Herbivore Oral Secreted Bacteria Trigger Distinct Defense Responses in Preferred and Non-Preferred Host Plants.
Insect symbiotic bacteria affect host physiology and mediate plant-insect interactions, yet there are few clear examples of symbiotic bacteria regulating defense responses in different host plants. We hypothesized that plants would induce distinct defense responses to herbivore- associated bacteria. We evaluated whether preferred hosts (horsenettle) or non-preferred hosts (tomato) respond similarly to oral secretions (OS) from the false potato beetle (FPB, Leptinotarsa juncta), and whether the induced defense triggered by OS was due to the presence of symbiotic bacteria in OS. Both horsenettle and tomato damaged by antibiotic (AB) treated larvae showed higher polyphenol oxidase (PPO) activity than those damaged by non-AB treated larvae. In addition, application of OS from AB treated larvae induced higher PPO activity compared with OS from non-AB treated larvae or water treatment. False potato beetles harbor bacteria that may provide abundant cues that can be recognized by plants and thus mediate corresponding defense responses. Among all tested bacterial isolates, the genera Pantoea, Acinetobacter, Enterobacter, and Serratia were found to suppress PPO activity in tomato, while only Pantoea sp. among these four isolates was observed to suppress PPO activity in horsenettle. The distinct PPO suppression caused by symbiotic bacteria in different plants was similar to the pattern of induced defense-related gene expression. Pantoea inoculated FPB suppressed JA-responsive genes and triggered a SA-responsive gene in both tomato and horsenettle. However, Enterobacter inoculated FPB eliminated JA-regulated gene expression and elevated SA-regulated gene expression in tomato, but did not show evident effects on the expression levels of horsenettle defense-related genes. These results indicate that suppression of plant defenses by the bacteria found in the oral secretions of herbivores may be a more widespread phenomenon than previously indicated.
Department of Ecology, South China Agricultural University, Guangzhou, Guangdong, 510640, China. jeerywang0813@gmail.com.|Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA. jeerywang0813@gmail.com.
Jie
http://orcid.org/0000-0001-8508-7675
J
Wang
Department of Entomology, Cornell University, Ithaca, NY, 14850, USA.
Seung Ho
SH
Chung
Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA.
Michelle
M
Peiffer
Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA, 16802, USA.
Cristina
C
Rosa
Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA.
Kelli
K
Hoover
Department of Ecology, South China Agricultural University, Guangzhou, Guangdong, 510640, China.|Department of Ecology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
Rensen
R
Zeng
Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA.
Gary W
GW
Felton
D000818:Animals; D001419:Bacteria; D004156:Catechol Oxidase / Q000378:metabolism; D001517:Coleoptera / Q000382:microbiology*; D003517:Cyclopentanes / Q000378:metabolism; D004435:Eating; D060434:Herbivory; D007814:Larva / Q000382:microbiology; D018551:Solanum lycopersicum / Q000166:cytology / Q000378:metabolism / Q000382:microbiology* / Q000502:physiology*; D054883:Oxylipins / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D013559:Symbiosis
D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid; D004156:Catechol Oxidase; D020156:Salicylic Acid
False potato beetle; Horsenettle; Induced resistance; Oral secretions; Plant defense; Symbiotic bacteria; Tomato