Volume 18, Issue 2 (4-2026)
J Crop Breed 2026, 18(2): 152-172 |
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Malihipour A, Najafi Mirak T, Sadeghi L, Delfan S, Omrani A. (2026). Evaluation of Durum Wheat Elite Lines for Resistance to Stem Rust (Puccinia graminis f. sp. tritici). J Crop Breed. 18(2), 152-172. doi:10.61882/jcb.2026.1642
URL: http://jcb.sanru.ac.ir/article-1-1642-en.html
URL: http://jcb.sanru.ac.ir/article-1-1642-en.html
Evaluation of Durum Wheat Elite Lines for Resistance to Stem Rust (Puccinia graminis f. sp. tritici)
1- Department of Cereal Research, Seed and Plant Improvement Institute (SPII), AREEO, Karaj, Iran
2- Department of Value of Cultivation and Use, Seed and Plant Certification Research Institute (SPCRI), AREEO, Karaj, Iran
3- Department of Crop and Horticultural Science Research, Agricultural and Natural Resources Research and Education Center of Ardabil Province (Moghan), AREEO, Parsabad, Iran
2- Department of Value of Cultivation and Use, Seed and Plant Certification Research Institute (SPCRI), AREEO, Karaj, Iran
3- Department of Crop and Horticultural Science Research, Agricultural and Natural Resources Research and Education Center of Ardabil Province (Moghan), AREEO, Parsabad, Iran
Abstract: (119 Views)
Extended Abstract
Background: Identifying disease-resistant lines for release or use in crosses is considered part of the goals of wheat breeding programs. Stem rust disease of wheat, caused by Puccinia graminis f. sp. tritici, is one of the diseases of this crop that has been a threat to wheat production since the past. Unlike bread wheat, no specialized and specific study has been conducted or published on durum wheat resistance to stem rust in Iran. In this study, 20 elite lines obtained from each of the country's durum wheat breeding programs, including temperate-2015, warm-2015, temperate-2016, and warm-2016, were evaluated for disease resistance at seedling and adult-plant stages.
Methods: To investigate seedling resistance, three sets of experimental lines, including temperate-2015, warm-2015, and temperate-2016, were evaluated against four isolates/races of stem rust pathogen, P. graminis f. sp. tritici, at the seedling stage in the greenhouses of Cereal Research Department, Seed and Plant Improvement, Karaj, Albprz Province, Iran. Seeds of wheat lines were sown in pots containing a mixture of ordinary soil and peat moss (70% and 30%, respectively). After 10 days, when the first leaf of the seedlings developed well, they were inoculated separately using the isolates/races of the pathogen. The pots containing the inoculated plants were kept in a dark room at a temperature of 18 ± 2 °C and near-saturated humidity for 24 hours and then transferred to a greenhouse at a temperature of 22 ± 2 °C with 16 hours of light per day. After 14 days, infection types of the inoculated plants were recorded on a 0–4 scale. To conduct adult-plant studies, the 2015 lines were sown during two crop years 2015-16 and 2016-17, and the 2015 lines were sown during two crop years 2016-17 and 2017-18 in late winter at the Kelardasht Cereal Research Station, Kelardasht, Mazandaran Province, Iran. Seven grams of seeds from each line were sown in a one-meter row with a distance of 20 cm from the adjacent row. While the lines from 2015 were evaluated under natural infection conditions and artificial inoculations in the first and second years of the experiment, respectively, the lines from 2016 were evaluated in both years of the experiment under artificial inoculations. Artificial inoculations were carried out at early-heading wheat stage using the fungus isolate 94-32 (TTTTF race) previously collected from the Kelardasht region and increased in the greenhouse after purification. Inoculation was carried out by spraying a mixture of fungal spores and talc powder using a backpack sprayer. The severity of the disease was recorded at the end of the wheat soft dough stage (the color of the stems changed from green to straw color) according to the percentage of stem coverage by stem rust lesions on a scale of 0-100. Simultaneously, wheat response to infection was recorded, i.e., determining the infection types of resistance (R), moderate resistance (MR), modereate susceptibile (MS), and susceptibile (S). For data analysis, infection types 0, 1, and 2 (low infection types) were regarded as resistance, and infection types 3 and 4 (high infection types) were considered susceptibility, according to the method mentioned for disease assessment at the seedling stage. In terms of resistance at the adult-plant stage, lines with disease severity of 30 or less, provided that they were not accompanied by the susceptibility infection type (S), were considered selectable lines.
