Toward understanding the role of CYP78A9 during Arabidopsis reproduction.

After fertilization in Arabidopsis, auxin response in ovules triggers fruit development through the stimulation of gibberellin metabolism. In a recent work, we showed that this model could not explain why CYP78A9 overexpression can uncouple these processes. The specific expression pattern of CYP78A9 suggests its involvement during reproductive development. Moreover, controlled pollination showed that CYP78A9 responds to fertilization. The genetic evidence supports the idea that CYP78A9 and its closest paralogs participate in a pathway that control floral organ size and ovule integuments development as denoted by the phenotypes of es1-D overexpression and cyp78a8 cyp78a9 double mutants. Furthermore, according to previous predictions, perturbations in the flavonol biosynthesis pathway were detected in cyp78a9, cyp78a8 cyp78a9 and es1-D mutants. However, they do not cause the observed phenotypes. Our results add new insights into the role of CYP78A9 in plant reproduction and present the first characterization of metabolite differences between mutants in this gene family.