Pest management using mint volatiles to elicit resistance in soy: mechanism and application potential

Abstract

Plants can eavesdrop on volatile cues emitted from neighboring plants to boost their defense responses. When 10 categories of mints were tested for their effects on Glycine max (soybean) plants cultivated nearby, candy mint (Mentha × piperita cv. Candy) and peppermint (Mentha × piperita L.) induced the strongest enhancement in RNA levels of defense genes in the soybean leaves. The mechanism by which the mint volatiles enhanced these transcript levels was based on histone acetylation within the promoter regions of defense genes. These increases in transcript levels were induced when receiver plants were cultivated near to candy mint, but the priming of the defense responses was instead induced when receiver plants were cultivated at mid-length intervals. Field assays revealed that anti-herbivore ability of soy was strengthened both by co-cultivation and by pre-incubation of receiver plants with candy mint. The same held true for another receiver, Brassica rapa, when the receiver was co-cultivated or pre-incubated with peppermint. Exposure to mint volatiles resulted in lower damage to receiver plants, although ecological effects on the herbivores and predators probably also contributed. Together, our findings indicate that pest management systems relying on mint as companion plants might be commercially useful for reducing herbivore damage in crops.

Foliar behaviour of biogenic semi-volatiles: potential applications in sustainable pest management

“…Emissions of SQTs are normally diurnal and peak in daytime (Schaub et al 2010), when the temperature is high enough for diffusion from storage and there is enough light for photosynthesis and thus carbon availability for biosynthesis (Arimura et al 2004). Potential high emission rates of sVOCs close to emitter plants supports the idea that constitutive emissions of VOCs, and sVOCs could cause other plants to elicit or prime defences (Sukegawa et al 2018). Also, the repellent role of the sVOCs may exist on the foliage of other plants, when SVOCs are deposited there (Himanen et al 2010(Himanen et al , 2015.…”

“…(Merr.) (Fabaceae) or Brassica rapa L. (Brassicaceae) activated defence genes such as trypsin inhibitor genes and pathogenesis-related genes in receiver crop plans (Sukegawa et al 2018). These plants received significantly lower levels of herbivory by natural herbivores in the field and in a greenhouse when compared to control plants that were not first exposed to Mentha plant volatiles.…”

“…These plants received significantly lower levels of herbivory by natural herbivores in the field and in a greenhouse when compared to control plants that were not first exposed to Mentha plant volatiles. Sukegawa et al (2018) suggested that the activation of defence genes might be related to increased depolarisation of the membrane potential by high concentrations of typical Mentha VOCs such as menthofuran, pulegone, neomenthol, menthol and menthone. Binding of Mentha VOCs to the cell membranes of receiver plants possibly altered ion permeability of the plasma membrane and triggered an oxidative burst.…”

“…VOC-emitting secondary plants, e.g. aromatic plants such as mint (Sukegawa et al 2018), might not be suitable for growing alongside crops currently grown in large monocultures such as cereals and leguminous crops. Development of the system would at least need to be done in horticultural crops and smaller-scale agriculture (Table 3).…”

“…If using a known medicinal plant as a crop plant companion (Gahukar 2012), some of the specific sVOCs appearing in high concentrations can be toxic to humans. For example, the odour of R. tomentosum with very high concentrations of ledol in the air may Compound abbreviations as in Table 1 Sukegawa et al (2018) cause headache and nausea (Dampc and Luczkiewicz 2013). However, recent field experiments with R. tomentosum as a companion plant with broccoli ( Fig.…”