Functional variability of the Lr34 durable resistance gene in transgenic wheat.

Breeding for durable disease resistance is challenging, yet essential to improve crops for sustainable agriculture. The wheat Lr34 gene is one of the few cloned, durable resistance genes in plants. It encodes an ATP binding cassette transporter and has been a source of resistance against biotrophic pathogens, such as leaf rust (Puccinina triticina), for over 100 years. As endogenous Lr34 confers quantitative resistance, we wanted to determine the effects of transgenic Lr34 with specific reference to how expression levels affect resistance. Transgenic Lr34 wheat lines were made in two different, susceptible genetic backgrounds. We found that the introduction of the Lr34 resistance allele was sufficient to provide comparable levels of leaf rust resistance as the endogenous Lr34 gene. As with the endogenous gene, we observed resistance in seedlings after cold treatment and in flag leaves of adult plants, as well as Lr34-associated leaf tip necrosis. The transgene-based Lr34 resistance did not involve a hypersensitive response, altered callose deposition or up-regulation of PR genes. Higher expression levels compared to endogenous Lr34 were observed in the transgenic lines both at seedling as well as adult stage and some improvement of resistance was seen in the flag leaf. Interestingly, in one genetic background the transgenic Lr34-based resistance resulted in improved seedling resistance without cold treatment. These data indicate that functional variability in Lr34-based resistance can be created using a transgenic approach.

[1]  D. Garvin,et al.  Lr34-mediated leaf rust resistance in wheat: transcript profiling reveals a high energetic demand supported by transient recruitment of multiple metabolic pathways. , 2008, Molecular plant-microbe interactions : MPMI.

[2]  J. Dubcovsky,et al.  High-temperature adult-plant (HTAP) stripe rust resistance gene Yr36 from Triticum turgidum ssp. dicoccoides is closely linked to the grain protein content locus Gpc-B1 , 2005, Theoretical and Applied Genetics.

[3]  P. Dyck,et al.  INHERITANCE OF ADULT-PLANT LEAF RUST RESISTANCE DERIVED FROM THE COMMON WHEAT VARIETIES EXCHANGE AND FRONTANA' , 1966 .

[4]  J. Brown,et al.  Leaf Rust Resistance Gene LR34 is Involved in Powdery Mildew Resistance of Cimmyt Bread Wheat Line Saar , 2007 .

[5]  H. Leung,et al.  Nonhost resistance of rice to rust pathogens. , 2011, Molecular plant-microbe interactions : MPMI.

[6]  S. Muthukrishnan,et al.  Development of a lesion-mimic phenotype in a transgenic wheat line overexpressing genes for pathogenesis-related (PR) proteins is dependent on salicylic acid concentration. , 2003, Molecular plant-microbe interactions : MPMI.

[7]  D. Rubiales,et al.  Characterization of Lr34, a major gene conferring nonhypersensitive resistance to wheat leaf rust. , 1995 .

[8]  T. Schnurbusch,et al.  Dissection of quantitative and durable leaf rust resistance in Swiss winter wheat reveals a major resistance QTL in the Lr34 chromosomal region , 2004, Theoretical and Applied Genetics.

[9]  W. Spielmeyer,et al.  Powdery mildew resistance and Lr34/Yr18 genes for durable resistance to leaf and stripe rust cosegregate at a locus on the short arm of chromosome 7D of wheat , 2005, Theoretical and Applied Genetics.

[10]  J. Kolmer,et al.  Effect of gene Lr34 in the enhancement of resistance to leaf rust of wheat , 1992, Theoretical and Applied Genetics.

[11]  E. Delhaize,et al.  Engineering greater aluminium resistance in wheat by over-expressing TaALMT1. , 2010, Annals of botany.

[12]  R. Park,et al.  Characterisation of wheat leaf rust resistance gene Lr34 in Australian wheats using components of resistance and the linked molecular marker csLV34 , 2007 .

[13]  M. Warburton,et al.  Identification of highly transformable wheat genotypes for mass production of fertile transgenic plants. , 2002, Genome.

[14]  O. Ratcliffe,et al.  Regulating the Regulators: The Future Prospects for Transcription-Factor-Based Agricultural Biotechnology Products , 2008, Plant Physiology.

[15]  R. Singh,et al.  Effect of leaf rust resistance gene Lr34 on components of slow rusting at seven growth stages in wheat , 2003, Euphytica.

