BIG regulates the shoot stem cell population. The shoot apical meristem (SAM) contains a population of self-renewing cells, and provides daughter cells for initiation and development of aerial parts of plants. However, the underlying mechanisms of SAM size regulation remain largely unclear. Here, we identified a mutant that displayed a large SAM, designated big-shoot meristem (big-m), in Arabidopsis thaliana. The phenotype of big-m is caused by a new T-DNA insertion allele of BIG, causing a loss of function. The big-m mutant had more stem cells in the SAM than in the wild type. Expression of WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM) was promoted in big-m compared with the wild type, showing that BIG functions upstream of WUS and STM. Therefore, BIG is an important regulator of the stem cell population in the SAM. Furthermore, genetic analysis indicated that BIG acts synergistically with PIN-FORMED1 (PIN1) in controlling SAM size. Our results suggest that BIG plays an important role in controlling Arabidopsis thaliana SAM growth via PIN1-mediated auxin homeostasis.

中文翻译：

---

BIG 基因控制拟南芥茎尖分生组织的大小。

BIG 调节芽干细胞群。茎尖分生组织 (SAM) 包含一群自我更新的细胞，并为植物地上部分的起始和发育提供子细胞。然而，SAM 大小调节的潜在机制在很大程度上仍不清楚。在这里，我们在拟南芥中发现了一种突变体，该突变体显示出一个大的 SAM，称为大茎分生组织 (big-m)。big-m 的表型是由 BIG 的一个新的 T-DNA 插入等位基因引起的，导致功能丧失。big-m 突变体在 SAM 中的干细胞比野生型中的多。与野生型相比，big-m中WUSCHEL（WUS）和SHOOTMERISTEMLESS（STM）的表达明显升高，表明BIG在WUS和STM上游起作用。因此，BIG 是 SAM 中干细胞群的重要调节因子。此外，遗传分析表明，BIG 在控制 SAM 大小方面与 PIN-FORMED1 (PIN1) 协同作用。我们的研究结果表明，BIG 通过 PIN1 介导的生长素稳态在控制拟南芥 SAM 生长中起重要作用。