International Potato Center, Lima 12, P.O. Box 1558, Lima, Peru.
Theor Appl Genet. 2010 Apr;120(6):1265-78. doi: 10.1007/s00122-009-1254-4.
Main and interaction effects of day-length and pathogen isolate on the reaction and expression of field resistance to Phytophthora infestans were analyzed in a sample of standard clones for partial resistance to potato late blight, and in the BCT mapping population derived from a backcross of Solanum berthaultii to Solanum tuberosum. Detached leaves from plants grown in field plots exposed to short- and long day-length conditions were independently inoculated with two P. infestans isolates and incubated in chambers under short- and long photoperiods, respectively. Lesion growth rate (LGR) was used for resistance assessment. Analysis of variance revealed a significant contribution of genotype x isolate x day-length interaction to variation in LGR indicating that field resistance of genotypes to foliar late blight under a given day-length depended on the infecting isolate. An allele segregating from S. berthaultii with opposite effects on foliar resistance to late blight under long- and short day-lengths, respectively, was identified at a quantitative trait locus (QTL) that mapped on chromosome 1. This allele was associated with positive (decreased resistance) and negative (increased resistance) additive effects on LGR, under short- and long day-length conditions, respectively. Disease progress on whole plants inoculated with the same isolate under field conditions validated the direction of its effect in short day-length regimes. The present study suggests the occurrence of an isolate-specific QTL that displays interaction with isolate behavior under contrasting environments, such as those with different day-lengths. This study highlights the importance of exposing genotypes to a highly variable population of the pathogen under contrasting environments when stability to late blight resistance is to be assessed or marker-assisted selection is attempted for the manipulation of quantitative resistance to late blight.
对具有马铃薯晚疫病部分抗性的标准品系和来自 Solanum berthaultii 与 Solanum tuberosum 回交的 BCT 作图群体，分析了日照长度和病原菌分离株对田间抗性反应和表达的主效和互作效应。在分别暴露于短日照和长日照条件下生长的田间小区植株上，取下的叶片独立接种两个 P. infestans 分离株，并分别在短日照和长光照培养箱中培养。使用病斑生长率（LGR）评估抗性。方差分析显示，基因型 x 分离株 x 日照长度互作对 LGR 变异的显著贡献表明，在给定日照长度下，基因型对叶片晚疫病的田间抗性取决于侵染分离株。在一个数量性状位点（QTL）上鉴定出一个来自 S. berthaultii 的等位基因，该等位基因在长日照和短日照下分别对叶片晚疫病抗性具有相反的作用，该 QTL 位于 1 号染色体上。该等位基因与 LGR 的正（抗性降低）和负（抗性增加）加性效应分别相关，分别在短日照和长日照条件下。在田间条件下用相同分离株接种整株植物的病情进展验证了其在短日照条件下的作用方向。本研究表明，在不同环境（如不同日照长度）下，存在与分离株行为相互作用的分离株特异性 QTL。本研究强调了在评估晚疫病抗性稳定性或尝试利用标记辅助选择操纵晚疫病数量抗性时，将基因型暴露于具有高度变异的病原菌群体中，以及在不同环境下的重要性。
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