Molecular and functional characterization of the SBP-box transcription factor SPL-CNR in tomato fruit ripening and cell death. (4th February 2020)

• Record Type: Journal Article
• Authors: Lai, Tongfei; Wang, Xiaohong; Ye, Bishun; Jin, Mingfei; Chen, Weiwei; Wang, Ying; Zhou, Yingying; Blanks, Andrew M; Gu, Mei; Zhang, Pengcheng; Zhang, Xinlian; Li, Chunyang; Wang, Huizhong; Liu, Yule; Gallusci, Philippe; Tör, Mahmut; Hong, Yiguo
• Editors: Costa, Fabrizio
• Is Part Of: Journal of experimental botany. Volume 71:Number 10(2020)
• Page Start: 2995
• Page End: 3011
• Publication Date: 2020-02-04
• Subjects: Cell death -- Colourless non-ripening -- nuclear localization signal -- SlSnRK1 -- SlSPL-CNR -- tomato (Solanum lycopersicum) fruit ripening -- zinc-finger motif; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/eraa067
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract: SlSPL-CNR, an SBP-box transcription factor (TF) gene residing at the epimutant Colourless non-ripening ( Cnr ) locus, is involved in tomato ripening. This epimutant provides a unique model to investigate the (epi)genetic basis of fruit ripening. Here we report that SlSPL-CNR is a nucleus-localized protein with a distinct monopartite nuclear localization signal (NLS). It consists of four consecutive residues ' 30 KRKR33 ' at the N-terminus of the protein. Mutation of the NLS abolishes SlSPL-CNR's ability to localize in the nucleus. SlSPL-CNR comprises two zinc-finger motifs (ZFMs) within the C-terminal SBP-box domain. Both ZFMs contribute to zinc-binding activity. SlSPL-CNR can induce cell death in tomato and tobacco, dependent on its nuclear localization. However, the two ZFMs have differential impacts on SlSPL-CNR's induction of severe necrosis or mild necrotic ringspot. NLS and ZFM mutants cannot complement Cnr fruits to ripen. SlSPL-CNR interacts with SlSnRK1. Virus-induced SlSnRK1 silencing leads to reduction in expression of ripening-related genes and inhibits ripening in tomato. We conclude that SlSPL-CNR is a multifunctional protein that consists of a distinct monopartite NLS, binds to zinc, and interacts with SlSnRK1 to affect cell death and tomato fruit ripening. Abstract : The tomato transcription factor SlSPL-CNR is a multi-functional protein that has a role in fruit ripening and is capable of triggering cell death.