scholarly journals Differential Seed Infection of Wheat Cultivars by Stagonospora nodorum

Plant Disease ◽  
2000 ◽  
Vol 84 (7) ◽  
pp. 749-752 ◽  
Author(s):  
Denis A. Shah ◽  
Gary C. Bergstrom ◽  
Mark E. Sorrells
Keyword(s):  
New York ◽  
Winter Wheat ◽  
Agar Medium ◽  
Stagonospora Nodorum ◽  
Seed Infection ◽  
Wheat Cultivars ◽  
Production Environment ◽  
Flag Leaves ◽  
Initial Inoculum ◽  
Relative Susceptibility

Seed of soft white winter wheat collected from New York regional cultivar trials in 1995 and 1996 were assayed on an agar medium selective for Stagonospora nodorum. Incidence of seed infection varied with production environment. Relative incidence of seed infection differed significantly among cultivars and was consistent across environments. The flag leaves and ears of 12 cultivars were inoculated quantitatively at flowering in a glasshouse. Cultivars did not differ significantly in disease on the flag leaves. Incidence of seed infection for all cultivars was above 60%, but was significantly lower in Delaware and Houser than in other cultivars. Results confirm that wheat cultivars differ in their relative susceptibility to seed infection by S. nodorum. Resistance in wheat to seed infection by S. nodorum may be a useful mechanism for reducing initial inoculum in areas where infected seed is considered the primary inoculum source for Stagonospora nodorum blotch.

scholarly journals Quantifying the Effects of Wheat Residue on Severity of Stagonospora nodorum Blotch and Yield in Winter Wheat

2015 ◽  
Vol 105 (11) ◽  
pp. 1417-1426 ◽  
Author(s):  
L. K. Mehra ◽  
C. Cowger ◽  
R. Weisz ◽  
P. S. Ojiambo
Keyword(s):  
North Carolina ◽  
Winter Wheat ◽  
Disease Severity ◽  
Block Design ◽  
Soil Surface ◽  
Kernel Weight ◽  
Stagonospora Nodorum ◽  
Wheat Crop ◽  
Stagonospora Nodorum Blotch ◽  
Initial Inoculum

Stagonospora nodorum blotch (SNB), caused by the fungus Parastagonospora nodorum, is a major disease of wheat (Triticum aestivum). Residue from a previously infected wheat crop can be an important source of initial inoculum, but the effects of infected residue on disease severity and yield have not previously been quantified. Experiments were conducted in Raleigh and Salisbury, North Carolina, in 2012, 2013, and 2014 using the moderately susceptible winter wheat cultivar DG Shirley. In 2014, the highly susceptible cultivar DG 9012 was added to the experiment and the study was conducted at an additional site in Tyner, North Carolina. Four (2012) or six (2013 and 2014) wheat residue treatments were applied in the field in a randomized complete block design with five replicates. Treatments in 2012 were 0, 30, 60, and 90% residue coverage of the soil surface, while 10 and 20% residue treatments were added in 2013 and 2014. Across site-years, disease severity ranged from 0 to 50% and increased nonlinearly (P < 0.05) as residue level increased, with a rapid rise to an upper limit and showing little change in severity above 20 to 30% soil surface coverage. Residue coverage had a significant (P < 0.05) effect on disease severity in all site-years. The effect of residue coverage on yield was only significant (P < 0.05) for DG Shirley at Raleigh and Salisbury in 2012 and for DG 9012 at Salisbury in 2014. Similarly, residue coverage significantly (P < 0.05) affected thousand-kernel weight only of DG 9012 in 2014 at Raleigh and Salisbury. Our results showed that when wheat residue was sparse, small additions to residue density produced greater increases in SNB than when residue was abundant. SNB only led to effects on yield and test weight in the most disease-conducive environments, suggesting that the economic threshold for the disease may be higher than previously assumed and warrants review.

scholarly journals A Rainfall-Based Model for Predicting the Regional Incidence of Wheat Seed Infection by Stagonospora nodorum in New York

