Journal Article

Assessing the genetic relatedness of higher ozone sensitivity of modern wheat to its wild and cultivated progenitors/relatives

D. K. Biswas, H. Xu, Y. G. Li, M. Z. Liu, Y. H. Chen, J. Z. Sun and G. M. Jiang

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 4, pages 951-963
Published in print March 2008 | ISSN: 0022-0957
Published online February 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ern022

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Modern wheat (Triticum aestivum L.) is one of the most ozone (O3)-sensitive crops. However, little is known about its genetic background of O3 sensitivity, which is fundamental for breeding O3-resistant cultivars. Wild and cultivated species of winter wheat including donors of the A, B and D genomes of T. aestivum were exposed to 100 ppb O3 or charcoal-filtered air in open top chambers for 21 d. Responses to O3 were assessed by visible O3 injury, gas exchange, chlorophyll fluorescence, relative growth rate, and biomass accumulation. Ozone significantly decreased light-saturated net photosynthetic rate (−37%) and instantaneous transpiration efficiency (−42%), but increased stomatal conductance (+11%) and intercellular CO2 concentration (+11%). Elevated O3 depressed ground fluorescence (−8%), maximum fluorescence (−26%), variable fluorescence (−31%), and maximum photochemical efficiency (−7%). Ozone also decreased 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 interspecies variation in the impacts of elevated O3 on photosynthesis and growth. Primitive cultivated wheat demonstrated the highest relative O3 tolerance followed by modern wheat and wild wheat showed the lowest. Among the genome donors of modern wheat, Aegilops tauschii (DD) behaved as the most O3-sensitive followed by T. monococcum (AA) and Triticum turgidum ssp. durum (AABB) appeared to be the most O3-tolerant. It was concluded that the higher O3 sensitivity of modern wheat was attributed to the increased O3 sensitivity of Aegilops tauschii (DD), but not to Triticum turgidum ssp. durum (AABB) during speciation.

Keywords: Biomass; Chl a fluorescence; genome; ozone sensitivity; relative growth rate; stomatal conductance; winter wheat

Journal Article.  7039 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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