The Knl1-Mis12-Ndc80 (KMN) network is an essential component of the kinetochore–microtubule attachment interface, which is required for genomic stability in eukaryotes. However, little is known about plant Knl1 proteins because of their complex evolutionary history. Here, we cloned the Knl1 homolog from maize (Zea mays) and confirmed it as a constitutive central kinetochore component. Functional assays demonstrated their conserved role in chromosomal congression and segregation during nuclear division, thus causing defective cell division during kernel development when Knl1 transcript was depleted. A 145 aa region in the middle of maize Knl1, that did not involve the MELT repeats, was associated with the interaction of spindle assembly checkpoint (SAC) components Bub1/Mad3 family proteins 1 and 2 (Bmf1/2) but not with the Bmf3 protein. They may form a helical conformation with a hydrophobic interface with the TPR domain of Bmf1/2, which is similar to that of vertebrates. However, this region detected in monocots shows extensive divergence in eudicots, suggesting that distinct modes of the SAC to kinetochore connection are present within plant lineages. These findings elucidate the conserved role of the KMN network in cell division and a striking dynamic of evolutionary patterns in the SAC signaling and kinetochore network.

Knl1-Mis12-Ndc80 (KMN) 网络是动粒-微管连接界面的重要组成部分，是真核生物基因组稳定性所必需的。然而，由于其复杂的进化历史，人们对植物 Knl1 蛋白知之甚少。在这里，我们克隆了Knl1从玉米同源物（玉米) 并确认它是本构中心动粒成分。功能测定证明了它们在核分裂过程中的染色体聚集和分离中的保守作用，从而导致当 Knl1 转录物耗尽时内核发育过程中的细胞分裂缺陷。玉米 Knl1 中间的一个 145 aa 区域，不涉及 MELT 重复，与纺锤体组装检查点 (SAC) 组件 Bub1/Mad3 家族蛋白 1 和 2 (Bmf1/2) 的相互作用有关，但与 Bmf3 无关蛋白质。它们可能与 Bmf1/2 的 TPR 结构域形成具有疏水界面的螺旋构象，类似于脊椎动物的结构。然而，在单子叶植物中检测到的这个区域在双子叶植物中表现出广泛的差异，这表明 SAC 与动粒连接的不同模式存在于植物谱系中。