Transcriptomics at Maize Embryo/Endosperm Interfaces Identifies a Transcriptionally Distinct Endosperm Sub-domain Adjacent to the Embryo Scutellum

First author: Nicolas M. Doll; Affiliations: Ecole Normale superieure de Lyon France  (里昂高等师范学院): Lyon, France

Corresponding author: Thomas Widiez

Seeds are complex biological systems comprising three genetically distinct tissues nested one inside another (embryo, endosperm and maternal tissues). However, the complexity of the kernel makes it difficult to understand inter compartment interactions without access to spatially accurate information. Here we took advantage of the large size of the maize kernel to characterize genome-wide expression profiles of tissues at embryo/endosperm interfaces. Our analysis identifies specific transcriptomic signatures in two interface tissues compared to whole seed compartments: The scutellar aleurone layer (SAL), and the newly named endosperm adjacent to scutellum (EAS). The EAS, which appears around 9 days after pollination and persists for around 11 days, is confined to one to three endosperm cell layers adjacent to the embryonic scutellum. Its transcriptome is enriched in genes encoding transporters. The absence of the embryo in an embryo specific (emb) mutant can alter the expression pattern of EAS marker genes. The detection of cell death in some EAS cells together with an accumulation of crushed cell walls suggests that the EAS is a dynamic zone from which cell layers in contact with the embryo are regularly eliminated, and to which additional endosperm cells are recruited as the embryo grows.

种子是一种复杂的生物系统，包含三种遗传上不同的组织，相互嵌套在一起，包括胚胎、胚乳和母体组织。然而，种子的复杂性使得我们在没有精确了解种子各组分的空间信息时很难理解它们之间的相互作用。本文中，作者利用大颗粒的玉米种子来对胚胎和胚乳相接处的组织进行全基因组范围的基因表达谱研究。作者的分析鉴定了相比于整个种子组分，两个胚胎/胚乳相接处的组织存在特异的转录信号，这两个组织分别是盾片糊粉层（SAL）和与盾片相接的胚乳（EAS）。EAS组织大概在授粉后第9天开始出现，然后存在大约11天的时间，局限在与胚胎盾片毗邻的1到3层胚乳细胞。该组织的转录组显示其富集与转运蛋白相关的基因。在一个缺少胚胎的突变体中，EAS标记基因的表达模式也会改变。在EAS组织中检测到的一些EAS死亡细胞以及积累的破碎细胞壁显示EAS是一个动态的组织区域，其与胚胎相接的细胞层会定期被消除，而随着胚胎的生长发育，额外的胚乳细胞也会持续被招募。

通讯：Thomas Widiez (http://www.ens-lyon.fr/RDP/spip.php?rubrique15=&lang=en)

研究方向：玉米种子不同组分之间的通信。

doi: https://doi.org/10.1105/tpc.19.00756

Journal: Plant Cell

Published date: February 21, 2020