UC San Diego

The fruit is perhaps the most essential organ in Arabidopsis thaliana, not only because it houses and protects the developing seeds and later disperses them, but also because it is also the only link between that plant and the next generation. The majority of the Arabidopsis thaliana fruit is comprised of an ovary, which consists of three primary tissue types: the valves, the repla and the valve margins. Our previous studies have shown there is a complex regulatory network controlling the formation of each of these territories. The MADS-box gene FRUITFULL (FUL) is one of the most important factors regulating valve development in the Arabidopsis fruit. Our previous studies delimited the regulatory regions required to reproduce FUL endogenous expression in which several cis-regulatory motifs were identified. In this context we wanted to further investigate the transcriptional control of the FUL gene by determining the importance of some of these regulatory motifs. We have found that two of the transcription factors modulating FUL expression in the valves are in turn, post-transcriptionally regulated by small RNAs. Collaborating with FUL, the JAG/FIL function is also required for proper valve formation. From our studies we have also identified a putative upstream microRNA-regulatory node modulating JAG/FIL activity in valves. We have incorporated these novel functions into our models and created a revised regulatory network controlling fruit development