Endophytes of Lippia citriodora (Syn. Aloysia triphylla) enhance its growth and antioxidant activity

Abstract

Endophytes of medicinal plants are valuable resources for plant growth promotion and lead drug discovery. Lemon verbena, Lippia citriodora Kunth. (Verbenaceae), is an ethnomedicinal shrub. Here, the endophytic bacterium Sphingomonas paucimobilis and the endophytic fungus Aspergillus sp. isolated from L. citriodora were used for plant interaction studies. Foliar spraying and soil drenching methods of endophyte’s inocula application were used for in planta assays. The results showed that both fungal and bacterial endophytes increased the growth parameters of L. citriodora including plant height, leaf number, fresh weight and dry weight of shoot, root and leaf. Indeed, soil drenching of S. paucimobilis increased the root weight, but its foliar spray increased the plant height. Also, soil drenching of Aspergillus sp. increased the leaves dry weight, while its foliar spray increased the number of branches, leaves, and the leaves fresh weight. Soil drenching of either of both endophytes increased the antioxidant activity of L. citriodora’s foliage, but foliar sprays yielded lower increases. Endophytes had no apparent effects on the phenolics and flavonoids at the time of sampling, i.e. 30 days post-inoculation. Our findings indicate the enhancing effects of endophyte application on the growth and antioxidant property of L. citriodora.