شناسایی منابع مقاومت به بیماری زنگ برگ گندم در نمونه های ژنتیکی منتخب از گندم نان بانک ژن گیاهی ملی ایران در استان خوزستان

Leaf rust, a major disease of wheat, has been spreading in the southern regions of the country in recent years. To investigate the sources of resistance to this disease, 100 bread wheat accessions were selected from the National Plant Gene Bank of Iran. The experiment was conducted using an augmentation design in five blocks with random replication of three common cultivars (Barat, Sarang and Sahar) in each block. To facilitate the spread of the epidemic, a series of spraying operations were carried out at ten-day intervals with a mixture of regional isolates from the seedling stage onwards. Evaluation was initiated when the susceptible cultivars Bolani and Morocco displayed more than 80% disease severity. Resistance components, including type of infection and disease severity, were recorded three times and the results using FDS=Final Disease Severity, CI=Coefficient of Infection, AUDPC=Area Under Disease Progress Curve and rAUDPC=Relative Area Under Disease Progress Curve were analyzed. Statistical analysis of the data was performed using SAS 9.2 and Minitab 17.3.1 software. The correlation coefficients of the resistance components under field conditions showed that AUDPC, rAUDPC and CI were positively correlated at the 1% probability level. The AUDPC and rAUDPC values and the susceptibility of the accessions increased with increasing CI. The analysis of variance of the resistance components under field conditions shows that there was no significant difference between the blocks. On the accessions, a significant difference was calculated at the‌1%‌level. The accessions were divided into three categories according to disease severity. The first category includes‌8%‌of the accessions and the cultivars Bolani and Morocco with a disease severity of more than 60%, the second category includes‌21%‌of the accessions with a disease severity of 21-59%, the third category includes 71% of the accessions and the cultivars Barat, Sarang and Sahar with a disease severity of 1-20%. In terms of infection type,‌47%‌of the accessions showed susceptibility reaction; S, 7% moderately susceptible reaction; MS, 13% moderately resistance reaction; MR and the rest of the accessions showed resistance reaction. R. Among the accessions, Bolani and Morocco showed S reaction, Barat and Sahar showed MS reaction and Sarang showed MR reaction. Based on the area under the disease progression curve of the accessions,‌28%‌of the accessions had a value above 200 and 72% of the accessions with the cultivars Barat, Sarang and Sahar had a value below 200. Also, the cultivars Bolani and Morocco had 100% rAUDPC,‌18%‌of the accessions had rAUDPC above‌20%‌and‌25%‌of the accessions had rAUDPC below‌1%. Other accessions, together with the Barat, Sarang and Sahar cultivars, had rAUDPC between 1 and‌20%.‌Accessions with zero to‌20%‌rAUDPC and resistance up to relative resistance have been introduced for use in projects of breeding wheat leaf rust resistant cultivars.