Characterization of a sub-family of Arabidopsis genes with the SPX domain reveals their diverse functions in plant tolerance to phosphorus starvation

• Published in: The Plant journal : for cell and molecular biology Vol. 54; no. 6; pp. 965 - 975
• Main Authors: Duan, Ke, Yi, Keke, Dang, Lei, Huang, Hongjie, Wu, Wei, Wu, Ping
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.06.2008; Blackwell Publishing Ltd; Blackwell Science
• Subjects: Adaptation to environment and cultivation conditions; Agronomy. Soil science and plant productions; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Botany; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Plant; gene function; Genetics; Genetics and breeding of economic plants; Multigene Family; Mutagenesis, Insertional; Mutation; phosphate starvation; Phosphates - metabolism; Phosphorus; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; RNA Interference; RNA, Plant - genetics; Signal Transduction; SPX domain gene; Transcription, Genetic; Varietal selection. Specialized plant breeding, plant breeding aims; Arabidopsis; SPX domain gene; Tolerance; gene function; Gene expression; phosphate starvation; Gene; Cruciferae; Dicotyledones; Angiospermae; Spermatophyta; Mutation; Adaptation
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2008.03460.x

Four genes of Arabidopsis ( At5g20150, At2g26660, At2g45130 and At5g15330) encoding no conservative region other than an SPX domain (SYG1, Pho81 and XPR1) were named AtSPX1-AtSPX4. The various subcellular localizations of their GFP fusion proteins implied function variations for the four genes. Phosphate starvation strongly induced expression of AtSPX1 and AtSPX3 with distinct dynamic patterns, while AtSPX2 was weakly induced and AtSPX4 was suppressed. Expression of the four AtSPX genes was reduced to different extents in the Arabidopsis phr1 and siz1 mutants under phosphate starvation, indicating that they are part of the phosphate-signaling network that involves SIZ1/PHR1. Over-expression of AtSPX1 increased the transcript levels of ACP5, RNS1 and PAP2 under both phosphate-sufficient and phosphate-deficient conditions, suggesting a potential transcriptional regulation role of AtSPX1 in response to phosphate starvation. Partial repression of AtSPX3 by RNA interference led to aggravated phosphate-deficiency symptoms, altered P allocation and enhanced expression of a subset od phosphate-responsive genes including AtSPX1. Our results indicate that both AtSPX1 and AtSPX3 play positive roles in plant adaptation to phosphate starvation, and AtSPX3 may have a negative feedback regulatory role in AtSPX1 response to phosphate starvation.