The switch from plant vegetative growth to reproductive development (transition to flowering), is a critical stage in the life cycle of a plant. As such, flowering is tightly controlled by diverse developmental, hormonal and environmental cues, day length and temperature being the most important of these environmental signals (Posè et al. Curr Opin Plant Biol. 2012; Huijser and Schmid, Development 2011). Flowering time diversity has adaptive value in natural populations and plays a major role in agricultural production. Specifically, flowering delay in different environmental conditions is a crucial breeding trait for yield and nutritive quality of leafy crops and forages. Genetic and molecular analyses in the model plant Arabidopsis thaliana have identified regulatory pathways that control the floral transition (Turck et al. Annu. Rev. Plant Biol. 2008; Amasino Plant J. 2010; Fornara et al. Cell 2010). These pathways act in different tissues of the plant but ultimately converge at the shoot apical meristem (SAM) (Huijser and Schmid, Development 2011). Our studies aim to translate the knowledge acquired in Arabidopsis to leafy vegetables of high commercial value, endive and escarole (Cichorium endivia), whose transcriptome was recently sequenced in our lab in collaboration with the International seed breeding company Enza Zaden (R&D Italia). The final goal is to identify novel functional single nucleotide polymorphisms (SNPs), which may account for flowering time diversity as a tool for molecular breeding of leafy crops. We used a candidate gene approach and focus on well known Arabidopsis regulators of flowering transition and novel potential regulators belonging to the TALE (Three Amino acid Loop Extension, KNOX and BLH genes) family of homeobox transcription factors, which are expressed in the SAM (Hake et al. 2004; Di Giacomo et al. 2013). In silico analysis of Arabidopsis genome identified potential TALE binding sites in the regulatory regions of several flowering time genes. Sequenced genomes of A. thaliana natural accessions were screened for SNPs in the potential TALE binding sites to select Arabidopsis accessions for further studies. Characterization of the flowering time response of mutants and transgenics with altered KNOX expression is in progress. Homologous genes for known Arabidopsis regulators of flowering transition and TALEs were identified in the C. endivia transcriptome. Identification of putative functional SNPs in flowering regulatory genes and TALEs in different C. endivia varieties is in progress. Transcript profiling of adult leaves through RNAseq, in varieties which display different flowering time responses, identified possible gene expression markers of flowering time to be considered for functional validation.
TALE TRANSCRIPTION FACTORS AND FLOWERING TIME: FROM MODEL SPECIES TO LEAFY CROPS
DI GIACOMO E;TESTONE G;GIANNINO D;MELE G;FRUGIS G
2014
Abstract
The switch from plant vegetative growth to reproductive development (transition to flowering), is a critical stage in the life cycle of a plant. As such, flowering is tightly controlled by diverse developmental, hormonal and environmental cues, day length and temperature being the most important of these environmental signals (Posè et al. Curr Opin Plant Biol. 2012; Huijser and Schmid, Development 2011). Flowering time diversity has adaptive value in natural populations and plays a major role in agricultural production. Specifically, flowering delay in different environmental conditions is a crucial breeding trait for yield and nutritive quality of leafy crops and forages. Genetic and molecular analyses in the model plant Arabidopsis thaliana have identified regulatory pathways that control the floral transition (Turck et al. Annu. Rev. Plant Biol. 2008; Amasino Plant J. 2010; Fornara et al. Cell 2010). These pathways act in different tissues of the plant but ultimately converge at the shoot apical meristem (SAM) (Huijser and Schmid, Development 2011). Our studies aim to translate the knowledge acquired in Arabidopsis to leafy vegetables of high commercial value, endive and escarole (Cichorium endivia), whose transcriptome was recently sequenced in our lab in collaboration with the International seed breeding company Enza Zaden (R&D Italia). The final goal is to identify novel functional single nucleotide polymorphisms (SNPs), which may account for flowering time diversity as a tool for molecular breeding of leafy crops. We used a candidate gene approach and focus on well known Arabidopsis regulators of flowering transition and novel potential regulators belonging to the TALE (Three Amino acid Loop Extension, KNOX and BLH genes) family of homeobox transcription factors, which are expressed in the SAM (Hake et al. 2004; Di Giacomo et al. 2013). In silico analysis of Arabidopsis genome identified potential TALE binding sites in the regulatory regions of several flowering time genes. Sequenced genomes of A. thaliana natural accessions were screened for SNPs in the potential TALE binding sites to select Arabidopsis accessions for further studies. Characterization of the flowering time response of mutants and transgenics with altered KNOX expression is in progress. Homologous genes for known Arabidopsis regulators of flowering transition and TALEs were identified in the C. endivia transcriptome. Identification of putative functional SNPs in flowering regulatory genes and TALEs in different C. endivia varieties is in progress. Transcript profiling of adult leaves through RNAseq, in varieties which display different flowering time responses, identified possible gene expression markers of flowering time to be considered for functional validation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
