title: Bacterial citrate synthase expression and soil aluminum tolerance in transgenic alfalfa.
abstract: Alfalfa is very sensitive to soil acidity and its yield and stand duration are compromised due to inhibited root growth and reduced nitrogen fixation caused by Al toxicity. Soil improvement by liming is expensive and only partially effective, and conventional plant breeding for Al tolerance has had limited success. Because tobacco and papaya plants overexpressing Pseudomonas aeruginosa citrate synthase (CS) have been reported to exhibit enhanced tolerance to Al, alfalfa was engineered by introducing the CS gene controlled by the Arabidopsis Act2 constitutive promoter or the tobacco RB7 root-specific promoter. Fifteen transgenic plants were assayed for exclusion of Al from the root tip, for internal citrate content, for growth in in vitro assays, or for shoot and root growth in either hydroponics or in soil assays. Overall, only the soil assays yielded consistent results. Based on the soil assays, two transgenic events were identified that were more aluminum-tolerant than the non-transgenic control, confirming that citrate synthase overexpression can be a useful tool to help achieve aluminum tolerance.
authors.affiliation: Department of Crop and Soil Sciences, University of Georgia, 30602, Athens, GA, USA. pib8@uiuc.edu
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Barone
authors.forename: Daniele
authors.initials: D
authors.lastname: Rosellini
authors.forename: Peter
authors.initials: P
authors.lastname: Lafayette
authors.forename: Joseph
authors.initials: J
authors.lastname: Bouton
authors.forename: Fabio
authors.initials: F
authors.lastname: Veronesi
authors.forename: Wayne
authors.initials: W
authors.lastname: Parrott
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D000535:Aluminum / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015139:Blotting, Southern; D002950:Citrate (si)-Synthase / Q000235:genetics* / Q000378:metabolism; D002951:Citrates / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D000455:Medicago sativa / Q000235:genetics* / Q000502:physiology; D008957:Models, Genetic; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001426:Bacterial Proteins; D002951:Citrates; D000535:Aluminum; D002950:Citrate (si)-Synthase