Poster: Regulation of gene expression

Abs # 787: The IBT4 gene encoding the Arabidopsis cleavage stimulation factor (AtCstF-64) controls trichome and leaf shape

Presenter:	Zhang, Xiaoguo , xgzhang@ufl.edu
Authors	Zhang, Xiaoguo  (A)   Oppenheimer, David G. (A)
Affiliations:	(A): University of Florida

The cleavage and polyadenylation of animal nuclear mRNAs at their 3’ ends are regulated by cleavage stimulation factors (CstF), i.e. CstF-64, CstF-77, and CstF-50. Plant mRNAs have analogous sequences to the animal consensus sequence, AAUAAA, and U-rich sequences. Additionally, the N- terminal domain of AtCstF-64 binds the mRNA 3’ non-coding region in a similar manner to the animal protein. During an enhancer screen of the trichome branching mutation, zwi-3, we identified a trichome mutation that affects branch position and length. This mutant was named irregular trichome branch 4 (itb4). We isolated the ITB4 gene through positional cloning and found that it encodes AtCstF-64. Our genetic data indicate it is required for the normal development of trichomes, leaves, and flowers in Arabidopsis. A weak itb4 allele affects only trichomes, but plants homozygous for a putative null allele (a T-DNA insertion) show additional defects in leaf and flower development. Also, the fully recessive zwi-3 mutation can act as a dominant enhancer of the weak itb4 allele. Preliminary results from GFP-fusions suggest that AtCstF-64 is located in the cytoplasm in trichome cells. (This research was funded by a grant from NSF to DGO)