[16]  M. Wolter,et al.  The mlo resistance alleles to powdery mildew infection in barley trigger a developmentally controlled defence mimic phenotype , 1993, Molecular and General Genetics MGG.

[17]  David B. Collinge,et al.  Subcellular localization of H2O2 in plants. H2O2 accumulation in papillae and hypersensitive response during the barley—powdery mildew interaction , 1997 .

[18]  D. Garvin,et al.  Expression of a Thatcher Wheat Adult Plant Stem Rust Resistance QTL on Chromosome Arm 2BL is Enhanced by Lr34 , 2011 .

[19]  R. Singh.  Genetic association of leaf rust resistance gene Lr34 with adult plant resistance to stripe rust in bread wheat , 1992 .

[20]  J. Manners,et al.  Methyl jasmonate induced gene expression in wheat delays symptom development by the crown rot pathogen Fusarium pseudograminearum , 2005 .

[21]  B. Keller,et al.  Transgenic Pm3b wheat lines show resistance to powdery mildew in the field. , 2011, Plant biotechnology journal.

[22]  M. Sutherland.  The generation of oxygen radicals during host plant responses to infection , 1991 .

[23]  R. Singh,et al.  Genetics of adult-plant resistance of leaf rust in 'Frontana' and three CIMMYT wheats , 1992 .

[24]  Musharaf Ahmad,et al.  Using leaf tip necrosis as a phenotypic marker to predict the presence of durable rust resistance gene pair Lr34/Yr18 in wheat , 2011, Journal of General Plant Pathology.

[25]  J. Aist,et al.  A papilla-regulating extract that induces resistance to barley powdery mildew , 1991 .

[26]  R. Singh.  Expression of wheat leaf rust resistance gene Lr34 in seedlings and adult plants , 1992 .

[27]  J. Fellers,et al.  Gene expression patterns in near isogenic lines for wheat rust resistance gene lr34/yr18. , 2007, Phytopathology.

[28]  G. Shaner,et al.  Oligogenic Inheritance of Length of Latent Period in Six Slow Leaf-Rusting Wheat Cultivars , 1985 .

[29]  B. Moerschbacher,et al.  Histopathology and PR-protein markers provide insight into adult plant resistance to stripe rust of wheat. , 2008, Molecular plant pathology.

[30]  Yanjun Kou,et al.  Broad-spectrum and durability: understanding of quantitative disease resistance. , 2010, Current opinion in plant biology.

[31]  P. Dyck.  Genetics of Adult‐Plant Leaf Rust Resistance in ‘Chinese Spring’ and ‘Sturdy’ Wheats , 1991 .

[32]  M. Perazzolli,et al.  AtCYS1, a cystatin from Arabidopsis thaliana, suppresses hypersensitive cell death. , 2003, European journal of biochemistry.

[33]  Tao Li,et al.  Lesion mimic associates with adult plant resistance to leaf rust infection in wheat , 2009, Theoretical and Applied Genetics.

[34]  Alex Levine,et al.  H2O2 from the oxidative burst orchestrates the plant hypersensitive disease resistance response , 1994, Cell.

[35]  S. Cloutier,et al.  Fine-mapping of the leaf rust Lr34 locus in Triticum aestivum (L.) and characterization of large germplasm collections support the ABC transporter as essential for gene function , 2010, Theoretical and Applied Genetics.

[36]  M. Weiß,et al.  The root endophytic fungus Piriformospora indica requires host cell death for proliferation during mutualistic symbiosis with barley , 2006, Proceedings of the National Academy of Sciences.

[37]  G. Hu,et al.  Adult Plant Phenotype of the Rp1-DJ Compound Rust Resistance Gene in Maize. , 1997, Phytopathology.

[38]  Jeff Schell,et al.  Expression of intron modified NPT II genes in monocotyledonous and dicotyledonous plant cells , 1997, Molecular Breeding.

[39]  T. Bozkurt,et al.  Cellular and transcriptional responses of wheat during compatible and incompatible race-specific interactions with Puccinia striiformis f. sp. tritici. , 2010, Molecular plant pathology.

[40]  Jonathan D. G. Jones,et al.  The plant immune system , 2006, Nature.

[41]  R. Singh,et al.  Characterization of variability and relationships among components of partial resistance to leaf rust in CIMMYT bread wheats , 1991, Theoretical and Applied Genetics.

[42]  P. Dyck,et al.  An interchromosomal reciprocal translocation in wheat involving leaf rust resistance gene Lr34. , 1994, Genome.

