Prevalence and importance of sensitivity to the Stagonospora nodorum necrotrophic effector SnTox3 in current Western Australian wheat cultivars

2011 ◽  
Vol 62 (7) ◽  
pp. 556 ◽  
Author(s):  
Ormonde D. C. Waters ◽  
Judith Lichtenzveig ◽  
Kasia Rybak ◽  
Timothy L. Friesen ◽  
Richard P. Oliver
Keyword(s):  
Triticum Aestivum L ◽  
Stagonospora Nodorum ◽  
Similar Reaction ◽  
Wheat Cultivars ◽  
Australian Wheat ◽  
Necrotrophic Effector ◽  
Microbial Systems ◽  
Necrotrophic Effectors ◽  
Host Specific Toxins ◽  
Western Australian

Stagonospora nodorum is a major pathogen of wheat in many parts of the world and particularly in Western Australia. The pathosystem is characterised by interactions of multiple pathogen necrotrophic effectors (NE) (formerly host-specific toxins) with corresponding dominant host sensitivity loci. To date, five NE interactions have been reported in S. nodorum. Two proteinaceous NE (ToxA and SnTox3) have been cloned and expressed in microbial systems. The identification of wheat cultivars lacking sensitivity to one or more NE is a promising way to identify cultivars suitable for use in breeding for increased resistance to this economically important pathogen. The prevalence of sensitivity to the NE SnTox3 was investigated in 60 current Western Australian-adapted bread wheat (Triticum aestivum L.) cultivars. Infiltration of SnTox3 into seedling leaves caused a moderate or strong necrotic response in 52 cultivars. Six cultivars were insensitive and two cultivars exhibited a weak chlorotic response. Five of the cultivars that were insensitive or weakly sensitive to SnTox3 were noticeably more resistant to the disease. The 60 cultivars gave a very similar reaction to SnTox3 and to the crude S. nodorum SN15 culture filtrate demonstrating that SnTox3 is the dominant NE in this isolate. We conclude that a simple screen using both SnTox3 and ToxA effectors combined with simple greenhouse disease evaluation, will allow breeders to select cultivars that are more resistant to the disease, allowing them to concentrate resources on other still intractable breeding objectives.

scholarly journals Sensitivity to three Parastagonospora nodorum necrotrophic effectors in current Australian wheat cultivars and the presence of further fungal effectors

2014 ◽  
Vol 65 (2) ◽  
pp. 150 ◽  
Author(s):  
Kar-Chun Tan ◽  
Ormonde D. C. Waters ◽  
Kasia Rybak ◽  
Eva Antoni ◽  
Eiko Furuki ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Gene Interactions ◽  
Wheat Cultivars ◽  
Septoria Nodorum Blotch ◽  
Effector Genes ◽  
Australian Wheat ◽  
Parastagonospora Nodorum ◽  
Necrotrophic Effector ◽  
Necrotrophic Effectors ◽  
Western Australian

Parastagonospora nodorum is a major fungal pathogen of wheat in Australia, causing septoria nodorum blotch (SNB). Virulence of P. nodorum is quantitative and depends largely on multiple effector–host sensitivity gene interactions. The pathogen utilises a series of proteinaceous, necrotrophic effectors to facilitate disease development on wheat cultivars that possess appropriate dominant sensitivity loci. Thus far, three necrotrophic effector genes have been cloned. Proteins derived from these genes were used to identify wheat cultivars that confer effector sensitivity. The goal of this study was to determine whether effector sensitivity could be used to enhance breeding for SNB resistance. We have demonstrated that SnTox1 effector sensitivity is common in current commercial Western Australian wheat cultivars. Thirty-three of 46 cultivars showed evidence of sensitivity to SnTox1. Of these, 19 showed moderate or strong chlorotic/necrotic responses to SnTox1. Thirteen were completely insensitive to SnTox1. Disease susceptibility was most closely associated with SnTox3 sensitivity. We have also identified biochemical evidence of a novel chlorosis-inducing protein or proteins in P. nodorum culture filtrates unmasked in strains that lack expression of ToxA, SnTox1 and SnTox3 activities.

