Graduate student The university of Mississippi Oxford, Mississippi
Body of Abstract: Sabnam Ojha and Sarah Liljegren
Department of Biology, University of Mississippi, Oxford, MS
Abscission is a process in plants where structures such as leaves, fruit and floral organs are shed. In Arabidopsis flowers, abscission zones develop at boundaries between the floral organ bases and the underlying receptacle. Within the sepal abscission zones, a lignin brace provides mechanical support and facilitates precise detachment by confining the enzymes responsible for cell separation and cell wall modification to specific areas. Previous studies have shown that two homeodomain transcription factors—ATH1 and STM—promote formation of floral organ boundaries and the subsequent differentiation of abscission zone cells. While loss-of-function mutations in the ATH1 gene or a novel hypomorphic mutation in the STM gene prevent stamen abscission, flowers that contain mutations in both genes retain all of their outer floral organs. To determine whether STM and/or ATH1 regulate development of the lignin brace, we have examined the lignification pattern of cells in the sepal abscission zones of our mutants compared to those of wild-type flowers. Our results suggest that formation of the lignin brace is disorganized and reduced in the stm and ath1 single mutants, and fails to occur in the stm ath1 double mutant.