Results: Results of the evaluation of all four sets of experimental lines against different isolates/races of the pathogen at seedling stage indicated diversity in the reaction of all four sets of these lines. Based on these results, nine lines (DM-94-1, DM-94-15, DM-94-20, DM-95-18, DM-95-19, DW-94-6, DW-94-8, DW-94-15, and DW-94-16) showed resistance to all four isolates/races of the pathogen, 17 lines were susceptible to them, and the remaining lines were resistant to three, two, or one isolate/race. Given that no virulence was observed on any of the four resistance genes Sr24, Sr26, Sr32, and Sr40 by the four isolates/races used, the resistance of the nine lines mentioned against these isolates/races could have been caused by one or more of these genes or other unknown resistance genes. Based on the results of adult-plant studies, wheat lines of temperate-2015 and warm-2015, evaluated for their first year (2015-016) under natural disease infection, had a relatively low disease level, and it was possible to find lines with acceptable disease levels for selection. In the second year of the experiment of 2015 lines (2016-017) and in both years of the study of 2016 lines (2016-17 and 2017-18) that the experiments were conducted under artificial disease infection, the disease level of all the experimental lines was very high without any significant difference. Even though a significant number of experimental lines showed resistance to one or more isolates collected from Kelardasht at the seedling stage under greenhouse conditions, none of them had sufficient resistance to the disease at the adult-plant stage. This is probably due to the presence of different races at the time of the adult-plant stage in the Kelardasht region compared to the races used under greenhouse conditions.
Conclusion: Although a significant number of durum wheat lines had high resistance to one or more races of the stem rust pathogen at the seedling stage, given the high susceptibilty of these lines to the races of the fungus prevalent in the adult-plant experiment station (Kelardasht), it is clear that these lines do not have sufficient resistance to more races of the pathogen. Given this and the history of the epidemics of the disease on durum wheat by some races in some parts of the world, in case of a possible epidemic of the disease in Iran, it will be necessary to consider preparation for chemical control, in addition to relying on genetic resistance.
Background: Identifying disease-resistant lines for release or use in crosses is considered part of the goals of wheat breeding programs. Stem rust disease of wheat, caused by Puccinia graminis f. sp. tritici, is one of the diseases of this crop that has been a threat to wheat production since the past. Unlike bread wheat, no specialized and specific study has been conducted or published on durum wheat resistance to stem rust in Iran. In this study, 20 elite lines obtained from each of the country's durum wheat breeding programs, including temperate-2015, warm-2015, temperate-2016, and warm-2016, were evaluated for disease resistance at seedling and adult-plant stages.
