Investigating the susceptibility and resistance barley ( <i>Hordeum vulgare</i> L.) cultivars against the Russian wheat aphid <i>(Diuraphis noxia)</i>

Abstract Barley production is affected by many pests and diseases, but aphids cause significant economic losses due to their feeding and plant virus transmission. This study tested the susceptibility and resistance of five different barley cultivars to aphid reproduction using different techniques, including electrical penetration graph (EPG). Furthermore, their ability to stimulate the kinetics of five different barley cultivars was tested using a spectrophotometer. Peroxidase (POX) and polyphenol oxidase (PPO) are expressed in plants after physical or chemical stimulation. Finally, defense-related genes were expressed using quantitative real-time PCR. The EPG results showed that ICARDA 15 was a resistant cultivar against aphids by preventing them from feeding and transmitting viruses. The results also showed that the two cultivars of basil and Acsad 14/17 are resistant, which led to a significant increase in both PPO/POX enzymes compared with the control among all tested barley cultivars. As for gene expression, the results showed that Acsad 17/14, Arar, Ryhan, and ICARDA 15 cultivars are resistant, as the expression of these genes increased significantly compared to the cultivar, which is local cultivar. This study evaluated five barley cultivars using different techniques regarding their resistance or sensitivity to aphid attacks.