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Title: Real-time RT-PCR profiling of transcription factors including 34 MYBs and signaling components in white lupin reveals their P status dependent and organ-specific expression

item YAMAGISHI, MASUMI - Hokkaido University
item ZHOU, KEQIN - Hokkaido University
item OSAKI, MITSURU - Hokkaido University
item Miller, Susan - Sue
item Vance, Carroll

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2010
Publication Date: 1/12/2011
Citation: Yamagishi, M., Zhou, K., Osaki, M., Miller, S.S., Vance, C.P. 2011. Real-time RT-PCR profiling of transcription factors including 34 MYBs and signaling components in white lupin reveals their P status dependent and organ-specific expression. Plant and Soil Journal. 342(1-2):481-493.

Interpretive Summary: Phosphorus is a problem in agriculture. Too much phosphorus fertilizer added to fields results in water pollution. Too little phosphorus results in reduced crop yield and quality. Plant roots explore the soil and are the organs by which plants acquire phosphorus. Because roots occur in soil, they have been difficult to study. White lupin plants have a novel root modification when they are grown in phosphorus-deficient conditions. White lupins form complex root clusters that are very efficient in acquiring phosphorus. Little is known about the molecular mechanisms that contribute to white lupin cluster root development. The objective of this study was to characterize a group of genes called MYB transcription factors. MYB transcription factors have been implicated in global regulation of root development. In this report we identify 60 MYB transcription factors from white lupin roots and characterize their expression. Six of the MYB genes were up-regulated by phosphorus deficiency. They may be good candidates for use in biotechnology approaches to alter root growth and improve phosphorus acquisition. They will also be useful as markers for phosphorus deficiency.

Technical Abstract: Phosphorus (P) is often a limiting macronutrient because of its low availability in soils. White lupin (Lupinus albus L.) plants are well adapted to growth under P-deficient conditions. White lupin acclimation to P-deficiency includes changes in root architecture and enhanced expression of numerous genes including secreted acid phosphatase and phosphate transporters. However, information about transcription factors and signaling proteins that coordinate the P-starvation responses is limited in white lupin. In this study, genes encoding transcription factors and signaling proteins were isolated and their transcription profiles were clarified to facilitate the identification of key signal transduction genes necessary to improve P acquisition, allocation, and use. A total of 60 cDNA fragments including MYB-coiled coil (MYB-CC), R2R3-MYB, and signaling protein genes were isolated. Four MYB-CC genes showed high homology with Phosphate starvation response 1 in Arabidopsis which has been implicated in regulation of many P-starvation response genes. In addition, 29 R2R3-MYB genes were assorted to 11 subgroups and 4 independent genes. Transcription of the 60 genes, as measured by real-time reverse transcription-PCR, in normal roots, cluster roots, leaves, and shoot tips under P-deficient and P-sufficient conditions revealed that six (10%) and two (3.3%) genes were either induced or suppressed, respectively, by P starvation. It is noteworthy that 24 genes (40%) were organ specific.