Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

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modified method of Cooke and Jones (1970). The plants were inoculated with 106 spores/mL, with a surfactant, until the point of run-off using an airless spraypainting gun while the pots were revolving on a turntable at 33 rpm. After inoculation the plants were placed in a humidity chamber for 48 hours and then returned to the bench. The plants were rated using the youngest fully emerged leaf at the time of inoculation on the main tiller eight days after inoculation. The leaves were rated using disease score (DS), a 0 to 5 severity scale where 0 was an immune response and a score of 5 was given if the leaves were fully necrosed. The DS is based upon the number, size, and type of lesions, as well as the area of the leaf covered by the lesions. The two parental accessions were assessed twice for two components of resistance, and the F1 plants were assessed once. The components were the incubation period (IP, the number of days from the time of inoculation till symptoms first appear) and the infection frequency (IF, the number of lesions per square centimeter of leaf tissue at IP). In the first screening the IF had to be transformed using a natural logarithmic function, and during the second screening it was transformed using a square root function to remove the trends in the residuals. The F3 families were classified using the response of individual plants within an F3 family. During the rating it was evident from the parental accession’s response that a Inheritance of Septoria Nodorum Blotch Resistance in a Triticum tauschii Accession Controlled by a Single Gene 75 score of less than 2.5 was resistant and a score of equal to or greater than 2.5 was susceptible. A F3 family was classified as resistant if all its plants had a DS of less than 2.5 and as susceptible if all the plants had a disease score greater than or equal to 2.5. Any family with plants with a DS of less than 2.5 and greater than 2.5 were classified as segregating. Results In both tests the components of resistance showed significant differences between the resistant and susceptible parents in their response to infection. The IP for the parents was not significantly different in the first screening but the resistant parent (RL5271) had a Table 1. The incubation period (IP), infection frequency (IF), and disease score (DS) of the F1 mean response during screening 1, and the parental accessions, RL5271 and CPI110889, during screenings 1 and 2. IF IP (lesions/ (days) cm2 ) i DS Screening 1 F1 8.5bii RL5271 0.8a 1.3b (Resistant parent) CPI110889 6.8a 0.8a 0.4a (Susceptible parent) Screening 2 RL5271 5.9a 2.0b 2.2c (Resistant parent) CPI110889 5.5a 2.4a 0.9a (Susceptible parent) 3.5b 5.8b 3.3b i Back transformed values are presented for the IF in both screenings. ii Numbers from the same screening and for the same trait followed by different letters are significantly different from each other at p
76 Session 3B — N.E.A. Murphy, R. Loughman, R. Wilson, E.S. Lagudah, R. Appels, and M.G.K. Jones different from the expected genotypic ratio for a single gene (X2 =0.81, p=0.67) (Table 2). When the genotypic ratios of the two subpopulations were compared using a Pearson’s chi-squared test for homogeneity, they were not significantly different (X2 =0.84, p=0.66). The combined ratio (45 resistant F3 families, 97 segregating, and 52 susceptible families) was not significantly different from the genotypic ratio expected for a single gene (X2 =0.50, p=0.78) (Table 2). Discussion Resistance to septoria nodorum blotch in the Triticum tauschii accession RL5271 is controlled by a single gene. From the F1 mean response there was no evidence of complete dominance or recessiveness for resistance. The resistant parent took significantly longer to develop symptoms, developed significantly fewer infections and expressed significantly lower levels of disease than the susceptible parent. The variation in the resistance components between the two parents was consistent with previous studies reporting a resistance response. The IP has been shown to vary significantly among wheats with longer IP being associated with resistance (Wilkinson et al., 1990; Bruno and Nelson, 1990). The IF was significantly lower for the resistant parent, which is consistent with previous work where a low IF has been associated with resistance (Wilkinson et al., 1990; Ma and Hughes, 1993; Loughman et al., 1996). The inheritance of the IF has been found to be clearly dominant in the F1 (Ma and Hughes, 1993) which is consistent with this study. Resistance in Triticum tauschii accession RL5271 is the first singlegene resistance to septoria nodorum blotch identified in the D genome. Resistance to septoria nodorum blotch has been previously identified in another Triticum tauschii accession (=Aegilops squarrosa Tausch). It was found to be controlled by three genes, located on chromosomes 3D, 5D, and 7D, with 3D being the most important of the three (Nicholson et al., 1993). The simplicity of the inheritance and strong expression of the resistance gene in T. tauschii warrants making an attempt at introgressing the resistance into a bread wheat background. Acknowledgment This work was funded by the Grains Research and Development Corporation of Australia. References Bruno, H.H., and L.R. Nelson. 1990. Partial resistance to septoria glume blotch analyzed in winter wheat seedlings. Crop Science 30:54-59. Cooke, B.M., and D.G. Jones. 1970. The effect of near-ultraviolet irradiation and agar medium on the sporulation of Septoria nodorum and Septoria tritici. Transactions of the British Mycological Society 54:221-226. Loughman, R., R.E. Wilson, and G.J. Thomas. 1996. Components of resistance to Mycosphaerella graminicola and Phaeosphaeria nodorum in spring wheats. Euphytica 89:377-385. Ma, H., and G.R. Hughes. 1993. Resistance to septoria nodorum blotch in several Triticum species. Euphytica 70:151-157. 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. Murray, G.M., and J.F. Brown. 1987. The incidence and relative importance of wheat diseases in Australia. Australasian Plant Pathology 16:34-37. Nicholson, H., N. Rezanoor, and A.J. Worland. 1993. Chromosomal location of resistance to Septoria nodorum in a synthetic hexaploid wheat determined by the study of chromosomal substitution lines in Chinese Spring wheat. Plant Breeding 110:177-184. 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. Wilkinson, C.A., J.P. Murphy, and R.C. Rufty. 1990. Diallel analysis of components of partial resistance to Septoria nodorum. Plant Disease 74:47-50.
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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
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Molecular Analysis of a DNA Fingerp
Page 32 and 33: histidine kinase in yeast, although
Page 34 and 35: According to the previous observati
Page 36 and 37: cultivars. The presence of pycnidia
Page 38 and 39: Provided that S. nodorum fungal gen
Page 40 and 41: ;; yy ;; yy 6 28% 1 32% ;y; ; y y ;
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
Page 79 and 80: 72 Session 3B — N.E.A. Murphy, R.
Page 81: 74 Inheritance of Septoria Nodorum
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
Page 99 and 100: 92 Session 4 — Bennett, R.S., S.-
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
Page 107 and 108: Session 5 — C.A. Cordo, M.R. Sim
Page 109 and 110: 102 Epidemiology of Seedborne Stago
Page 111 and 112: Session 5 — D.A. Shah and G.C. Be
Page 113 and 114: 106 Session 6A / Session 6B — J.M
Page 119 and 120: Session 6A / Session 6B — C.C. Mu
Page 125 and 126: 118 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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