Increased biomass and salicylic acid elicitor activity in fennel (Foeniculum vulgare Miller)

Pedro Henrique Gorni,Matheus de Oliveira Brozulato,Eliana Cristina Generoso Konrad,Renan da Silva Lourenção

doi:10.1590/1981-6723.17216

Abstract

Abstract Fennel is a medicinal and aromatic plant that is commonly used in Brazilian cuisine and in the manufacture of cosmetics. The exogenous application of salicylic acid (SA) can act on the hormonal action stimulating plant growth and development and the induction of plant defense responses under stressful conditions. The objective of this study was to determine the effect of the foliar application of SA on the production of biomass and synthesis of secondary compounds in fennel plants. For this purpose, an experiment was carried out in potted plants in a greenhouse with the application of SA at concentrations of 0, 0.25, 0.50 and 1.00 mM, 20 days and 90 days after transplanting the seedlings to the pots. The effect of SA on the metabolism of the fennel plants was evaluated using growth and biochemical parameters. The exogenous application of SA increased the plant shoots dry weight at the concentration of 0.50 mM, whereas an improved dry root mass and root/shoot ratio was achieved with the concentration of 0.25 mM. The elicitor effect was observed at 0.25 mM of SA, resulting in greater economic value of the biomass due to the higher production of secondary compounds, such as phenolic compounds and flavonoids. In addition, an increase in antioxidant activity of the plant extracts and of the essential oil content of the species was obtained at the concentration of 1.00 mM.

Highlights

Foeniculum vulgare Miller (Apiaceae), known as fennel, is a medicinal species, native of Europe and widely cultivated throughout Brazil
Several studies have shown that the exogenous application of Salicylic acid (SA) can boost the growth and development of plants by acting on their signalling systems and inducing enzymes to catalyse the formation of defence compounds, which explains its role as a secondary metabolism elicitor, both in medicinal plants and in functional food species (GORNI; PACHECO, 2016)
In plants treated with 0.25 mM of SA, the dry root mass (DRM) increased 17.5% when compared to the control plants

Summary

Introduction

Foeniculum vulgare Miller (Apiaceae), known as fennel, is a medicinal species, native of Europe and widely cultivated throughout Brazil. It presents yellow flowers arranged in umbels and the fruits are deachenes (LORENZI; MATOS, 2002) and have carminative, digestive and diuretic properties. Salicylic acid (SA) is a phenolic compound, considered as an important molecular flag in plants related to the plant defence response, which explains its role as a secondary metabolism elicitor. Several studies have shown that the exogenous application of SA can boost the growth and development of plants by acting on their signalling systems and inducing enzymes to catalyse the formation of defence compounds, which explains its role as a secondary metabolism elicitor, both in medicinal plants and in functional food species (GORNI; PACHECO, 2016). SA induces the expression of genes related to the production of some classes of secondary metabolites in plants and activates phenylalanine ammonia-lyase (PAL), a key enzyme between the primary and secondary metabolism, involved in the phenylpropanoid compound production route of the secondary metabolism (DURRANT; DONG, 2004)

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