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  1. Vol. 52 No. 3, p. 1270-1280
     
    Received: Aug 5, 2011
    Published: May, 2012


    * Corresponding author(s): david@uckac.edu
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doi:10.2135/cropsci2011.08.0413

Sensitivity of Gas Exchange Parameters to Ozone in Diverse C4 Sugarcane Hybrids

  1. D. A. Grantz *a,
  2. H.-B. Vua,
  3. T. L. Tewb and
  4. J. C. Veremisbc
  1. a Dep. of Botany and Plant Sciences, Univ. of California, Riverside, CA, 92521 and Kearney Agric. Center, 9240 S. Riverbend Ave., Parlier, CA 93648
    b USDA-ARS, Sugarcane Research Lab., 5883 USDA Rd., Houma, LA 70360
    c present address, USDA-APHIS-PPQ, 4700 River Rd., Riverdale, MD 20737

Abstract

In early studies, C4 species exhibited greater tolerance to O3 than C3 species. But a C4 Saccharum spp. hybrid (sugarcane, cv. Elephant Cane) exhibited high sensitivity to O3. To investigate whether Saccharum is uniquely sensitive to O3 we exposed a morphologically diverse set of congeners to a range of O3. Here we test the null hypothesis that these diverse genotypes do not differ in baseline responses of carbon assimilation to intercellular CO2 or in the sensitivity of these responses to elevated O3 (4, 58, and 114 nmol mol−1, 12 h means). Elephant Cane was most sensitive but all exhibited declines in net carbon assimilation (An) and in capacities of phosphoenolpyruvate carboxylase (PEPCase) and rubisco. Phosphoenolpyruvate carboxylase was more sensitive than rubisco. The clones were distinguished by morphological traits and by estimated fraction of Saccharum spontaneum L. in their lineages. Baseline values of photosynthetic parameters were not consistently related to pedigree while morphology and sensitivity to O3 exhibited strong relationships. These results are not consistent with a generalized resistance of C4 plants to O3. This single C4 genus exhibited a wide range of sensitivities. The results suggest that sufficient variation may exist among Saccharum genotypes to allow selection for resistance to O3 and that introgression of S. spontaneum germplasm may confer resistance to O3 along with resistance to other abiotic stresses. Reduced sensitivity to O3 in dedicated biofuel feedstocks may facilitate development of production systems in novel production areas.

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Copyright © 2012. Copyright © by the Crop Science Society of America, Inc.