SummaryMaize lethal necrosis (MLN), which is caused by maize chlorotic mottle virus along with a potyvirus, has threatened the food security of smallholders in sub‐Saharan Africa. Mutations in eukaryotic translation initiation factors (eIFs), which also facilitate virus genome translation, are known to confer variable resistance against viruses. Following phylogenetic analysis, we selected two eIF4E proteins from maize as the most likely candidates to facilitate MLN infection. A knockout (KO) of each of the corresponding genes in elite but MLN‐susceptible maize lines conferred only partial protection. Our inability to knockout both the genes together suggested that at least one was required for survival. When we edited (ED) the eIF4E genes in Mini Maize, however, the plants with the eif4e1‐KO became highly resistant, whereas those with the eif4e2‐KO remained susceptible. Neither of the causal viruses could be detected in the MLN‐inoculated eif4e1‐KO plants. The eIF4E2 cDNA in Mini Maize lacked the entire 4th exon, causing a 22‐amino acid in‐frame deletion, which shortened the protein to 198 amino acids. When we introduced mutations in the 4th exon of the eIF4E2 gene in two elite, MLN‐susceptible lines pre‐edited for an eif4e1‐KO, we obtained as strong resistance against MLN as in eif4e1‐KO Mini Maize. The MLN‐inoculated lines with eif4e1‐KO/eIF4E2‐exon‐4ED performed as well as the uninoculated wild‐type lines. We demonstrate that the C‐terminal 38 amino acids of eIF4E2 are dispensable for normal plant growth but are required for the multiplication of MLN viruses. Our discovery has wide applications across plant species for developing virus‐resistant varieties.

中文翻译：

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编辑的真核翻译起始因子赋予对玉米致死性坏死的抵抗力


摘要玉米致死性坏死 （MLN） 是由玉米绿斑驳病毒和葡萄球菌病毒引起的，威胁着撒哈拉以南非洲小农户的粮食安全。已知真核翻译起始因子 （eIF） 的突变也促进病毒基因组翻译，可赋予对病毒的可变抗性。经过系统发育分析，我们从玉米中选择了两种 eIF4E 蛋白作为最有可能促进 MLN 感染的候选蛋白。在精英但易受 MLN 敏感的玉米品系中，每个相应基因的敲除 （KO） 仅提供部分保护。我们无法同时敲除这两个基因，这表明至少需要一个基因才能生存。然而，当我们在小型玉米中编辑 （ED） eIF4E 基因时，具有 eif4e1-KO 的植物变得高度抗性，而具有 eif4e2-KO 的植物仍然易感。在 MLN 接种的 eif4e1-KO 植物中均未检测到这两种致病病毒。小玉米中的 eIF4E2 cDNA 缺乏整个第 4 个外显子，导致 22 个氨基酸的框内缺失，从而将蛋白质缩短到 198 个氨基酸。当我们在两个为 eif4e1-KO 预先编辑的精英、MLN 易感品系中引入 eIF4E2 基因的第 4 个外显子突变时，我们获得了与 eif4e1-KO 迷你玉米一样强的对 MLN 的抗性。使用 eif4e1-KO/eIF4E2-外显子-4ED 接种的 MLN 细胞系与未接种的野生型细胞系表现良好。我们证明 eIF4E2 的 C 端 38 个氨基酸对于正常的植物生长是可有可无的，但对于 MLN 病毒的繁殖是必需的。我们的发现在植物物种中具有广泛的应用，可用于开发抗病毒品种。