title: The characterization of six auxin-induced tomato GH3 genes uncovers a member, SlGH3.4, strongly responsive to arbuscular mycorrhizal symbiosis.
abstract: In plants, the GH3 gene family is widely considered to be involved in a broad range of plant physiological processes, through modulation of hormonal homeostasis. Multiple GH3 genes have been functionally characterized in several plant species; however, to date, limited works to study the GH3 genes in tomato have been reported. Here, we characterize the expression and regulatory profiles of six tomato GH3 genes, SlGH3.2, SlGH3.3, SlGH3.4, SlGH3.7, SlGH3.9 and SlGH3.15, in response to different phytohormone applications and arbuscular mycorrhizal (AM) fungal colonization. All six GH3 genes showed inducible responses to external IAA, and three members were significantly up-regulated in response to AM symbiosis. In particular, SlGH3.4, the transcripts of which were barely detectable under normal growth conditions, was strongly activated in the IAA-treated and AM fungal-colonized roots. A comparison of the SlGH3.4 expression in wild-type plants and M161, a mutant with a defect in AM symbiosis, confirmed that SlGH3.4 expression is highly correlated to mycorrhizal colonization. Histochemical staining demonstrated that a 2,258 bp SlGH3.4 promoter fragment could drive β-glucuronidase (GUS) expression strongly in root tips, steles and cortical cells of IAA-treated roots, but predominantly in the fungal-colonized cells of mycorrhizal roots. A truncated 654 bp promoter failed to direct GUS expression in IAA-treated roots, but maintained the symbiosis-induced activity in mycorrhizal roots. In summary, our results suggest that a mycorrhizal signaling pathway that is at least partially independent of the auxin signaling pathway has evolved for the co-regulation of the auxin- and mycorrhiza-activated GH3 genes in plants.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China These authors contributed equally to this work.
authors.forename: Dehua
authors.initials: D
authors.lastname: Liao
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China These authors contributed equally to this work.
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China chenaq8@njau.edu.cn.
authors.forename: Aiqun
authors.initials: A
authors.lastname: Chen
authors.affiliation: MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Wang
authors.affiliation: MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Jianjian
authors.initials: J
authors.lastname: Liu
authors.affiliation: MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Junli
authors.initials: J
authors.lastname: Liu
authors.affiliation: MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Mian
authors.initials: M
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China.
authors.forename: Shubin
authors.initials: S
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, China MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Xu
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant; D005966:Glucuronidase / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics* / Q000382:microbiology; D009154:Mutation / Q000235:genetics; D038821:Mycorrhizae / Q000187:drug effects / Q000502:physiology*; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000382:microbiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013559:Symbiosis / Q000187:drug effects* / Q000235:genetics; D013997:Time Factors
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D005966:Glucuronidase
keywords: Arbuscular mycorrhiza; Auxin; Expression; GH3 genes; GUS reporter