The cloning and characterization of a poplar stomatal density gene
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EPIDERMAL PATTERNING FACTOR1 (EPF1) is a well characterized negative regulator of cell division in Arabidopsis thaliana (AtEPF1) where the primary 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 trichocarpa (PtaEPF1) were overexpressed in a hybrid poplar genotype. We attempted to identify the physiological role of PtaEPF1. Gene overexpression experiments were performed to determine if and how stomatal density (SD) numbers were affected. The poplar 717-1B4 (P. tremula × 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 significantly increased SD in several transgenic lines, an indication 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.
KeywordsStomatal density Tree physiology Poplar Transgenics
This study was financed by fellowships from the Fred M. van Eck Foundation and the Alliance for Graduate Education and Professoriate (AGEP) at Purdue University. The authors thank Drs. Martin-Michel Gauthier and John Gordon for their comments and critiques of earlier versions of this manuscript. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that also may be suitable.
Conflict of interest
The authors declare no conflict of interest regarding this article.
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