Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

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Discussion A marker linked to a resistance gene to septoria nodorum blotch in the Triticum tauschii accession RL5271 has been found. The marker and the resistance gene appear to be completely linked; however, a greater number of plants need to be tested to develop a more accurate estimate of the linkage. The multiple bands produced when the marker was used as an RFLP probe indicate that regions of repetitive DNA exist within the marker, which is not uncommon (Eastwood et al., 1994). The RFLP probe is currently being sequenced and primers designed that will allow the development of a sequence characterized amplified region (SCAR). This will allow a simpler and faster test to be developed. The simpler assay will be required if it is to be used extensively in a marker-assisted selection program. If the designed primers do amplify a polymorphism between the Identification of a Molecular Marker Linked to Septoria Nodorum Blotch Resistance in Triticum tauschii 73 resistant and the susceptible plants, it may be one of several types. The primers may amplify a region that is present in the resistant plants but not in the susceptible plants. This marker will be dominant and will not allow for the identification of heterozygotes; however, this will enable simple alternatives to running the PCR product on a gel to determine if the band is present or not to be used (Dedryver et al., 1996). This will remove one of the major time constraints and limiting factors in the screening of large numbers of plants. Alternatively, the SCAR primers could amplify different size fragments between the resistant and the susceptible plants. This type of polymorphism will allow heterozygotes to be identified (co-dominant), as both alleles will be amplified. This in turn will allow the selection of homozygotes for use in a backcrossing population, where the direct and accurate selection of homozygotes will be of greatest benefit. References Allen, F.L. 1994. Usefulness of plant genome mapping to plant breeding. In Plant Genome Analysis (G.M. Gresshoff, ed.). CRC Press, London. Dedryver, F., M.F. Jubier, J. Thouvenin, and H. Goyeau. 1996. Molecular markers linked to the leaf rust resistance gene Lr24 in different wheats. Genome 39:830- 835. Eastwood, R.F., E.S. Lagudah, and R. Appels. 1994. A directed search for DNA sequences tightly linked to cereal cyst nematode (CCN) resistance in Triticum tauschii. Genome 37:311-319. Mullaney, J., M. Martin, and A.L. Scharen. 1982. Generation mean analysis to identify and partition the components of genetic resistance to Septoria nodorum in wheat. Euphytica 31:539-545. Rosielle, A.A., and A.G.P. Brown. 1980. Selection for resistance to Septoria nodorum in wheat. Euphytica 29:337-346. Scharen, A.L., and J.M. Krupinsky. 1978. Detection and manipulation of resistance to Septoria nodorum in wheat. Phytopathology 68:245-248. Scott, P.R., P.W. Benedikz, and C.J. Cox. 1982. A genetic study of the relationship between height, time of ear emergence and resistance to Septoria nodorum in wheat. Plant Pathology 31:45-60. Smith, D.B., and R.B. Flavell. 1975. Characterisation of the wheat genome by renaturation kinetics. Chromosoma 50:223-242.
74 Inheritance of Septoria Nodorum Blotch Resistance in a Triticum tauschii Accession Controlled by a Single Gene N.E.A. Murphy, 1 R. Loughman, 2 R. Wilson, 2 E.S. Lagudah, 3 R. Appels, 3 and M.G.K. Jones1 1 WA State Agriculture Biotechnology Centre, Division of Science and Engineering, Murdoch University, Murdoch, Australia 2 Agriculture Western Australia, Bentley Delivery Centre, Western Australia 3 Plant Industries, CSIRO, Canberra, Australia Abstract A potentially useful source of resistance has been identified in an accession of Triticum tauschii. A cross was made between the resistant T. tauschii accession, RL5271, and a susceptible accession, CPI110889, to study the genetics of resistance from this source. The parental accessions and the F1 and F3 progeny were screened in the glasshouse as seedlings. The resistant parent took significantly longer to develop symptoms, developed significantly fewer lesions, and expressed significantly lower levels of disease than the susceptible parent. The F1 mean response for disease severity indicated there was no complete dominance. The genotypic ratios generated by screening the F3 families were not significantly different from the genotypic ratio expected for a single gene. The effectiveness and simple genetic control of the resistance in the T. tauschii accession RL5271 may be useful as a resistance source in a bread wheat breeding program. Septoria nodorum blotch, caused by Phaeosphaeria nodorum (E. Müller) Hedjaroude (anamorph Stagonospora nodorum (Berk.) Castellani, and E.G. Germano), is the principal foliar disease of wheat (Triticum aestivum L.) in the cereal belt of Western Australia (Murray and Brown, 1987). The preferred method of control is the use of resistant cultivars. In bread wheat inheritance of resistance to septoria nodorum blotch is reported to be complex, with an additive action of the genes (Mullaney et al., 1982; Scharen and Krupinsky, 1978). Resistance is often linked to a number of traits such as height and maturity (Rosielle and Brown, 1980; Scott et al., 1982), which makes breeding for resistance difficult. Promising levels of resistance to septoria nodorum blotch were found when a collection of T. tauschii accessions was investigated for resistance to septoria nodorum blotch. The ability to use these potential resistance sources in a wheat breeding program will be influenced by the number of genes controlling the resistance and its expression in a bread wheat background. The aim of this work was to investigate the differences between the parents in the components of resistance and to determine the number of genes controlling resistance to septoria nodorum blotch in the Triticum tauschii accession RL5271. Materials and Methods The resistant T. tauschii accession RL5271 was crossed to a susceptible accession CPI110889. The 17 F1 progenies were selfed, producing 300 F2s which were selfed to produce the F3 families. The F1 plants were screened for resistance to assess dominance, and the F3 plants were screened to determine the genotypic ratio, which was used to estimate the number of genes controlling resistance. The T. tauschii seed was germinated on sterile filter papers in petri dishes and vernalized before being sown into pots in a glasshouse. In the F3 generation, a random selection of approximately 200 F3 families was screened sequentially in two subpopulations. Each sub-population was grown on a single bench in the glasshouse, and each F3 family contained 10 plants. The plants were inoculated when the third leaf on the main stem had emerged. A single isolate of Stagonospora nodorum was used. The inoculum was produced using V8 Czapek-Dox agar (V8CDA) as a
