Yue Cao, Hao Ai, Ajay Jain, Xueneng Wu, Liang Zhang, Wenxia Pei, Aiqun Chen, Guohua Xu and Shubin Sun

BMC Plant Biology; 3 October 2016; 16:210 DOI: 10.1186/s12870-016-0853-x

Abstract

Background

Phosphorus (P), an essential macronutrient, is often limiting in soils and affects plant growth and development. In Arabidopsis thaliana, Low Phosphate Root1 (LPR1) and its close paralog LPR2 encode multicopper oxidases (MCOs). They regulate meristem responses of root system to phosphate (Pi) deficiency. However, the roles of LPR gene family in rice (Oryza sativa) in maintaining Pi homeostasis have not been elucidated as yet.

Results

Here, the identification and expression analysis for the homologs of LPR1/2 in rice were carried out. Five homologs, hereafter referred to as OsLPR1-5, were identified in rice, which are distributed on chromosome1 over a range of 65 kb. Phylogenetic analysis grouped OsLPR1/3/4/5 and OsLPR2 into two distinct sub-clades with OsLPR3 and 5 showing close proximity. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed higher expression levels of OsLPR3-5 and OsLPR2 in root and shoot, respectively. Deficiencies of different nutrients ie, P, nitrogen (N), potassium (K), magnesium (Mg) and iron (Fe) exerted differential and partially overlapping effects on the relative expression levels of the members of OsLPR family. Pi deficiency (−P) triggered significant increases in the relative expression levels of OsLPR3 and 5. Strong induction in the relative expression levels of OsLPR3 and 5 in osphr2 suggested their negative transcriptional regulation by OsPHR2. Further, the expression levels of OsLPR3 and 5 were either attenuated in ossiz1 and ospho2 or augmented in rice overexpressing OsSPX1.

Conclusions

The results from this study provided insights into the evolutionary expansion and a likely functional divergence of OsLPR family with potential roles of OsLPR3 and 5 in the maintenance of Pi homeostasis in rice.

See: http://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-016-0853-x

Fig. 1

Comparative identity matrices and gene structures of LPR genes in Arabidopsis and rice. a DNAMAN 7.0 program was used for multi-sequence alignments of nucleotides and amino acids for determining per cent identity matrices across them. b Schematic representation of genes showing UTR (empty boxes), CDS (black boxes) and introns (black lines) with numbers indicating length of each of them.