Tomato (Solanum lycopersicum) rin mutants completely fail to ripen: they do not produce red pigmentation, soften or induce an ethylene burst. Therefore, RIN has long been believed to function as a major regulator that is essential for the induction of ripening. Here, we provide evidence contradicting this concept of RIN function, showing induction of fruit ripening in the absence of RIN. A CRISPR/Cas9-mediated RIN-knockout mutation did not repress initiation of ripening and the mutant fruits showed moderate red colouring. Moreover, inactivation of the rin mutant allele partially restored the induction of ripening. Therefore, RIN is not required for the initiation of ripening and rin is not a null mutation, but rather is a gain-of-function mutation that produces a protein that actively represses ripening. Since the discovery of the rin mutant a half-century ago, many models have depicted RIN as indispensable for the induction of ripening; these models should be reconsidered in light of these results.

中文翻译：

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重新评估rin突变以及RIN在诱导番茄成熟中的作用。

番茄（Solanum lycopersicum）rin突变体完全无法成熟：它们不会产生红色色素沉着，不会软化或引起乙烯爆炸。因此，长期以来人们一直认为RIN可以作为诱导成熟的主要调节剂。在这里，我们提供了与RIN功能概念相反的证据，显示了在没有RIN的情况下诱导果实成熟。CRISPR / Cas9介导的RIN敲除突变不会抑制成熟的开始，并且突变的果实显示出中等的红色。此外，rin突变体等位基因的失活部分恢复了成熟的诱导。因此，RIN不是启动成熟所必需的，并且rin不是无效突变，而是功能获得的突变，其产生可主动抑制成熟的蛋白质。自半个世纪前发现rin突变体以来，许多模型都将RIN描述为诱导成熟必不可少的。鉴于这些结果，应重新考虑这些模型。