Our lab studies how organ size and shape are controlled in the flowering plant Arabidopsis thaliana. Reproductive competence of flowering plants requires proper development of the carpel, which is the female reproductive organ of the plant. The meristematic regions along the margin of the developing carpel generate ovules that will later develop into seeds. These meristematic regions are functionally analogous to the mammalian ovary and placenta.

A confocal microscopy image of a developing Arabidopsis gynoecium shows two rows of interdigitated ovule primordia arising from the carpel margin meristem. Once fertilized these ovule primordia will develop into seeds. Proper development of the carpel margin meristem is thus critical for female reproductive competence and for agricultural productivity in many agricultural varieties.

The carpel margin meristems (CMMs) provide an excellent system to study basic problems in developmental biology such as patterning, the regulation of cellular proliferation and the control of organ size and shape. Dr. Franks' research program seeks to clarify basic mechanisms of organ size and shape regulation and understand relationships between patterning cues and cellular proliferation within the carpel. Current research focuses on (1) characterization of expression patterns of key regulatory molecules and patterns of cellular division during carpel development and (2) identification and functional studies of additional genes that play a critical role in CMM development.

A scanning electron microscopy image of a mutant Arabidopsis flower. Loss-of-function mutations in two genes, SEUSS and LEUNIG, alter petal shape. Resulting petals are filamentous or club-shaped instead of blade-shaped. Our lab works to elucidate molecular genetic factors that control organ shape and size. See Development 129: 253-263.