title: Expression of apoplast-targeted plant defensin MtDef4.2 confers resistance to leaf rust pathogen Puccinia triticina but does not affect mycorrhizal symbiosis in transgenic wheat.
abstract: Rust fungi of the order Pucciniales are destructive pathogens of wheat worldwide. Leaf rust caused by the obligate, biotrophic basidiomycete fungus Puccinia triticina (Pt) is an economically important disease capable of causing up to 50 % yield losses. Historically, resistant wheat cultivars have been used to control leaf rust, but genetic resistance is ephemeral and breaks down with the emergence of new virulent Pt races. There is a need to develop alternative measures for control of leaf rust in wheat. Development of transgenic wheat expressing an antifungal defensin offers a promising approach to complement the endogenous resistance genes within the wheat germplasm for durable resistance to Pt. To that end, two different wheat genotypes, Bobwhite and Xin Chun 9 were transformed with a chimeric gene encoding an apoplast-targeted antifungal plant defensin MtDEF4.2 from Medicago truncatula. Transgenic lines from four independent events were further characterized. Homozygous transgenic wheat lines expressing MtDEF4.2 displayed resistance to Pt race MCPSS relative to the non-transgenic controls in growth chamber bioassays. Histopathological analysis suggested the presence of both pre- and posthaustorial resistance to leaf rust in these transgenic lines. MtDEF4.2 did not, however, affect the root colonization of a beneficial arbuscular mycorrhizal fungus Rhizophagus irregularis. This study demonstrates that the expression of apoplast-targeted plant defensin MtDEF4.2 can provide substantial resistance to an economically important leaf rust disease in transgenic wheat without negatively impacting its symbiotic relationship with the beneficial mycorrhizal fungus.
authors: Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA. jkaur@danforthcenter.org.
authors: Jagdeep
authors: J
authors: Kaur
authors: USDA-ARS-HWWGRU, Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA.
authors: John
authors: J
authors: Fellers
authors: Mycorrhizal Applications, 1005 North Warson Road, BRDG Park, St. Louis, MO, 63132, USA.
authors: Alok
authors: A
authors: Adholeya
authors: Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA.
authors: Siva L S
authors: SL
authors: Velivelli
authors: Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA.|Department of Biology, Kutztown University of Pennsylvania, Kutztown, PA, 19530, USA.
authors: Kaoutar
authors: K
authors: El-Mounadi
authors: Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
authors: Natalya
authors: N
authors: Nersesian
authors: Department of Agronomy and Horticulture/Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
authors: Thomas
authors: T
authors: Clemente
authors: Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA.
authors: Dilip
authors: D
authors: Shah
mesh_terms: D001487:Basidiomycota / Q000235:genetics / Q000472:pathogenicity; D023082:Defensins / Q000235:genetics*; D060467:Disease Resistance / Q000235:genetics; D046913:Medicago truncatula / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000382:microbiology; D013559:Symbiosis / Q000235:genetics; D014908:Triticum / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology
chemical_list: D023082:Defensins
keywords: Genetic engineering; Leaf rust; MtDEF4.2; Plant defensin; Puccinia triticina; Rhizophagus irregularis