title: Multiple phytohormone signalling pathways modulate susceptibility of tomato plants to Alternaria alternata f. sp. lycopersici.
abstract: Three phytohormone molecules - ethylene (ET), jasmonic acid (JA) and salicylic acid (SA) - play key roles in mediating disease response to necrotrophic fungal pathogens. This study investigated the roles of the ET, JA, and SA pathways as well as their crosstalk during the interaction between tomato (Solanum lycopersicum) plants and a necrotrophic fungal pathogen Alternaria alternata f. sp. lycopersici (AAL). Both the ET and JASMONIC ACID INSENSITIVE1 (JAI1) receptor-dependent JA signalling pathways are necessary for susceptibility, while SA response promotes resistance to AAL infection. In addition, the role of JA in susceptibility to AAL is partly dependent on ET biosynthesis and perception, while the SA pathway enhances resistance to AAL and antagonizes the ET response. Based on these results, it is proposed that ET, JA, and SA each on their own can influence the susceptibility of tomato to AAL. Furthermore, the functions of JA and SA in susceptibility to the pathogen are correlated with the enhanced or decreased action of ET, respectively. This study has revealed the functional relationship among the three key hormone pathways in tomato defence against AAL.
authors.affiliation: Key Laboratory of Horticultural Plant Growth,  Development and Quality improvement,  Ministry of Agriculture,  Department of Horticulture,  Zhejiang University, Hangzhou 310058,  China.
authors.forename: Chengguo
authors.initials: C
authors.lastname: Jia
authors.forename: Liping
authors.initials: L
authors.lastname: Zhang
authors.forename: Lihong
authors.initials: L
authors.lastname: Liu
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Wang
authors.forename: Chuanyou
authors.initials: C
authors.lastname: Li
authors.forename: Qiaomei
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000528:Alternaria / Q000502:physiology*; D003517:Cyclopentanes / Q000276:immunology*; D005030:Ethylenes / Q000276:immunology*; D018551:Solanum lycopersicum / Q000276:immunology* / Q000382:microbiology; D054883:Oxylipins / Q000276:immunology*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D010937:Plant Growth Regulators / Q000276:immunology*; D020156:Salicylic Acid / Q000276:immunology*; D015398:Signal Transduction
chemical_list: D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; D010937:Plant Growth Regulators; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid