title: Developmental regulation of Mi-mediated aphid resistance is independent of Mi-1.2 transcript levels.
abstract: Mi-1.2, a member of the intracellular, nucleotide-binding site-leucine-rich repeat family of resistance genes, confers resistance in tomato (Lycopersicon esculentum) against both root-feeding nematodes and leaf-feeding aphids. Nematode resistance is effective in all life stages of the plant; in contrast, Mi-mediated aphid resistance is developmentally regulated, and protects mature plants but not seedlings against aphid infestation. To determine if the onset of aphid resistance is regulated by Mi-1.2 transcript abundance, we compared aphid resistance and Mi-1.2 transcript levels in seedlings and flowering plants. Paired bioassays and RNase protection assays revealed that Mi-1.2 is transcribed in the leaves prior to the onset of aphid resistance, and that transcript levels are comparable in seedlings and flowering life stages. Furthermore, constitutive overexpression of Mi-1.2 in transgenic plants did not hasten the onset of aphid resistance in seedlings, or boost the level of resistance observed in flowering plants. These data demonstrate that Mi-1.2 transcript levels do not modulate the degree of aphid resistance in tomato leaves, or control the differences in regulation between aphid and nematode resistance.
authors.affiliation: Department of Entomology, University of Arkansas, 320 Agriculture Building, Fayetteville 72701, USA. fgoggin@uark.edu
authors.forename: Fiona L
authors.initials: FL
authors.lastname: Goggin
authors.forename: Gowri
authors.initials: G
authors.lastname: Shah
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Williamson
authors.forename: Diane E
authors.initials: DE
authors.lastname: Ullman
mesh_terms: D000818:Animals; D001042:Aphids / Q000254:growth & development*; D035264:Flowers / Q000235:genetics* / Q000254:growth & development / Q000469:parasitology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development / Q000469:parasitology; D010935:Plant Diseases / Q000235:genetics* / Q000469:parasitology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000469:parasitology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012098:Reproduction / Q000235:genetics / Q000502:physiology
chemical_list: C117349:MI-1 protein, Lycopersicon esculentum; D010940:Plant Proteins