Distribution and temperature sensitivities of genes for stem rust resistance in Australian oat cultivars and selected germplasm

Seedlings of 40 Australian oat cultivars and 154 elite oat lines were tested with various pathotypes of P. graminis avenae. Fourteen cultivars carried Pg-2 and/or Pg-4. One cultivar carried Pg-13 and 4 carried Pg-a. Several cultivars possessed different combinations of Pg-1, Pg-2, Pg-3, and/or Pg-4, but none possessed Pg-8 or Pg-9. Since most elite lines were resistant to all cultures collected from the pathogenicity survey in 1993 and gave similar low infection types, it was postulated that they all carried a common gene, Pg-a. All isolates from the 1993 survey, except one from northern New South Wales, were avirulent for Pg-a. Studies of the effect of temperature on reaction to stem rust showed that resistances in lines possessing Pg-8 and Pg-16 became ineffective at 21.5°C, but were effective at 17°C. Similarly, resistances in lines possessing Pg-4, Pg-12, and Pg-a were effective at 21.5°C, but became ineffective at or above 26°C. Resistances conferred by Pg-1, Pg-2, Pg-13, and Pg-Sa were not affected by temperature. Although resistance conferred by Pg-a was temperature-sensitive, the retardation of fungal growth with decrease in temperature suggested that increasing day temperatures would not cause the breakdown of this resistance provided night temperatures remain cool.

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Virulence Characterization of Puccinia graminis f. sp. avenae and Resistance of Oat Cultivars in China

Plant Disease ◽

10.1094/pdis-06-21-1239-re ◽

2021 ◽

Author(s):

Tianya Li ◽

Yiwei Xu ◽

Xue Zhang ◽

Xian Xin Wu ◽

Yazhao Zhang ◽

...

Keyword(s):

Stem Rust ◽

Rust Resistance ◽

Cost Effective ◽

Stem Rust Resistance ◽

Adult Plant ◽

Puccinia Graminis ◽

Resistant Cultivars ◽

Oat Cultivars ◽

First Time

Oat stem rust, caused by Puccinia graminis f. sp. avenae (Pga), is one of the most devastating diseases of oat. The most cost-effective and eco-friendly strategy to control this disease is the use of resistant cultivars. However, P. graminis f. sp. avenae can overcome the resistance of cultivars by rapidly changing its virulence. Thus, information on the virulence of P. graminis f. sp. avenae populations and resistance of cultivars is critical to control the disease. The current study was conducted to monitor the virulence composition and dynamics in the P. graminis f. sp. avenae population in China and to evaluate resistance of oat cultivars. Oat leaves naturally infected by P. graminis f. sp. avenae were collected during 2018 and 2019 and 159 isolates were derived from single uredinia. The isolates were tested on 12 international differential lines, and eight races, TJJ, TBD, TJB, TJD, TJL, TJN, TGD, and TKN, were identified for the first time in China. The predominant race was TJD, virulent against Pg1, Pg2, Pg3, Pg4, Pg8, Pg9, and Pg15, accounting for 35.8% and 37.8% in 2018 and 2019, respectively. The sub-predominant races were TJN (30.2% in 2018, 28.3% in 2019) and TKN (20.8% in 2018, 12.3% in 2019). All isolates were virulent to Pg1, Pg2, Pg3, and Pg4, and avirulent to Pg6 and Pg16. The three predominant races (TJD, TJN, and TKN) were used to evaluate resistance in 30 Chinese oat cultivars at the seedling and adult-plant stages. Five cultivars, Bayan 1, Baiyan 2, Baiyan 3, Baiyan 5, and Baiyan 9, were highly resistant to the three races at both seedling and adult-plant stages. The results of the virulences and frequencies of P. graminis f. sp. avenae races and the resistant cultivars will be useful in understanding the pathogen migration and evolution and for breeding oat cultivars with stem rust resistance.

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The Spread of Stem Rust Caused by Puccinia graminis f. sp. tritici, with Virulence on Sr31 in Wheat in Eastern Africa

Plant Disease ◽

10.1094/pd-90-0113a ◽

2006 ◽

Vol 90 (1) ◽

pp. 113-113 ◽

Cited By ~ 106

Author(s):

R. Wanyera ◽

M. G. Kinyua ◽

Y. Jin ◽

R. P. Singh

Keyword(s):

