title: Hormonal interactions during cluster-root development in phosphate-deficient white lupin (Lupinus albus L.).
abstract: This study addresses hormonal interactions involved in cluster-root (CR) development of phosphate (Pi)-deficient white lupin (Lupinus albus), which represents the most efficient plant strategy for root-induced mobilisation of sparingly soluble soil phosphorus (P) sources. Shoot-to-root translocation of auxin was unaffected by P-limitation, while strong stimulatory effects of external sucrose on CR formation, even in P-sufficient plants, suggest sucrose, rather than auxins, acts as a shoot-borne signal, triggering the induction of CR primordia. Ethylene may act as mediator of the sucrose signal, as indicated by moderately increased expression of genes involved in ethylene biosynthesis in pre-emergent clusters and by strong inhibitory effects of the ethylene antagonist CoCl2 on CR formation induced by sucrose amendments or P-limitation. As reported in other plants, moderately increased production of brassinosteroids (BRs) and cytokinin, in pre-emergent clusters, may be required for the formation of auxin gradients necessary for induction of CR primordia via interference with auxin biosynthesis and transport. The well-documented inhibition of root elongation by high doses of ethylene may be involved in the growth inhibition of lateral rootlets during CR maturation, indicated by a massive increased expression of gene involved in ethylene production, associated with a declined expression of transcripts with stimulatory effects (BR and auxin-related genes).
authors: Nutritional Crop Physiology (340h), Institute of Crop Science, University of Hohenheim, 70593 Stuttgart, Germany. Electronic address: zrwang717@gmail.com.
authors: Zhengrui
authors: Z
authors: Wang
authors: Nutritional Crop Physiology (340h), Institute of Crop Science, University of Hohenheim, 70593 Stuttgart, Germany.
authors: A B M Moshiur
authors: ABMM
authors: Rahman
authors: Centre for Resources, Environment and Food Security, Department of Plant Nutrition, China Agricultural University, Beijing 100193, PR China.
authors: Guoying
authors: G
authors: Wang
authors: Nutritional Crop Physiology (340h), Institute of Crop Science, University of Hohenheim, 70593 Stuttgart, Germany.
authors: Uwe
authors: U
authors: Ludewig
authors: Centre for Resources, Environment and Food Security, Department of Plant Nutrition, China Agricultural University, Beijing 100193, PR China.
authors: Jianbo
authors: J
authors: Shen
authors: Nutritional Crop Physiology (340h), Institute of Crop Science, University of Hohenheim, 70593 Stuttgart, Germany.
authors: Günter
authors: G
authors: Neumann
mesh_terms: D018506:Gene Expression Regulation, Plant; D031297:Lupinus / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D010758:Phosphorus / Q000172:deficiency / Q000378:metabolism; D010937:Plant Growth Regulators / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D010937:Plant Growth Regulators; D010758:Phosphorus
keywords: Cluster-roots; Hormonal interactions; Phosphate deficiency; White lupin (Lupinus albus L.)