Poster: Reproductive development

Abs # 361: PFS2 encodes a homeodomain protein that regulates ovule differenciation.

Presenter:	Park, Sung O., sop@ufl.edu
Authors	Park, Sung O. (A)   Bernard, Hauser A. (A)
Affiliations:	(A): University of Florida

The PRETTY FEW SEEDS2 (PFS2) gene encodes a homeodomain protein that regulates ovule development. As the name indicates, this mutant forms approximately 4 viable seeds per fruit. In strong pfs2-1 mutants, 95% of the embryo sacs fail to develop correctly and integuments display morphological abnormalities. The weaker pfs2-2 allele exhibits defects in embryo sac development, resulting in a ~50% reduction in seed set. Ectopic PFS2 expression yielded a variety of plant phenotypes. In many transformants, differentiation of organ from the meristem is altered. Some seedlings have enlarged apical meristem with undifferentiated leaf primordia, while others are highly fasciated and display altered phyllotaxy. PFS2 over-expressors that make reproductive organs have misshapen ovules. In the nucellus of these ovules, the megaspore mother cell rarely differentiates. Ectopic PFS2 expression blocks embryo sac differentiation and affects development of other organs. In peptide alignments of PFS2 with similar proteins, PFS2 and WUSHEL (WUS) are highly conserved throughout the homeodomain region. Based on our gain-of- function experiment and evaluation of the phenotype, PFS2 might function similarly to WUS and inhibit differentiation.