Root tip-dependent, active riboflavin secretion by Hyoscyamus albus hairy roots under iron deficiency

• Published in: Plant physiology and biochemistry 2008-04, Vol.46 (4), p.452-460
• Main Authors: Higa, Ataru, Miyamoto, Erika, Rahman, Laiq ur, Kitamura, Yoshie
• Format: Article
• Language: English
• Subjects: Agrobacterium rhizogenes; Agronomy. Soil science and plant productions; Biological and medical sciences; Citric acid; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Hairy roots; Hydrogen-Ion Concentration; Hyoscyamus; Hyoscyamus - metabolism; Hyoscyamus albus; Iron - deficiency; Malic acid; Plant Roots - metabolism; Plant Roots - microbiology; Proton-pump inhibitor; Rhizobium - growth & development; Riboflavin; Riboflavin - secretion; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...)
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2008.01.004

Hyoscyamus albus hairy roots with/without an exogenous gene (11 clones) were established by inoculation of Agrobacterium rhizogenes. All clones cultured under iron-deficient condition secreted riboflavin from the root tips into the culture medium and the productivity depended on the number and size of root tips among the clones. A decline of pH was observed before riboflavin production and root development. By studying effects of proton-pump inhibitors, medium acidification with external organic acid, and riboflavin addition upon pH change and riboflavin productivity, we indicate that riboflavin efflux is not directly connected to active pH reduction, and more significantly active riboflavin secretion occurs as a response to an internal requirement in H. albus hairy roots under iron deficiency.