ITEMS FROM THE UNITED KINGDOM

JOHN INNES CENTRE

Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom.

Genetics of resistance of wheat to Septoria tritici blotch. [p. 170-171]

We have recently completed a industrial LINK project on Breeding for Resistance to S. tritici, supported by the Department for the Environment, Food and Rural Affairs and six plant breeding companies with U.K. interests. We have discovered that many of the most widely-used sources of Septoria resistance in world wheat breeding have the gene Stb6. The widespread distribution of this gene limits the scope for transgressive segregation of resistance and points to the need to use a greater range of resistance genes. We have identified and mapped four new genes for resistance to Septoria, Stb9 in several European spring wheat cultivars; Stb10 and Stb12 in Kavkaz-K4500, an especially important source of resistance; and Stb11 in TE9111, a Portuguese breeding line that is the most resistant modern European wheat known. Through an associated genetic analysis, we also have shown that many genes, dispersed over the chromosomes of wheat, promote partial resistance to Septoria.

We are now beginning a new LINK project, Improved Resistance to S. tritici in Superior Varieties, in which we will quantify the contributions to disease reduction in the field of Septoria resistance genes identified in the previous LINK project and investigate the interaction of Septoria resistance with other plant traits important to U.K. and European wheat breeders.

Fusarium and eyespot diseases of cereals. [p. 171]

Paul Nicholson, Liz Chandler, Natalie Chapman, Richard Draeger, Nick Gosman, Wendy Monger, Andy Steed, and Martha Thomsett.

The study of the genetic basis of resistance to FHB in winter wheat is continuing. The resistance of Arina and WEK0609 has been analyzed and mapping and QTL analysis of resistance of these populations is nearing completion. Fine mapping of the T. aesvivum subsp. macha 4A FHB resistance is ongoing and is being combined with gene-expression studies to identify candidate resistance genes. Host-pathogen interaction is being studied in detail for infection of Arina and Riband by F. culmorum. Expression of wheat PR genes and fungal toxin-biosynthesis genes is being determined for the two hosts during infection and colonization of wheat spikes. A collaborative project is underway to assess the level of FHB resistance among U.K. wheat cultivars and to introduce and pyramid FHB from diverse sources to improve the level of resistance among winter wheat cultivars in the U.K. SSR analysis of U.K. and European wheats indicates the absence of any of the common FHB-resistance QTL of Chinese origin among this germ plasm lines are being developed to determine the combining ability of selected FHB QTL to identify the best combinations for use in breeding programs. Molecular diagnostics are being used to study effects of, and interactions between, Fusarium isolates of different chemotype on different cereal hosts. Molecular diagnostics also have revealed that the U.K. wheat crop is exposed to a more diverse array of chemotypes than that in the U.S. In addition to studies on FHB, mapping and molecular studies of two eyespot resistance genes (Pch1 and Pch2) are continuing.

Genetic biodiversity of adult-plant resistance to yellow rust in wheat. [p. 171]

Lesley A. Boyd, Clare Lewis, Muge Sayar, James Melichar, Luke Jagger, and Hale Tufan.

A number of QTL for APR to yellow (stripe) rust have been identified in the U.K. wheat cultivar Claire and within the Claire pedigree. Mapping work also is underway to identify the QTL for a source of partial APR to yellow rust in the cultivar Guardian.

The dissection of genetic biodiversity for yellow rust APR in U.K. wheat cultivars will be extended to include a comparison to biodiversity in Turkish wheats as part of a new collaboration between H-J. Braun (CIMMYT, Turkey) and M.T. Sayar (Bogazici University, Istanbul, Turkey).

Novel sources of resistance to biotrophic fungal pathogens in wheat. [p. 171-172]

James Melichar and Lesley A. Boyd.

A number of mutants, generated by gamma-radiation in the U.K. cultivar Guardian, were originally selected in the field for enhanced resistance to yellow rust. This enhanced resistance was shown not to express in seedlings, but to be developmentally regulated, expressing at adult plant growth stages. A microscopic-staining procedure has been developed in the group that allows detailed histological examination of yellow rust development in adult plant tissue. Using this methodology, the partial APR in Guardian has been shown to restrict sporulation, but this resistance is not associated with the release of hydrogen peroxide by the plant, a response common to race-specific resistance. However, the enhancement of resistance, due to mutation, is associated with the production of hydrogen peroxide.

In addition to the enhancement of resistance to yellow rust in adult plants, a number of the mutants also exhibit enhanced resistance to leaf rust and/or powdery mildew. Mapping populations have been developed for Guardian and two of the mutants, and these will be used to locate both the partial yellow rust APR in Guardian, the mutations responsible for the enhancement of yellow rust resistance, and the mutations conferring resistance to leaf rust and powdery mildew.