scholarly journals Reactive Oxygen Species in Host Plant Are Required for an Early Defense Response against Attack of Stagonospora nodorum Berk. Necrotrophic Effectors SnTox

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1586
Author(s):  
Svetlana Veselova ◽  
Tatyana Nuzhnaya ◽  
Guzel Burkhanova ◽  
Sergey Rumyantsev ◽  
Igor Maksimov
Keyword(s):  
Reactive Oxygen Species ◽  
Early Stage ◽  
Reactive Oxygen ◽  
Triticum Aestivum L ◽  
Redox Status ◽  
Stagonospora Nodorum ◽  
Ros Generation ◽  
Ros Production ◽  
Oxygen Species ◽  
Necrotrophic Effectors

Reactive oxygen species (ROS) play a central role in plant immune responses. The most important virulence factors of the Stagonospora nodorum Berk. are multiple fungal necrotrophic effectors (NEs) (SnTox) that affect the redox-status and cause necrosis and/or chlorosis in wheat lines possessing dominant susceptibility genes (Snn). However, the effect of NEs on ROS generation at the early stages of infection has not been studied. We studied the early stage of infection of various wheat genotypes with S nodorum isolates -Sn4VD, SnB, and Sn9MN, carrying a different set of NE genes. Our results indicate that all three NEs of SnToxA, SnTox1, SnTox3 significantly contributed to cause disease, and the virulence of the isolates depended on their differential expression in plants (Triticum aestivum L.). The Tsn1–SnToxA, Snn1–SnTox1and Snn3–SnTox3 interactions played an important role in inhibition ROS production at the initial stage of infection. The Snn3–SnTox3 inhibited ROS production in wheat by affecting NADPH-oxidases, peroxidases, superoxide dismutase and catalase. The Tsn1–SnToxA inhibited ROS production in wheat by affecting peroxidases and catalase. The Snn1–SnTox1 inhibited the production of ROS in wheat by mainly affecting a peroxidase. Collectively, these results show that the inverse gene-for gene interactions between effector of pathogen and product of host sensitivity gene suppress the host’s own PAMP-triggered immunity pathway, resulting in NE-triggered susceptibility (NETS). These results are fundamentally changing our understanding of the development of this economical important wheat disease.

Haploid production of Australian wheat (Triticum aestivum L.) cultivars through wheat × maize (Zea mays L.) crosses

1997 ◽  
Vol 48 (8) ◽  
pp. 1207 ◽  
Author(s):  
K. Suenaga ◽  
A. R. Morshedi ◽  
N. L. Darvey
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Zea Mays L ◽  
Culture Method ◽  
Triticum Aestivum L ◽  
Wheat Cultivars ◽  
Culture Methods ◽  
Haploid Production ◽  
Australian Wheat ◽  
Haploid Embryos

In order to reduce the labour for wheat haploid production through wheat maize crosses, several emasculation methods were investigated in combination with the ‘spike culture method’. Although the standard method whereby wheat spikes were hand-emasculated and pollinated on the day of anthesis gave a higher efficiency, the ‘non-emasculation method’ gave a comparable response. The use of the non-emasculation method and spike culture could eliminate much of the labour required for emasculation and treatment with 2,4-D, which is normally applied by injection into wheat internodes or by dropping onto florets after pollination with maize. Most of the selfed seeds were easily identified by the presence of endosperm, and the probability of contamination by the embryos originating from selfing among the presumptive haploid embryos in the non-emasculation method was very low. Twenty-seven Australian wheat cultivars were investigated for haploid production through wheat × maize crosses using the non-emasculation and spike culture methods. All of the 27 cultivars produced embryos after crossing with maize, with a mean efficiency of 33·1% (embryos/florets). Except for one cultivar, Tincurrin, plants were recovered from all of the cultivars (average of 61·5% including Tinccurin). This innovation of haploid production through wheat maize crosses is discussed.

