Poster: Reproductive Development

Abs # 480: b-Expansins in Maize pollen, Role of Zea m 1 in Development and Fertilization

Presenter:	Valdivia, Elene R, erv105@psu.edu
Authors	Valdivia, Elene R (A)   Durachko, Daniel M (A)   Wagner, Edward  (A)   Stephenson, Andrew G (A)   Cosgrove, Daniel J (A)
Affiliations:	(A): Dept of Biology, Penn State University

Group-1 grass pollen allergens are glycoproteins 28-35 kDa in size and are specifically expressed in grass pollen. Group-1 pollen allergens make up a sub class of b-expansins, which are cell wall loosening proteins that loosen plant cell walls in characteristic ways. Group-1 pollen allergens are proposed to loosen the cell walls of the silks to aid in the penetration and growth of the pollen tube through the silks. In maize, the group-1 pollen allergens are called Zea m 1 and there are two divergent forms of Zea m 1. Each of the two forms is encoded by two genes, making a total of four Zea m 1 genes in maize. To assess the function of Zea m 1, maize plants were transformed with an RNAi construct for RNA silencing, driven by a pollen specific promoter. The first generation of transgenic plants have the following unusual traits: low pollen production, shriveled anthers, continued silk growth post pollination and low seed set. These phenotypes are more extensive than that found previously for a maize line carrying an Mu insertion in one of the Zea m 1 genes. Immunohistostaining, using monoclonal antibodies specific to group-1 pollen allergens, is also being performed on male and female flowers at various developmental stages to examine the localization of allergens during development.