Maize rough dwarf disease (MRDD) caused by pathogenic viruses in the genus Fijivirus in the family Reoviridae is one of the most destructive diseases in maize. The pyramiding of effective resistance genes into maize varieties is a potential approach to reduce the damage resulting from the disease. Two major quantitative trait loci (QTLs) (qMrdd2 and qMrdd8) have been previously identified. The resistance genes ZmGLK36 and ZmGDIα-hel have also been cloned with the functional markers Indel-26 and IDP25K, respectively. In this study, ZmGLK36 and ZmGDIα-hel were introgressed to improve MRDD resistance of maize lines (Zheng58, Chang7-2, B73, Mo17, and their derived hybrids Zhengdan958 and B73 × Mo17) via marker-assisted selection (MAS). The converted lines and their derived hybrids, carrying one or two genes, were evaluated for MRDD resistance using artificial inoculation methods. The double-gene pyramiding lines and their derived hybrids exhibited increased resistance to MRDD compared to the monogenic lines and the respective hybrids. The genetic backgrounds of the converted lines were highly similar (90.85–98.58%) to the recurrent parents. In addition, agronomic trait evaluation demonstrated that pyramiding lines with one or two genes and their derived hybrids were not significantly different from the recurrent parents and their hybrids under nonpathogenic stress, including period traits (tasseling, pollen shedding, and silking), yield traits (ear length, grain weight per ear and 100-kernel weight) and quality traits (protein and starch content). There were differences in plant architecture traits between the improved lines and their hybrids. This study illustrated the successful development of gene pyramiding for improving MRDD resistance by advancing the breeding process.

玉米粗缩病（MRDD）由呼肠孤病毒科斐济病毒属病原病毒引起，是玉米最具破坏性的病害之一。将有效抗性基因金字塔化到玉米品种中是减少该疾病造成的损害的潜在方法。先前已鉴定出两个主要数量性状基因座 (QTL)（qMrdd2和qMrdd8 ）。抗性基因ZmGLK36和ZmGDIα-hel也已分别与功能标记 Indel-26 和 IDP25K 一起克隆。在本研究中，ZmGLK36和ZmGDIα-hel被基因渗入，通过标记辅助选择（MAS）提高玉米品系（Zheng58、Chang7-2、B73、Mo17及其衍生杂种Zhengdan958和B73×Mo17）的MRDD抗性。使用人工接种方法评估携带一或两个基因的转化品系及其衍生杂种的 MRDD 抗性。与单基因系和各自的杂种相比，双基因金字塔系及其衍生的杂种表现出对MRDD增强的抗性。转化品系的遗传背景与轮回亲本高度相似（90.85-98.58%）。此外，农艺性状评价表明，在非病原胁迫下，带有1或2个基因的金字塔系及其杂种与轮回亲本及其杂种没有显着差异，包括时期性状（抽雄、花粉脱落和吐丝）、产量性状（穗长、每穗粒重和百粒重）和品质性状（蛋白质和淀粉含量）。改良品系及其杂种之间的株型性状存在差异。这项研究说明了基因金字塔的成功开发，通过推进育种过程来提高 MRDD 抗性。