evaluation of resistance to stripe rust (puccinia striiformis f. sp. tritici) in newly developed wheat elite lines in the moghan plain, iran

Objective: yellow rust, or stripe rust, caused by the fungal pathogen puccinia striiformis f. sp. tritici (pst), is one of the most significant diseases affecting wheat crops worldwide, including iran. the most fundamental method for controlling this disease involves the use of effective and durable genetic resistance.methods: to determine the virulence factors (genes)/resistance factors (genes) present in the pathogen's race population in the moghan region, ardabil province, iran, the response of a set of yellow rust differential varieties was evaluated over two consecutive growing seasons (2023 and 2024) in trap nurseries at the adult plant stage under natural field conditions (without artificial inoculation). resistance evaluation of newly developed wheat lines (33 elite lines) was conducted at both the seedling stage (under artificial inoculation) and the adult plant stage (under natural field conditions). the resistance response of elite lines at the seedling stage was assessed using a randomized complete block design with three replications. disease severity at the flag leaf emergence stage was assessed after uniform disease development was observed on the susceptible check cultivar bolani, by estimating the percentage of leaf area covered by infection (0-100%). infection type was scored based on a 0-9 scale. to calculate the coefficient of infection, data on disease severity and infection type were combined. the coefficient of infection was obtained by multiplying the disease severity by a constant corresponding to the host reaction type: immune = 0.0, resistant (r) = 0.2, moderately resistant (mr) = 0.4, moderate (m) = 0.6, moderately susceptible (ms) = 0.8, moderately to susceptible (mss) = 0.9, susceptible (s) = 1.0.results: the results revealed that the virulence patterns within the pathogen's race population in the moghan region varied between the two years. in both years, avirulence was observed for the differential varieties carrying resistance genes yr2, yr3, yr4, yr5, yr10, yr15, yr27, yrcv, yrnd, and yrsd. a significant difference in virulence patterns between the two p. striiformis pathogen populations was observed across the two experimental years for the resistance genes yr1, yr9, yr27, yr28, yr29, yr32, and yrsp. different combinations of the aforementioned resistance genes could be beneficial forpyramiding effective resistance genes into high-yielding and desirable wheat lines. based on the measured resistance components at both stages, the following elite lines exhibited acceptable levels of resistance: n-1400-9, n-1400-10, s-1400-2, s-1400-26, s-1400-30, s-1400-38, m-1400-5, m-1400-11, m-1400-19, mdh-1400-6, mdh-1400-10, cd-1400-8, cd-1400-19, c-1400-11, and d-1400-14.conclusion: the lines with acceptable levels of resistance can serve as effective sources of resistance for developing new and durable resistant varieties against the pathogen's race population in the moghan region and similar areas in the northern part of iran in wheat breeding programs.