Sorghum downy mildew (SDM), caused by Peronosclerospora sorghi is one of the important diseases in maize. Here, we illustrate the transfer of two QTLs for SDM on chromosome 3 and 6 from UMI 936 (w) into an elite maize inbred line UMI 79 through marker-assisted backcross breeding (MABC). For foreground selection, plants carrying heterozygote allele for the QTLs for SDM were selected from F 1 and three back cross (BC 1 -BC 3 ) generations using simple sequence repeat (SSR) markers linked to the targeted QTLs region of SDM. Consequently, foreground positive plants from BC 3 F 1 generation selfed to produce BC 3 F 2 and plants carrying the favorable alleles for the QTLs for SDM were selected followed by stringent phenotyping against SDM and advanced to BC 3 F 3. As a result, two improved lines (79/936–1–7-7-7-46-46 and 79/936–1–7-7-10-80-80) possessing QTLs for SDM were obtained. Background selection using 146 SSR markers distributed evenly across the maize genome revealed 92.45% and 89.68% recovery of recurrent parent genome (RPG) in two improved lines. Phenotypic characterization of the improved lines showed more than 90% of recovery of the recurrent parents in morphological traits and a resistance to SDM. In conclusion, the newly developed SDM resistant inbred lines are a potential source for improving SDM resistance in maize breeding programs.

中文翻译：

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通过标记辅助回交育种 (MABC) 将决定高粱霜霉病 (SDM) 抗性的 QTL 基因渗入优良玉米品系 UMI 79

由高粱霜霉病引起的高粱霜霉病(SDM)是玉米的重要病害之一。在这里，我们说明了通过标记辅助回交育种 (MABC) 将 3 号和 6 号染色体上 SDM 的两个 QTL 从 UMI 936 (w) 转移到优良玉米自交系 UMI 79 中。对于前景选择，使用与 SDM 的目标 QTL 区域相连的简单序列重复 (SSR) 标记，从 F 1 和三个回交 (BC 1 -BC 3 ) 世代中选择带有 SDM QTL 杂合等位基因的植物。因此，从 BC 3 F 1 代自交产生 BC 3 F 2 的前景阳性植物和携带 SDM QTL 有利等位基因的植物被选中，然后针对 SDM 进行严格的表型分析并发展为 BC 3 F 3。结果，获得了两个具有 SDM QTL 的改良品系（79/936-1-7-7-7-46-46 和 79/936-1-7-7-10-80-80）。使用在玉米基因组中均匀分布的 146 个 SSR 标记进行背景选择显示，在两个改良品系中，回归亲本基因组 (RPG) 的回收率分别为 92.45% 和 89.68%。改良品系的表型特征表明，轮回亲本的形态性状恢复率超过 90%，并且对 SDM 具有抗性。总之，新开发的 SDM 抗性自交系是提高玉米育种计划中 SDM 抗性的潜在来源。改良品系的表型特征表明，轮回亲本的形态性状恢复率超过 90%，并且对 SDM 具有抗性。总之，新开发的 SDM 抗性自交系是提高玉米育种计划中 SDM 抗性的潜在来源。改良品系的表型特征表明，轮回亲本的形态性状恢复率超过 90%，并且对 SDM 具有抗性。总之，新开发的 SDM 抗性自交系是提高玉米育种计划中 SDM 抗性的潜在来源。