جستجوی مقالات مرتبط با کلیدواژه "adult plant resistance" در نشریات گروه "گیاهپزشکی"

Stem rust of wheat caused by Puccinia graminis f. sp. tritici, the most important disease of wheat in the past, is currently a potential threat to wheat production. The present research was conducted to determine the reaction of 38 elite lines of temperate agro-climate breeding program including 20 lines obtained from this program in 2015 (ERWYT-M-94) and 18 lines from 2016 (ERWYT-M-95) at seedling and adult-plant stages. Investigating seedling stage resistance was carried out by determining the reaction of experimental lines to three common races of Kelardasht, Mazandaran and one Ug99 race from Shavour, Khouzestan in the greenhouse. Investigating adult-plant resistance was carried out under field conditions in Kelardasht during two cropping years of 2015-16 and 2016-2017 for ERWYT-M-94 lines and two cropping years of 2016-2017 and 2017-2018 for ERWYT-M-95 lines. Results showed that the experimental lines had different reactions to disease at both seedling and adult-plant stages. At the seedling stage, the most lines with low infection type (resistance) were observed against the isolate 94-15 (race PTRTF), followed by the isolates 94-32 (race TTTTF), 95-95 31 (race TKTTF), and 2-95 (race TTKTK). In terms of adult-plant resistance, most of the lines had a lower disease rate compared to the susceptible check, and among them four lines of M-94-2, M-94-5, M-94-15 and M-94-16 from ERWYT-M-94 and three lines of M-95-2, M-95-9 and M-95-15 from ERWYT-M-95 were less susceptible compared to other lines. The reason for this could be the presence of adult-plant resistance genes in these lines.

Rusts have always been considered as important diseases of wheat, have significant economic losses worldwide and cultivation of resistant cultivars is the most effective way to control the disease. This research project was conducted in order to evaluate reaction of 101 advanced and commercial wheat genotypes of Iran to wheat leaf rust at seedling and adult plant stages with artificial inoculation. These genotypes were evaluated in two cropping years of 2020 and 2021 in Dezful, Gorgan, Ardabil and Moghan under field conditions. In Karaj, resistance of genotypes was evaluated at seedling stage and under greenhouse conditions using four wheat leaf rust pathotypes with a specific virulence/avirulence formula. According the results of the present study, 63 percent of the genotypes of the South warm and dry zone, 96 percent of the genotypes of the North warm and humid zone, 26 percent of the genotypes of the cold zone, 57 percent of the genotypes of the moderate zone, 10 percent of the genotypes of the salinity program, and all durum wheat genotypes responded acceptable level of resistance. Under seedling conditions, 33 percent of the genotypes were resistant to four wheat leaf rust pathotypes. In this study, five cultivars Aflak, Shoush, Sirvan, Zarrineh and Ehsan were resistant in field conditions but reacted susceptibility to four leaf rust pathotypes at the seedling stage. It seems that these cultivars probably have adult plant resistance gene or genes.

Kalhaydari is a tall, drought tolerant and rain-fed cultivar which has been a dominant rain-fed cultivar in Fars and Kohgelouyeh and Boyerahmad provinces for a long time (more than 70 years). However, this superior cultivar is susceptible to yellow rust, caused by Puccinia striiformis f. sp. tritici. Yellow rust causes a severe damage to this cultivar in high rainfall years. The aim of the present study was to transfer two seedling resistance genes (Yr5 and Yr15) and two adult plant resistance genes (Yr18 and Yr29) from standard lines to this cultivar using marker assisted backcross. In four separate breeding projects, Kalhaydari was crossed with four donor parents including Yr5/6*Avocet'S', Yr15/6*Avocet'S', Lalbahadur/Pavon and Opata 85 to transfer Yr5, Yr15, Yr18 and Yr29 genes, respectively. The first generation (F1) was backcrossed with Kalhaydari (BC1F1). In the offspring, selection for desirable genotypes was performed using markers assisted selection. Then, offspring carrying the favorable genes were entered the second backcross. The third backcross was performed using the same method. After a few more backcrosses and a selfing generation four yellow rust-resistant lines with the same genetic background, Kalhaydari cultivar, will be created. Durable resistance can be achieved using genes pyramiding.

Identification the sources of seedling and adult plant resistance genes is important for gene pyramiding, gene deployment, and developing durable wheat cultivars to control the leaf rust with Puccinia triticinea Erickss agent. In this study, 218 Iranian wheat genotypes collected from different regions were cultivated in one-meter lines in the experimental farm of Golestan Agricultural Research Station in Ahwaz during 2019-2020 and treated with Khouzestan leaf rust prevalent pathotypes including LR-98-8, LR-98-5, LR-94-5 and LR-9-4. Seedling reactions with five prevalent pathotypes were carried out in a randomized complete block design with two replications in the greenhouses of the Cereal Pathology Unit of Seed and Plant Breeding Institute, Karaj. To evaluate resistance, we used Infection Type (IT), AUDPC (Area Under Disease Progression Curve), Final Disease Severity(FDS) and Coefficient Infection (CI) indices. The results showed that 10 percent and 7 percent of the genotypes are resistant in greenhouse and field conditions, respectively. In the adult plant stage, the responses of 23 genotypes were moderately resistant (MR) and 14 genotypes were moderately susceptible (MS). The correlation coefficients between the final disease severity, with the coefficient infection and rAUDPC were 0.989 and 0.949, respectively. Finally, 30 genotypes with the desired characteristics, ie final disease severity between 0-40%, coefficient of infection between 0-40 and rAUDPC between 0-30% were selected as the suitable genotypes. Cluster analysis classified the genotypes into four groups: susceptible (S), moderately susceptible (MS), moderately resistant (MR) and resistant (R).

