Studies on gray leaf spot (GLS) of maize have reported inconsistencies in the relationship between partial disease resistance and agronomic traits. Understanding this variation could facilitate the use of agronomic traits as a basis for selection to improve partial resistance to GLS. Coinheritance of nine agronomic traits with partial resistance to GLS was examined among 48 maize (Zea mays L.) inbred lines artificially infected with Cercospora zeina in field evaluations across nine environments in western Kenya in 2013 and 2014. Five measures of disease severity and two disease resistance components were evaluated for their association with agronomic traits. Standardized area under disease progress curve (SAUDPC) was the most efficient in delineating differences in GLS severity between genotypes, whereas latent period (LP) was the least effective. Among maize genotypes, values of SAUDPC ranged from 29.3 to 97.9 across environments. Genotypic and phenotypic correlations were strongest between SAUDPC and the absolute rate of disease increase (ρ; r = .71), final percent diseased leaf area (r = .66) and International Maize and Wheat Improvement Center (CIMMYT) disease severity grade (r = .60), but weakest between SAUDPC and LP (r = −.19). Correlations of SAUDPC were significant (P = .05) with eight of the 11 agronomic traits examined, with the strongest being between SAUDPC and the stay-green characteristic (SGR; r = −.87), days to maturity (DTM; r = −.60) and ear/plant height ratio (r = −.52). Genotypic and phenotypic coefficients of correlation of SAUDPC with agronomic traits were all negative. Overall, absolute genotypic correlations were numerically larger than the corresponding coefficients of phenotypic correlation with the magnitude and direction of coheritability estimates mimicking trends in genotypic and phenotypic correlations. Causal mediation analysis indicated that covariation of GLS resistance with agronomic traits was mainly due to direct effects of days to anthesis and DTM and indirect effects of SGR and silking–maturity interval.

中文翻译：

---

优良玉米种质农艺性状与灰斑病部分抗性的遗传关联

对玉米灰斑病 (GLS) 的研究报道了部分抗病性和农艺性状之间关系的不一致。了解这种变异可以促进使用农艺性状作为选择的基础，以提高对 GLS 的部分抗性。在人工感染玉米尾孢的 48 个玉米 ( Zea mays L.) 自交系中检测了 9 个对 GLS 具有部分抗性的农艺性状的共遗传2013 年和 2014 年在肯尼亚西部的九个环境中进行了实地评估。评估了疾病严重程度的五项措施和两个抗病性成分与农艺性状的关联。疾病进展曲线下的标准化面积 (SAUDPC) 在描述基因型之间 GLS 严重程度的差异方面最有效，而潜伏期 (LP) 的效果最差。在玉米基因型中，跨环境的 SAUDPC 值范围为 29.3 至 97.9。SAUDPC 与绝对疾病增加率 (ρ; r = .71)、最终患病叶面积百分比 ( r = .66) 和国际玉米和小麦改良中心 (CIMMYT) 疾病严重程度等级 ( r= .60)，但在 SAUDPC 和 LP 之间最弱 ( r = −.19)。SAUDPC 与所检查的 11 种农艺性状中的 8 种相关性显着 ( P = .05)，其中 SAUDPC 与保持绿色特性 (SGR; r = −.87)、成熟天数 (DTM; r = −.60) 和穗/株高比 ( r= −.52)。SAUDPC与农艺性状的基因型和表型相关系数均为负值。总的来说，绝对基因型相关性在数值上大于表型相关性的相应系数，相关性估计的大小和方向模仿基因型和表型相关性的趋势。因果中介分析表明，GLS 抗性与农艺性状的协变主要是由于开花天数和 DTM 的直接影响以及 SGR 和吐丝-成熟间隔的间接影响。