Assessing the genetic relatedness of higher ozone sensitivity of modern wheat to its wild and cultivated progenitors/relatives |
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| Authors: | Biswas D K Xu H Li Y G Liu M Z Chen Y H Sun J Z Jiang G M |
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| Affiliation: | State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, 20 Nanxincun, 100093 Beijing, PR China. |
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| Abstract: | Modern wheat (Triticum aestivum L.) is one of the most ozone(O3)-sensitive crops. However, little is known about its geneticbackground of O3 sensitivity, which is fundamental for breedingO3-resistant cultivars. Wild and cultivated species of winterwheat including donors of the A, B and D genomes of T. aestivumwere exposed to 100 ppb O3 or charcoal-filtered air in opentop chambers for 21 d. Responses to O3 were assessed by visibleO3 injury, gas exchange, chlorophyll fluorescence, relativegrowth rate, and biomass accumulation. Ozone significantly decreasedlight-saturated net photosynthetic rate (–37%) and instantaneoustranspiration efficiency (–42%), but increased stomatalconductance (+11%) and intercellular CO2 concentration (+11%).Elevated O3 depressed ground fluorescence (–8%), maximumfluorescence (–26%), variable fluorescence (–31%),and maximum photochemical efficiency (–7%). Ozone alsodecreased relative growth rate and the allometric coefficient,which finally reduced total biomass accumulation (–54%),but to a greater extent in roots (–77%) than in the shoot(–44%). Winter wheat exhibited significant interspeciesvariation in the impacts of elevated O3 on photosynthesis andgrowth. Primitive cultivated wheat demonstrated the highestrelative O3 tolerance followed by modern wheat and wild wheatshowed the lowest. Among the genome donors of modern wheat,Aegilops tauschii (DD) behaved as the most O3-sensitive followedby T. monococcum (AA) and Triticum turgidum ssp. durum (AABB)appeared to be the most O3-tolerant. It was concluded that thehigher O3 sensitivity of modern wheat was attributed to theincreased O3 sensitivity of Aegilops tauschii (DD), but notto Triticum turgidum ssp. durum (AABB) during speciation. Key words: Biomass, Chl a fluorescence, genome, ozone sensitivity, relative growth rate, stomatal conductance, winter wheatReceived 20 September 2007; Revised 30 November 2007 Accepted 16 January 2008 |
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| Keywords: | Biomass Chl a fluorescence genome ozone sensitivity relative growth rate stomatal conductance winter wheat |
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