Cell fate maintenance is an integral part of plant cell differentiation and the production of functional cells, tissues, and organs. Fleshy fruit development is characterized by the accumulation of water and solutes in the enlarging cells of parenchymatous tissues. In tomato (Solanum lycopersicum), this process is associated with endoreduplication in mesocarp cells. The mechanisms that preserve this developmental program, once initiated, remain unknown. We show here that analysis of a previously identified tomato ethyl methanesulfonate-induced mutant that exhibits abnormal mesocarp cell differentiation could help elucidate determinants of fruit cell fate maintenance. We identified and validated the causal locus through mapping-by-sequencing and gene editing, respectively, and performed metabolic, cellular, and transcriptomic analyses of the mutant phenotype. The data indicate that disruption of the SlGBP1 gene, encoding GUANYLATE BINDING PROTEIN1, induces early termination of endoreduplication followed by late divisions of polyploid mesocarp cells, which consequently acquire the characteristics of young proliferative cells. This study reveals a crucial role of plant GBPs in the control of cell cycle genes, and thus, in cell fate maintenance. We propose that SlGBP1 acts as an inhibitor of cell division, a function conserved with the human hGBP-1 protein.

细胞命运维持是植物细胞分化和功能细胞、组织和器官产生的一个组成部分。肉质果实发育的特点是水和溶质在薄壁组织增大的细胞中积累。在番茄（Solanum lycopersicum），这个过程与中果皮细胞的核内复制有关。一旦启动，维持这种发育程序的机制仍然未知。我们在此表明​​，对先前鉴定的番茄甲磺酸乙酯诱导的表现出异常中果皮细胞分化的突变体的分析可能有助于阐明果实细胞命运维持的决定因素。我们分别通过测序作图和基因编辑来识别和验证因果位点，并对突变表型进行代谢、细胞和转录组分析。数据表明SlGBP1的破坏编码鸟苷酸结合蛋白1的基因诱导内复制的早期终止，随后多倍体中果皮细胞的晚期分裂，从而获得年轻增殖细胞的特征。这项研究揭示了植物 GBP 在细胞周期基因控制中的关键作用，从而在细胞命运维持中发挥着关键作用。我们认为 SlGBP1 作为细胞分裂的抑制剂，这是人类 hGBP-1 蛋白保守的功能。