title: Plant growth regulators enhance gold uptake in Brassica juncea.
abstract: The use of plant growth regulators is well established and they are used in many fields of plant science for enhancing growth. Brassica juncea plants were treated with 2.5, 5.0 and 7.5 microM auxin indole-3-butyric acid (IBA), which promotes rooting. The IBA-treated plants were also sprayed with 100 microM gibberellic acid (GA3) and kinetin (Kin) to increase leaf-foliage. Gold (I) chloride (AuCl) was added to the growth medium of plants to achieve required gold concentration. The solubilizing agent ammonium thiocyanate (1 g kg(-1)) (commonly used in mining industries to solubilize gold) was added to the nutrient solution after six weeks of growth and, two weeks later, plants were harvested. Plant growth regulators improved shoot and root dry biomass of B. juncea plants. Inductively Coupled Plasma Optical Emission Spectrometry analysis showed the highest Au uptake for plants treated with 5.0 microM IBA. The average recovery of Au with this treatment was significantly greater than the control treatment by 45.8 mg kg(-1) (155.7%). The other IBA concentrations (2.5 and 7.5 microM) also showed a significant increase in Au uptake compared to the control plants by 14.7 mg kg(-1) (50%) and 42.5 mg kg(-1) (144.5%) respectively. A similar trend of Au accumulation was recorded in the roots of B. juncea plants. This study conducted in solution culture suggests that plant growth regulators can play a significant role in improving phytoextraction of Au.
authors.affiliation: Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Scottsville, South Africa.
authors.forename: Manoj G
authors.initials: MG
authors.lastname: Kulkarni
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Stirk
authors.forename: Colin
authors.initials: C
authors.lastname: Southway
authors.forename: Heino B
authors.initials: HB
authors.lastname: Papenfus
authors.forename: Pierre A
authors.initials: PA
authors.lastname: Swart
authors.forename: Alexander
authors.initials: A
authors.lastname: Lux
authors.forename: Marek
authors.initials: M
authors.lastname: Vaculík
authors.forename: Michal
authors.initials: M
authors.lastname: Martinka
authors.forename: Johannes
authors.initials: J
authors.lastname: Van Staden
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D004305:Dose-Response Relationship, Drug; D006046:Gold / Q000032:analysis / Q000378:metabolism*; D018527:Hydroponics; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009149:Mustard Plant / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D006046:Gold