The endoplasmic reticulum-localized DnaJ family 3B (ERdj3B), is a component of the stromal cell-derived factor 2 (SDF2)-ERdj3B-binding immunoglobulin protein (BiP) chaperone complex, which functions in protein folding, translocation, and quality control. We found that ERdj3B mutations affected integument development in the Ler ecotype but not in the Col-0 ecotype of Arabidopsis (Arabidopsis thaliana). Map-based cloning identified the ERECTA (ER) gene as a natural modifier of ERdj3B. The double mutation of ERdj3B and ER caused a major defect in the inner integument under heat stress. Additional mutation of the ER paralog ERECTA-LIKE 1 (ERL1) or ERL2 to the erdj3b er double mutant exacerbated the defective integument phenotype. The double mutation of ER and SDF2, the other component of the SDF2-ERdj3B-BiP complex, resulted in similar defects in the inner integument. Furthermore, both the protein abundance and plasma membrane partitioning of ER, ERL1, and ERL2 were markedly reduced in erdj3b plants, indicating that the SDF2-ERdj3B-BiP chaperone complex might control the translocation of ERECTA-family proteins from the endoplasmic reticulum to the plasma membrane. Our results suggest that the SDF2-ERdj3B-BiP complex functions in ovule development and the heat stress response in coordination with ERECTA-family receptor kinases.

中文翻译：

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拟南芥 ERdj3B 与 ERECTA 家族受体激酶协调调节胚珠发育和热应激反应。

内质网定位的 DnaJ 家族 3B (ERdj3B) 是基质细胞衍生因子 2 (SDF2)-ERdj3B 结合免疫球蛋白 (BiP) 伴侣复合物的组成部分，其在蛋白质折叠、易位和质量控制中发挥作用。我们发现 ERdj3B 突变影响拟南芥 (Arabidopsis thaliana) Ler 生态型的珠被发育，但不影响 Col-0 生态型。基于图谱的克隆鉴定出 ERECTA (ER) 基因是 ERdj3B 的天然修饰因子。ERdj3B和ER的双重突变导致热应激下内珠被出现重大缺陷。ER 旁系同源物 ERECTA-LIKE 1 (ERL1) 或 ERL2 额外突变为 erdj3b er 双突变体，加剧了珠被表型的缺陷。ER 和 SDF2（SDF2-ERdj3B-BiP 复合物的另一个组成部分）的双重突变导致内珠被出现类似的缺陷。此外，erdj3b植物中ER、ERL1和ERL2的蛋白质丰度和质膜分配均显着减少，表明SDF2-ERdj3B-BiP伴侣复合物可能控制ERECTA家族蛋白质从内质网到血浆的易位膜。我们的结果表明，SDF2-ERdj3B-BiP 复合物在胚珠发育和热应激反应中与 ERECTA 家族受体激酶协调发挥作用。