Improved Growth and Stress Tolerance in the Arabidopsis oxtl Mutant Triggered by Altered Adenine Metabolism  

作　　者：Suchada Sukrong Kil-Young Yun Patrizia Stadler Charan Kumar Tony Facciuolo Barbara A.Moffatt Deane L.Falconec 

机构地区：[1]Department of Plant and Soil Science,University of Kentucky,Lexington,KY 40546,USA [2]Present address:Department of Pharmacognosy,Faculty of Pharmaceutical Sciences,Chulalongkorn University,Bangkok,Thailand [3]Department of Biological Sciences,University of Massachusetts,One University Avenue,Lowell,MA 01854,USA [4]Present address:Fungi and Plant Co.Ltd,Chungcheongbuk-do,Republic of Korea [5]Department of Biology,University of Waterloo,Waterloo,Ontario,Canada

出　　处：《Molecular Plant》2012年第6期1310-1332,共23页分子植物（英文版）

摘　　要：Plants perceive and respond to environmental stresses with complex mechanisms that are often associ- ated with the activation of antioxidant defenses. A genetic screen aimed at isolating oxidative stress-tolerant lines of Arabidopsis thaliana has identified oxtl, a line that exhibits improved tolerance to oxidative stress and elevated temperature but displays no apparent deleterious growth effects under non-stress conditions. Oxtl harbors a muta- tion 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 oxtl mutation results in decreased APT1 expression that leads to reduced enzymatic activity. Correspondingly, oxtl plants possess elevated levels of adenine. Decreased APT enzyme activity dir- ectly correlates with stress resistance in transgenic lines that ectopically express APT1. The metabolic alteration in oxtl plants also alters the expression of several antioxidant defense genes and the response of these genes to oxidative chal- lenge. 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.Plants perceive and respond to environmental stresses with complex mechanisms that are often associ- ated with the activation of antioxidant defenses. A genetic screen aimed at isolating oxidative stress-tolerant lines of Arabidopsis thaliana has identified oxtl, a line that exhibits improved tolerance to oxidative stress and elevated temperature but displays no apparent deleterious growth effects under non-stress conditions. Oxtl harbors a muta- tion 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 oxtl mutation results in decreased APT1 expression that leads to reduced enzymatic activity. Correspondingly, oxtl plants possess elevated levels of adenine. Decreased APT enzyme activity dir- ectly correlates with stress resistance in transgenic lines that ectopically express APT1. The metabolic alteration in oxtl plants also alters the expression of several antioxidant defense genes and the response of these genes to oxidative chal- lenge. 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.

关 键 词：abiotic/oxidative environmental stress ACCLIMATION PRIMING purine signaling salvage pathway thermotolerance. 

分 类 号：Q554[生物学—生物化学] X703[环境科学与工程—环境工程]