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Crop Biotech Update

CRISPR Helps Clarify the Mechanism Behind Tomato rin Mutants

May 16, 2018

Tomato (Solanum lycopersicum) rin mutants completely fail to ripen. These mutants do not produce red pigmentation, soften, or induce an ethylene burst. Therefore, RIN has long been believed to function as a major regulator for the induction of ripening. The team of Yasuhiro Ito from the National Agriculture and Food Research Organization in Japan aimed to contradict this concept of RIN function and show fruit ripening induction in the absence of RIN.

The team first developed RIN-knockout tomato mutants using CRISPR-Cas9. The resulting mutants did not exhibit repressed initiation of ripening and the mutant fruits actually showed moderate red coloring. Moreover, inactivation of the mutant allele in rin mutants partially restored the induction of ripening.

RIN is not required for the initiation of ripening in tomato. Further analysis also found that the rin mutant does not actually have a null mutation, but has a gain-of-function mutation. This then produces a protein that represses ripening.

For more information, read the full article in Nature Plants.