Antagonistic Bacillus thuringiensis isolates from citrus rhizosphere effective against Phytophthora nicotianae

Document Type : Original Article

Authors

1 Head, Plant Protection Department, Kerman Agricultural and Natural Resources Research and Education Center, AREEO, Kerman, Iran

2 Horticulture Group, College of Agriculture, Islamic Azad University, Jiroft Branch, Jiroft, Iran

Abstract

Citrus root rot, caused by Phytophthora nicotianae, is one of the most important diseases affecting citrus trees worldwide. This study aimed to isolate, identify, characterize, and evaluate the antagonistic effect of bacilli rhizobacteria isolated from the citrus rhizosphere in Kerman province, Iran, against P. nicotiana. According to the in vitro dual culture bioassays, five out of 67 Bacillus-like isolates showing the highest antagonistic effect were selected and characterized using phenotypic and PCR-based molecular tests for identification. Phenotypic characteristics and nucleotide sequence analyses of the 16S rRNA gene revealed that the isolates were highly similar and belonged to Bacillus thuringiensis. Findings enhance our understanding of the importance and potential role of B. thuringiensis isolates as biocontrol agents against P. nicotianae, offering a promising alternative to chemical fungicides for managing citrus root rot disease in integrated management and sustainable agriculture programs. These five antagonist isolates could be further evaluated in greenhouse and field experiments for their commercial exploitation.

Keywords

Journal of Advances in Plant Protection
Volume 2, Issue 1
June 2025
Pages 71-78

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