NAC100 regulates silique growth during the initial phase of fruit development through the gibberellin biosynthetic pathway

The NAC transcription factor family is a large class of DNA-binding proteins found in several plant species. In the model plant Arabidopsis thaliana, NAC transcription factors are expressed in different organs, and they are known to modulate many diverse developmental processes, such as meristem formation, flower and fruit development, leaf and fruit senescence. From a previous time-lapse transcriptomic analysis of developing siliques performed by our group, we found a NAC transcription factor, NAC100, that is upregulated during silique development. In this work, we characterized the role of the NAC100 transcription factor and demonstrated that NAC100 contributes to regulating silique growth during the initial phase of their development. nac100 mutant siliques are smaller but such defects can be rescued through the application of exogenous bioactive gibberellin. Gene expression analysis, transactivation assay and endogenous gibberellin quantification indicate that NAC100 modulates gibberellin metabolism, by both directly and indirectly regulating GA-metabolic genes expression, ultimately affecting silique elongation.