Overexpression of a Maize Transcription Factor ZmPHR1 Improves Shoot Inorganic Phosphate Content and Growth of Arabidopsis under Low-Phosphate Conditions
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Maize (Zea mays L.) yield is limited by the poor availability of inorganic phosphate (Pi) in many arable areas worldwide. Phosphorus use efficiency (PUE) is a complex multigene trait, with a single gene contributing only a small percentage to the phenotype. Transcription factors (TFs) are very important as a single TF frequently coordinates the expression of multiple genes in response to environmental signals. Previous studies have indicated that the TFs AtPHR1 and OsPHR2 play important roles in the regulation of plant phosphorus accumulation. However, little is known about the functions of PHR-like genes in maize. In this study, a member of the MYB-CC family encoding a 449-amino acid protein, ZmPHR1, was isolated. The ZmPHR1∷GFP fusion was localized in the nucleus, which indicates that ZmPHR1 is also a TF. Phylogenetic tree analysis revealed that ZmPHR1 belongs to the same subfamily of MYB-CCs as OsPHR1, OsPHR2 and AtPHR1. Transgenic Arabidopsis lines overexpressing ZmPHR1 were used to investigate the pleiotropic effects of this gene under low Pi conditions. Overexpression of ZmPHR1 led to the upregulation of multiple genes that regulate metabolism during Pi-starvation, which in turn resulted in an elevation in Pi content in shoots. Most notably, Arabidopsis overexpressing ZmPHR1 showed better growth under low-Pi conditions. The results presented in this study suggest that PUE could be improved through the manipulation of the TF ZmPHR1 in maize and possibly in other species under Pi-deficient conditions.
KeywordsMaize Transcription factor ZmPHR1 Phosphorus use efficiency Arabidopsis thaliana
We thank Dr. Yiping Tong, Dr. Yu Cheng, Dr. Hui Liang and Mrs. Yuxiang Wen from the Institute of Genetics and Developmental Biology, Chinese Academy of Science for their helpful suggestions and observation of GFP with the Laser Confocal Scanning Microscope. The authors are grateful to Dr. Hongjie Li from the Institute of Crop Science, Chinese Academy of Agriculture Science, and Dr. Ling Yuan from the Department of Plant and Soil Sciences, University of Kentucky for their critical reviews of this manuscript. The research was supported by the grants of Major Transgenic Organism Breeding Projects from Chinese Ministry of Agriculture (2009ZX08003-017B and 2011ZX08003-001) and Shanxi International Cooperation Project (2012081005-1).
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