Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011, USA.
Corn Insects and Crop Genetics Research, USDA-ARS, Ames, IA, 50011, USA.
BMC Genomics. 2021 Dec 11;22(1):887. doi: 10.1186/s12864-021-08147-3.
Pyramiding different resistance genes into one plant genotype confers enhanced resistance at the phenotypic level, but the molecular mechanisms underlying this effect are not well-understood. In soybean, aphid resistance is conferred by Rag genes. We compared the transcriptional response of four soybean genotypes to aphid feeding to assess how the combination of Rag genes enhanced the soybean resistance to aphid infestation.
A strong synergistic interaction between Rag1 and Rag2, defined as genes differentially expressed only in the pyramid genotype, was identified. This synergistic effect in the Rag1/2 phenotype was very evident early (6 h after infestation) and involved unique biological processes. However, the response of susceptible and resistant genotypes had a large overlap 12 h after aphid infestation. Transcription factor (TF) analyses identified a network of interacting TF that potentially integrates signaling from Rag1 and Rag2 to produce the unique Rag1/2 response. Pyramiding resulted in rapid induction of phytochemicals production and deposition of lignin to strengthen the secondary cell wall, while repressing photosynthesis. We also identified Glyma.07G063700 as a novel, strong candidate for the Rag1 gene.
The synergistic interaction between Rag1 and Rag2 in the Rag1/2 genotype can explain its enhanced resistance phenotype. Understanding molecular mechanisms that support enhanced resistance in pyramid genotypes could facilitate more directed approaches for crop improvement.
将不同的抗性基因叠加到一个植物基因型中可以在表型水平上赋予增强的抗性，但这种效应的分子机制尚不清楚。在大豆中，蚜虫抗性由 Rag 基因赋予。我们比较了四种大豆基因型对蚜虫取食的转录反应，以评估 Rag 基因的组合如何增强大豆对蚜虫侵害的抗性。
鉴定出 Rag1 和 Rag2 之间的强烈协同作用，定义为仅在叠加基因型中差异表达的基因。这种 Rag1/2 表型中的协同效应在早期（取食后 6 小时）非常明显，涉及独特的生物学过程。然而，在取食后 12 小时，易感和抗性基因型的反应有很大的重叠。转录因子（TF）分析确定了一个相互作用的 TF 网络，该网络可能整合 Rag1 和 Rag2 的信号，以产生独特的 Rag1/2 反应。叠加导致植物化学物质的快速诱导和木质素的沉积，以加强次生细胞壁，同时抑制光合作用。我们还鉴定出 Glyma.07G063700 是 Rag1 基因的一个新的强候选基因。
Rag1/2 基因型中 Rag1 和 Rag2 之间的协同相互作用可以解释其增强的抗性表型。了解支持叠加基因型中增强抗性的分子机制可以促进更有针对性的作物改良方法。
