Mechanism of Flower Patterning in Plants

Complex patterning traits such as speckling and spotting offer a great opportunity to explore fundamental principles of plant evolution and development. In our system, the hybridization between two inter-fertile sister species from the Chile Mimulus luteus complex, M. l. variegatus (lavender color) and M. cupreus (orange color) yield a novel, highly patchy distribution of red anthocyanin pigment on flower petal lobe in both F1 and F2 generations. Back crossing and phenotype segregation have suggested a strong genetic basis behind this complex patterning trait, and several transcriptional regulators of the luteus anthocyanin pathway (such as pla1 and pla2 from the R2R3 MYB superfamily) have already been identified. To further address the genetic mechanism and inter-genomic interactions responsible for anthocyanin patterning in the hybrids, we develop a digital image analysis system to investigate the complexity of petal lobe traits, such as the pigment intensity and spatial variation. The quantifiable phenotypical information will be combined with population-wide genome sequencing data (using RAD-Seq) to enable genetic mapping and analysis. These advances in understanding the regulatory networks allows us to conjecture a mathematical model based on a reaction-diffusion dynamics of the interaction between the activators (a Myb5 and a Myb2b) and the repressor (presumably a R3 MYB). Taken together, our findings will reveal the genetic architecture of hybrid anthocyanin patterning, in a system that is ideal for future evolutionary, molecular, and developmental studies of underlying mechanisms.

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