Potato bacterial wilt suppression and plant health improvement after application of different antioxidants

Abstract

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease that often threatens potato production and exportation. The potential of four antioxidants (seaweed extract (SWE), yeast, chitosan and ascorbic acid (ASA)) in controlling the disease was evaluated in vitro, under glasshouse and field conditions. The field experiment was conducted in two naturally infested locations: Wardan, Giza (sandy soil), and Talia, Minufiya (silty clay soil). Only chitosan showed antibacterial properties against the pathogen in vitro. SWE, yeast and chitosan showed disease suppression under both glasshouse and field conditions. The disease suppression was accompanied by an increase in the ratio of soil copiotrophic to oligotrophic bacteria. The three antioxidants increased plant nitrogen content, decreased soil OM content and decreased C/N ratio. Disease suppression after chitosan application was clearly observed only in Wardan area, which was characterized by a higher soil alkalinity. A high percentage of antagonistic fluorescent strains similar to Pseudomonas putida group were detected for chitosan‐treated plants in Wardan area (sandy soil). ASA drastically decreased the count of the pathogen in soil, but was conducive to the pathogen in plant tissues. A remarkable increase in microbial (bacterial and fungal) soil and rhizosphere diversity as indicated by PCR‐DGGE analysis for bacterial 16S rRNA and fungal 18S rRNA was recorded. In Talia area (silty clay soil), the soil microbial community was more stable and was in general resistant to the disease where the soils were characterized by high electrical conductivity. SWE, yeast and ASA significantly increased crop production in Talia area only.

Potential use of soilborne lytic Podoviridae phage as a biocontrol agent against Ralstonia solanacearum

“…The host range of the isolated phage was evaluated against a restricted panel of other seven R. solanacearum strains, belongs to Phylotype IIa, sequevar 1, and also against some other plant pathogenic bacteria as well as antagonistic bacterial strains isolated from soil by ref. , namely Serratia marcescens , Pseudomonas fluorescense, Stenotrophomonas maltophilia, Bacillus thuringiensis, Pectobacterium carotovorum, Pectobacterium atrosepticum, Dickeya dianthicola, Dickeya solani, Pseudomonas aeruginosa, Enterobacter aerogenes, Pseudomonas japonica , (kindly provided by STDF project No. 2905 in Egypt, listed in Table ).…”

Influence of hydrogen cyanide-producing rhizobacteria in controlling the crown gall and root-knot nematode, Meloidogyne incognita

“…In order to confirm the identification, the 16S rDNA analysis was used. The sequencing process was conducted at the Potato Brown Rot Project laboratories (Giza, Egypt), using forward primer (U968-f ) 5′-AACGCGAA-GAACCTTAC-3′ and reverse primer (L1401-r) 5′-CGGTGTGTACAAGACCC-3′ as described by Farag et al (2017). The RKN, M. incognita inoculum, was obtained from Nematode Diseases Research Department, Plant Pathology Research Institute, Agricultural Research Center (ARC), Giza, Egypt.…”

Microbial biodiversity as related to crop succession and potato intercropping for management of brown rot disease

“…DNA sequencing was made either by amplifying the V6 to V8 region of the 16S rRNA gene (Table 1), as described in Hiddink et al (2005) or by MicroSeq®500 targeting the first 500 bp of the 17S rRNA gene (using 16S rDNA microbial identification kit) provided by Applied Biosystem. DNA sequencing and identification was obtained using 8-capillary Genetic Analyzer (Applied Biosystem), provided by STDF (Science and Technology Development Fund)) at ARC, Egypt, as described in Farag et al (2017). Bioedit software was employed and fasta DNA consensus sequence database was compared with the sequences of the DNA Gene Bank database using the BLASTN algorithm (http://blast.ncbi.nlm.nih.gov/Blast.cgi).…”