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Septoria and Stagonospora Diseases
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ii The Organizing Committee express
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iv 87 Genetic Variability in a Coll
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vi Foreword In the mid-1970s the id
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2 Opening Remarks — S. Rajaram ar
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4 Opening Remarks — S. Rajaram Ta
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6 Opening Remarks — S. Rajaram cu
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8 Opening Remarks — S. Rajaram br
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10 Opening Remarks — S. Rajaram T
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12 Opening Remarks — S. Rajaram t
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14 Opening Remarks — S. Rajaram C
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16 Opening Remarks — S. Rajaram r
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Session 1: Pathogen Biology Biology
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Table 2. The Septoria tritici/Stago
Page 30 and 31: Molecular Analysis of a DNA Fingerp
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Page 42 and 43: Table 1. Sources of isolates or DNA
Page 44 and 45: Septoria/Stagonospora Leaf Spot Dis
Page 46: Interrelations among Septoria triti
Page 49 and 50: 42 Session 2 — B.M. Cunfer disper
Page 51 and 52: 44 Session 2 — B.M. Cunfer beyond
Page 53 and 54: 46 Aggressiveness of Phaeosphaeria
Page 55 and 56: 48 Session 2 — P. Halama, F. Lala
Page 57 and 58: 50 Growth of Stagonospora nodorum L
Page 59 and 60: 52 Session 3A — G.H.J. Kema and E
Page 61 and 62: 54 A Possible Gene-for-Gene Relatio
Page 63 and 64: 56 Diallel Analysis of Septoria Tri
Page 65 and 66: 58 Session 3A — X. Zhang, S.D. Ha
Page 67 and 68: 60 Session 3A — L. Gilchrist, C.
Page 69 and 70: 62 Session 3A — L. Gilchrist, C.
Page 71 and 72: 64 Session 3B — E. Arseniuk and P
Page 75 and 76: 68 Cultivar variances Cultivar vari
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Page 83 and 84: 76 Session 3B — N.E.A. Murphy, R.
Page 85 and 86: 78 Session 4 — B.A. McDonald, C.C
Page 91 and 92: 84 Session 4 — E. Arseniuk, H.S.
Page 93 and 94: 86 Session 4 — C. Cowger, C.C. Mu
Page 95 and 96: 88 each isolate. Two of the probes
Page 97 and 98: 90 Mating Type-Specific PCR Primers
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Page 101 and 102: 94 Session 5 — M.W. Shaw and the
Page 103 and 104: 96 Session 5 — M.W. Shaw The path
Page 105 and 106: 98 Spore Dispersal of Leaf Blotch P
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Page 109 and 110: 102 Epidemiology of Seedborne Stago
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Page 113 and 114: 106 Session 6A / Session 6B — J.M
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124 Session 6C — M. van Ginkel an
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126 Session 6C — M. van Ginkel an
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Session 6C — G. Shaner 128 An exa
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Session 6C — G. Shaner 130 Anothe
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Session 6C — M. Díaz de Ackerman
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134 Septoria tritici Resistance Sou
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Session 6C — L. Gilchrist et al.
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Session 6C — L. Gilchrist et al.
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140 Selecting Wheat for Resistance
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Session 6C — R.M. Gonzalez I., S.
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Session 6C — R.M. Gonzalez I., S.
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Session 6C — R. Loughman, R.E. Wi
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148 Field Resistance of Wheat to Se
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150 Using Precise Genetic Stocks to
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Session 6C — C.M. Ellerbrook, V.
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154 Evaluating Triticum durum x Tri
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156 Sources of Resistance to Septor
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Session 6C — H. Toubia-Rahme and
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160 Partial Resistance to Stagonosp
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Session 6C — C.G. Du, L.R. Nelson
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Session 6C — D.E. Fraser, J.P. Mu
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Session 6C — C.G. Du, L.R. Nelson
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Session 6C — M. Mincu 168 Arcsin
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170 Comparison of Greenhouse and Fi
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Session 6C — S.L. Walker, S. Leat
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Session 6D — L.N. Jørgensen, K.E
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Concluding Remarks — Z. Eyal 178
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184 Dr. Patrice Halama Professor In
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186 Dr. Hala Toubia-Rahme Research
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