Knockout of SlYTH2, encoding a YTH domain-containing protein, caused plant dwarfing, delayed fruit internal ripening, and increased seed abortion rate in tomato

Abstract

The m⁶A is one of the most abundant and widespread modifications in eukaryotic mRNAs, which regulates gene expression at the post-transcriptional level and plays key roles in many physiological processes. The YT521-B homologous (YTH) domain-containing proteins act as m⁶A readers to regulate m⁶A-RNA metabolism processes and mediate the various functions of m⁶A modification. Previously, we reported tomato contains 9 YTH genes, among which SlYTH2 is relatively highly expressed. This study reports the physiological functions of SlYTH2 in tomato. SlYTH2 protein is distributed in the nucleus and cytoplasm, and its three-dimensional structure is highly similar to human HsYTHDF1. SlYTH2 knockout through Crispr/Cas9 gene editing technology leaded to pleiotropic phenotypes, including dwarfing plant, delayed fruit internal ripening process, and increased seed abortion rate. The deletion of SlYTH2 gene increased the accumulation of endogenous ABA, decreased the content of endogenous GA₃, and enhanced the sensitivity of seed germination to exogenous ABA and seedling growth to exogenous GA₃. RNA-Seq data showed that the expression levels of multiple hormone-related genes were altered in SlYTH2 knockout line. These facts suggested SlYTH2 plays its physiological roles related to ABA, gibberellin and other hormones in tomato.

Keywords: Fruit ripening; Phytohormone; Plant growth; Tomato; YTH domain-containing protein.