Biological Control of Potato Common Scab With Rare Isatropolone C Compound Produced by Plant Growth Promoting Streptomyces A1RT

Abstract

Potato is prone to many drastic diseases like potato common scab (CS). As no highly effective methods exist for managing CS, this study explored the possibility of using biological control. Ten bacterial strains were isolated from CS-infected potato tubers from four different locations of Punjab, Pakistan, and identified based on biochemical and molecular analysis. Analysis of 16s rDNA sequences amplified by PCR revealed the isolated bacterial strains to be Streptomyces scabies, S. turgidiscabies and S. stelliscabiei. Pathogenic islands were also confirmed among the isolates after identification of txtAB, nec1, and tomA genes with PCR amplification. One strain isolated from soil was antagonistic to the pathogenic Streptomyces spp., and determined to be Streptomyces A1RT on the basis of 16s rRNA sequencing. A methanolic extract of Streptomyces A1RT contained Isatropolone C, which was purified and structurally determined by 1H- and 13C-NMR, 1H/1H-COSY, HMQC, and HMBC techniques. Streptomyces A1RT also produced the plant growth hormone indole-3-acetic acid (IAA) with a titer of 26 μg ml-1 as confirmed by spectrophotometry and HPLC. In a greenhouse assay, disease severity index was established from 0 to 500. Average disease severity indexes were recorded as 63, 130.5, and 78 for Streptomyces scabies, S. turgidiscabies and S. stelliscabiei, respectively. When Streptomyces A1RT was applied in soil that contained one of these pathogenic isolates, the average disease severity indexes were significantly (P < 0.05) reduced to 11.1, 5.6 and 8.4, respectively. A significant increase in tuber weight and shoot development was also observed with the tubers treated with Streptomyces A1RT. The use of the plant growth-promoting Streptomyces A1RT against potato CS thus provides an alternative strategy to control the disease without affecting environmental, plants, animals and human health.

Isolation and effect of Trichoderma citrinoviride Snef1910 for the biological control of root-knot nematode, Meloidogyne incognita

“…Many antagonistic microorganisms including Trichoderma spp., Streptomyces spp., Pseudomonas spp., Bacillus spp. have been screened and widely exploited to control a wide range of plant pathogens [8][9][10][11]. Some microorganisms have been identified as biological control agents against M. incognita such as Pasteuria penetrans, B. subtilis, T. harzianum and T. viride, Pochonia chlamydosporia and Purpureocillium lilacinum [12][13][14][15][16].…”

Chemical entrapment and killing of insects by bacteria

“…These are unique insights in Streptomyces- insect biology. Aside from plant pathogens such as Streptomyces scabies 52 , 53 , and strains such as S. somaliensis and S. sudanensis which cause extremely rare subcutaneous infections in humans 54 , 55 , streptomycetes are generally regarded as harmless. They have no genes that are homologous to known virulence determinants or pathogenicity islands 56 – 58 .…”

Investigation of Streptomyces scabies Causing Potato Scab by Various Detection Techniques, Its Pathogenicity and Determination of Host-Disease Resistance in Potato Germplasm

“…These results were also reported by many previous studies conducted by [ 13 , 54 ]; (S) scabies is dominant species in many countries of the world, such as China [ 15 ], South Africa [ 16 ], Pakistan [ 17 ], Iran [ 18 ], Russia [ 19 ], India, United States [ 20 ]. Previous studies demonstrated that S. scabies, S. acidiscabies, S. europaeiscabiei and S. turgidiscabies cause common scab disease of Potato [ 56 , 57 ]. However, the diversity and pathogenicity of Streptomyces species are distinct in the current study.…”