Stem Rust ◽

Rust Resistance ◽

Infection Type ◽

Single Gene ◽

Stem Rust Resistance ◽

Eastern Africa ◽

Puccinia Graminis ◽

High Infection ◽

Infection Types ◽

Sr Genes

Stem rust resistance in wheat cultivars with Sr31 has been effective and durable worldwide for more than 30 years. Isolates of Puccinia graminis f. sp. tritici with virulence to Sr31 were detected in Uganda in 1999 (1). During 2003 and 2004, a majority of current Kenyan cultivars and a large portion of CIMMYT wheat germplasm with gene Sr31 planted in Kenya were susceptible to stem rust. Six isolates collected during 2004 at different locations in Kenya were tested for virulence on the 16 North American stem rust race differentials with the following Sr genes: Sr5, 6, 7b, 8a, 9a, 9b, 9d, 9e, 9g, 10, 11, 17, 21, 30, 36, and Tmp. An extended set of designated Sr genes (Sr13, 19, 22, 24, 25, 26, 29, 31, 32, 33, 35, 37, 39, 40, 44, and Wld-1) was also tested at the seedling stage. An isolate from Uganda collected in 1999 with virulence on Sr31 was used for comparison. Urediniospores suspended in a lightweight mineral oil were inoculated onto 7-day-old seedlings. Inoculated plants were placed in a dew chamber for 14 h at 18°C in the dark and then for an additional period of 3 to 4 h placed under fluorescent light. Plants were incubated in a greenhouse at 18 ± 2°C with a photoperiod of 16 h. Infection types (IT), described by Stakman et al. (3), were assessed after 14 days postinoculation. All isolates from Kenya exhibited a low infection type (IT 0) on line W2691SrTt-1 (donor of Sr36), a low infection type (IT 2) on cv. Triumph 64 (donor of SrTmp), and high infection types (IT 3 or 4) on all other lines in the differential set (2); thus these isolates were keyed to race TTKS. The virulence pattern of the isolate collected in 1999 from Uganda was identical to that from Kenya on the differential set and on the extended set of designated Sr genes. In this study, these isolates produced a high infection type (IT 3) on Einkorn and CnSSr21Tm (a derivative of Triticum monococcum in Chinese Spring background), two sources of Sr21 used in our study, whereas the isolate with Sr31-virulence from Uganda in 1999 was reported to be avirulent on Sr21 (1). These isolates produced high infection types on single gene lines with Sr31 and winter wheat cvs. Custer, Foster, GA-Dozier, Patton, and Pioneer 26R61, which were known to carry the 1BL.1RS translocation with Sr31. These isolates were also virulent on SrWld-1, a gene used in spring wheat for its resistance to North American stem rust isolates. In addition to Sr36 and SrTmp, other stem rust resistance genes that were effective against TTKS at the seedling stage include Sr13, 22, 24, 25, 26, 27, 29, 32, 33, 35, 37, 39, 40, and 44. Cultivars, breeding germplasm, and single gene lines are currently being evaluated for adult plant reaction in Kenya. Results from this study indicated that stem rust isolates with virulence on Sr31 are now wide spread in the Eastern Africa highlands and pose a threat to wheat production in the region, as well as in other wheat production areas where Sr31 resistance is important. A rapid deployment of effective resistance genes to this race in breeding programs throughout Eastern Africa and Asia is needed to reduce this threat. References: (1) Z. A. Pretorius et al. Plant Dis. 84:203, 2000. (2) A. P. Roelfs and J. W. Martens. Phytopathology 78:526, 1988. (3) E. C. Stakman et al. U.S. Department of Agriculture. ARS E-617, 1962.

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Specificity of a Rust Resistance Suppressor on 7DL in the Spring Wheat Cultivar Canthatch

Phytopathology ◽

10.1094/phyto-09-14-0261-r ◽

2015 ◽

Vol 105 (4) ◽

pp. 477-481 ◽

Cited By ~ 2

Author(s):

Mina Talajoor ◽

Yue Jin ◽

Anmin Wan ◽

Xianming Chen ◽

Sridhar Bhavani ◽

...

Keyword(s):

Spring Wheat ◽

Resistance Genes ◽

Stem Rust ◽

Rust Resistance ◽

Suppressor Gene ◽

Stem Rust Resistance ◽

B Genome ◽

Infection Types ◽

Stem Rust Resistance Genes ◽

Rust Resistance Genes

The spring wheat ‘Canthatch’ has been shown to suppress stem rust resistance genes in the background due to the presence of a suppressor gene located on the long arm of chromosome 7D. However, it is unclear whether the suppressor also suppresses resistance genes against leaf rust and stripe rust. In this study, we investigated the specificity of the resistance suppression. To determine whether the suppression is genome origin specific, chromosome location specific, or rust species or race specific, we introduced 11 known rust resistance genes into the Canthatch background, including resistance to leaf, stripe, or stem rusts, originating from A, B, or D genomes and located on different chromosome homologous groups. F1 plants of each cross were tested with the corresponding rust race, and the infection types were scored and compared with the parents. Our results show that the Canthatch 7DL suppressor only suppressed stem rust resistance genes derived from either the A or B genome, and the pattern of the suppression is gene specific and independent of chromosomal location.

