2017年12月29日，PNAS在线发表了福建农林大学秦源教授的文章。文章揭示了胚珠原基体细胞协同染色质重塑，将生殖细胞的特性限制在单个细胞中的机理。即：KLU 和SWR1 通过促进MMC 周围的皮下体细胞中WRKY28 表达，来抑制异位MMC命运的机理

原题目为：

KLU suppresses megasporocyte cell fate through SWR1-mediated activation of WRKY28 expression in Arabidopsis

在开花植物中，雌性生殖系以胚珠中称为大孢子母细胞（MMC）的单细胞开始。限制MMC命运到一个细胞的机制在很大程度上仍然是未知的。本研究表明，拟南芥细胞色素P450基因KLU 在胚珠原基中通过染色质重塑复合物SWR1促进WRKY28 表达。WRKY28表达于MMC周围的一些体细胞中，并且是抑制这些细胞获得类MMC细胞命运所需要的。与非细胞自主KLU 活性一致，表达KLU 的细胞和表达WRKY28 的细胞既不相同也不相邻。我们的研究表明，细胞-细胞相互作用仅涉及在胚珠原基中的体细胞，这确保了单个MMC 的特异化。

In flowering plants, the female germ line begins as a single cell known as the megaspore mother cell (MMC) in each ovule. The mechanisms that restrict MMC fate to a single cell remain largely unknown. We show that the Arabidopsis cytochrome P450 gene KLU acts through the chromatin remodeling complex SWR1 to promote WRKY28 expression in ovule primordia. We show that WRKY28 is expressed in a few somatic cells surrounding the MMC and is required to inhibit these cells from acquiring the MMC-like cell fate. Consistent with non–cell-autonomous KLU activity, KLU-expressing cells and WRKY28-expressing cells are neither identical nor adjacently positioned. Our study demonstrates that cell–cell interactions involving only somatic cells in ovule primordia ensure the specification of a single MMC.

生殖系特化对有性繁殖至关重要。在大多数开花植物的胚珠中，只有单一的皮下细胞扩大并分化成为大孢子母细胞（MMC），即雌性生殖系的起始细胞。将MMC特化限制为单细胞的分子机制仍然是不清楚的。拟南芥转录因子WRKY28专门表达在围绕MMC的皮下体细胞，并且是限制这些细胞获得类似MMC 细胞特性所必需的。在这个过程中，SWR1染色质重塑复合物介导WRKY28基因座上组蛋白变体H2A.Z的掺入。此外，在内珠被原基中表达的细胞色素P450基因KLU，非细胞自发性地通过H2A.Z沉积在WRKY28上促进其表达。综上所述，我们的研究结果显示了胚珠原基体细胞协同染色质重塑，将生殖细胞的特性限制在单个细胞中的机理。

Germ-line specification is essential for sexual reproduction. In the ovules of most flowering plants, only a single hypodermal cell enlarges and differentiates into a megaspore mother cell (MMC), the founder cell of the female germ-line lineage. The molecular mechanisms restricting MMC specification to a single cell remain elusive. We show that the Arabidopsis transcription factor WRKY28 is exclusively expressed in hypodermal somatic cells surrounding the MMC and is required to repress these cells from acquiring MMC-like cell identity. In this process, the SWR1 chromatin remodeling complex mediates the incorporation of the histone variant H2A.Z at the WRKY28 locus. Moreover, the cytochrome P450 gene KLU, expressed in inner integument primordia, non–cell-autonomously promotes WRKY28 expression through H2A.Z deposition at WRKY28. Taken together, our findings show how somatic cells in ovule primordia cooperatively use chromatin remodeling to restrict germ-line cell specification to a single cell.

Proposed model for the coordinated action of KLU and SWR1 in suppressing ectopic MMC fate by promoting WRKY28 expression in the hypodermal somatic cells surrounding the MMC

每日一词

megaspore

英['megəspɔ:]

美['megəˌspoʊr]

n. 大孢子，（种子植物的）胚囊;

[例句]In theterosporous species, a distinction is usually made between megaspore mother cells and microspore mother cells.

在异型孢子体种类中，可区分为大孢子母细胞和小孢子母细胞。