scholarly journals Genes Conferring Sensitivity to Stagonospora nodorum Necrotrophic Effectors in Stagonospora Nodorum Blotch-Susceptible U.S. Wheat Cultivars

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 746-753 ◽  
Author(s):  
Matthew Bertucci ◽  
Gina Brown-Guedira ◽  
J. Paul Murphy ◽  
Christina Cowger
Keyword(s):  
United States ◽  
Southeastern United States ◽  
Stagonospora Nodorum ◽  
Wheat Cultivars ◽  
Perfect Agreement ◽  
Stagonospora Nodorum Blotch ◽  
Diagnostic Potential ◽  
Moderately Resistant ◽  
Necrotrophic Effectors ◽  
Sensitivity Gene

Stagonospora nodorum is a necrotrophic fungal pathogen that causes Stagonospora nodorum blotch (SNB), a yield- and quality-reducing disease of wheat. S. nodorum produces a set of necrotrophic effectors (NEs) that interact with the products of host sensitivity genes to cause cell death and increased susceptibility to disease. The focus of this study was determination of NE sensitivity among 25 winter wheat cultivars, many of them from the southeastern United States, that are susceptible to SNB, as well as the moderately resistant ‘NC-Neuse’. Thirty-three isolates of S. nodorum previously collected from seven southeastern U.S. states were cultured for NE production, and the culture filtrates were used in an infiltration bioassay. Control strains of Pichia pastoris that expressed SnToxA, SnTox1, or SnTox3 were also used. All SNB-susceptible cultivars were sensitive to at least one NE, while NC-Neuse was insensitive to all NEs tested. Among the sensitive lines, 32% contained sensitivity gene Tsn1 and 64% contained sensitivity gene Snn3. None were sensitive to SnTox1. Additionally, 10 molecular markers for sensitivity genes Tsn1, Snn1, Snn2, and Snn3 were evaluated for diagnostic potential. Only the marker Xfcp623 for Tsn1 was diagnostic, and it was in perfect agreement with the results of the infiltration bioassays. The results illuminate which NE sensitivity genes may be of concern in breeding for resistance to SNB in the southeastern United States.

Differential responses of Australian wheat cultivars to cadmium concentration in wheat grain

1995 ◽  
Vol 46 (5) ◽  
pp. 873 ◽  
Author(s):  
DP Oliver ◽  
JW Gartrell ◽  
KG Tiller ◽  
R Correll ◽  
GD Cozens ◽  
...  
Keyword(s):  
Selection Process ◽  
Cadmium Concentration ◽  
Wheat Variety ◽  
Wheat Cultivars ◽  
Wheat Grain ◽  
Cd Accumulation ◽  
Australian Wheat ◽  
Breeding Selection ◽  
A Site ◽  
Western Australian

Cadmium concentration in grain was studied for wheat cultivars grown nationally in the Interstate Wheat Variety (IWV) experiments (1988 and 1989) and cultivars grown in the Western Australian (WA) experiments (1990-1992). These experiments covered a range of differing soil and environmental conditions. The adaptation of these cultivars to changes in cadmium potential at a site was determined. Significant cultivar effects were identified, but these were less significant than the site effects. The Cd concentrations in grain exceeded the current Australian maximum permitted concentration (MPC) of 0.05 mg kg-1 at one site in the IWV experiments while the concentration exceeded the MPC at a larger proportion of sites in the WA experiments. Several trends in cultivar accumulation of Cd in grain were evident. Reeves and Kulin were found to have the highest Cd concentration at a number of sites for several years in both the IWV and WA experiments. The similar pedigrees of these two cultivars suggest that while wheat breeders were selecting for certain traits during the breeding selection process, they were inadvertently selecting for the ability to accumulate Cd. In the 1992 WA cultivar experiments, generally Aroona had the highest Cd concentration in grain. Aroona has different pedigree to Reeves and Kulin. Several of the cultivars that were low Cd accumulators also had similar pedigrees. This indicates that there is potential for selecting lines that are low Cd accumulators to be grown in areas where Cd accumulation in grain is a problem.

