Biological control of Alternaria alternata MW970059, the causal agent of tomato rot, by Aspergillus nidulans MW732187 isolated from green household waste

Abstract

The development of fungal resistance to fungicides is a significant challenge in agricultural disease management, and the research axis is in current scientific discourse. The objective of the current study aims to search for new biological agents to control Alternaria alternata ( A. alternata ) causal agent of tomato rot. 73 fungal isolates where tested in the in vitro screening. Aspergillus sp. isolated from decayed tangerine peel microflora, showed the performing antagonistic strain against A. alternata . Aspergillus sp. exhibited significant inhibition of A. alternata ; the growth fungal inhibition (%FI) rate was 66.66±0.25% causing various morphological mycelia changes, swellings, deformations and vacuolization. A. alternata and the antagonist Aspergillus sp. were identified based on morphology trails and molecular tool as Alternaria alternata and Aspergillus nidulans , respectively. Cell-free supernatant (CFS) showed that the metabolites produced by A. nidulans are involved in the control of A. alternata . The half maximal effective concentration (EC 50 ) value of A. alternata was estimated at 1% (v/v), the inhibition rate was 50.97±0.85%. Fourier Transform Infra-Red (FT-IR Spectrometry) analysis of organic (ethanol, methanol) and aqueous extracts of CFS revealed distinct characteristic peak values corresponding to various functional groups in the extracts such as phenolic, lipids, and possibly proteins/peptides compounds. In vivo application of A. nidulans strain to tomato fruits significantly reduced postharvest decay caused by A. alternata by 41.34% after the 10th day of inoculation. Overall, the findings from this study suggest that A. nidulans strain may be a potential promising bio-agent to control the phytopathogen A. alternata .