Wheat yellow rust, caused by Puccinia striiformis f. sp. titici , is one of the most important and most destructive diseases of wheat in many parts of Iran, which decreases crop yield in epidemic years. Host resistance is the most economical method for the management of yellow rust and partial resistance (a type of quantitative resistance), proven to be more durable than other types of resistances. In this study, partial resistance parameters including coefficient of infection (CI), final disease severity (FDS), relative area under disease progress curve (rAUDPC) and apparent infection rate (r) were evaluated in a set of twenty-four wheat genotypes along with susceptible control during two crop years from 2015 to 2016. The research was conducted at Allarough Agricultural Research Station in Ardabil, under natural and artificial inoculation conditions. Artificial infection of genotypes was performed using the yellow rust race population having virulence for Yr2, Yr6, Yr7, Yr9, Yr17, Yr22, Yr22, Yr23, Yr24, Yr25, Yr26, Yr27, Yr26, Yr27, Yr21, Yr21, Yr31, Yr32 and YrSU resistance genes. Seedling response was also evaluated under field conditions. The evaluation of resistance parameters showed that six lines were resistant at both seedling and adult plant stages. Eleven lines showed resistance reaction at seedling stage, but moderate or susceptible reactions at adult plant stage. Seven lines (entries; 1, 4, 7, 8, 9, 16, 22) were susceptible at the seedling and had moderate (MR, M or MS) reactions at adult plant stages. Therefore, these lines having low values ​​of different resistance parameters are likely to have varying degrees of partial resistance or high temperature adult plant resistance (a type of non-specific or durable resistance). Cluster analysis based on the reaction of seedling and adult plant, divided the lines into different groups, which also indicated a high diversity of lines in response to yellow rust disease.

Stripe (yellow) rust of barley (Hordeum vulgare L.), caused by Puccinia striiformis f. sp. hordei, is one of the most important diseases of barley in many parts of the world which can cause yield losses due to severe epidemics. Stripe rust of barley is become increasingly important in some parts of Iran due to the cultivation of susceptible cultivars and or appearing new pathotypes. Yield losses of 30 to 70 % occurred in these regions. New, more effective fungicides are available to control yellow rust, but the most efficient, economical, and environmentally friendly approach, is to grow resistant cultivars. It should be noted that the majority of designated Yr-genes are race-specific and therefore become ineffective in combating current pathogen populations due to development of new races. The average lifetime of the genes conferring race-specific resistance is estimated to be five years on the global basis. An alternative procedure for wheat breeders is the use of quantitative resistance. Two types of quantitative resistance, including high-temperature adult-plant (HTAP) resistance and slow rusting resistance, have been intensively investigated. Although several studies have been carried out for assessment of different barley genotypes to yellow rust in Iran, no research has been reported on the screening of barley cultivars for different pathotypes of barley and wheat yellow rusts.
In order to, resistance evaluation, seedling and adult plant reactions of 30 barley cultivars were evaluated to yellow rust. The seedling reaction was evaluated in a greenhouse using four barley pathotypes (PSH-51, PSH-84, PSH-85, and PSH-89) and one wheat pathotype (6E150A, Yr27). The seedling reactions were recorded under greenhouse conditions, based on a 0-to-9 scale. Race population was considered avirulent on the differential set when there were either no symptoms (IT 0) or there were necrotic or chlorotic flecks (IT 1), necrotic or chlorotic blotches without sporulation (IT 2), or necrotic or chlorotic blotches with only a trace to slight sporulation (IT 3 to 4). Race population was considered to be virulent if it caused moderate to abundant sporulation, with or without necrosis or chlorosis (IT 5, 6, 7, 8, or 9).
Adult plant resistance was also evaluated by measuring final rust severity (FRS) and coefficient of infection (CI) under natural infection conditions with two times artificial inoculations. Artificial inoculation, during 2010-2011 cropping years, was carried out by barley and wheat yellow rust inoculum. Percent severity was recorded three times, starting when check reached 50% severity according to the modified Cobb,s scale, and reaction based on Roelfs et al. (1992). The coefficient of infection (CI) was calculated by multiplying disease severity (DS) and constant values of infection type (IT). The constant values for infection types were used based on; resistant (R) =0.1, moderately resistant (MR)=0.25, moderate or moderately resistant to moderately susceptible (M)=0.5, moderately susceptible (MS)=0.75, susceptible (S)=1.
Results of evaluations for resistance parameters showed that cultivars Eram, D10, Shori-5, Topper, Afzal, Goharjow and Torsh had susceptible reaction at seedling stage and the high values of FRS and CI, therefore were selected as susceptible cultivars. The cultivars Emir, Asterix and Makouee were resistant both at the seedling and adult plant stages, so they carry race-specific resistance genes against all used-pathotypes. Six cultivars showed resistant at seedling at least against pathotype PSH-85, but moderate or susceptible reactions at adult plant stage in Ardabil. The thirteen cultivars (entries; 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 26), was susceptible at the seedling at least against one pathotype, but had moderate (MR, M or MS) reactions at adult plant stages.
The results of the current study showed that the cultivars had a diversity of reactions, ranging from complete resistance to full susceptibility. Most of the evaluated cultivars exhibited moderate or low performance under high disease pressure shown by the susceptible check. The resistance of all categories (including complete resistance, to partial resistance) to stripe rust was observed. The cultivars having the low level of different parameters supposed to be having gene/s for varying degrees of slow rusting resistance or high-temperature adult-plant (HTAP) resistance. Cluster analysis of barley cultivars based on adult plant resistance parameters and seedling infection types revealed different groups/clusters which indicate considerable diversity for a level of resistance of these barley cultivars.