2002 ◽  
Vol 92 (5) ◽  
pp. 511-518 ◽  
Author(s):  
Denis A. Shah ◽  
Gary C. Bergstrom
Keyword(s):  
New York ◽  
Simple Model ◽  
Stagonospora Nodorum ◽  
Seed Infection ◽  
Independent Data ◽  
Wheat Seed ◽  
Binomial Probability ◽  
Actual Distribution ◽  
Central New York ◽  
Distribution Parameters

Our goal was to develop a simple model for predicting the incidence of wheat seed infection by Stagonospora nodorum across western and central New York in any given year. The distribution of the incidence of seed infection by S. nodorum across the region was well described by the beta-binomial probability distribution (parameters p and θ). Mean monthly rainfalls in May and in June across western and central New York were used to predict p. The binary power law was used to predict θ. The model was validated with independent data collected from New York. The predicted distribution of seed infection incidence was not statistically different from the actual distribution of the incidence of seed infection.

RECEPTIVITE DE CULTIVARS DE CEREALES DE PRINTEMPS A LA CONTAMINATION DES GRAINES SUR INFLORESCENCE PAR LES Fusarium SPP.

1982 ◽  
Vol 62 (1) ◽  
pp. 29-34 ◽  
Author(s):  
LUC COUTURE
Keyword(s):  
Avena Sativa ◽  
Agar Medium ◽  
Significant Negative Correlation ◽  
Seed Infection ◽  
Wheat Cultivars ◽  
Malting Barley ◽  
Fusarium Spp ◽  
Hard Wheat ◽  
Spring Cereals ◽  
Wheat Lines

The incidence of Fusarium spp. in seeds was determined in 21 samples of each of 34 lines of spring cereals, namely 13 lines of common wheat (Triticum aestivum), 13 lines of oats (Avena sativa) and 8 lines of barley (Hordeum vulgare), harvested in Québec in 1978. The number of surface-sterilized seeds displaying Fusarium on a selective agar medium was used as a basis of determination. Average infection in wheat cultivars was 11%, as against 15% in oats and in barley. Significant differences were found among cultivars in all three cereals, being the most marked in wheat and the least marked in barley. There is a significant negative correlation between plant height and seed infection of the lines involved in the three species: r = −0,61 (wheat), −0,66 (oats), −0,90 (barley). Life span of the crop is also significantly related to infection of wheat lines (r = +0,76). Moreover, lines of hard wheat (Neepawa, BW-20, Sinton) are all less infected than lines of soft wheat, just as lines of malting barley (OAC 21, Conquest, Bonanza) are all less infected than feed barley types.

Gas Exchange Responses to CO2 Concentration Instantaneously Elevated in Flag Leaves of Winter Wheat Cultivars Released in Different Years

2002 ◽  
Vol 40 (2) ◽  
pp. 237-242 ◽  
Author(s):  
H.Q. Liu ◽  
G.M. Jiang ◽  
Q.D. Zhang ◽  
J.Z. Sun ◽  
R.J. Guo ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Winter Wheat ◽  
Wheat Cultivars ◽  
Flag Leaves ◽  
Winter Wheat Cultivars

scholarly journals Novel Necrotrophic Effectors from Stagonospora nodorum and Corresponding Host Sensitivities in Winter Wheat Germplasm in the Southeastern United States

2012 ◽  
Vol 102 (5) ◽  
pp. 498-505 ◽  
Author(s):  
A. D. Crook ◽  
T. L. Friesen ◽  
Z. H. Liu ◽  
P. S. Ojiambo ◽  
C. Cowger
Keyword(s):  
United States ◽  
Winter Wheat ◽  
Block Design ◽  
Southeastern United States ◽  
The United States ◽  
Stagonospora Nodorum ◽  
Wheat Cultivars ◽  
Breeding Programs ◽  
Culture Filtrates ◽  
Necrotrophic Effectors

