Poster: vegetative biology

Abs # 195: A potato homeobox gene (POTH1) involved in plant development.

Presenter:	Rosin, Faye M., faye@iastate.edu
Authors	Rosin, Faye M. (A) (B)  Hart, Jennifer K. (B)   Hannapel, David J. (A) (B)
Affiliations:	(A): Molecular, Cellular, and Developmental Biology Program (B): Department of Horticulture, Iowa State University

POTH1 ( potato homeobox 1 ) was isolated from an early tuber cDNA library of Solanum tuberosum 'Superior'. Sequence analysis showed that POTH1 is a member of the class I knox (knotted-like homeobox) gene family and of the TALE (three amino acid loop extension) superclass of homeobox genes. To examine the affect of POTH1 on both tuber and whole plant development, transgenic potato plants that constitutively overexpress POTH1 were produced. Overexpression of POTH1 resulted in plants with altered leaf morphologies including small, wrinkled, or curved leaves with shortened petioles. These transgenic plants have traits similar to gibberellin (GA)- deficient mutants. POTH1 -overexpressing plants were reduced in size due to a decrease in internode length and produced tubers in vitro under noninducing conditions. Treatment with a bioactive GA caused an increase in plant height. In addition, northern analysis revealed that the RNA accumulation of GA20-oxidase1, an enzyme involved in the biosynthesis of GA, was reduced in transgenic plants. Our results indicate that POTH1 may act as a negative regulator in the signaling pathway of GA biosynthesis in potato.