Factors affecting yellow rust infection efficiency. [p. 172]

Ruth MacCormack and Lesley A. Boyd.

A new program in the laboratory of L.A. Boyd examines the early stages of yellow rust infection to determine what factors optimize infection efficiency of this fungal pathogen. Having identified the physiological factors that the pathogen requires to successfully enter the plant through open stomata, phenotypic screens will be established to look for genetic variation within wheat for infection efficiency.

An immortal population of mutagenized spring wheat. [p. 172]

Simon Orford, Pauline Stephenson, and Robert Koebner.

As part of our contribution to the Wheat Genetic Improvement Network (see AWN 50:192), we are developing an immortal population of EMS-mutagenized spring wheat cultivar Paragon by single-seed descent. The initial M1 population numbered ~ 3,500 individuals, from which two M2 seeds/M1 plant were sown. The population is currently (spring-summer 2005) being advanced from M3 to M4 as ~ 7,000 independent lines. From the M6, we intend to field multiply the lines and make them available to collaborators for gene discovery and functional gene analysis.

Homoeologous silencing in hexaploid wheat. [p. 172]

Andrew Bottley and Robert Koebner.

Our SSCP-based analysis of patterns and frequency of homoeolog silencing in wheat continues to surprise. We are working with single-copy EST sequences located to homoeologous group under the NSF wheat EST program, comparing amplicon patterns generated from cDNA templates from both root and leaf tissue. Globally, around 15 % of the loci are nontranscribed, but we have noted a significant frequency of cases where in the presence of additional doses of a chromosome (as are present in the nullisomic-tetrasomic stocks), a homoeolocus silenced in the euploid condition is transcribed. To avoid noncomparability between genomic and cDNA profiles, we are using the rice genome sequence to target amplicons lacking intron sequence.

Publications. [p. 172-173]

