1000 ppm retarded the growth of P. aphanidermatum. This study showed that P. aphanidermatum is the most prevalent species in greenhouses in Oman and exhibited a moderate level of genetic diversity. Most of the isolates exhibited differences in tolerance to hymexazol but showed no resistance.
(© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
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