title: Improved growth and stress tolerance in the Arabidopsis oxt1 mutant triggered by altered adenine metabolism.
abstract: Plants perceive and respond to environmental stresses with complex mechanisms that are often associated with the activation of antioxidant defenses. A genetic screen aimed at isolating oxidative stress-tolerant lines of Arabidopsis thaliana has identified oxt1, a line that exhibits improved tolerance to oxidative stress and elevated temperature but displays no apparent deleterious growth effects under non-stress conditions. Oxt1 harbors a mutation that arises from the altered expression of a gene encoding adenine phosphoribosyltransferase (APT1), an enzyme that converts adenine to adenosine monophosphate (AMP), indicating a link between purine metabolism, whole-plant growth responses, and stress acclimation. The oxt1 mutation results in decreased APT1 expression that leads to reduced enzymatic activity. Correspondingly, oxt1 plants possess elevated levels of adenine. Decreased APT enzyme activity directly correlates with stress resistance in transgenic lines that ectopically express APT1. The metabolic alteration in oxt1 plants also alters the expression of several antioxidant defense genes and the response of these genes to oxidative challenge. Finally, it is shown that manipulation of adenine levels can induce stress tolerance to wild-type plants. Collectively, these results show that alterations in cellular adenine levels can trigger stress tolerance and improve growth, leading to increases in plant biomass. The results also suggest that adenine might play a part in the signals that modulate responses to abiotic stress and plant growth.
authors.affiliation: Department of Plant and Soil Science, University of Kentucky Lexington, KY 40546, USA.
authors.forename: Suchada
authors.initials: S
authors.lastname: Sukrong
authors.forename: Kil-Young
authors.initials: KY
authors.lastname: Yun
authors.forename: Patrizia
authors.initials: P
authors.lastname: Stadler
authors.forename: Charan
authors.initials: C
authors.lastname: Kumar
authors.forename: Tony
authors.initials: T
authors.lastname: Facciuolo
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Moffatt
authors.forename: Deane L
authors.initials: DL
authors.lastname: Falcone
mesh_terms: D000225:Adenine / Q000378:metabolism* / Q000494:pharmacology; D000228:Adenine Phosphoribosyltransferase / Q000235:genetics; D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000235:genetics; D018533:Biomass; D002374:Catalase / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D010641:Phenotype; D013696:Temperature
chemical_list: D000975:Antioxidants; D060387:Ascorbate Peroxidases; D002374:Catalase; D000228:Adenine Phosphoribosyltransferase; D000225:Adenine