Abstract
The histone acetyltransferase (HAT) general control non-repressed protein 5 (GCN5) plays important roles in plant development via epigenetic regulation of its target genes. However, the role of GCN5 in tomato, especially in the regulation of tomato shoot meristem and flower development, has not been well-understood. In this study, we found that silencing of Solanum lycopersicum GCN5 (SlGCN5, Solyc10g045400.1.1) by virus-induced gene silencing (VIGS) and RNA interference (RNAi) resulted in the loss of shoot apical dominance, reduced shoot apical meristem (SAM) size, and dwarf and bushy plant phenotype. Besides, we occasionally observed extra carpelloid stamens and carpels fused with stamens at the late stages of flower development. Through gene expression analysis, we noticed that SlGCN5 could enhance SlWUS transcript levels in both SAM and floral meristem (FM). Similar to the known function of GCN5 in Arabidopsis, we demonstrated that SIGCN5 may form a HAT unit with S. lycopersicum alteration/deficiency in activation 2a (SlADA2a) and SlADA2b proteins in tomato. Therefore, our results provide insights in the SlGCN5-mediated regulation of SAM maintenance and floral development in tomato.
Highlights
Plants have a unique ability to give rise to new organs continuously due to the indeterminate production of undifferentiated stem cells located in specific regions of meristems
Results of quantitative real-time (qRT)-PCR showed that SlGCN5 transcription level in the tobacco rattle virus (TRV)-SlGCN5-infected plants was significantly lower than plants infected with TRV control (Figure 1C), confirming that the abnormal phenotypes are caused by SlGCN5 gene silencing
Results showed that SlGCN5-GFP fusion protein driven by constitutive cauliflower mosaic virus 35S promoter exclusively localized in the nucleus (Figure 2A), suggesting that SlGCN5 may have a putative role in histone modification
Summary
Plants have a unique ability to give rise to new organs continuously due to the indeterminate production of undifferentiated stem cells located in specific regions of meristems. Unlike Arabidopsis, tomato is a typical sympodial plant. After the formation of 8–10 leaves, tomato SAM terminated and transforms into inflorescence meristem (IM) and sympodial meristem (SYM), which are formed at the leaf axils beneath the IM to sustain continuous growth. Thereafter, IM transforms to floral meristem (FM) and initiates a second IM in the meantime (Schmitz and Theres, 1999; Périlleux et al, 2014). Tomato FMs generate four whorls of floral organs, namely, sepals, petals, stamens, and carpels, sequentially in concentric whorls (Sekhar and Sawhney, 1984)
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