title: Rhizobacteria activates (+)-δ-cadinene synthase genes and induces systemic resistance in cotton against beet armyworm (Spodoptera exigua).
abstract: Gossypol is an important allelochemical produced by the subepidermal glands of some cotton varieties and important for their ability to respond to changing biotic stress by exhibiting antibiosis against some cotton pests. Plant growth-promoting rhizobacteria (PGPR) are root-colonizing bacteria that increase plant growth and often elicit defence against plant pathogens and insect pests. Little is known about the effect of PGPR on cotton plant-insect interactions and the potential biochemical and molecular mechanisms by which PGPR enhance cotton plant defence. Here, we report that PGPR (Bacillus spp.) treated cotton plants showed significantly higher levels of gossypol compared with untreated plants. Similarly, the transcript levels of the genes (i.e. (+)-δ-cadinene synthase gene family) involved in the biosynthesis of gossypol were higher in PGPR-treated plants than in untreated plants. Furthermore, the levels of jasmonic acid, an octadecanoid-derived defence-related phytohormone and the transcript level of jasmonic acid responsive genes were higher in PGPR-treated plants than in untreated plants. Most intriguingly, Spodoptera exigua showed reduced larval feeding and development on PGPR-treated plants. These findings demonstrate that treatment of plants with rhizobacteria may induce significant biochemical and molecular changes with potential ramifications for plant-insect interactions.
authors.affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA.|Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD, 21853, USA.
authors.forename: Simon
authors.initials: S
authors.lastname: Zebelo
authors.affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA.|College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Kloepper
authors.affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Fadamiro
mesh_terms: D000818:Animals; D001835:Body Weight; D003517:Cyclopentanes / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D003368:Gossypium / Q000235:genetics* / Q000276:immunology / Q000382:microbiology / Q000469:parasitology*; D006072:Gossypol / Q000378:metabolism; D007535:Isomerases / Q000235:genetics*; D007814:Larva / Q000502:physiology; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000469:parasitology; D060888:Real-Time Polymerase Chain Reaction; D012231:Rhizobium / Q000502:physiology*; D018411:Spodoptera / Q000502:physiology*
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid; D007535:Isomerases; C097608:delta-cadinene synthase; D006072:Gossypol
keywords: CAD; PGPR; gene expression; gossypol; jasmonic acid (JA); larval feeding