The application of n-butanol improves embryo and green plant production in anther culture of Australian wheat (Triticum aestivum L.) genotypes

2011 ◽  
Vol 62 (10) ◽  
pp. 813 ◽  
Author(s):  
Sue Broughton
Keyword(s):  
Triticum Aestivum ◽  
Anther Culture ◽  
Doubled Haploids ◽  
Triticum Aestivum L ◽  
Green Plant ◽  
Plant Production ◽  
Wheat Cultivars ◽  
Green Plants ◽  
Australian Wheat ◽  
New Treatments

The objective of this study was to improve the production from anther culture of embryos and green plants in Australian spring wheat genotypes by testing new treatments such as n-butanol, as well as other protocol modifications. To date, the use of n-butanol to enhance embryogenesis has only been tested in two European wheat cultivars; this is the first study which demonstrates its application across a range of breeding crosses. A 5-h treatment using 0.1 or 0.2% (v/v) n-butanol following anther pretreatment on a solid mannitol medium significantly improved the production of embryos, green plants and doubled haploids in a range of Australian wheat crosses and varieties. Green plant production increased between 3- and 6-fold in the crosses Yitpi/2*Bumper, Tammarin Rock/2*Bumper and Tammarin Rock/2*Magenta. The addition of calcium (Ca) and macronutrients to the mannitol pretreatment medium also significantly improved the number of embryos and green plants in varieties and crosses, but only when used in combination with n-butanol treatment. A factorial experiment with four varieties and two treatments (n-butanol and Ca/macronutrients) revealed significant interactions between treatments and genotype. In three of the four varieties, the application of n-butanol resulted in significant increases in embryos and green plants with either pretreatment medium although the best results were obtained with Ca and macronutrients in the pretreatment medium, with 200, 193 and 52 green plants per 100 anthers obtained for Bumper, Gladius and Magenta, respectively. In the variety Fortune however, n-butanol treatment did not improve embryo or green plant production unless it was combined with Ca and macronutrients in the pretreatment medium and then there were dramatic improvements; from 0 to 27 green plants per 100 anthers.

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.

Enhanced shoot regeneration in nine Australian wheat cultivars by spermidine and water stress treatments

2001 ◽  
Vol 28 (12) ◽  
pp. 1243 ◽  
Author(s):  
Harjeet K. Khanna ◽  
Grant E. Daggard
Keyword(s):  
Triticum Aestivum ◽  
Water Stress ◽  
Triticum Aestivum L ◽  
Callus Cultures ◽  
Dehydration Stress ◽  
Regeneration Ability ◽  
Wheat Cultivars ◽  
Regeneration Potential ◽  
Negative Effect ◽  
Australian Wheat

The regeneration potential of ageing calli initiated from isolated scutella of immature embryos was increased in nine elite Australian cultivars (QT7208, QT9685, QT7709, Kennedy, Lang, Sunvale, Giles, Petrie and Veery) of wheat (Triticum aestivum L.). Firstly, the effects of 4–32 h of dehydration stress on regeneration of 4- to 20-week old calli were evaluated. Cultivars such as Veery, Kennedy and Sunvale showed significant improvement in regeneration from calli up to 12-weeks old that had undergone 16 h of dehydration stress. Secondly, 4- to 20-week old callus cultures were treated with 0.05–5 mM spermidine to evaluate its effect on regeneration. While spermidine had a negative effect on regeneration from 4-week old calli at all tested concentrations (as compared with untreated controls), there was a 3–50% improvement in the regeneration ability of older calli (16- to 20-week old) of all cultivars. Finally, exogenous application of 1 mM spermidine to 16-week old cultures, in combination with 16 h dehydration stress, improved plant regeneration by 10–65% in all nine cultivars.

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