Increase of Essential Oil Yield in Mentha piperita by Inoculation with Plant Growth-Promoting Rhizobacteria

CAPPELLARI, LORENA DEL ROSARIO; PALERMO, TAMARA B.; SANTORO, MARICEL VALERIA; BANCHIO, ERIKA; CHIAPPERO, JULIETA

What to Know about Essential Oils

NOVA SCIENCE PUBLISHERS, INC.

Año: 2020; p. 283 - 311

Peppermint (Mentha piperita) is one of the most important EO(essential oil crops) and is cultivated worldwide. It is composed primarilyof monoterpenes, whose medicinal properties are mainly due to their EO composition, accumulated in glandular trichomes. Nowadays, agriculturerelies heavily on the use of synthetic chemicals, such as fertilizers andpesticides, to achieve high yields but without taking into account theirdeleterious effects on the environment. However, there is an interestingbiotechnological alternative using microorganisms to increase theavailability and intake of nutrients by crops and to control phytopathogenicorganisms and herbivorous insects. The group of bacteria termed plantgrowth-promoting rhizobacteria (PGPR) colonizes the rhizosphere andstimulates plant growth and development by direct or indirect mechanisms.Thus, in the search for new strategies of plant production to optimizeessential oil (EO) yield, inoculation with PGPR is an interesting candidate.We present here an integrated summary of our experimental findings froman analysis of the community of fluorescent Pseudomonas strains in therhizosphere of commercially grown Mentha piperita, including the effectsof inoculation and co-inoculation with different PGPR strains (native andwild type) on total EO yield and glandular trichome density. Thequalitative and quantitative compositions of the main monoterpenes(menthol, menthone, pulegone, limonene and linalool) were alsodetermined to analyze the effects of the volatiles emitted byPGPR rhizobacteria on EO production. The various PGPR strains(Bacillus amyloliquefaciens GB03, Pseudomonas fluorescens WCS417r,Azospirillum brasilense SP7, Pseudomonas putida SJ04-SJ25-SJ48) andco-inoculations evaluated produced significant increases in the productionof EO in peppermint plants, but at different magnitudes. Bacterialinoculants are thus an effective biotechnological tool for stimulating thesecondary metabolism in plants. Application of these techniques maycontribute to environmental conservation, increased crop productivity andsustainable agricultural practices.