Increase of secondary metabolite content in marigold (Tagetes minuta) by inoculation with plant growth-promoting rhizobacteria

CAPPELLARI, L., SANTORO, M., NIEVAS, F., GIORDANO, W., BANCHIO, E.

Congreso; 2nd Meeting of the Latin American Association of Chemical Ecology (ALAEQ); 2012

The effects of single inoculation and co-inoculation of two plant growth-promoting rhizobacteria (PGPR) (Pseudomonas fluorescens, Azospirillum brasilense) on growth and essential oil (EO) composition and phenolic content were evaluated in marigold (Tagetes minuta). Plant growth parameters (shoot fresh weight, root dry weight, leaf number, node number) were measured. EO yield increased 70% in P. fluorescens-inoculated and co-inoculated plants in comparison with control (non-inoculated) plants, without altering EO composition. The biosynthesis of the major EO components was increased in the inoculated plants. Shoot fresh weight and EO yield were significantly higher in P. fluorescens-inoculated and in co-inoculated plants than in control plants. The total phenolic content was 2-fold higher in singly-inoculated or co-inoculated treatments than in controls. In view of the economic importance of monoterpenes and phenols compounds for a variety of applications in the food and cosmetic industries, P. fluorescens and other PGPR have clear potential for improving the productivity of cultivated of aromatic plants. Better understanding of the processes that affect secondary metabolites accumulation will lead to increased yields of these commercially valuable natural products.