Responses of twenty four selected wheat genotypes including commercial cultivars and isogenic lines against the yellow rust (Puccinia striiformis f. sp. tritici; 6E158A pathotype) were evaluated in Kermanshah province, Iran. Infection type and disease severity as the resistance characteristics were studied in greenhouse and field conditions for seedlings and adult plants respectively. Cluster analysis of seedling stages based on infection type indicated that 8% of the genotypes had probably resistant genes with minor while major effects and other genotypes were controlled by major effect genes. Area under disease progress curve (AUDPC) and relative area under disease progress curve (rAUDPC) criteria were calculated for wheat genotypes in adult plants stages. Cluster analysis using infection type of the first leaf data showed that 29% of the genotypes were susceptible in seedling and adult plant stages; 8% of genotypes were sensitive in the seedling stage but resistant in the adult stage. Additionally, it was found that 25% of the genotypes were resistant in whole periods of growth. High significant correlation (P≤0.01) was calculated for the infection type of the first leaf and two other parameters included AUDPC of flag leaf and infection coefficient.

Yellow (stripe) rust caused by Puccinia striiformis f. sp. tritici is an important disease that threatens wheat production worldwide. Host resistance is the most economical strategy to manage wheat stripe rust. For this purpose، 18 promising wheat lines of moderate zone were evaluated against yellow rust in Ardabil in order to determine their resistance level. The seedling reaction was evaluated in greenhouse by using race 6E150A+، Yr27. Adult plant resistance was also evaluated by measuring of final rust severity (FRS) and coefficient of infection (CI) under field infection conditions with two times artificial inoculations. Artificial inoculation was carried out using yellow rust race population virulent resistance genes including Yr2، Yr6، Yr7، Yr9، Yr22، Yr23، Yr24، Yr25، Yr26، Yr27، YrA، and YrSU. Field evaluation was conducted based on randomized complete block design with three replications during 2011-2012 cropping season at Ardabil Agricultural Research Station (Iran). Results showed that lines M-90-13، M-90-15، M-90-18 along with susceptible check (Bolani) had the highest values of FRS and CI. The lines M-90-2، M-90-4، M-90-5، M-90-7، M-90-8، M-90-13 and M-90-17 were susceptible at the seedling stage and had low level infection at the adult plant stage. Consequently، these lines had different levels of durable resistance based on the results of this investigation and their pedigree information. The remaining lines that had low level of infection at the seedling and adult plant stages were selected as moderately resistant or resistant lines.

Twenty promising wheat lines together with tow susceptible control cultivars Bolani and Morocco were evaluated for slow rusting resistance in Ardebil during 2013-2014 cropping season. Different components of slow rusting including coefficient of infection (CI), final rust severity (FRS), relative area under diseas progress curve (rAUDPC) and apparent infection rate(r) were assessed at both seedling and adult plant stages under filed condition. Pustule size and pustule density were also measured at both grow stages. The results showed that lines  M-91-17 and  M-91-4 were susceptible or moderately susceptible at seedling stage but resistant or immune at adult plant stage which indicates the presence of adult plant resistance in these lines. Lines  M-91-18, M-91-20, M-91-5, M-91-6 and M-91-7 were moderately resistant at seedling stage but showed favorable levels of slow rusting at adult plant stage. Lines  M-91-13, M-91-14,  M-91-12 and M-91-8 which were susceptible at seedling stage and showed higher levels of slow rusting at adult plant steges, seems to pocess some adult plant recsistant genes. Susceptible control cultivars  had the highest r, CI, FRS, rAUDPC, pustule density and pustule size. Based on the values of the measured traits, except M-91-2,  M-91-3, M-91-9, M-91-10, M-91-11,  M-91-15 and M-91-16, the remaining lines had medium to high levels of slow rusting resistance. Correlation cofficients between FRS and CI, rAUDPC and r were 98%, 97% and 97%, respectiveiy.