The cloning and characterization of a poplar stomatal density gene

Abstract

EPIDERMAL PATTERNING FACTOR1 (EPF1) is a well characterized negative regulator of cell division in Arabidopsis thaliana (AtEPF1) where the pri- mary region of localization is the leaf. However, little data have been reported on the role of EPF1 in other plant species. In this study, the EPF1 gene from Arabidopsis and the newly identified poplar ortholog from Populus tricho- carpa (PtaEPF1) were overexpressed in a hybrid poplar genotype. We attempted to identify the physiological role of PtaEPF1. Gene overexpression experiments were per- formed to determine if and how stomatal density (SD) numbers were affected. The poplar 717-1B4 (P. tremula 9 P. alba) genotype was used in the study. Results presented here suggest that overexpression of PtaEPF1 and AtEPF1 in poplar led to significantly altered SD and also affected transgenic water stress tolerance. Overexpression of AtEPF1 in 717-1B4 led to the most dramatic decrease in SD while overexpression of PtaEPF1 in 717-1B4 signifi- cantly increased SD in several transgenic lines, an indica- tion that EPF1 may have additional functions in poplar. Also, abnormalities in leaf morphology were discovered that indicated overexpression of AtEPF1 or PtaEPF1 in poplar triggered aberrant phenotypes not seen in other published Arabidopsis studies, an indication of additional pathway involvement.