Production of methyl sulfide and dimethyl disulfide from soil-incorporated plant materials and implications for controlling soilborne pathogens

Abstract

Soil-incorporated plant materials have been associated with reduction in soilborne pathogens and diseases. Mechanisms of the biocidal actions are complex and not well understood. A glasshouse experiment, a non replicated field demonstration, and a field experiment were conducted to determine volatile compounds after incorporation of various plant species and their effect on pest control. Cabbage (Brassica oleracea), canola (Brassica rapa), kale (Brassica oleracea var. acephala), lettuce (Lactuca sativa var. valmaine), two mustard varieties -Caliente (Brassica juncea) and Green wave (Brassica juncea), two radish varieties -Oil seed (Raphanus sativus var. oleiformis) and Cherriette (Raphanus sativus), common rye (Secale cereale), and sorghum Sudan grass (Sorghum bicolor var. sudanese) were used in the glasshouse experiment. Caliente 199 mustard (Brassica hirta) was planted in the field demonstration and white mustard (Sinapis alba) was used in the field experiment. Fresh plant materials were chopped manually in the glasshouse experiment and mechanically in the field studies at the flowering stage before incorporation in natural field soils. In the glasshouse experiment, the equivalent biomass dry weight ranged from a minimum of 573 gm −2 for L. sativa var. valmaine to a maximum of 1851 gm −2 for S. bicolor var. sudanese. The average biomass was 792 gm −2 for B. hirta and 804 gm −2 for S. alba in the two field studies, respectively. The glasshouse experiment used a loamy sand field soil inoculated with a natural fine sandy loam soil that was known to contain high populations of Verticillium dahliae. Soils at both field sites belonged to the sandy loam series, and efforts were made to maintain sufficient soil moisture for plant growth. Although the interest was to determine all volatile compounds in general, only methyl sulfide and dimethyl disulfide were identified and subsequently quantified. Depending on plant species and time of sampling (one to seven days after soil incorporation), 2.7 to 346.4μg g −1 plant dry weight for methyl sulfide and 0 to 283.2μg g −1 plant dry weight for dimethyl disulfide were found in the glasshouse experiment. In general, high concentrations of dimethyl disulfide and methyl sulfide appeared to have reduced V. dahliae colony counts in bioassay potato stem saps in the glasshouse experiment. However, the correlation was weak (R 2 =0.31), but a relatively stronger correlation

Dimethyl Disulfide Produced by the Naturally Associated Bacterium Bacillus sp B55 Promotes Nicotiana attenuata Growth by Enhancing Sulfur Nutrition

“…DMDS was first described as produced by bacteria isolated from decomposing chicken (Freeman et al, 1976). Surprisingly, DMDS, along with other VOCs emitted by rhizobacteria Pseudomonas fluorescens B-4117 and Serratia plymuthica IC1270, was found to exert antimicrobial and nematicidal activity Wang et al, 2009;Huang et al, 2010;Dandurishvili et al, 2011) and to inhibit the cell-cell communication quorumsensing network of various bacteria . Furthermore, DMDS functions as a plant defense compound against nonspecialist herbivores feeding on Allium porrum (Dugravot et al, 2003(Dugravot et al, , 2004 and as both an oviposition repellent and an attractant to different natural enemies of the cabbage root fly Delia radicum (Ferry et al, 2007(Ferry et al, , 2009.…”

Quantification of Fusarium oxysporum in fumigated soils by a newly developed real-time PCR assay to assess the efficacy of fumigants for Fusarium wilt disease in strawberry plants

“…DMDS is a ubiquitous natural product that is common in the global sulfur cycle and is detected as a metabolite in numerous biological processes. DMDS has been identified as one of the volatile compounds produced when soil is amended with cabbage and solarized, which leads to a reduction in fungal plant pathogens and nematodes …”

Effects of intraspecific variation in white cabbage (Brassica oleracea var. capitata) on soil organisms

“…Glucosinolates are a group of secondary plant compounds prominently present in the Brassicaceae which could potentially influence the soil food web (Yang et al 2009). Upon tissue damage, glucosinolates are degraded by the enzyme myrosinase, thereby forming toxic breakdown products such as (iso)thiocyanates (Wang et al 2009). Belowground, glucosinolates and their breakdown products are known to reduce the abundance of phytophagous organisms such as rootfeeding nematodes (Lazzeri et al 2004;Potter et al 1998;Potter et al 2000), fungi (Bressan et al 2009;Rumberger and Marschner 2003;Snapp et al 2007), and bacteria (Aires et al 2009;Bressan et al 2009;Rumberger and Marschner 2003).…”