Evaluation of Resistance to Southern Corn Rust and Detection of Resistance Genes in New Summer Corn Varieties in Henan Province

WANG Ziming; ZHANG Yuyang; WANG Ziqi; FAN Zhuo; YUAN Hongxia; YANG Xue; LI Honglian; SHI Yan

doi:10.15933/j.cnki.1004-3268.2025.07.011

Abstract：Southern corn rust resistance of corn varieties participating in regional trials and introduced variety registration trials in Henan Province from 2021 to 2024 was evaluated using a combination of field nurseries and artificial inoculation.Additionally,resistance gene detection was conducted on varieties exhibiting moderate resistance or higher levels in 2023 and 2024,to determine the resistance status of newly bred corn varieties to southern corn rust,and provide theoretical basis for breeding and promoting resistant corn cultivars.The results showed that 134,121,87,and 119 corn varieties were tested in the Henan regional trials from 2021 to 2024,respectively.Among them,the proportions of varieties showing moderate resistance or higher to southern corn rust were 36.57%,92.57%,57.47%,and 86.55%,respectively.For the introduced variety registration trials,68,82,43,and 14 corn varieties were tested,and the proportions of varieties showing moderate resistance or higher to southern corn rust were 32.35%,95.12%,51.16%,and 71.43%,respectively,demonstrating a generally consistent trend.However,there were notable year-to-year variations in the proportion of resistant and susceptible varieties.In years with southern corn rust epidemics,such as 2021 and 2023,the proportion of resistant varieties was relatively lower.In 2023,resistance genes were detected in varieties showing moderate resistance or higher levels.The results showed that 48.61%of these varieties carried the resistance gene RppC,while RppM was not detected in any of the tested varieties.Furthermore,51.39%of the varieties lacked both RppC and RppM.In 2024,detection of RppC,RppM,and RppK genes in varieties showing moderate resistance or higher levels was conducted.The results showed that RppC had the highest detection ratio of 92.92%,followed by RppK and RppM with the detection ratio of 21.24%and 20.35%,respectively.However,three varieties tested were negative for all the three resistance genes.In conclusion,a relatively high proportion of corn varieties evaluated in recent years in Henan Province exhibited resistance to southern corn rust,with an overall increasing trend.The resistance gene RppC continues to play a key role in corn production,while RppK and RppM are beginning to be applied in southern corn rust-resistant breeding.Further exploration and utilization of additional resistance genes are still needed.