Dual Efficacy of Aspergillus oryzae SAF1 in Suppressing Fusarium Wilt and Anthracnose and Promoting Tomato and Chili Growth

Abstract

The development of sustainable alternatives to chemical fungicides is imperative for managing economically significant plant diseases such as Fusarium wilt in tomato and anthracnose in chili. This study aimed to isolate and screen native fungi for antagonistic activity and biocontrol traits, identify the most promising candidate, evaluate its plant growth-promoting capabilities, and assess its efficacy in suppressing disease and enhancing growth in pot experiments under open greenhouse conditions. In vitro screening showed that SAF1 exhibited antagonistic activity against Fusarium oxysporum f. sp. lycopersici, Colletotrichum acutatum, C. capsici, and C. gloeosporioides, alongside biocontrol traits including siderophores and hydrolytic enzymes (chitinase, cellulase, amylase, and lipase) production. Morphological and ITS analyses identified the isolate as Aspergillus oryzae SAF1. Based on this species-level classification, A. oryzae SAF1 presents a potentially safe profile for agriculture. A. oryzae SAF1 exhibited plant growth-promoting traits, including the synthesis of indole-3-acetic acid (IAA) and ammonia, complemented by its ability to grow and form a clear zone on nitrogen-free medium, suggesting potential nitrogen fixation, a trait previously unreported for A. oryzae. In pot experiments, A. oryzae SAF1 application significantly reduced the disease index of Fusarium wilt (to 15.00%) and anthracnose (to 7.50%), while enhancing shoot length and biomass in both crops. This study provided the first evidence of A. oryzae as a dual-action agent that simultaneously suppresses anthracnose and promotes growth in chili under pot conditions. These findings demonstrate that A. oryzae SAF1 is a highly promising candidate for development as a bioinoculant to sustainably enhance crop protection and growth.