背景回顾：Seeds are a key life cycle stage for many plants. Seeds are also the basis of agriculture and the primary source of calories consumed by humans. 

主要研究：Here, we employ single-nucleus RNA-sequencing to generate a transcriptional atlas of developing Arabidopsis thaliana seeds, with a focus on endosperm. 

研究对象：Endosperm, the primary site of gene imprinting in flowering plants, mediates the relationship between the maternal parent and the embryo. 

结果1：We identify transcriptionally uncharacterized nuclei types in the chalazal endosperm, which interfaces with maternal tissue for nutrient unloading. 

结果2：We demonstrate that the extent of parental bias of maternally expressed imprinted genes varies with cell-cycle phase, and that imprinting of paternally expressed imprinted genes is strongest in chalazal endosperm. Thus, imprinting is spatially and temporally heterogeneous. 

结论：Increased paternal expression in the chalazal region suggests that parental conflict, which is proposed to drive imprinting evolution, is fiercest at the boundary between filial and maternal tissues.

 摘 要 

种子是许多植物十分关键的生命阶段之一。同时，种子还是农业的基础，也是人类摄入卡路里的主要来源。本文中，作者通过单核RNA测序技术，获得了拟南芥正在发育中种子的转录图谱，并且重点关注了胚乳组织。胚乳，是有花植物存在基因印记的主要组织部位，作为植物母本组织与胚胎之间的桥梁发挥作用。作者在合点端胚乳中鉴定到了一些之前未能从转录特征识别的细胞类型，发现其会与母本组织互作来完成营养卸载。作者发现母本表达的印记基因的亲本偏向性在不同细胞周期阶段存在变异，并且父本表达的印记基因在合点端胚乳中的印记表达最为强烈。因此，基因印记在时间和空间上均存在异质性。合点端胚乳中父本表达的增加表明，驱动印记演化的亲本冲突在子代和母本组织的交界处最为激烈。