Application of Aureobasidium pullulans in iron‐poor soil. Can the production of siderophores improve iron bioavailability and yeast antagonistic activity?

Abstract

Iron is a fundamental element for plants as well as for microorganisms and several pathogens, including Rhizoctonia solani, one of the main soil-borne pathogens of tomato. This study demonstrated the ability of Aureobasidium pullulans strain L1 to produce siderophores and how these molecules were, directly and indirectly, connected to its antagonistic activity and iron bioavailability. By ICP-OES (Inductively Coupled Plasma-Optical Emission Spectroscopy) trace analysis, the strain displayed the ability to increase the bioavailability of Fe (II) in the soil by almost 50% 30 days after inoculation. Also, the bioavailability of Mn, Cu and Zn was increased after 30 days of incubation in the soil by 31.8, 38.4 and 27.1%, respectively. In in vivo assays, A. pullulans L1 strain showed a growth promotion of tomato roots length and stem diameter, respectively, by 19.1 and 27.3%, and acted as a biocontrol agent (BCA) against R. solani (80% of inhibition). The results demonstrate a new aspect of this microorganism, usually applied as an antagonist of postharvest fruit diseases, to explore in different environments and against different pathogens, such as soil-borne pathogens.

Structure and Function of the Soil Rhizosphere Fungal Communities in Medicinal Plants—A Preliminary Study

“…Although it may be pathogenic to some plants, multiple studies of different crops show that Aureobasidium functions as an antagonist to several plant pathogens [30,34]. It can increase the soil availability of several nutrients and plant growth [35].…”

Use of Aureobasidium in a sustainable economy

“…Siderophores can be used to stimulate plant growth (Di Francesco et al 2022 ). These low-molecular-weight, iron-chelating compounds are produced by nearly all microbes to retrieve this metal from the environment (Chi et al 2009 ; Johnson 2008 ).…”

“…A. pullulans strain HN6.2 produces 1.1 g l −1 of siderophores (Wang et al 2009 ) . The siderophores of A. pullulans strain L1 not only increase the bioavailability of Fe in the soil but also that of Mn, Cu, and Zn by 50, 31.8, 38.4, and 27.1%, respectively, after 30 days of incubation with the fungus (Di Francesco et al 2022 ). This is accompanied by an increased tomato root and stem diameter of 19.1 and 27.3%, respectively.…”