Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2009
Publication Date: 4/28/2009
Publication URL: http://hdl.handle.net/10113/46895
Citation: Zinn, K.E., Liu, J., Allan, D.L., Vance, C.P. 2009. White Lupin (Lupinus albus) Response to Phosphorus Stress: Evidence for Complex Regulation of LaSAP1. Plant and Soil Journal. Available: http://www.springerlink.com/content/d323708676454538/. Interpretive Summary: The element phosphorus (P) is required for crop growth and development. In developed countries, P fertilizer is used extensively and is a primary contributor to water pollution. By comparison, in developing countries P fertilizer is frequently not available due to cost and lack of transport vehicles. Improving crop use and acquisition of soil P would help decrease fertilizer use in the U.S. and improve farmers' profit margins. The objective of this study was to identify genetic elements which control the expression of crop genes involved in acquiring and using P. We isolated, characterized, and defined a region of DNA that is crucial to controlling the expression of a gene from lupin that is important in adapting to P-deficiency stress. We showed that a piece of DNA less than 100 nucleotides long was required for expression of the gene during P-stress. Identification of this 100 nucleotide region will be useful in mapping genes involved in crop P-stress. The results will also be useful in developing plants with improved P-use efficiency.
Technical Abstract: White lupin (Lupinus albus) has a unique adaptation to phosphorus deficiency stress, such that a set of tightly coordinated physiological and morphological responses gives rise to the formation of cluster, or proteoid roots, structures that allow the plant to live in extremely infertile soils. The cascade of events that signals P-deficiency induced gene expression in proteoid roots remains unknown. Through promoter::GUS analysis we showed that expression of acid phosphatase (LaSAP1) in P-deficient proteoid roots depends on DNA located from -465 to -345 bp 5' of the ATG start codon and that the P1BS (PHR1 Binding Site) element, located at -160 bp, also contributes regulatory control. Electrophoretic mobility shift assays showed that DNA located within the -414 to -250 bp region of the LaSAP1 promoter was bound by nuclear proteins isolated from P-sufficient normal roots but not by nuclear proteins isolated from P-deficient proteoid roots, suggesting negative regulation. A LaSAP1 promoter motif characterized through EMSA oligonucleotide competition experiments was used as "bait" in a yeast one-hybrid (Y1H) experiment and 31 putative DNA binding proteins were isolated.