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Usefulness of Gene Pg10 as a Source of Stem Rust Resistance in Oat Breeding

Phytopathology ◽

10.1094/phyto.1999.89.12.1214 ◽

1999 ◽

Vol 89 (12) ◽

pp. 1214-1217 ◽

Cited By ~ 8

Author(s):

Donald E. Harder

Keyword(s):

Resistance Gene ◽

Stem Rust ◽

Rust Resistance ◽

Single Gene ◽

Stem Rust Resistance ◽

Complementary Effect ◽

Effective Level ◽

Infection Types ◽

Moderate Resistance ◽

Oat Breeding

Infection types produced by Puccinia graminis f. sp. avenae on plants of Avena sativa with the stem rust resistance gene Pg10 are characterized by moderate-sized uredinia surrounded by an area of chlorosis and a larger variable zone of dark brown necrosis. This study was undertaken to assess the effectiveness of gene Pg10 as a source of resistance to stem rust and to determine the interactions of this gene with other common Pg genes. A derived Pg10 line was tested with 58 distinct pathotypes of P. graminis f. sp. avenae and was crossed to substituted single-gene lines carrying the resistance gene Pg1, Pg2, Pg3, Pg4, Pg8, Pg9, Pg13, Pg15, Pg16, or Pga. The Pg10 line showed moderate resistance to all 58 patho-types, and there was no indication of specificity in virulence by any isolate. Gene Pg10 was inherited independently of the other Pg genes and had a complementary effect on the expression of resistance by these genes. An effective level of resistance conferred by Pg10 was demonstrated in a field nursery artificially inoculated with P. graminis f. sp. avenae. It was concluded that Pg10 is a potentially useful source of stem rust resistance in oat breeding, with its main attributes being an apparent broad base of resistance, ease of combining with other Pg genes, and complementary effects on the expression of other Pg genes

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Characterization of Seedling Infection Types and Adult Plant Infection Responses of Monogenic Sr Gene Lines to Race TTKS of Puccinia graminis f. sp. tritici

Plant Disease ◽

10.1094/pdis-91-9-1096 ◽

2007 ◽

Vol 91 (9) ◽

pp. 1096-1099 ◽

Cited By ~ 181

Author(s):

Y. Jin ◽

R. P. Singh ◽

R. W. Ward ◽

R. Wanyera ◽

M. Kinyua ◽

...

Keyword(s):

Resistance Genes ◽

Stem Rust ◽

Rust Resistance ◽

Stem Rust Resistance ◽

Adult Plant ◽

Puccinia Graminis ◽

Plant Infection ◽

Infection Types ◽

Sr Genes ◽

Seedling Infection

Stem rust, caused by Puccinia graminis f. sp. tritici, historically was one of the most destructive diseases of wheat and barley. The disease has been under effective control worldwide through the widespread use of host resistance. A number of stem rust resistance genes in wheat have been characterized for their reactions to specific races of P. graminis f. sp. tritici. Adult plant responses to race TTKS (also known as Ug99) of monogenic lines for Sr genes, a direct measurement of the effectiveness for a given gene, have not been investigated to any extent. This report summarizes adult plant infection responses and seedling infection types for monogenic lines of designated Sr genes challenged with race TTKS. High infection types at the seedling stage and susceptible infection responses in adult plants were observed on monogenic lines carrying Sr5, 6, 7a, 7b, 8a, 8b, 9a, 9b, 9d, 9g, 10, 11, 12, 15, 16, 17, 18, 19, 20, 23, 30, 31, 34, 38, and Wld-1. Monogenic lines of resistance genes Sr13, 22, 24, 25, 26, 27, 28, 32, 33, 35, 36, 37, 39, 40, 44, Tmp, and Tt-3 were effective against TTKS both at the seedling and adult plant stages. The low infection types to race TTKS observed for these resistance genes corresponded to the expected low infections of these genes to other incompatible races of P. graminis f. sp. tritici. The level of resistance conferred by these genes at the adult plant stage varied between highly resistant to moderately susceptible. The results from this study were inconclusive for determining the effectiveness of resistance genes Sr9e, 14, 21, and 29 against race TTKS. The understanding of the effectiveness of individual Sr genes against race TTKS will facilitate the utilization of these genes in breeding for stem rust resistance in wheat.

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