Methods: To investigate seedling resistance, three sets of experimental lines, including temperate-2015, warm-2015, and temperate-2016, were evaluated against four isolates/races of stem rust pathogen, P. graminis f. sp. tritici, at the seedling stage in the greenhouses of Cereal Research Department, Seed and Plant Improvement, Karaj, Albprz Province, Iran. Seeds of wheat lines were sown in pots containing a mixture of ordinary soil and peat moss (70% and 30%, respectively). After 10 days, when the first leaf of the seedlings developed well, they were inoculated separately using the isolates/races of the pathogen. The pots containing the inoculated plants were kept in a dark room at a temperature of 18 ± 2 °C and near-saturated humidity for 24 hours and then transferred to a greenhouse at a temperature of 22 ± 2 °C with 16 hours of light per day. After 14 days, infection types of the inoculated plants were recorded on a 0–4 scale. To conduct adult-plant studies, the 2015 lines were sown during two crop years 2015-16 and 2016-17, and the 2015 lines were sown during two crop years 2016-17 and 2017-18 in late winter at the Kelardasht Cereal Research Station, Kelardasht, Mazandaran Province, Iran. Seven grams of seeds from each line were sown in a one-meter row with a distance of 20 cm from the adjacent row. While the lines from 2015 were evaluated under natural infection conditions and artificial inoculations in the first and second years of the experiment, respectively, the lines from 2016 were evaluated in both years of the experiment under artificial inoculations. Artificial inoculations were carried out at early-heading wheat stage using the fungus isolate 94-32 (TTTTF race) previously collected from the Kelardasht region and increased in the greenhouse after purification. Inoculation was carried out by spraying a mixture of fungal spores and talc powder using a backpack sprayer. The severity of the disease was recorded at the end of the wheat soft dough stage (the color of the stems changed from green to straw color) according to the percentage of stem coverage by stem rust lesions on a scale of 0-100. Simultaneously, wheat response to infection was recorded, i.e., determining the infection types of resistance (R), moderate resistance (MR), modereate susceptibile (MS), and susceptibile (S). For data analysis, infection types 0, 1, and 2 (low infection types) were regarded as resistance, and infection types 3 and 4 (high infection types) were considered susceptibility, according to the method mentioned for disease assessment at the seedling stage. In terms of resistance at the adult-plant stage, lines with disease severity of 30 or less, provided that they were not accompanied by the susceptibility infection type (S), were considered selectable lines.
Results: Results of the evaluation of all four sets of experimental lines against different isolates/races of the pathogen at seedling stage indicated diversity in the reaction of all four sets of these lines. Based on these results, nine lines (DM-94-1, DM-94-15, DM-94-20, DM-95-18, DM-95-19, DW-94-6, DW-94-8, DW-94-15, and DW-94-16) showed resistance to all four isolates/races of the pathogen, 17 lines were susceptible to them, and the remaining lines were resistant to three, two, or one isolate/race. Given that no virulence was observed on any of the four resistance genes Sr24, Sr26, Sr32, and Sr40 by the four isolates/races used, the resistance of the nine lines mentioned against these isolates/races could have been caused by one or more of these genes or other unknown resistance genes. Based on the results of adult-plant studies, wheat lines of temperate-2015 and warm-2015, evaluated for their first year (2015-016) under natural disease infection, had a relatively low disease level, and it was possible to find lines with acceptable disease levels for selection. In the second year of the experiment of 2015 lines (2016-017) and in both years of the study of 2016 lines (2016-17 and 2017-18) that the experiments were conducted under artificial disease infection, the disease level of all the experimental lines was very high without any significant difference. Even though a significant number of experimental lines showed resistance to one or more isolates collected from Kelardasht at the seedling stage under greenhouse conditions, none of them had sufficient resistance to the disease at the adult-plant stage. This is probably due to the presence of different races at the time of the adult-plant stage in the Kelardasht region compared to the races used under greenhouse conditions.
Conclusion: Although a significant number of durum wheat lines had high resistance to one or more races of the stem rust pathogen at the seedling stage, given the high susceptibilty of these lines to the races of the fungus prevalent in the adult-plant experiment station (Kelardasht), it is clear that these lines do not have sufficient resistance to more races of the pathogen. Given this and the history of the epidemics of the disease on durum wheat by some races in some parts of the world, in case of a possible epidemic of the disease in Iran, it will be necessary to consider preparation for chemical control, in addition to relying on genetic resistance.
Keywords: Adult-plant resistance, Artificial inoculation, Epidemics, Seedling resistance, Susceptibility
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