International Institute of Tropical Agriculture, Ibadan, Nigeria.
First Technical University, Ibadan, Nigeria.
BMC Plant Biol. 2023 Aug 10;23(1):386. doi: 10.1186/s12870-023-04385-7.
Maize production in lowland agro-ecologies in West and Central Africa is constrained by the fungus Exserohilum turcicum, causal agent of Northern Corn Leaf Blight (NCLB). Breeding for resistance to NCLB is considered the most effective management strategy. The strategy would be even more effective if there is adequate knowledge of the characteristics of E. turcicum in a target region. Maize leaves showing NCLB symptoms were collected during field surveys in three major maize growing areas in Nigeria: Ikenne, Ile-Ife, and Zaria during 2018/2019 and 2019/2020 growing seasons to characterize E. turcicum populations interacting with maize using morphological and molecular criteria.
A total of 217 E. turcicum isolates were recovered. Most of the isolates (47%) were recovered from the Ikenne samples while the least were obtained from Zaria. All isolates were morphologically characterized. A subset of 124 isolates was analyzed for virulence effector profiles using three primers: SIX13-like, SIX5-like, and Ecp6. Inter- and intra-location variations among isolates was found in sporulation, growth patterns, and presence of the effectors. Candidate effector genes that condition pathogenicity and virulence in E. turcicum were found but not all isolates expressed the three effectors.
Morphological and genetic variation among E. turcicum isolates was found within and across locations. The variability observed suggests that breeding for resistance to NCLB in Nigeria requires selection for quantitative resistance to sustain the breeding efforts.
在西非和中非的低地农业生态系统中，玉米生产受到北方玉米叶枯病（NCLB）病原体 Exserohilum turcicum 的限制。培育对 NCLB 的抗性被认为是最有效的管理策略。如果在目标区域有足够的 E. turcicum 特征知识，该策略将更加有效。在 2018/2019 和 2019/2020 生长季节期间，在尼日利亚三个主要玉米种植区（Ikenne、Ile-Ife 和 Zaria）的田间调查中收集了表现出 NCLB 症状的玉米叶片，以使用形态学和分子标准来表征与玉米相互作用的 E. turcicum 种群。
共回收了 217 株 E. turcicum 分离株。大多数分离株（47%）来自 Ikenne 样本，而来自 Zaria 的分离株最少。所有分离株均进行了形态特征分析。使用三个引物（SIX13-like、SIX5-like 和 Ecp6）对 124 个分离株的毒性效应子谱进行了分析。在各地点之间和各地点内部，分离株在孢子形成、生长模式和效应子存在方面存在差异。在 E. turcicum 中条件致病性和毒性的候选效应子基因被发现，但并非所有分离株都表达这三个效应子。
在各地点内和各地点之间发现了 E. turcicum 分离株的形态和遗传变异。观察到的变异性表明，在尼日利亚对 NCLB 的抗性选育需要选择数量抗性以维持选育工作。