Stagonospora nodorum blotch (SNB), caused by the necrotrophic fungus Stagonospora nodorum (teleomorph: Phaeosphaeria nodorum), is among the most common diseases of winter wheat in the United States. New opportunities in resistance breeding have arisen from the recent discovery of several necrotrophic effectors (NEs, also known as host-selective toxins) produced by S. nodorum, along with their corresponding host sensitivity (Snn) genes. Thirty-nine isolates of S. nodorum collected from wheat debris or grain from seven states in the southeastern United States were used to investigate the production of NEs in the region. Twenty-nine cultivars with varying levels of resistance to SNB, representing 10 eastern-U.S. breeding programs, were infiltrated with culture filtrates from the S. nodorum isolates in a randomized complete block design. Three single-NE Pichia pastoris controls, two S. nodorum isolate controls, and six Snn-differential wheat controls were also used. Cultivar–isolate interactions were visually evaluated for sensitivity at 7 days after infiltration. Production of NEs was detected in isolates originating in each sampled state except Maryland. Of the 39 isolates, 17 produced NEs different from those previously characterized in the upper Great Plains region. These novel NEs likely correspond to unidentified Snn genes in Southeastern wheat cultivars, because NEs are thought to arise under selection pressure from genes for resistance to biotrophic pathogens of wheat cultivars that differ by geographic region. Only 3, 0, and 23% of the 39 isolates produced SnToxA, SnTox1, and SnTox3, respectively, by the culture-filtrate test. A Southern dot-blot test showed that 15, 74, and 39% of the isolates carried the genes for those NEs, respectively; those percentages were lower than those found previously in larger international samples. Only two cultivars appeared to contain known Snn genes, although half of the cultivars displayed sensitivity to culture filtrates containing unknown NEs. Effector sensitivity was more frequent in SNB-susceptible cultivars than in moderately resistant (MR) cultivars (P = 0.008), although some susceptible cultivars did not exhibit sensitivity to NEs produced by isolates in this study and some MR cultivars were sensitive to NEs of multiple isolates. Our results suggest that NE sensitivities influence but may not be the only determinant of cultivar resistance to S. nodorum. Specific knowledge of NE and Snn gene frequencies in this region can be used by wheat breeding programs to improve SNB resistance.

scholarly journals Inheritance of Resistance to Stagonospora nodorum Leaf Blotch in Kansas Winter Wheat Cultivars

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 530-536 ◽  
Author(s):  
Yong-ki Kim ◽  
Gina L. Brown-Guedira ◽  
Thomas S. Cox ◽  
William W. Bockus
Keyword(s):  
Winter Wheat ◽  
Dominant Gene ◽  
Wheat Breeding ◽  
Stagonospora Nodorum ◽  
Inheritance Of Resistance ◽  
Single Dominant Gene ◽  
Wheat Cultivars ◽  
Stagonospora Nodorum Blotch ◽  
Winter Wheat Cultivars ◽  
The Cross

Stagonospora nodorum blotch can cause serious yield and quality losses of wheat (Triticum aestivum) in many countries worldwide. Although there are other control methods, host resistance is the most desirable. Three recent Kansas winter wheat cultivars (Betty, Heyne, and 2163) have been developed with moderate levels of resistance to the leaf phase of Stagonospora nodorum blotch. To determine inheritance of resistance and allelism, these cultivars were crossed with one of three susceptible lines (Larned, KS96WGRC39, or Newton) and intercrossed in all possible combinations, including reciprocals. The parents, F1, F2, and F3 generations were tested for resistance to S. nodorum in the greenhouse as 4-week-old seedlings. Cytoplasmic effects were not detected in any cross. The mean levels of infection in the F1s of the two crosses Betty × Larned and Heyne × KS96WGRC39 indicated resistance was dominant. The observed phenotypic ratios of F2 plants for both crosses were not significantly different from the expected ratio for a single dominant gene. The ratio observed for F3 lines in the Betty × Larned cross fit that expected for a single dominant gene. However, the observed ratio of the F3 lines from the cross Heyne × KS96WGRC39 did not fit the ratio expected for a single dominant gene. The allelism test for Betty and Heyne indicated that they have different resistance genes. The F1 mean rating of the cross 2163 × Newton was intermediate between the two parents, indicating the absence of dominance for resistance in 2163. The phenotypic ratio observed in the F2 plants from this cross did not fit the ratio expected for a single dominant gene. The simple genetic control of resistance in cv. Betty makes it a useful source of resistance for wheat breeding programs.

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