SummaryEukaryotic translation initiation factors (eIFs) are important for mRNA translation but also pivotal for plant‐virus interaction. Most of these plant‐virus interactions were found between plant eIFs and the viral protein genome‐linked (VPg) of potyviruses. In case of lost interaction due to mutation or deletion of eIFs, the viral translation and subsequent replication within its host is negatively affected, resulting in a recessive resistance. Here we report the identification of the Beta vulgaris Bv‐eIF(iso)4E as a susceptibility factor towards the VPg‐carrying beet chlorosis virus (genus Polerovirus). Using yeast two‐hybrid and bimolecular fluorescence complementation assays, the physical interaction between Bv‐eIF(iso)4E and the putative BChV‐VPg was detected, while the VPg of the closely related beet mild yellowing virus (BMYV) was found to interact with the two isoforms Bv‐eIF4E and Bv‐eIF(iso)4E. These VPg‐eIF interactions within the polerovirus‐beet pathosystem were demonstrated to be highly specific, as single mutations within the predicted cap‐binding pocket of Bv‐eIF(iso)4E resulted in a loss of interaction. To investigate the suitability of eIFs as a resistance resource against beet infecting poleroviruses, B. vulgaris plants were genome edited by CRISPR/Cas9 resulting in knockouts of different eIFs. A simultaneous knockout of the identified BMYV‐interaction partners Bv‐eIF4E and Bv‐eIF(iso)4E was not achieved, but Bv‐eIF(iso)4EKO plants showed a significantly lowered BChV accumulation and decrease in infection rate from 100% to 28.86%, while no influence on BMYV accumulation was observed. Still, these observations support that eIFs are promising candidate genes for polerovirus resistance breeding in sugar beet.

中文翻译：

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甜菜褪绿病毒的隐性抗性是由甜菜中的真核翻译起始因子 (iso)4E 赋予的

摘要真核翻译起始因子 (eIF) 对于 mRNA 翻译很重要，而且对于植物-病毒相互作用也至关重要。大多数植物-病毒相互作用是在植物 eIF 和马铃薯病毒组病毒蛋白基因组连锁 (VPg) 之间发现的。如果由于 eIF 突变或删除而失去相互作用，病毒的翻译和随后在宿主内的复制就会受到负面影响，从而导致隐性耐药。在此我们报告身份甜菜 Bv-eIF(iso)4E作为对携带 VPg 的甜菜失绿病毒（属波罗病毒）。使用酵母双杂交和双分子荧光互补测定，检测到 Bv-eIF(iso)4E 和假定的 BChV-VPg 之间的物理相互作用，同时发现密切相关的甜菜轻度黄化病毒 (BMYV) 的 VPg 与两种亚型 Bv-eIF4E 和 Bv-eIF(iso)4E。这些 VPg-eIF 在马铃薯病毒-甜菜病理系统内的相互作用被证明是高度特异性的，因为 Bv-eIF(iso)4E 的预测帽结合口袋内的单个突变导致相互作用丧失。为了研究 eIF 作为对抗甜菜感染极病毒的抗性资源的适用性，寻常双歧杆菌植物通过 CRISPR/Cas9 进行基因组编辑，导致不同 eIF 的敲除。尚未实现同时敲除已识别的 BMYV 相互作用伙伴 Bv-eIF4E 和 Bv-eIF(iso)4E，但Bv-eIF(iso)4EKO植物的 BChV 积累显着降低，感染率从 100% 降至 28.86%，但对 BMYV 积累没有影响。尽管如此，这些观察结果支持 eIF 是甜菜中极小病毒抗性育种的有希望的候选基因。