title: The role of strigolactones and ethylene in disease caused by Pythium irregulare.
abstract: Plant hormones play key roles in defence against pathogen attack. Recent work has begun to extend this role to encompass not just the traditional disease/stress hormones, such as ethylene, but also growth-promoting hormones. Strigolactones (SLs) are the most recently defined group of plant hormones with important roles in plant-microbe interactions, as well as aspects of plant growth and development, although the knowledge of their role in plant-pathogen interactions is extremely limited. The oomycete Pythium irregulare is a poorly controlled pathogen of many crops. Previous work has indicated an important role for ethylene in defence against this oomycete. We examined the role of ethylene and SLs in response to this pathogen in pea (Pisum sativum L.) at the molecular and whole-plant levels using a set of well-characterized hormone mutants, including an ethylene-insensitive ein2 mutant and SL-deficient and insensitive mutants. We identified a key role for ethylene signalling in specific cell types that reduces pathogen invasion, extending the work carried out in other species. However, we found no evidence that SL biosynthesis or response influences the interaction of pea with P. irregulare or that synthetic SL influences the growth or hyphal branching of the oomycete in vitro. Future work should seek to extend our understanding of the role of SLs in other plant interactions, including with other fungal, bacterial and viral pathogens, nematodes and insect pests.
authors.affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
authors.forename: Sara N
authors.initials: SN
authors.lastname: Blake
authors.affiliation: Tasmanian Institute of Agriculture & School of Land and Food, University of Tasmania, Private Bag 98, Hobart, Tasmania, 7001, Australia.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Barry
authors.affiliation: Tasmanian Institute of Agriculture & School of Land and Food, University of Tasmania, Private Bag 98, Hobart, Tasmania, 7001, Australia.
authors.forename: Warwick M
authors.initials: WM
authors.lastname: Gill
authors.affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
authors.forename: James B
authors.initials: JB
authors.lastname: Reid
authors.affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
authors.forename: Eloise
authors.initials: E
authors.lastname: Foo
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D025301:Hyphae / Q000254:growth & development; D007783:Lactones / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D018532:Pisum sativum / Q000235:genetics / Q000382:microbiology; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology; D011775:Pythium / Q000502:physiology*; D013170:Spores / Q000502:physiology
chemical_list: D005030:Ethylenes; D007783:Lactones; D010940:Plant Proteins; C036216:ethylene
keywords: Pythium irregulare; ethylene; pea; root pathogen; strigolactones