Interactions between light intensity and phosphorus nutrition affect the phosphate-mining capacity of white lupin (Lupinus albus L.).
Light intensity affects photosynthetic carbon (C) fixation and the supply of carbon to roots. To evaluate interactions between carbon supply and phosphorus (P) supply, effects of light intensity on sucrose accumulation, root growth, cluster root formation, carboxylate exudation, and P uptake capacity were studied in white lupin (Lupinus albus L.) grown hydroponically with either 200 µmol m(-2) s(-1) or 600 µmol m(-2) s(-1) light and a sufficient (50 µM P) or deficient (1 µM P) P supply. Plant biomass and root:shoot ratio increased with increasing light intensity, particularly when plants were supplied with sufficient P. Both low P supply and increasing light intensity increased the production of cluster roots and citrate exudation. Transcripts of a phosphoenol pyruvate carboxylase gene (LaPEPC3) in cluster roots (which is related to the exudation of citrate), transcripts of a phosphate transporter gene (LaPT1), and P uptake all increased with increasing light intensity, under both P-sufficient and P-deficient conditions. Across all four experimental treatments, increased cluster root formation and carboxylate exudation were associated with lower P concentration in the shoot and greater sucrose concentration in the roots. It is suggested that C in excess of shoot growth capabilities is translocated to the roots as sucrose, which serves as both a nutritional signal and a C-substrate for carboxylate exudation and cluster root formation.
Department of Plant Nutrition, China Agricultural University, Beijing 100193, P. R. China.
Lingyun
L
Cheng
Department of Plant Nutrition, China Agricultural University, Beijing 100193, P. R. China.
Xiaoyan
X
Tang
Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108, USA.
Carroll P
CP
Vance
Ecological Sciences Group, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom.
Philip J
PJ
White
Department of Plant Nutrition, China Agricultural University, Beijing 100193, P. R. China.
Fusuo
F
Zhang
Department of Plant Nutrition, China Agricultural University, Beijing 100193, P. R. China. jbshen@cau.edu.cn.
Jianbo
J
Shen
D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D031297:Lupinus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D010788:Photosynthesis; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013395:Sucrose / Q000378:metabolism
D027321:Anion Transport Proteins; D010940:Plant Proteins; D010758:Phosphorus; D013395:Sucrose; D010730:Phosphoenolpyruvate Carboxylase
Photosynthesis; citrate exudation; cluster roots; phosphorus deficiency; sucrose; white lupin.