Drought stress and PGPR: this interaction influence the total essential oil yield and peltate glandular trichome number on Mentha piperita plants? ?

CHIAPPERO, J; ., CAPPELLARI, L; PALERMO, T; MENEGUZZI, R

Buenos Aires

Congreso; 6to Congreso de la Asociación Latino Americana de Ecología Química; 2021

Asociación Latino Americana de Ecología Química

Plant responses to stress are manifested at organ, tissue or cellular level, and modify the biochemical, physiological and developmental processes including essential oil (EO) biosynthesis and glandular trichome (GT) development. Inoculation with plant growth-promoting rhizobacteria (PGPR) has gained considerable attention because of their capacity to increase EOs yield and to ameliorate the effects of stress. The aim of this work was to determine the effect of inoculation with PGPR on Mentha piperita plants cultivated under drought stress over EOs biosynthesis and GT number. M. piperita shoots were inoculated with PGPR strains Bacillus amyloliquefaciens GB03 or Pseudomonas simiae WCS417r. Drought stress was induced by the suppression of water (MS: moderate stress, SS: severe stress). The following nine experimental treatments were performed: (1) control: normal irrigation (100% field capacity); (2) moderate stress (MS): irrigation until 10 days before harvest, (50% field capacity); (3) severe stress (SS): irrigation until 20 days before harvest, (35% field capacity); (4) inoculated with WCS417 r; (5) MS+WCS417 r; (6) SS+WCS417 r; (7) inoculated with GB03; (8) MS+GB03; (9)SS+GB03. At 27 days after the inoculation, EOs yield and peltate GT density were evaluated. EOs yield increase 5 times in non-inoculated stressed plants (MS and SS) compared to control plants (non- stressed, non-inoculated), and the same trend was observed when plants were inoculated with GB03 or WCS417r. The plants with the treatments PGPR + Stress did not show differences with the correspondent control, only MS + GB03 showed a slight increase in EO yield in relation to MS non- inoculated plants. GT density increases in non-inoculated stressed plants and inoculated stressed plants. The inoculation did not show any effect of GT density in relation with non-inoculated stressed plants. The lack of significant differences between non-inoculated + Stressed and PGPR + Stressed plants suggest that stress or inoculation conditions per-se increase the analyzed parameters and there is not a positive interaction between them. We observed a relationship among the GT density and the EOs yield, this could be because these structures are responsible for the EOs biosynthesis and storage. However, from a biotechnological point of view, it could be considered the idea of managing drought stress through the inoculation with PGPR to improve the indirect production of EOs, since PGPR elicited mechanisms which contribute to plant health and increase the biomass among other parameters like the antioxidant status (data not shown, Chiappero et al., 2019).