Functional analysis of SlEZ1 a tomato Enhancer of zeste (E(z)) gene demonstrates a role in flower development

Abstract

The Enhancer of Zeste (E(z)) Polycomb group (PcG) proteins, which are encoded by a small gene family in Arabidopsis thaliana, have been shown to participate to the control of flowering and seed development. For the time being, little is known about the function of these proteins in other plants. In tomato E(z) proteins are encoded by at least two genes namely SlEZ1 and SlEZ2 while a third gene, SlEZ3, is likely to encode a truncated non-functional protein. The analysis of the corresponding mRNA demonstrates that these two genes are differentially regulated during plant and fruit development. We also show that SlEZ1 and SlEZ2 are targeted to the nuclei. These results together with protein sequence analysis makes it likely that both proteins are functional E(z) proteins. The characterisation of SlEZ1 RNAi lines suggests that although there might be some functional redundancy between SlEZ1 and SlEZ2 in most plant organs, the former protein is likely to play specific function in flower development.

Rosaceae Fruit Development, Ripening and Post-harvest: An Epigenetic Perspective

“…The expression profile of enzymes responsible for PTMs has been determined in many fruit species, suggesting their potential role in specific moments of growth, in both early and late fruit development (described below; Janssen et al, 2008; Aquea et al, 2010; Cigliano et al, 2013). Functional analyses that have contributed to attribute a function to histone modifiers in fruits were performed mainly in tomato model: for example the PRC2 Polycomb repressive complex is composed by different subunits with specific functions among which the deposition of H3K27me3 mark, with a fundamental role in fruits shape, flower formation, cutin accumulation, and fruit shelf life in tomato (How-Kit et al, 2010; Liu D. D. et al, 2012; Boureau et al, 2016; Liu et al, 2016). In Rosaceae family, the important role of PcG proteins, in relation to specific agronomic traits, was described: in particular, by the ectopic expression in tomato of a PRC2 PcG protein homolog Malus hupehensis FERTILIZATION-INDEPENDENT ENDOSPERM (MhFIE) leads to a co-suppression of the tomato homolog protein, resulting in various tomato phenotypes similar to those described in How-Kit et al (2010), Boureau et al (2016), and Liu et al (2016).…”

DNA Methylation and Chromatin Regulation during Fleshy Fruit Development and Ripening

“…The results indicate that some of the genes involved in histone PTMs are preferentially or specifically expressed in fruits and may present stage preferential expression, suggesting their recruitment for the regulation of fruit development. For example, a few tomato HMT genes, among which those encoding the ENHANCER OF ZESTE [E(z)] proteins, were shown to be expressed during early phases of tomato fruit development ( How Kit et al, 2010 ; Cigliano et al, 2013 ) suggesting an early programming of chromatin structure necessary for proper fruit development. This is consistent with the functional analysis of the two tomato SlEZ1 and S lEZ2 genes which encode the tomato E(z) proteins orthologous to the Arabidopsis SWINGER and CURLY LEAF, respectively ( How Kit et al, 2010 ; Boureau et al, 2016 ).…”

Polycomb-group protein SlMSI1 represses the expression of fruit-ripening genes to prolong shelf life in tomato

“…Recently, increasing evidence has indicated that epigenetic modulations are involved in the control of fruit ripening. Some PcG genes, such as SlEZ1 25 and SlVIN3 26, have been found to regulate flower/fruit development and floral organ differentiation in tomato, and SlEZ2 27 has been shown to function in fruit development and ripening.…”