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Updated: Oct 5, 2025

Establishment of a Chilli Thrips (Scirtothrips dorsalis Hood) Rearing System for Virulence Screening of Entomopathogenic Fungi
Published on: July 18, 2025
Rhizosphere bacteria induce programmed cell death defence genes and signalling in chilli pepper
Sharifah Farhana Syed-Ab-Rahman1, Alexander Arkhipov1, Taylor J Wass1
1Plant-Microbe Interactions Laboratory, School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Aim:
To understand how beneficial bacteria assist chilli plants (Capsicum annuum) in defence against biotrophic or hemibiotrophic pathogens.
Method And Results:
We quantified marker genes of plant defence pathways in Phytophthora capsici-infected chilli pepper treated with anti-oomycete plant growth-promoting rhizobacteria, Bacillus amyloliquefaciens, Bacillus velezensis and Acinetobacter sp. Plants displayed strong resistance, and the pathogen load in the roots was significantly lower in infected plants treated with bacterial biocontrol agents at all time points tested (1, 2 and 7 days after pathogen inoculation, p < 0.05). Gene expression profiling revealed that P. capsici infection in the absence of beneficial bacteria led to the upregulation of a wide array of defence genes. The addition of biocontrol bacteria modulated defence by further enhancing genes involved in programmed cell death, such as CaLOX1, CaPAL1, CaChitIV and CaPTI1, while suppressing others CaLRR1, a negative regulator of cell death.
Conclusions:
Our results suggest that the bacteria exerted a combined effect by directly antagonizing the pathogen and enhancing the expression of key plant defence genes, including those involved in cell death, causing resistance at early stages of infection by this hemibiotrophic pathogen.
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