Abstract
Previous research has demonstrated that AtPHR1 plays a central role in phosphate (Pi)-starvation signaling in Arabidopsis thaliana. In this work, two OsPHR genes from rice (Oryza sativa) were isolated and designated as OsPHR1 and OsPHR2 based on amino acid sequence homology to AtPHR1. Their functions in Pi signaling in rice were investigated using transgenic plants. Our results showed that both OsPHR1 and OsPHR2 are involved in Pi-starvation signaling pathway by regulation of the expression of Pi-starvation-induced genes, whereas only OsPHR2 overexpression results in the excessive accumulation of Pi in shoots under Pi-sufficient conditions. Under Pi-sufficient conditions, overexpression of OsPHR2 mimics Pi-starvation stress in rice with enhanced root elongation and proliferated root hair growth, suggesting the involvement of OsPHR2 in Pi-dependent root architecture alteration by both systematic and local pathways. In OsPHR2-overexpression plants, some Pi transporters were up-regulated under Pi-sufficient conditions, which correlates with the strongly increased content of Pi. The mechanism behind the OsPHR2 regulated Pi accumulation will provide useful approaches to develop smart plants with high Pi efficiency.
Highlights
Previous research has demonstrated that AtPHR1 plays a central role in phosphate (Pi)-starvation signaling in Arabidopsis thaliana
The full-length complementary DNAs of the two genes were obtained from rice (‘Nipponbare’), followed by PCR amplification using primers predicted from the cDNA sequences
High expression of OsPHR2 leads to increased Pi accumulation in shoot under Pi-sufficient conditions and is in accordance with recent studies in Arabidopsis by overexpression of AtPHR1 in wild type and in the phr1 mutant
Summary
Previous research has demonstrated that AtPHR1 plays a central role in phosphate (Pi)-starvation signaling in Arabidopsis thaliana. Two OsPHR genes from rice (Oryza sativa) were isolated and designated as OsPHR1 and OsPHR2 based on amino acid sequence homology to AtPHR1. Their functions in Pi signaling in rice were investigated using transgenic plants. Our results showed that both OsPHR1 and OsPHR2 are involved in Pi-starvation signaling pathway by regulation of the expression of Pi-starvation-induced genes, whereas only OsPHR2 overexpression results in the excessive accumulation of Pi in shoots under Pi-sufficient conditions. Function loss of AtSIZ1 causes Arabidopsis to exhibit exaggerated prototypical Pi-starvation responses, including cessation of primary root growth, extensive lateral root and root hair development, increased root-shoot mass ratio, and greater anthocyanin accumulation. Our results indicate that both OsPHR1 and OsPHR2 are involved in the Pisignaling pathway, whereas only the overexpression of OsPHR2 results in Pi accumulation in shoots of rice
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