title: The impact of elevated CO2on growth and photosynthesis in Agrostis canina L. ssp. monteluccii adapted to contrasting atmospheric CO2concentrations.
abstract: The aim of this study was to characterise growth and photosynthetic capacity in plants adapted to long-term contrasting atmospheric CO2concentrations (Ca). Seeds of Agrostis canina L. ssp. monteluccii were collected from a natural CO2transect in central-western Italy and plants grown in controlled environment chambers at both ambient and elevated CO2(350 and 700 μmol mol-1) in nutrient-rich soil. Seasonal mean Caat the source of the plant material ranged from 610 to 451 μmol CO2mol-1, derived from C4leaf stable carbon isotope discrimination (δ13C). Under chamber conditions, CO2enrichment stimulated the growth of all populations. However, plants originating from elevated Caexhibited higher initial relative growth rates (RGRs) irrespective of chamber CO2concentrations and a positive relationship was found between RGR and Caat the seed source. Seed weight was positively correlated with Ca, but differences in seed weight were found to explain no more than 34% of the variation in RGRs at elevated CO2. Longer-term experiments (over 98 days) on two populations originating from the extremes of the transect (451 and 610 μmol CO2mol-1) indicated that differences in growth between populations were maintained when plants were grown at both 350 and 700 μmol CO2mol-1. Analysis of leaf material revealed an increase in the cell wall fraction (CWF) in plants grown at elevated CO2, with plants originating from high Caexhibiting constitutively lower levels but a variable response in terms of the degree of lignification. In vivo gas exchange measurements revealed no significant differences in light and CO2saturated rates of photosynthesis and carboxylation efficiency between populations or with CO2treatment. Moreover, SDS-PAGE/ LISA quantification of leaf ribulose bisphosphate carboxylase/oxygenase (Rubisco) showed no difference in Rubisco content between populations or CO2treatments. These findings suggest that long-term adaptation to growth at elevated CO2may be associated with a potential for increased growth, but this does not appear to be linked with differences in the intrinsic capacity for photosynthesis.
authors.affiliation: Department of Agricultural and Environmental Science, Ridley Building, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK fax: (0191) 222-5229; E-mail: j.d.barnes@ncl.ac.uk, , , , , , GB.
authors.forename: J D
authors.initials: JD
authors.lastname: Barnes
authors.affiliation: Institute of Agrometeorology and Environmental Analysis, Consiglio Nazionale delle Richerche (IATA-CNR), P. le delle Cascine, 18, 50144 Firenze, Italy, , , , , , IT.
authors.forename: I
authors.initials: I
authors.lastname: Bettarini
authors.affiliation: Institut für Forstbotanik und Baumphysiologie, Albert-Ludwigs Universität Freiburg, Am Flughafen 17, D-79085 Freiburg, Germany, , , , , , DE.
authors.forename: A
authors.initials: A
authors.lastname: Polle
authors.affiliation: Department of Biological and Chemical Sciences, John Taylor Laboratories, Wivenhoe Park, Essex University, UK, , , , , , GB.
authors.forename: N
authors.initials: N
authors.lastname: Slee
authors.affiliation: Department of Biological and Chemical Sciences, John Taylor Laboratories, Wivenhoe Park, Essex University, UK, , , , , , GB.
authors.forename: C
authors.initials: C
authors.lastname: Raines
authors.affiliation: Institute of Agrometeorology and Environmental Analysis, Consiglio Nazionale delle Richerche (IATA-CNR), P. le delle Cascine, 18, 50144 Firenze, Italy, , , , , , IT.
authors.forename: F
authors.initials: F
authors.lastname: Miglietta
authors.affiliation: Institute of Agrometeorology and Environmental Analysis, Consiglio Nazionale delle Richerche (IATA-CNR), P. le delle Cascine, 18, 50144 Firenze, Italy, , , , , , IT.
authors.forename: A
authors.initials: A
authors.lastname: Raschi
authors.affiliation: Department of Agricultural and Environmental Science, Ridley Building, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK fax: (0191) 222-5229; E-mail: j.d.barnes@ncl.ac.uk, , , , , , GB.
authors.forename: M
authors.initials: M
authors.lastname: Fordham
keywords: CO2 vents; Key words Agrostis canina; growth; lignification; photosynthesis