بررسی مقاومت نمونه های ژنتیکی منتخب گندم نان بانک ژن گیاهی ملی ایران نسبت به بیماری زنگ برگ گندم در گلخانه

Leaf rust is the most common and widespread wheat rust disease in the world and can reduce yield by up to‌50%, if infected in the early stages of growth. For resistance evaluation at the seedling stage,‌100‌germplasm from National Plant Gene Bank of Iran were selected along with 10 common cultivars‌(Araz, Sirvan, Chamran, Sarang, Sahar, Tirgan, Kalate, Barat, Pishgam and Mehrgan)‌of bread wheat and two susceptible control‌(Bolani and Morocco). Seeds were grown in the greenhouse in a completely randomized design with three replications. The pathogen was collected from the Dezful region, purified, multiplied in the greenhouse and the race was determined using the leaf rust differential lines. Seedlings were inoculated with purified spores when they were about‌10‌cm tall. The inoculated seedlings were first placed at a temperature of-18-24°C, 100%‌humidity, and absolute darkness for 18 hours and then in the greenhouse at a temperature of‌18-24°C, 40-60%‌humidity.The resistance components studied included the infection‌ types according to Rolfe's method‌ (1992)‌ and the incubation period. After the appearance of the rust pustules in the greenhouse, the length of the incubation period and‌14 days after inoculation, the infection‌ types were recorded. Statistical analysis of the data was carried out using SAS 9.2‌and Minitab‌17.3.1‌software. The present study examined two methods for classifying infection types. In the first method,60% of wheat germplasms displayed a low infection type(L) while 40% exhibited a high-infection type(H). Two cultivars, Bolani and Morocco, exhibited a high-‌infection type, and the response of other cultivars was low-infection type. In the second method, the germplasms were classified according to infection‌ ‌types, ranging from resistant to susceptible. The results showed that among the wheat accessions, 38%-were in the susceptible(S) ‌and moderately-‌susceptible‌(MS) ‌,‌27%‌ in the moderately-‌resistant-(MR) and‌ 47%‌ in the resistant(R)‌. Bolani and Morocco cultivars were in the susceptible, Sarang and Araz cultivars were in the moderately-‌resistant and other cultivars were in the resistant(R)‌. The correlation coefficients of the resistance components at the seedling stage showed that the infection ‌type was negatively correlated with the incubation period. The tested germplasms showed less infection type with increasing incubation period. The analysis of variance showed that there was a very significant difference at the‌1% ‌level between the germplasms for the resistance components. As a result of this study, the germplasms that had a longer incubation period at the seedling stage and were placed in the category of moderately-susceptible or moderately-resistant are likely to have an adult plant stage resistance or presence of non-race-specific resistance genes. The germplasms that showed resistance at the seedling stage may have race‌-specific genes or non‌-race‌specific genes that are masked by the effect of race‌-specific genes. Therefore, additional studies on these germplasms at adult plant stage are needed to determine the resistance type.