Poster: Developmental Patterning

Abs # 341: Interacting transcription factors from the TALE superclass regulate processes of growth in potato

Presenter:	Chen, Hao , haochen@iastate.edu
Additional Authors	Rosin, Faye M (A) (C)  Prat-Monguio, Salomé  (D)   Hannapel, David J (A) (B)
Affiliations:	(A): Iowa State University, Dept of Horticulture (B): Iowa State University, Interdepartmental Plant Physiology Major (C): Iowa State University; Molecular, Cellular, and Developmental Biology Major (D): Institut de Biología Molecular de Barcelona-CSIC, Department de Genética Molecular

Using the yeast two-hybrid system and a potato KNOX protein, designated POTH1, as bait, we have identified seven distinct interacting proteins from a vegetative meristem library of potato. All seven cDNAs are members of the BEL1-like family of transcription factors. Among these proteins, there are at least four regions of sequence conservation including the homeodomain, the proline-tyrosine-proline tale, the SKY-box domain, and the BEL domain, a 120-amino acid region upstream from the homeodomain. Through deletion mutation analysis, we identified a protein-binding domain present in the carboxyl-end of the KNOX region of POTH1. Any constructs containing this fifty-amino acid region interacted with a representative BEL partner. The protein-binding domain in the BEL protein is located in the amino-terminal half of the 120-residue conserved region of the BELs. RNA blot analysis showed differential patterns of RNA accumulation for the BELs in various potato organs. Two subfamilies of the BELs exhibited mRNA accumulation throughout the plant and were developmentally regulated in tuberizing stolons. Accumulation of the mRNA of two other subfamilies, represented by StBEL-13 and StBEL-14, was most abundant in flowers and shoot apical meristems and in flowers and leaves, respectively. Similar to sense mutants of POTH1, transgenic lines that overexpressed one of the BELs exhibited enhanced tuber formation even under noninductive conditions. The BEL overexpression lines, however, do not exhibit the severe leaf morphology characteristic of POTH1 overexpressers. Our results demonstrate that interacting transcription factors from the TALE superclass regulate processes of growth in potato.