Poster abstracts

Poster number 34 submitted by Isabella Mendes

A pollen expressed kinesin-4 in Arabidopsis thaliana pollen tubes assists in male germ unit trafficking and is required for full seed set

Isabella Mendes (Molecular, Cellular, and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH, USA, Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA ), Norman R Groves (Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA, Center for Applied Plant Sciences, The Ohio State University, Columbus, OH, USA), Iris Meier (Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA, Center for Applied Plant Sciences, The Ohio State University, Columbus, OH, USA, Center for RNA Biology, The Ohio State )

Abstract:
Fertilization is a key component of plant reproduction that is necessary for agriculture. While the basic process of fertilization has been understood for centuries, the mechanism underlying how plant sperm is trafficked to the egg remains poorly understood. To achieve fertilization, the sperm cells must be trafficked through the growing pollen tube to reach ovules – a distance of several millimeters. In our research, we seek to identify which motor proteins play a role in this trafficking. Myosins have been well-studied in pollen-tube tip growth, but the roles of Kinesins in pollen tubes have not been established. To determine which motors are involved in male germ unit movement, we have screened insertional mutants in 17 pollen-expressed Kinesins (PEK1-PEK17) for fertility defects. Insertional mutants in a kinesin-4 (pek14) display a drastic seed set reduction phenotype in three separate insertional mutants. Through reciprocal crosses, we determined that this observed defect is male derived. Pollen viability and pollen tube growth were then analyzed. pek14 pollen was found to be viable, and no defect in pollen tube growth rate or ovule targeting was detected. When analyzing the movement of the sperm cells and the nucleus of the pollen tube over the duration of pollen tube growth, it was observed that the sperm and nucleus displayed aberrant motion in 30% of pollen tubes. We hypothesize that this aberrant motion contributes to the lack of seed produced by pek14 plants. GFP tagging of PEK14 has revealed it possesses a cell plate and/or phragmoplast localization in roots. Future experiments will endeavor to determine the location and functional role of PEK14 in pollen.

Keywords: Male Germ Unit, Pollen Tube, Kinesin