Muñoz-Zavala Carlos, Loladze Alexander, Vargas-Hernández Mateo, García-León Elizabeth, Alakonya Amos Emitati, Tovar-Pedraza Juan Manuel, Goodwin Paul H, Leyva-Mir Santos Gerardo
Departamento de Parasitología Agrícola, Universidad Autónoma Chapingo, Texcoco 56230, Estado de México, Mexico.
International Maize and Wheat Improvement Center (CIMMYT), Texcoco 56237, Estado de México, Mexico.
Plant Dis. 2023 Apr;107(4):1054-1059. doi: 10.1094/PDIS-03-22-0626-RE. Epub 2023 Apr 20.
Turcicum leaf blight (TLB) is a common foliar disease of maize in Mexico that is caused by the fungal pathogen . The most effective management strategy against TLB is monogenic race-specific resistance. Among the 140 isolates from symptomatic leaves collected from maize fields in Mexico, 100 were obtained from tropical (Veracruz) and temperate areas (Estado de México) between 2010 and 2019, and 40 isolates were obtained from tropical (Sinaloa, Tamaulipas, Veracruz, and Chiapas), subtropical (Nayarit, Jalisco, and Guanajuato), and temperate areas (Estado de Mexico, Hidalgo, and Puebla) collected in 2019. All the isolates caused TLB symptoms on the positive control (), showing that they were all pathogenic. Six physiological races of (2, 3, 23, 3N, 23N, and 123N) were identified based on resistant or susceptible responses displayed by five maize differential genotypes (A619, A619, A619, B68, and A619). The most common was race 23, accounting for 68% of the isolates, followed by races 23N, 123N, 3, 2, and 3N at 15, 8, 6, 2, and 1%, respectively. Race 123N was able to infect the greatest number of maize differential genotypes used in the study. Race 123N was detected in Sinaloa and Estado de México. Race 3 was detected in Nayarit and Jalisco. Race 2 was detected in Jalisco, Estado de México, and Veracruz, and race 3N was detected in Tamaulipas. Race 23 was equally dominant in the tropical, subtropical, and temperate regions, while race 123N was more common in the tropical environment, and race 23N was more common in the tropical and temperate environments. There was no evidence for shifts in the races between 2010 and 2019.
玉米大斑病（TLB）是墨西哥玉米常见的叶部病害，由真菌病原体引起。防治玉米大斑病最有效的管理策略是单基因小种特异性抗性。在从墨西哥玉米田有症状叶片上采集的140个分离株中，100个于2010年至2019年取自热带地区（韦拉克鲁斯）和温带地区（墨西哥州），40个分离株于2019年取自热带地区（锡那罗亚、塔毛利帕斯、韦拉克鲁斯和恰帕斯）、亚热带地区（纳亚里特、哈利斯科和瓜纳华托）以及温带地区（墨西哥州、伊达尔戈和普埃布拉）。所有分离株在阳性对照上均引起玉米大斑病症状，表明它们均具有致病性。基于5个玉米鉴别基因型（A619、A619、A619、B68和A619）表现出的抗性或感病反应，鉴定出了病原菌的6个生理小种（2、3、23、3N、23N和123N）。最常见的是小种23，占分离株的68%，其次是小种23N、123N、3、2和3N，分别占15%、8%、6%、2%和1%。小种123N能够感染该研究中使用的最多数量的玉米鉴别基因型。在锡那罗亚和墨西哥州检测到了小种123N。在纳亚里特和哈利斯科检测到了小种3。在哈利斯科、墨西哥州和韦拉克鲁斯检测到了小种2，在塔毛利帕斯检测到了小种3N。小种23在热带、亚热带和温带地区同样占主导地位，而小种123N在热带环境中更为常见，小种23N在热带和温带环境中更为常见。没有证据表明2010年至2019年期间小种发生了变化。
