title: Identification of I-7 expands the repertoire of genes for resistance to Fusarium wilt in tomato to three resistance gene classes.
abstract: The tomato I-3 and I-7 genes confer resistance to Fusarium oxysporum f. sp. lycopersici (Fol) race 3 and were introgressed into the cultivated tomato, Solanum lycopersicum, from the wild relative Solanum pennellii. I-3 has been identified previously on chromosome 7 and encodes an S-receptor-like kinase, but little is known about I-7. Molecular markers have been developed for the marker-assisted breeding of I-3, but none are available for I-7. We used an RNA-seq and single nucleotide polymorphism (SNP) analysis approach to map I-7 to a small introgression of S. pennellii DNA (c. 210 kb) on chromosome 8, and identified I-7 as a gene encoding a leucine-rich repeat receptor-like protein (LRR-RLP), thereby expanding the repertoire of resistance protein classes conferring resistance to Fol. Using an eds1 mutant of tomato, we showed that I-7, like many other LRR-RLPs conferring pathogen resistance in tomato, is EDS1 (Enhanced Disease Susceptibility 1) dependent. Using transgenic tomato plants carrying only the I-7 gene for Fol resistance, we found that I-7 also confers resistance to Fol races 1 and 2. Given that Fol race 1 carries Avr1, resistance to Fol race 1 indicates that I-7-mediated resistance, unlike I-2- or I-3-mediated resistance, is not suppressed by Avr1. This suggests that Avr1 is not a general suppressor of Fol resistance in tomato, leading us to hypothesize that Avr1 may be acting against an EDS1-independent pathway for resistance activation. The identification of I-7 has allowed us to develop molecular markers for marker-assisted breeding of both genes currently known to confer Fol race 3 resistance (I-3 and I-7). Given that I-7-mediated resistance is not suppressed by Avr1, I-7 may be a useful addition to I-3 in the tomato breeder's toolbox.
authors.affiliation: Division of Plant Sciences, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Gonzalez-Cendales
authors.affiliation: Division of Plant Sciences, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia.
authors.forename: Ann-Maree
authors.initials: AM
authors.lastname: Catanzariti
authors.affiliation: Plant Gene Expression Center, University of California-Berkeley, 800 Buchanan Street, Albany, CA, 94710, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Baker
authors.affiliation: Agri-Science Queensland, Queensland Department of Agriculture and Fisheries, Gatton, Qld, 4343, Australia.
authors.forename: Des J
authors.initials: DJ
authors.lastname: Mcgrath
authors.affiliation: Division of Plant Sciences, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT, 2601, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Jones
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D032461:Chromosomes, Plant / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D005670:Fusarium / Q000502:physiology*; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000235:genetics* / Q000382:microbiology*; D005810:Multigene Family; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D017423:Sequence Analysis, RNA
chemical_list: D010940:Plant Proteins
keywords: Fusarium oxysporum f. sp. lycopersici; Fusarium wilt; Solanum lycopersicum; Solanum pennellii; leucine-rich repeat; plant disease resistance gene; receptor-like protein