title: Can the exceptional chilling tolerance of C4 photosynthesis found in Miscanthus × giganteus be exceeded? Screening of a novel Miscanthus Japanese germplasm collection.
abstract: OBJECTIVE
  A clone of the hybrid perennial C4 grass Miscanthus × giganteus (Mxg) is known for achieving exceptionally high rates of leaf CO2 uptake during chilling. This is a requisite of success in the early spring, as is the ability of the leaves to survive occasional frosts. The aim of this study was to search for genotypes with greater potential than Mxg for photosynthesis and frost survival under these conditions.
  
  
  METHODS
  A total of 864 accessions representing 164 local populations of M. sacchariflorus (Msa), M. sinensis (Msi) and M. tinctorius (Mti) collected across Japan were studied. Accessions whose leaves survived a natural late frost in the field were screened for high maximum photosystem II efficiency (Fv/Fm) following chilling weather, as an indicator of their capacity for light-limited photosynthesis. Those showing the highest Fv/Fm were transferred to a high-light-controlled environment and maintained at chilling temperatures, where they were further screened for their capacities for high-light-limited and light-saturated leaf uptake of CO2 (ΦCO2,max and Asat, respectively).
  
  
  RESULTS
  For the first time, relatives of Mxg with significantly superior capacities for photosynthesis at chilling temperatures were identified. Msa accession '73/2' developed leaves in the spring that survived night-time frost, and during growth under chilling maintained a statistically significant 79 % higher ΦCO2,max, as a measure of light-limited photosynthesis, and a 70 % higher Asat, as a measure of light-saturated photosynthesis. A second Msa accession, '73/3' also showed significantly higher rates of leaf uptake of CO2.
  
  
  CONCLUSIONS
  As remarkable as Mxg has proved in its chilling tolerance of C4 photosynthesis, this study shows that there is still value and potential in searching for yet more superior tolerance. Msa accession '73/2' shows rates of light-limited and light-saturated photosynthesis at chilling temperatures that are comparable with those of the most cold-tolerant C3 species. This adds further proof to the thesis that C4 photosynthesis is not inherently limited to warm climates.
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
authors: Katarzyna
authors: K
authors: Głowacka
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
authors: Uffe
authors: U
authors: Jørgensen
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
authors: Jens B
authors: JB
authors: Kjeldsen
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
authors: Kirsten
authors: K
authors: Kørup
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
authors: Idan
authors: I
authors: Spitz
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
authors: Erik J
authors: EJ
authors: Sacks
authors: University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA University of Illinois, Institute of Genomic Biology, 1206 W. Gregory Dr. 138 IGB, Urbana IL 61801, USA, Institute of Plant Genetics, Polish Academy of Sciences, ul. Strzeszyńska 34, 60-479 Poznań, Poland, Department of Agroecology, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark and Department of Plant Biology, University of Illinois, 1201 W. Gregory Dr., Urbana, IL 61801, USA slong@illinois.edu.
authors: Stephen P
authors: SP
authors: Long
mesh_terms: D000222:Adaptation, Physiological; D000388:Air; D002245:Carbon Dioxide / Q000378:metabolism; D003433:Crosses, Genetic; D060146:Ecotype; D005615:Freezing; D007564:Japan; D017785:Photons; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000502:physiology; D006109:Poaceae / Q000502:physiology*; D000068098:Seed Bank; D012987:Soil; D013696:Temperature
chemical_list: D045332:Photosystem II Protein Complex; D012987:Soil; D002245:Carbon Dioxide
keywords: Bioenergy crops; C4 photosynthesis; Miscanthus sacchariflorus; Miscanthus sinensis; Miscanthus tinctorius; Miscanthus × giganteus; chilling tolerance; light-limited photosynthesis; light-saturated photosynthesis.