Previous studies have suggested that the plastid translation elongation factor, elongation factor thermo unstable (EF‐Tu), encoded by RAB GTPASE HOMOLOG 8D (RAB8D) is essential for plant growth. Here, through analyzing the root phenotypes of two knock‐down alleles of RAB8D (rab8d‐1 and rab8d‐2), we further revealed a vital role for RAB8D in primary root development through the maintenance of both the stem cell niche (SCN) and the meristem. Our results showed that RAB8D deficiency affects the root auxin response and SCN maintenance signaling. RAB8D interacts with GENOMES UNCOUPLED 1 (GUN1) in vivo. Further analysis revealed that GUN1 is over‐accumulated and is required for both stem cell death and maintenance of root architecture in rab8d Arabidopsis mutants. The ATAXIA‐TELANGIECTASIA‐MUTATED (ATM)–SUPPRESSOR OF GAMMA RESPONSE 1 pathway is involved in the regulation of root meristem size through upregulating SIAMESE‐RELATED 5 expression in the rab8d‐2 allele. Moreover, ETHYLENE RESPONSE FACTOR 115 is highly expressed in rab8d‐2, which plays a role in further quiescent center division. Our observations not only characterized the role of RAB8D in root development, but also uncovered functions of GUN1 and ATM in response to plastid EF‐Tu deficiency.

中文翻译：

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维持根干细胞生境和分生组织都需要RAB GTPASE HOMOLOG 8D

先前的研究表明，由RAB GTPASE HOMOLOG 8D（RAB8D）编码的质体翻译延伸因子，热不稳定延伸因子（EF-Tu）对植物生长至关重要。在这里，通过分析RAB8D的两个敲除等位基因（rab8d-1和rab8d-2）的根表型，我们进一步揭示了RAB8D通过维持干细胞生态位（SCN）和SCN的存在而在初级根发育中起着至关重要的作用。分生组织。我们的结果表明，RAB8D缺乏会影响根生长素反应和SCN维持信号。RAB8D在体内与GENOMES UNCOUPLED 1（GUN1）相互作用。进一步的分析表明，在rab8d拟南芥突变体中，GUN1过度积累，是干细胞死亡和维持根结构所需的。共济失调性毛细血管扩张症突变（ATM）-SUPPRESSOR GAMMA的响应1途径通过上调参与根分生组织大小的调节连体-相关5在表达式rab8d-2等位基因。此外，乙烯响应因子115在rab8d-2中高度表达，它在进一步使中心静止时发挥作用。我们的观察结果不仅表征了RAB8D在根发育中的作用，而且还揭示了对质体EF-Tu缺乏症响应的GUN1和ATM的功能。