Ethylene induced nitrile and VOC synthesis by soil microbes; Improved root elongation & reduced risk of fungal infection in plants.

Abstract

The scope of the project was to develop a method to induce soil microbes to inhibit fungal infection and improve root elongation. The study was randomized. Gladiolus bulbs selected for the study were visibly inspected to for viability and visible signs of infection. Two trials were conducted from Aug. 5th – Sept. 5th 2014 with 4 replicates per condition over a 7-d period in damp outdoor conditions in late summer. A mixed culture of plant growth promoting rhizobacteria (PGPR) were collected from soil surrounding the roots of young fruit bearing trees. Microbes were mixed with minimal media (no-carbon source), and cultured with an ethylene and used as potting soil. Bulbs planted in ethylene induced soil displayed 0% visible fungal growth, while 38% of bulbs grown in control conditions displayed some form of fungal growth and/or infection. Ethylene induced soil increased root length by 225% in bulbs in 7-d period. GC Mass Spectrophotometry data suggest ethylene may induce soil microbes to synthesize several VOCs including (ethanol, 3-methyl-1-butanol, pentanol) and esters (ethyl acetate), that may have synergistic benefits to lower the risk of fungal infection by soil mold, while nitrile compounds improve root elongation. The findings are preliminary, additional studies are required to understand the mechanism.

Sugarcane Rhizosphere Bacteria Community Migration Correlates with Growth Stages and Soil Nutrient

“…The physiological activities of rhizosphere microbes have obvious effects on soil properties, plant nutrient absorption and plant growth and development [ 22 , 23 , 24 ]. The population of rhizosphere microbes is also related to the health of plants and affects the yield and quality of crops to a large extent [ 25 , 26 ]. For instance, some rhizosphere microorganisms can produce hormones to promote the decomposition of soil organic matter, induce plants to increase resistance, etc., or indirectly promote plant growth by inhibiting the growth of pathogenic bacteria by competing for nutrients and occupying niches [ 27 ].…”