• Bourdon V, Wickham A, Lonsdale D, and Harwood W. 2004. Additional introns inserted within the luciferase reporter gene stabilise transgene expression in wheat. Plant Sci 167:1143-1149.
• Castro AM, Vasicek A, Ellerbrook C, Gimenez DO, Tocho E, Tacaliti MS, Clua A, and Snape JW. 2004. Mapping quantitative trait loci in wheat for resistance against greenbug and Russian wheat aphid. Plant Breed 123:361-365.
• Chartrain L. 2004. Genes for isolate-specific and partial resistance to septoria tritici blotch (Mycosphaerella graminicola) in wheat. PhD Thesis, University of East Anglia. 151 pp.
• Chartrain L, Berry ST, and Brown JKM. 2005. Resistance of the wheat line Kavkaz-K4500 L6.A4 to Septoria tritici blotch controlled by isolate-specific resistance genes. Phytopath (In press).
• Chartrain L, Brading PA, Makepeace JC, and Brown JKM. 2004. Sources of resistance to Septoria tritici blotch and implications for wheat breeding. Plant Path 53:454-460.
• Chartrain L, Brading PA, Widdowson JP, and Brown JKM. 2004. Partial resistance to Septoria tritici blotch (Mycosphaerella graminicola) in wheat cultivars Arina and Riband. Phytopath 94:497-504.
• Chartrain L, Brading PA, and Brown JKM. 2005. The presence of the Stb6 gene for resistance to Septoria tritici blotch (Mycosphaerella graminicola) in cultivars used in wheat breeding programmes world-wide. Plant Path (In press).
• Chartrain L, Joaquim P, Berry ST, Arraiano LS, Azanza F, and Brown JKM. 2005. Genetics of resistance to Septoria tritici blotch in the Portuguese wheat breeding line TE 9111. Theor Appl Genet (In press).
• Dawson WAJM, Jestoi M, Rizzo A, Nicholson P, and Bateman GL. 2004. Field evaluation of fungal competitors of Fusarium culmorum and Fusarium graminearum, casual agents for ear blight of winter wheat, for the control of mycotoxin production in grain. Biocontrol Sci Tech 14:783-799.
• Foote TN, Griffiths S, Allouis S, and Moore G. 2004. Construction and analysis of a BAC library in the grass Brachypodium sylvaticum: its use as a tool to bridge the gap between rice and wheat in elucidating gene content. Funct Integr Genomics 4:26-33.
• Foulkes MJ, Sylvester-Bradley R, Worland AJ, and Snape JW. 2004. Effects of a photoperiod-response gene Ppd-D1 on yield potential and drought resistance in UK winter wheat. Euphytica 135:63-73.
• Gosman N, Chandler E, Thomsett M, Draeger R, and Nicholson P. 2005. Analysis of the relationship between parameters of resistance to Fusarium head blight and in vitro tolerance to deoxynivalenol of the winter wheat cultivar WEK0609. Eur J Plant Path 111:57-66.
• Guilleroux M, and Osbourn A. 2004. Gene expression during infection of wheat roots by the 'take-all' fungus Gaeumannomyces graminis. Mol Plant Path 5:203-216.
• Hayden MJ, Stephenson P, Logojan AM, Khatkar D, Rogers C, Koebner RMD, Snape JW, and Sharp PJ. 2004. A new approach to extending the wheat marker pool by anchored PCR amplification of compound SSRs. Theor Appl Genet 108:733-742.
• Jennings P, Coates ME, Walsh K, Turner JA, and Nicholson P. 2004. Determination of deoxynivalenol- and nivalenol-producing chemotypes of Fusarium graminearum isolated from wheat crops in England and Wales. Plant Path 53:643-652
• Jennings P, Coates ME, Turner JA, Chandler EA, and Nicholson P. 2004. Determination of deoxynivalenol and nivalenol chemotypes of Fusarium culmorum isolates from England and Wales by PCR assay. Plant Path 53:182-190.
• Mohler V, Lukman R, Ortiz-Islas S, William M, Worland AJ, van Beem J, and Wenzel G. 2004. Genetic and physical mapping of photoperiod insensitive gene Ppd-B1 in common wheat. Euphytica 138:33-40.
• Nicholson P, Simpson DR, Wilson AH, Chandler E, and Thomsett M. 2004. Detection and differentiation of trichothecene and enniatin-producing Fusarium species on small-grain cereals. Eur J Plant Path 110:503-514.
• Prins R, Ramburan VP, Pretorius ZA, Boyd LA, Boshoff WHP, Smith PH, and Louw JH. 2005. Development of a doubled haploid mapping population and linkage map for the bread wheat cross Kariega x Avocet S. S Afr J Plant Soil 22:1-8.
• Ramburan VP, Pretorius ZA, Louw JH, Boyd LA, Smith PH, Boshoff WHP, and Prins RA. 2004. Genetic analysis of adult plant resistance to stripe rust in the wheat cultivar Kariega. Theor Appl Genet 108:1426-1433.
• Ribeiro-Carvalho C, Guedes-Pinto H, Igrejas G, Stephenson P, Schwarzacher T, and Heslop-Harrison JS. 2004. High levels of genetic diversity throughout the range of the Portuguese wheat landrace 'Barbela'. Ann Bot 94:699-705.
• Rodrigues P, Garrood JM, Shen Q-H, Smith PH, and Boyd LA. 2004. The genetics of non-host disease resistance in wheat to barley yellow rust. Theor Appl Genet 109:425-432.
• Simon MR, Worland AJ, and Struik PC. 2004. Influence of plant height and heading date on the expression of the resistance to Septoria tritici blotch in near isogenic lines in wheat. Crop Sci 44:2078-2085.
• Smith PH, Howie JA, Worland AJ, Statford R, and Boyd LA. 2004. Mutations in wheat exhibiting growth-stage-specific resistance to biotrophic fungal pathogens. Mol Plant-Microbe Interact 17:1242-1249.
• Toth B, Mesterhazy A, Nicholson P, Teren J, and Varga J. 2004. Mycotoxin production and molecular variability of European and American isolates of Fusarium culmorum. Eur J Plant Path 110:587-599.
• Turner AS, Bradburne RP, Fish L, and Snape JW. 2004. New quantitative trait loci influencing grain texture and protein content in bread wheat. J Cereal Sci 40:51-60.
• Verma V, Foulkes MJ, Worland AJ, Sylvester-Bradley R, Caligari PDS, and Snape JW. 2004. Mapping quantitative trait loci for flag leaf senescence as a yield determinant in winter wheat under optimal and drought-stressed environments. Euphytica 135:255-263.
• Vorontsova M, Shaw P, Reader S, and Moore G. 2004. Effect of 5-azacytidine and trichostatin A on somatic centromere association in wheat. Genome 47:399-403.
• Xu X-M, Parry DW, Edwards SG, Cooke BM, Doonan FM, van Maanen A, Brennan JM, Monaghan S, Moretti A, Tocco G, Mule G, Hornok L, Giczey G, Tatnell J, Nicholson P, and Ritieni A. 2004. Relationship between the incidences of ear and spikelet infection of Fusarium ear blight in wheat. Eur J Plant Path 110:959-971.