[43]  D. Somers,et al.  Fungal development and induction of defense response genes during early infection of wheat spikes by Fusarium graminearum. , 2000, Molecular plant-microbe interactions : MPMI.

[44]  K. Breuker,et al.  Breakdown of chlorophyll: A nonenzymatic reaction accounts for the formation of the colorless “nonfluorescent” chlorophyll catabolites , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[45]  T. Wicker,et al.  Lr34 multi-pathogen resistance ABC transporter: molecular analysis of homoeologous and orthologous genes in hexaploid wheat and other grass species. , 2011, The Plant journal : for cell and molecular biology.

[46]  J. Dubcovsky,et al.  A Kinase-START Gene Confers Temperature-Dependent Resistance to Wheat Stripe Rust , 2009, Science.

[47]  Paul Schulze-Lefert,et al.  Arabidopsis PEN3/PDR8, an ATP Binding Cassette Transporter, Contributes to Nonhost Resistance to Inappropriate Pathogens That Enter by Direct Penetration[W][OA] , 2006, The Plant Cell Online.

[48]  Chung-Mo Park,et al.  Membrane-bound transcription factors in plants. , 2008, Trends in plant science.

[49]  R. Singh,et al.  Molecular genetic characterization of the Lr34/Yr18 slow rusting resistance gene region in wheat , 2006, Theoretical and Applied Genetics.

[50]  R. Singh,et al.  The adult plant rust resistance loci Lr34/Yr18 and Lr46/Yr29 are important determinants of partial resistance to powdery mildew in bread wheat line Saar , 2008, Theoretical and Applied Genetics.

[51]  Z. Pretorius,et al.  Effects of combinations amongst genes Lr13, Lr34 and Lr37 on components of resistance in wheat to leaf rust , 1997 .

[52]  J. Manners,et al.  The Fusarium mycotoxin deoxynivalenol elicits hydrogen peroxide production, programmed cell death and defence responses in wheat. , 2008, Molecular plant pathology.

[53]  D. Garvin,et al.  Analysis of the Lr34/Yr18 Rust Resistance Region in Wheat Germplasm , 2008 .

[54]  R. Singh,et al.  Microsatellite markers for genes lr34/yr18 and other quantitative trait Loci for leaf rust and stripe rust resistance in bread wheat. , 2003, Phytopathology.

[55]  E. Lagudah.  Molecular genetics of race non-specific rust resistance in wheat , 2011, Euphytica.

[56]  R. McIntosh,et al.  Close genetic linkage of genes conferring adult-plant resistance to leaf rust and stripe rust in wheat , 2007 .

[57]  S. Volrath,et al.  Wheat genes encoding two types of PR-1 proteins are pathogen inducible, but do not respond to activators of systemic acquired resistance. , 1999, Molecular plant-microbe interactions : MPMI.

[58]  B. Keller,et al.  A Putative ABC Transporter Confers Durable Resistance to Multiple Fungal Pathogens in Wheat , 2009, Science.

[59]  M. Meghji,et al.  Phosphomannose isomerase: An efficient selectable marker for plant transformation , 2001, In Vitro Cellular & Developmental Biology - Plant.

[60]  K. Shirasu,et al.  The arms race continues: battle strategies between plants and fungal pathogens. , 2005, Current opinion in microbiology.

[61]  R. Singh,et al.  Detection of Virulence to Wheat Stem Rust Resistance Gene Sr31 in Puccinia graminis. f. sp. tritici in Uganda. , 2000, Plant disease.

[62]  M. Hinchee,et al.  A simplified method for the detection of neomycin phosphotransferase II activity in transformed plant tissues , 1987, Plant Molecular Biology Reporter.

[63]  R. Singh,et al.  Genetics and Breeding for Durable Resistance to Leaf and Stripe Rusts in Wheat , 2005 .

[64]  M. Hayden,et al.  An introgression on wheat chromosome 4DL in RL6077 (Thatcher*6/PI 250413) confers adult plant resistance to stripe rust and leaf rust (Lr67) , 2010, Theoretical and Applied Genetics.

[65]  H. Shew,et al.  Applications of KOH-Aniline Blue Fluorescence in the Study of Plant-Fungal Interactions , 1996 .

[66]  M. Hayden,et al.  New slow-rusting leaf rust and stripe rust resistance genes Lr67 and Yr46 in wheat are pleiotropic or closely linked , 2010, Theoretical and Applied Genetics.