My interests are in plant cell and developmental biology, with an emphasis on flower organ growth and pollination. One major focus in my lab now is the role of the gynoecium in pollination. Our model is that interaction between the transmitting tract extracellular matrices (ECMs) of the gynoecium or pistil, and the pollen tube, act to guide the tube cell and its component sperm cells, to the ovule (Lord and Russell 2002). We discovered an adhesion event between the pollen tube and the stylar transmitting tract in several species and have isolated the molecules from the style that cause this adhesion. Our hypothesis is that adhesion events between the pollen tube and the style facilitate tube cell movement to the ovary. Adhesion molecules are common in animal development and are involved in cell movement and differentiation but none had been described in plants. To look for the adhesion molecules in the style we developed an in vitro adhesion assay that mimics the in vivo interaction between the pollen tube and the style in lily. We used this assay to isolate the two molecules necessary for pollen tube adhesion to the stylar ECM; they are a pectic polysaccharide and a 9kD protein, SCA (stigma/stylar cysteine-rich adhesin). We are studying how these two molecules interact to cause adhesion. The two molecules are necessary together to allow for adhesion and one requirement is that they bind to one another. One approach we are taking is to selectively remove parts of the pectic polysaccharide to determine the mode of interaction between the pectin and the peptide. Another goal using several enzymes is to elucidate the essential components of the pectin in adhesion.
