Fall Armyworm-Associated Gut Bacteria Modulate Plant Defense Responses

Area of Science:

• Plant Biology
• Insect-Microbe Interactions
• Biochemistry

Background:

• Insect feeding and oral secretions trigger plant defense responses, often mediated by jasmonic acid.
• The role of microbes within insect oral secretions in modulating these plant defenses is not fully understood.

Purpose of the Study:

• To investigate the impact of bacteria from fall armyworm oral secretions on induced plant defenses in tomato and maize.
• To determine how these bacteria influence herbivore-induced defense proteins and gene expression.

Main Methods:

• Isolation and identification of bacteria from fall armyworm oral secretions using culture-dependent methods.
• Assessing the activity of plant defensive proteins (polyphenol oxidase, trypsin proteinase inhibitors, peroxidase) in treated tomato plants.
• Analyzing the expression of the maize proteinase inhibitor (mpi) gene in treated maize plants.
• Evaluating the effect of bacterial isolates on caterpillar growth on both plant species.

Main Results:

• Seven bacterial isolates from the Enterobacteriaceae family were identified.
• Specific isolates differentially modulated defense protein activity in tomato, downregulating some and upregulating others.
• All tested bacterial isolates upregulated the expression of the herbivore-induced maize proteinase inhibitor (mpi) gene.
• Treatment with Pantoea ananatis and Enterobacteriaceae-1 enhanced caterpillar growth on tomato but reduced it on maize.

Conclusions:

• Herbivore-associated microbes play a significant role in mediating insect-plant interactions.
• Bacterial components in fall armyworm secretions can manipulate plant defenses in a host-specific manner.
• These findings highlight the complex interplay between insects, plants, and their associated microbes in ecological interactions.