Tissue specificity and differential expression of transcription factors in tomato provide hints of unique regulatory networks during fruit ripening.

Tissue specificity or dramatically different expression levels of transcription factors in different tissue types allows differential regulation of tissue development as well as alternate modes of metabolic regulation. Recently we reported (Rohrmann et al., 2011) the development of a quantitative real-time PCR platform (qRT-PCR) that allows accurate quantification of the expression level of approximately 1000 tomato transcription factors. Application of this platform to samples collected during a ripening time course of wild type tomato and the high pigment mutant hp1 allowed us to identify transcription factors of importance both to ripening per se and to the metabolic shifts that occur during this critical biological process. Here we extend the quantitative real-time PCR analyses to include samples from flower, leaf, stem and root of wild type tomato. Co-expression network analysis to identify both conserved and unique regulatory networks both between individual tissues of tomato and also in cross-species comparisons of specific tissues, suggested some key TF genes which are involved in photosynthesis and fruit development.