Effect of a non-mycorrhizal endophyte isolated fromMentha piperitaon in vitro culture ofOcimum basilicumcuttings

Abstract

This is the author's final version of the contribution published as:Dovana, F., Fusconi, A., Berta, G., Camusso, W. AbstractFungi form different types of long-term associations with plants, from mutualistic to pathogenic. Fungal endophytes, which live within host tissues, may confer stress tolerance to the associated plants increasing plant fitness and biomass. In vitro micropropagation and large scale production of aromatic and medicinal plants may benefit from endophyte inoculation. Beside increasing plant growth, fungal endophytes may allow for a reduction of the amount of plant growth regulators in culture media and can be employed to increase the survival rates of micropropagated plants during acclimatization in soil and alleviate the transplantation shock. Previous experiments have shown that a plant growth promoter-hyaline sterile fungus (PGP-HSF) isolated from Mentha piperita L. increased plant growth and influenced the essential oil composition in the same species. In this paper we analysed the SSU rDNA regions of PGP-HSF to determine/confirm its systematic position, which is still uncertain, and investigated the effect of the fungus on in vitro sweet basil (Ocimum basilicum L.) cuttings cultured on a diluted MS medium. The Bayesian and maximum likelihood analysis of SSU rDNA regions confirmed the previously recognized collocation of PGP-HSF in the Sordariomycetes, positioning it as a sister taxon of clade Ophiostomataceae. After 35 days of co-culture of O. basilicum with the fungus, most of the growth parameters were significantly increased. Plant fresh and dry weights, number of leaves, as well as the total leaf area per plant showed an increase greater or equal to 100% in inoculated plants as compared with non-inoculated control plants. The rootto-shoot biomass ratio also increased. These results encourage us to deepen the effects of this endophyte on basil, by studying its influence on the production of essential oils and the post-in vitro culture.