Timed termination of floral meristem (FM) is crucial for proper development of floral organs and fruits. In Solanum lycopersicum, CLAVATA3 (CLV3)-WUSCHEL (WUS) feedback regulation maintains FM homeostasis in early stage of floral buds. It is known that the zinc finger protein SlKNUCKLES (SlKNU) functions to promote FM determinacy by directly repressing the stem cell identity gene SlWUS. However, how the robust FM activity is suppressed to secure fruit development is not fully understood in tomato. Here, we demonstrate that SlKNU also directly represses the stem cell marker gene SlCLV3 and the receptor gene SlCLV1 for FM determinacy control. Besides, loss-of-function mutants of SlKNU generated by CRISPR-Cas9 show increased fruit size of tomato. Moreover, overexpression of SlKNU attenuates the activities of the shoot apical meristem (SAM) and FM in Arabidopsis, but normal carpel development is still maintained. Hence, although the function of KNU in tomato and Arabidopsis may diverge during evolution, the role of KNU for FM determinacy and fruit size control is conserved and may potentially be useful for enhancing fruit yield of tomato.

中文翻译：

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SlKNUCKLES 调节 Solanum lycopersicum 的花分生组织活性并控制果实大小


花分生组织 （FM） 的定时终止对于花器官和果实的正常发育至关重要。在 Solanum lycopersicum 中，CLAVATA3 （CLV3） -WUSCHEL （WUS） 反馈调节维持花芽早期的 FM 稳态。众所周知，锌指蛋白 SlKNUCKLES （SlKNU） 通过直接抑制干细胞身份基因 SlWUS 来促进 FM 决定性。然而，番茄中如何抑制强大的 FM 活性以确保果实发育尚不完全清楚。在这里，我们证明 SlKNU 还直接抑制干细胞标志物基因 SlCLV3 和受体基因 SlCLV1 以进行 FM 决定性控制。此外，CRISPR-Cas9 产生的 SlKNU 功能丧失突变体显示番茄果实大小增加。此外，SlKNU 的过表达减弱了拟南芥中芽尖分生组织 （SAM） 和 FM 的活性，但仍然维持正常的心皮发育。因此，尽管 KNU 在番茄和拟南芥中的功能在进化过程中可能会有所不同，但 KNU 对 FM 决定性和果实大小控制的作用是保守的，并且可能有助于提高番茄的果实产量。